Biophysical and economic limits to negative CO2 emissions

Sustainability

The Paris Climate Agreements and Sustainable Development Goals, signed by 197 countries, present agendas and address key issues for implementing multi-scale responses for sustainable development under climate change—an effort that must involve local, regional, national, and supra-national stakeholders. In that regard, Continental Carbon Sequestration (CoCS) and conservation of carbon sinks are recognized increasingly as having potentially important roles in mitigating climate change and adapting to it. Making that potential a reality will require indicators of success for various stakeholders from multidisciplinary backgrounds, plus promotion of long-term implementation of strategic action towards civil society (e.g., law and policy makers, economists, and farmers). To help meet those challenges, this discussion paper summarizes the state of the art and uncertainties regarding CoCS, taking an interdisciplinary, holistic approach toward understanding these complex issues. The first p...

Food Security

The livestock sector is a major driver of climate change, accounting for 14.5% of anthropogenic greenhouse gas emissions. Population growth and rising prosperity are expected to see global consumption of meat rise by 76% by mid-century, a rate which is associated with significant social and environmental costs. There is therefore a compelling case for public measures to promote dietary shifts towards a more sustainable model, but little action has been taken at the international or national level. This article reports on an international study, with research conducted across the UK, US, China and Brazil, which examines the role the media might play in driving social change in this area. The study focused specifically on the negotiation of new information around meat consumption and climate change and its impacts on existing attitudes and behaviours. Findings indicate that perceptions and beliefs on climate change are culturally specifictending to reflect national political and social priorities -but are contextualised within individually constructed media environments. Key determining factors include assessments of trust and credibility in regard to scientists and other experts, perceptions of the role of government and questions of individual versus collective responsibility. These shape the parameters within which arguments about the impact of meat consumption upon climate change are received, and these responses interact with cultural and structural barriers and opportunities to shape the likelihood of behaviour change.

Nature Communications

It is generally accepted that animal heartbeat and lifespan are often inversely correlated, however, the relationship between productivity and longevity has not yet been described for trees growing under industrial and pre-industrial climates. Using 1768 annually resolved and absolutely dated ring width measurement series from living and dead conifers that grew in undisturbed, high-elevation sites in the Spanish Pyrenees and the Russian Altai over the past 2000 years, we test the hypothesis of grow fast-die young. We find maximum tree ages are significantly correlated with slow juvenile growth rates. We conclude, the interdependence between higher stem productivity, faster tree turnover, and shorter carbon residence time, reduces the capacity of forest ecosystems to store carbon under a climate warming-induced stimulation of tree growth at policy-relevant timescales.

Nature Climate Change, 2016

The recent negotiations on climate change in Paris have left partly open the discussion on a long-term global goal, in the form of an upper limit to warming. Agreement on such a limit is a political decision that need to be informed by scientific knowledge through a mapping that systematically explores the consequences of different policy choices. Such a multidisciplinary effort, based on the analysis of a set of scenarios, helped structure the IPCC AR5 Synthesis Report. This Perspective summarizes this approach and its results, reviews its strengths and limitations, and discusses how decision-makers can use these results in practice. It also identifies research needs to facilitate integrated analysis of the climate change problem and to help better inform policy-makers and the public.

Frontiers in Marine Science

The Paris Agreement target of limiting global surface warming to 1.5-2 • C compared to pre-industrial levels by 2100 will still heavily impact the ocean. While ambitious mitigation and adaptation are both needed, the ocean provides major opportunities for action to reduce climate change globally and its impacts on vital ecosystems and ecosystem services. A comprehensive and systematic assessment of 13 global-and local-scale, ocean-based measures was performed to help steer the development and implementation of technologies and actions toward a sustainable outcome. We show that (1) all measures have tradeoffs and multiple criteria must be used for a comprehensive assessment of their potential, (2) greatest benefit is derived by combining global and local solutions, some of which could be implemented or scaled-up immediately, (3) some measures are too uncertain to be recommended yet, (4) political consistency must be achieved through effective cross-scale governance mechanisms, (5) scientific effort must focus on effectiveness, co-benefits, disbenefits, and costs of poorly tested as well as new and emerging measures.

Global change biology, 2018

Most climate mitigation scenarios involve negative emissions, especially those that aim to limit global temperature increase to 2°C or less. However, the carbon uptake potential in land-based climate change mitigation efforts is highly uncertain. Here, we address this uncertainty by using two land-based mitigation scenarios from two land-use models (IMAGE and MAgPIE) as input to four dynamic global vegetation models (DGVMs; LPJ-GUESS, ORCHIDEE, JULES, LPJmL). Each of the four combinations of land-use models and mitigation scenarios aimed for a cumulative carbon uptake of ~130 GtC by the end of the century, achieved either via the cultivation of bioenergy crops combined with carbon capture and storage (BECCS) or avoided deforestation and afforestation (ADAFF). Results suggest large uncertainty in simulated future land demand and carbon uptake rates, depending on the assumptions related to land use and land management in the models. Total cumulative carbon uptake in the DGVMs is highl...

Nature Climate Change

The Paris Agreement-which is aimed at holding global warming well below 2 °C while pursuing efforts to limit it below 1.5 °C-has initiated a bottom-up process of iteratively updating nationally determined contributions to reach these longterm goals. Achieving these goals implies a tight limit on cumulative net CO 2 emissions, of which residual CO 2 emissions from fossil fuels are the greatest impediment. Here, using an ensemble of seven integrated assessment models (IAMs), we explore the determinants of these residual emissions, focusing on sector-level contributions. Even when strengthened pre-2030 mitigation action is combined with very stringent long-term policies, cumulative residual CO 2 emissions from fossil fuels remain at 850-1,150 GtCO 2 during 2016-2100, despite carbon prices of US$130-420 per tCO 2 by 2030. Thus, 640-950 GtCO 2 removal is required for a likely chance of limiting end-of-century warming to 1.5 °C. In the absence of strengthened pre-2030 pledges, long-term CO 2 commitments are increased by 160-330 GtCO 2 , further jeopardizing achievement of the 1.5 °C goal and increasing dependence on CO 2 removal.

Environmental Research Letters

View the article online for updates and enhancements. Related content Global economic consequences of deploying bioenergy with carbon capture and storage (BECCS) Matteo Muratori, Katherine Calvin, Marshall Wise et al.-Methane and nitrous oxide emissions affect the life-cycle analysis of algal biofuels Edward D Frank, Jeongwoo Han, Ignasi Palou-Rivera et al.-Impacts of European livestock production: nitrogen, sulphur, phosphorus and greenhouse gas emissions, land-use, water eutrophication and biodiversity Adrian Leip, Gilles Billen, Josette Garnier et al.-Recent citations Development of algae biorefinery concepts for biofuels and bioproducts; a perspective on process-compatible products and their impact on cost-reduction Lieve M. L. Laurens et al-Geoengineering, marine microalgae, and climate stabilization in the 21st century Charles H. Greene et al

Earth's Future

Bioenergy carbon capture and storage (BECCS) has been proposed to reduce atmospheric CO 2 concentrations, but concerns remain about competition for arable land and freshwater. The synergistic integration of algae production, which does not require arable land or freshwater, with BECCS (called "ABECCS") can reduce CO 2 emissions without competing with agriculture. This study presents a technoeconomic and life-cycle assessment for colocating a 121-ha algae facility with a 2,680-ha eucalyptus forest for BECCS. The eucalyptus biomass fuels combined heat and power (CHP) generation with subsequent amine-based carbon capture and storage (CCS). A portion of the captured CO 2 is used for growing algae and the remainder is sequestered. Biomass combustion supplies CO 2 , heat, and electricity, thus increasing the range of sites suitable for algae cultivation. Economic, energetic, and environmental impacts are considered. The system yields as much protein as soybeans while generating 61.5 TJ of electricity and sequestering 29,600 t of CO 2 per year. More energy is generated than consumed and the freshwater footprint is roughly equal to that for soybeans. Financial break-even is achieved for product value combinations that include 1

Climatic Change

This study explores sense-making about climate engineering among lay focus group participants in Japan, New Zealand, the USA and Sweden. In total, 23 qualitative focus group interviews of 136 participants were conducted. The analyses considered sense-making strategies and heuristics among the focus group participants and identified commonalities and variations in the data, exploring participants' initial and spontaneous reactions to climate engineering and to several recurrent arguments that feature in scientific and public debate (e.g. climate emergency). We found that, despite this study's wide geographical scope, heterogeneous focus group compositions, and the use of different moderators, common themes emerged. Participants made sense of climate engineering in similar ways, for example, through context-dependent analogies and metaphorical Climatic Change

Nature Communications

The large majority of climate change mitigation scenarios that hold warming below 2 °C show high deployment of carbon dioxide removal (CDR), resulting in a peak-and-decline behavior in global temperature. This is driven by the assumption of an exponentially increasing carbon price trajectory which is perceived to be economically optimal for meeting a carbon budget. However, this optimality relies on the assumption that a finite carbon budget associated with a temperature target is filled up steadily over time. The availability of net carbon removals invalidates this assumption and therefore a different carbon price trajectory should be chosen. We show how the optimal carbon price path for remaining well below 2 °C limits CDR demand and analyze requirements for constructing alternatives, which may be easier to implement in reality. We show that warming can be held at well below 2 °C at much lower long-term economic effort and lower CDR deployment and therefore lower risks if carbon p...

Nature, 2016

The Paris climate agreement aims at holding global warming to well below 2 degrees Celsius and to "pursue efforts" to limit it to 1.5 degrees Celsius. To accomplish this, countries have submitted Intended Nationally Determined Contributions (INDCs) outlining their post-2020 climate action. Here we assess the effect of current INDCs on reducing aggregate greenhouse gas emissions, its implications for achieving the temperature objective of the Paris climate agreement, and potential options for overachievement. The INDCs collectively lower greenhouse gas emissions compared to where current policies stand, but still imply a median warming of 2.6-3.1 degrees Celsius by 2100. More can be achieved, because the agreement stipulates that targets for reducing greenhouse gas emissions are strengthened over time, both in ambition and scope. Substantial enhancement or over-delivery on current INDCs by additional national, sub-national and non-state actions is required to maintain a rea...

Climate Policy

The target of zero emissions sets a new standard for industry and industrial policy. Industrial policy in the twenty-first century must aim to achieve zero emissions in the energy and emissions intensive industries. Sectors such as steel, cement, and chemicals have so far largely been sheltered from the effects of climate policy. A major shift is needed, from contemporary industrial policy that mainly protects industry to policy strategies that transform the industry. For this purpose, we draw on a wide range of literatures including engineering, economics, policy, governance, and innovation studies to propose a comprehensive industrial policy framework. The policy framework relies on six pillars: directionality, knowledge creation and innovation, creating and reshaping markets, building capacity for governance and change, international coherence, and sensitivity to socioeconomic implications of phase-outs. Complementary solutions relying on technological, organizational, and behavioural change must be pursued in parallel and throughout whole value chains. Current policy is limited to supporting mainly some options, e.g. energy efficiency and recycling, with some regions also adopting carbon pricing, although most often exempting the energy and emissions intensive industries. An extended range of options, such as demand management, materials efficiency, and electrification, must also be pursued to reach zero emissions. New policy research and evaluation approaches are needed to support and assess progress as these industries have hitherto largely been overlooked in domestic climate policy as well as international negotiations. Key policy insights. Energy and emission intensive industries can no longer be complacent about the necessity of zero greenhouse gas (GHG) emissions.. Zero emissions require profound technology and organizational changes across whole material value chains, from primary production to reduced demand, recycling and end-of-life of metals, cement, plastics, and other materials.. New climate and industrial policies are necessary to transform basic materials industries, which are so far relatively sheltered from climate mitigation.

Energy Efficiency

Science (New York, N.Y.), 2018

Some energy services and industrial processes-such as long-distance freight transport, air travel, highly reliable electricity, and steel and cement manufacturing-are particularly difficult to provide without adding carbon dioxide (CO) to the atmosphere. Rapidly growing demand for these services, combined with long lead times for technology development and long lifetimes of energy infrastructure, make decarbonization of these services both essential and urgent. We examine barriers and opportunities associated with these difficult-to-decarbonize services and processes, including possible technological solutions and research and development priorities. A range of existing technologies could meet future demands for these services and processes without net addition of CO to the atmosphere, but their use may depend on a combination of cost reductions via research and innovation, as well as coordinated deployment and integration of operations across currently discrete energy industries.

Frontiers in Climate, 2019

Frontiers in Climate

In recent years Direct Air Capture (DAC) has established itself as a promising approach to atmospheric Carbon Dioxide Removal (CDR) also referred to as Negative Emissions. However, due to the amounts likely needed to be removed CDR technologies like DAC will only become climate relevant if they rapidly reach gigaton scale, around the middle of this century. Here we give a brief insight into DAC and in particular, the modular low temperature DAC technology developed by Climeworks of Switzerland. We discuss potential co benefits, in particular in relation to the Sustainable Development Goals (SDGs) of the United Nations and conclude by suggesting some policy approaches on how a climate relevant scale could be achieved in time.

PloS one, 2018

Sustainably feeding the next generation is often described as one of the most pressing "grand challenges" facing the 21st century. Generally, scholars propose addressing this problem by increasing agricultural production, investing in technology to boost yields, changing diets, or reducing food waste. In this paper, we explore whether global food production is nutritionally balanced by comparing the diet that nutritionists recommend versus global agricultural production statistics. Results show that the global agricultural system currently overproduces grains, fats, and sugars while production of fruits and vegetables and protein is not sufficient to meet the nutritional needs of the current population. Correcting this imbalance could reduce the amount of arable land used by agriculture by 51 million ha globally but would increase total land used for agriculture by 407 million ha and increase greenhouse gas emissions. For a growing population, our calculations suggest that...

The New phytologist, 2018

Contents Summary 507 I. Introduction 507 II. The return on investment approach 508 III. COresponse spectrum 510 IV. Discussion 516 Acknowledgements 518 References 518 SUMMARY: Land ecosystems sequester on average about a quarter of anthropogenic COemissions. It has been proposed that nitrogen (N) availability will exert an increasingly limiting effect on plants' ability to store additional carbon (C) under rising CO, but these mechanisms are not well understood. Here, we review findings from elevated COexperiments using a plant economics framework, highlighting how ecosystem responses to elevated COmay depend on the costs and benefits of plant interactions with mycorrhizal fungi and symbiotic N-fixing microbes. We found that N-acquisition efficiency is positively correlated with leaf-level photosynthetic capacity and plant growth, and negatively with soil C storage. Plants that associate with ectomycorrhizal fungi and N-fixers may acquire N at a lower cost than plants associated...

GCB Bioenergy

The growth of biomass is considered the most efficient method currently available to extract carbon dioxide from the atmosphere. However, biomass carbon is easily degraded by microorganisms releasing it in the form of greenhouse gases back to the atmosphere. If biomass is pyrolyzed, the organic carbon is converted into solid (biochar), liquid (bio-oil), and gaseous (permanent pyrogas) carbonaceous products. During the last decade, biochar has been discussed as a promising option to improve soil fertility and sequester carbon, although the carbon efficiency of the thermal conversion of biomass into biochar is in the range of 30%-50% only. So far, the liquid and gaseous pyrolysis products were mainly considered for combustion, though they can equally be processed into recalcitrant forms suitable for carbon sequestration. In this review, we show that pyrolytic carbon capture and storage (PyCCS) can aspire for carbon sequestration efficiencies of >70%, which is shown to be an important threshold to allow PyCCS to become a relevant negative emission technology. Prolonged residence times of pyrogenic carbon can be generated (a) within the terrestrial biosphere including the agricultural use of biochar; (b) within advanced biobased materials as long as they are not oxidized (biochar, bio-oil); and (c) within suitable geological deposits (bio-oil and CO 2 from permanent pyrogas oxidation). While pathway (c) would need major carbon taxes or similar governmental incentives to become a realistic option, pathways (a) and (b) create added economic value and could at least partly be implemented without other financial incentives. Pyrolysis technology is already well established, biochar sequestration and bio-oil sequestration in soils, respectively biomaterials, do not present ecological hazards, and global scale-up appears feasible within a time frame of 10-30 years. Thus, PyCCS could evolve into a decisive tool for global carbon governance, serving climate change mitigation and the sustainable development goals simultaneously. K E Y W O R D S biochar, bio-oil, carbon sequestration, climate mitigation, permanent pyrogas, pyrolysis, tCDR 1 | INTRODUCTION To keep global warming in the range that has sustained civilization during the past millennia, the carbon balance between emissions to the atmosphere and carbon accumulation in the terrestrial system has to return to an equilibrium by 2050 at the latest (Obersteiner et al., 2018; Rockström et al., 2016, 2009). To achieve this, greenhouse gas (GHG) emissions need to be reduced by at least 90%

Sustainability

Willow biochar can help to sequestrate carbon. However, biomasses should not be grown on arable lands, as it would increase competition with food production and lead to sustainability issues such as increased food prices and decreased food security. The purpose of this study is to calculate the carbon footprint (CF) of willow biochar in Finland and assess the greenhouse gas compensation potential of marginal lands if they are utilized for willow biochar production. The CF of willow biochar is inadequately assessed together with marginal lands in the literature. A cradle-to-grave Life Cycle Assessment (LCA) of willow biochar was conducted. The results were then applied to assess the total CF of marginal lands. It was found that the CF of willow biochar is −1875 kgCO2eq t−1 of dry biochar. Grown on marginal lands in Finland, willow biochar could compensate 7.7% of yearly agricultural greenhouse gas emissions. On buffer zones, willow biochar could also compensate some of the emissions ...

Forests

Research Highlights: We find that biochar plus fertilizer has synergistic and positive effects on seedling growth and robustness, but slightly lowers early seedling survival. Biochar plus fertilizer has the potential to greatly decrease costs associated with afforestation as compared to traditional fertilization and gives better results. Background and Objectives: Biochar can improve soil fertility and plant yield in crops. However, there is little information regarding the effects of biochar on trees, even though reforestation/afforestation projects are increasing and are often unsuccessful due to soil fertility limitations. This study aims to increase knowledge of biochar use as a reforestation tool. Materials and Methods: We measured survival and growth in an early ((Guazuma crinita Mart. [n = 240])) and a late (Terminalia amazonia (J.F. Gmel.) Exell. [n = 240]) successional species under 6 different biochar treatments in a 6-month nursery experiment. Results: (i) Survival was hi...

2018

To maintain the chance of keeping the average global temperature increase below 2 degrees C and to limit long-term climate change, removing carbon dioxide from the atmosphere (carbon dioxide removal, CDR) is becoming increasingly necessary. We analyze optimal and cost-effective climate policies in the dynamic integrated assessment model (IAM) of climate and the economy (DICE2016R) and investigate (1) the utilization of (ocean) CDR under different climate objectives, (2) the sensitivity of policies with respect to carbon cycle feedbacks, and (3) how well carbon cycle feedbacks are captured in the carbon cycle models used in state-of-the-art IAMs. Overall, the carbon cycle model in DICE2016R shows clear improvements compared to its predecessor, DICE2013R, capturing much better long-term dynamics and also oceanic carbon outgassing due to excess oceanic storage of carbon from CDR. However, this comes at the cost of a (too) tight short-term remaining emission budget, limiting the model s...

Nature Climate Change, 2016

Biology

Epigenetics has emerged as an important research field for crop improvement under the on-going climatic changes. Heritable epigenetic changes can arise independently of DNA sequence alterations and have been associated with altered gene expression and transmitted phenotypic variation. By modulating plant development and physiological responses to environmental conditions, epigenetic diversity—naturally, genetically, chemically, or environmentally induced—can help optimise crop traits in an era challenged by global climate change. Beyond DNA sequence variation, the epigenetic modifications may contribute to breeding by providing useful markers and allowing the use of epigenome diversity to predict plant performance and increase final crop production. Given the difficulties in transferring the knowledge of the epigenetic mechanisms from model plants to crops, various strategies have emerged. Among those strategies are modelling frameworks dedicated to predicting epigenetically control...

Proceedings of the National Academy of Sciences

Philosophical transactions. Series A, Mathematical, physical, and engineering sciences, 2018

A 1.5°C global average target implies that we should no longer focus on merely incremental emissions reductions from the electricity system, but rather on fundamentally re-envisaging a system that, sooner rather than later, becomes carbon free. Many low-carbon technologies are surpassing mainstream predictions for both uptake and cost reduction. Their deployment is beginning to be disruptive within established systems. 'Smart technologies' are being developed to address emerging challenges of system integration, but their rates of future deployment remain uncertain. We argue that transition towards a system that can fully displace carbon generation sources will require expanding the focus of our efforts beyond technical solutions. Recognizing that change has social and technical dimensions, and that these interact strongly, we set out a socio-technical review that covers electricity infrastructure, citizens, business models and governance. It describes some of the socio-tech...

Wiley Interdisciplinary Reviews: Climate Change, 2020

Sunlight reflection and carbon removal proposals for "climate engineering" (CE) confront governance challenges that many emerging technologies face: their futures are uncertain, and by the time one can discern their shape or impacts, vested interests may block regulation, and publics are often left out of decisionmaking about them. In response to these challenges, "responsible research and innovation" (RRI) has emerged as a framework to critique and correct for technocratic governance of emerging technologies, and CE has emerged as a prime case of where it can be helpfully applied. However, a critical lens is rarely applied to RRI itself. In this review, we first survey how RRI thinking has already been applied to both carbon removal and sunlight reflection methods for climate intervention. We examine how RRI is employed in four types of activities: Assessment processes and reports, principles and protocols for research governance, critical mappings of research, and deliberative and futuring engagements. Drawing upon this review, we identify tensions in RRI practice, including whether RRI forms or informs choices, the positionalities of RRI practitioners, and ways in which RRI activities enable or disable particular climate interventions. Finally, we recommend that RRI should situate CE within the long arc of sociotechnical proposals for addressing climate change, more actively connect interrogations of the knowledge economy with reparative engagements, include local or actor-specific contexts, design authoritative assessments grounded in RRI, and go beyond treating critique and engagement as "de facto" governance.

Carbon Management

Knoop (2018) Long-term low greenhouse gas emission development strategies for achieving the 1.5 °C target-insights from a comparison of German bottom-up energy scenarios, Carbon

Environmental Research Letters, 2019

Bioenergy with carbon capture and storage (BECCS) is envisaged as a critical element of most deep decarbonisation pathways compatible with the Paris Agreement. Such a transformational upscalingto 3-7 Gt CO 2 /yr by 2050-requires an unprecedented technological, economic, socio-cultural and political effort, along with, crucially, transparent communication between all stakeholders. Integrated Assessment Models (IAMs) that underpin the 1.5°C scenarios assessed by IPCC have played a critical role in building and assessing deep decarbonisation narratives. However, their high-level aggregation and their complexity can cause them to be perceived as non-transparent by stakeholders outside of the IAM community. This paper bridges this gap by offering a comprehensive assessment of BECCS assumptions as used in IAMs so as to open them to a wider audience. We focus on key assumptions that underpin five aspects of BECCS: biomass availability, BECCS technologies, CO 2 transport and storage infrastructure, BECCS costs, and wider system conditions which favour the deployment of BECCS. Through a structured review, we find that all IAMs communicate wider system assumptions and major cost assumptions transparently. This quality however fades as we dig deeper into modelling details. This is particularly true for sets of technological elements such as CO 2 transport and storage infrastructure, for which we found the least transparent assumptions. We also found that IAMs are less transparent on the completeness of their treatment of the five BECCS aspects we investigated, and not transparent regarding the inclusion and treatment of socio-cultural and institutional-regulatory dimensions of feasibility which are key BECCS elements as suggested by the IPCC. We conclude with a practical discussion around ways of increasing IAM transparency as a bridge between this community and stakeholders from other disciplines, policy decision makers, financiers, and the public.

Nature Communications

Carbon dioxide removal technologies, such as bioenergy with carbon capture and direct air capture, are valuable for stringent climate targets. Previous work has examined implications of carbon removal, primarily bioenergy-based technologies using integrated assessment models, but not investigated the effects of a portfolio of removal options on power systems in detail. Here, we explore impacts of carbon removal technologies on electric sector investments, costs, and emissions using a detailed capacity planning and dispatch model with hourly resolution. We show that adding carbon removal to a mix of low-carbon generation technologies lowers the costs of deep decarbonization. Changes to system costs and investments from including carbon removal are larger as policy ambition increases, reducing the dependence on technologies like advanced nuclear and long-duration storage. Bioenergy with carbon capture is selected for net-zero electric sector emissions targets, but direct air capture d...

Scientific Reports

The number of reforestation projects worldwide is increasing. In many cases funding is obtained through the claimed carbon capture of the trees, presented as immediate and durable, whereas reforested plots need time and maintenance to realise their carbon capture potential. Further, claims usually overlook the environmental costs of natural or anthropogenic disturbances during the forest’s lifetime, and greenhouse gas (GHG) emissions associated with the reforestation are not allowed for. This study uses life cycle assessment to quantify the carbon footprint of setting up a reforestation plot in the Peruvian Amazon. In parallel, we combine a soil carbon model with an above- and below-ground plant carbon model to predict the increase in carbon stocks after planting. We compare our results with the carbon capture claims made by a reforestation platform. Our results show major errors in carbon accounting in reforestation projects if they (1) ignore the time needed for trees to reach the...

Nature Communications

A rapid transition away from unabated coal use is essential to fulfilling the Paris climate goals. However, many countries are actively building and operating coal power plants. Here we use plant-level data to specify alternative trajectories for coal technologies in an integrated assessment model. We then quantify cost-effective retirement pathways for global and country-level coal fleets to limit long-term temperature change. We present our results using a decision-relevant metric: the operational lifetime limit. Even if no new plants are built, the lifetimes of existing units are reduced to approximately 35 years in a well-below 2 °C scenario or 20 years in a 1.5 °C scenario. The risk of continued coal expansion, including the near-term growth permitted in some Nationally Determined Contributions (NDCs), is large. The lifetime limits for both 2 °C and 1.5 °C are reduced by 5 years if plants under construction come online and 10 years if all proposed projects are built.

Clean Technologies and Environmental Policy, 2021

Biochar application and enhanced weathering are negative emission technologies (NETs) with the potential for large-scale deployment for the removal of CO2 from the atmosphere. Biochar is a solid product of pyrolysis that can permanently store carbon when applied in soil due to its chemical recalcitrance. Enhanced weathering is based on the acceleration of the natural reaction of moisture, CO2, and alkaline minerals. Both of these NETs rely on the application of pulverized material to different types of terrestrial sinks, which can include marginal and agricultural land. These two NETs can be used separately or concurrently, depending on local sink conditions. In some cases, simultaneous application of biochar and mineral powder to soil has the advantage of attaining additional beneficial effects of soil amendment. Although recent papers have reported the development of process integration models for optimizing carbon management networks based on either biochar application or enhance...

Nature communications, 2018

Scenarios that limit global warming to below 2 °C by 2100 assume significant land-use change to support large-scale carbon dioxide (CO) removal from the atmosphere by afforestation/reforestation, avoided deforestation, and Biomass Energy with Carbon Capture and Storage (BECCS). The more ambitious mitigation scenarios require even greater land area for mitigation and/or earlier adoption of CO removal strategies. Here we show that additional land-use change to meet a 1.5 °C climate change target could result in net losses of carbon from the land. The effectiveness of BECCS strongly depends on several assumptions related to the choice of biomass, the fate of initial above ground biomass, and the fossil-fuel emissions offset in the energy system. Depending on these factors, carbon removed from the atmosphere through BECCS could easily be offset by losses due to land-use change. If BECCS involves replacing high-carbon content ecosystems with crops, then forest-based mitigation could be m...

Journal of Applied Ecology, 2021

1. Many national governments have incorporated nature-based solutions (NbS) in their plans to reduce net greenhouse gas emissions. However, uncertainties persist regarding both feasibility and consequences of major NbS deployment. Using the United Kingdom as a national-level case study, we examined the potential contribution of three terrestrial NbS: peatland restoration, saltmarsh creation and woodland creation. 2. While there is substantial political and societal interest in these three NbS, they also have strong potential for competition with other land uses, which will be a critical barrier to substantial deployment. We conducted a national mapping exercise to assess the potential area available for woodland creation. We then assessed the combined climate change mitigation potential to 2100 for the three NbS options under a range of ambition levels. 3. In line with the most ambitious targets examined, 2 Mha of land is potentially available for new woodland. However, climate change mitigation benefits of woodland are strongly dependent on management choices. By 2100, scenarios with a greater proportion of broadleaved woodlands outsequester non-native conifer plantations, which are limited by regular timber harvesting. 4. Peatland restoration offers the greatest mitigation per unit area, whilst the contribution from saltmarsh creation is limited by the small areas involved. Overall, the contribution of these NbS to the United Kingdom's net zero emissions target is relatively modest. Even with the most ambitious targets considered here, by 2100, the total cumulative mitigation from the three NbS is equivalent to only 3 years' worth of UK emissions at current levels. Major deployment of nature-based solutions (NbS) is possible in the United Kingdom but reaching 'net zero' primarily requires substantial and sustained reductions in fossil fuel use. However, facilitating these NbS at the national scale could offer many additional benefits for people and biodiversity.

GCB Bioenergy, 2016

Reliance on fossil fuels is causing unprecedented climate change and is accelerating environmental degradation and global biodiversity loss. Together, climate change and biodiversity loss, if not averted urgently, may inflict severe damage on ecosystem processes, functions and services that support the welfare of modern societies. Increasing renewable energy deployment and expanding the current protected area network represent key solutions to these challenges, but conflicts may arise over the use of limited land for energy production as opposed to biodiversity conservation. Here, we compare recently identified core areas for the expansion of the global protected area network with the renewable energy potential available from land-based solar photovoltaic, wind energy and bioenergy (in the form of Miscanthus 9 giganteus). We show that these energy sources have very different biodiversity impacts and net energy contributions. The extent of risks and opportunities deriving from renewable energy development is highly dependent on the type of renewable source harvested, the restrictions imposed on energy harvest and the region considered, with Central America appearing at particularly high potential risk from renewable energy expansion. Without restrictions on power generation due to factors such as production and transport costs, we show that bioenergy production is a major potential threat to biodiversity, while the potential impact of wind and solar appears smaller than that of bioenergy. However, these differences become reduced when energy potential is restricted by external factors including local energy demand. Overall, we found that areas of opportunity for developing solar and wind energy with little harm to biodiversity could exist in several regions of the world, with the magnitude of potential impact being particularly dependent on restrictions imposed by local energy demand. The evidence provided here helps guide sustainable development of renewable energy and contributes to the targeting of global efforts in climate mitigation and biodiversity conservation.

GCB Bioenergy, 2019

New contingency policy plans are expected to be published by the United Kingdom government to set out urgent actions, such as carbon capture and storage, greenhouse gas removal and the use of sustainable bioenergy to meet the greenhouse gas reduction targets of the 4th and 5th Carbon Budgets. In this study, we identify two plausible bioenergy production pathways for bioenergy with carbon capture and storage (BECCS) based on centralized and distributed energy systems to show what BECCS could look like if deployed by 2050 in Great Britain. The extent of agricultural land available to sustainably produce biomass feedstock in the centralized and distributed energy systems is about 0.39 and 0.5 Mha, providing approximately 5.7 and 7.3 Mt DM /year of biomass respectively. If this land-use change occurred, bioenergy crops would contribute to reduced agricultural soil GHG emission by 9 and 11 Mt CO 2 eq /year in the centralized and distributed energy systems respectively. In addition, bioenergy crops can contribute to reduce agricultural soil ammonia emissions and water pollution from soil nitrate leaching, and to increase soil organic carbon stocks. The technical mitigation potentials from BECCS lead to projected CO 2 reductions of approximately 18 and 23 Mt CO 2 /year from the centralized and distributed energy systems respectively. This suggests that the domestic supply of sustainable biomass would not allow the emission reduction target of 50 Mt CO 2 /year from BECCS to be met. To meet that target, it would be necessary to produce solid biomass from forest systems on 0.59 or 0.49 Mha, or alternatively to import 8 or 6.6 Mt DM /year of biomass for the centralized and distributed energy system respectively. The spatially explicit results of this study can serve to identify the regional differences in the potential capture of CO 2 from BECCS, providing the basis for the development of onshore CO 2 transport infrastructures. agricultural GHG emissions, BECCS, bioenergy crops, carbon capture and storage, climate mitigation strategy, future energy scenarios, greenhouse gases, land-use change ORCID

Science Advances, 2019

CO2 accumulation in confined spaces represents an increasing environmental and health problem. Trace CO2 capture remains an unmet challenge because human health risks can occur at 1000 parts per million (ppm), a level that challenges current generations of chemisorbents (high energy footprint and slow kinetics) and physisorbents (poor selectivity for CO2, especially versus water vapor, and/or poor hydrolytic stability). Here, dynamic breakthrough gas experiments conducted upon the ultramicroporous material SIFSIX-18-Ni-β reveal trace (1000 to 10,000 ppm) CO2 removal from humid air. We attribute the performance of SIFSIX-18-Ni-β to two factors that are usually mutually exclusive: a new type of strong CO2 binding site and hydrophobicity similar to ZIF-8. SIFSIX-18-Ni-β also offers fast sorption kinetics to enable selective capture of CO2 over both N2 (SCN) and H2O (SCW), making it prototypal for a previously unknown class of physisorbents that exhibit effective trace CO2 capture under...

New Forests, 2018

Forests provide a wide variety of ecosystem services and international conventions and national policies for climate change mitigation and biodiversity conservation recommend forest protection and restoration. However, global forest cover continues to decline, and recent evidence suggests deforestation rates are accelerating. Against this background the area of planted forests has increased globally. Recognizing the substantial potential of well-managed forest plantations, the new generation plantations (NGP) platform was launched in 2007. NGP encourages well-managed planted forests in the right places to conserve biodiversity and meet human needs. Here we describe the NGP approach and analyze data and information from NGP participants and others over 10 years. This shows that NGP participants are responsible for c.11.1 million ha of land, much of it previously degraded or abandoned; 43% is managed as timber plantations, with the remainder being wildlife reserves, restored natural forest, grassland and agriculture. NGP case studies illustrate a range of biodiversity, conservation and socioeconomic achievements. These achievements, considered together with future projections of timber demand and of the land available for restoration to tree cover, demonstrate the potential of well-managed plantations to protect natural forests, provide timber, conserve biodiversity and mitigate climate change. The NGP concept works in a variety of countries and contexts; participants have shown that it is possible to produce timber while maintaining and enhancing ecosystems

Climate Policy, 2017

Existing international emissions reduction policies are not sufficient to meet the internationally agreed objective of limiting average global temperature rise to 'well below' two degrees, resulting in an emissions gap. Materialssuch as aluminium, cement, paper, plastics and steelact as a carrier of industrial energy that allows, through trade, the transfer of embodied emissions between sectors and countries. However, the use of materials has been overshadowed by policies focusing on energy efficiency improvements and deployment of a low carbon energy supply. This article argues that policies based on material and product demand can support domestic climate change mitigation and reduce the emissions gap, yet there is little obvious integration between climate and material efficiency policies. The article investigates current 'emissions flows' through the EU economy and how much of these are captured and excluded from existing EU climate policies. We analyse the potential increase in emissions coverage that would be achieved by extending EU directives that currently target the energy use of products (cars, buildings and appliances) in operation, to include the emissions required to produce the goods (i.e. embodied emissions). The analysis shows that a greater integration of material efficiency strategies within climate change mitigation policy could significantly increase the emissions coverage of existing product policies. Key policy insights. Consumption is a key driver of emissions and demand reduction is an important policy option in reducing emissions, at least in the short-term, to reduce the risks of a longer-term reliance on technology breakthroughs and while the EU carbon price remains low.. Emissions embodied in material-intensive manufactured products consumed in the EU represent the equivalent of over 40% of EU production emissions, offering significant scope for emissions reductions along product supply chains.. Consumption measures that target the use of materials and products offer complementary mitigation options to low carbon energy supply technologies alongside costs savings.. Existing EU policies addressing the energy efficiency of products can be used to scale up material efficiency measures.

Climatic Change, 2017

A wide range of carbon dioxide removal (CDR) strategies has been proposed to address climate change. As most CDR strategies are unfamiliar to the public, it is unknown how increased media and policy attention on CDR might affect public sentiment about climate change. On the one hand, CDR poses a potential moral hazard: if people perceive that CDR solves climate change, they may be less likely to support efforts to reduce carbon emissions. On the other hand, the need for CDR may increase the perceived severity of climate change and, thus, increase support for other types of mitigation. Using an online survey of US adults (N = 984), we tested these competing hypotheses by exposing participants to information about different forms of CDR. We find that learning about certain CDR strategies indirectly reduces support for mitigation policies by reducing the perceived threat of climate change. This was found to be true for participants who read about CDR in general (without mention of specific strategies), bioenergy with carbon capture and storage, or direct air capture. Furthermore, this risk compensation pattern was more pronounced among political conservatives than liberals-although in some cases, was partially offset by positive direct effects. Learning about

Climatic Change, 2019

Carbon dioxide removal (CDR) describes a suite of controversial approaches to mitigating climate change that involve removing existing carbon dioxide from the atmosphere. Through an online survey experiment with US adults (N = 980), we examine three factors that may shape public support for different types of CDR strategies: (1) perceptions that CDR tampers with nature, (2) individual-level variation in the degree to which people are uncomfortable with activities that tamper with nature, and (3) information about the risks and benefits associated with each CDR strategy. Using a moderated mediation analysis, we find that support for different CDR strategies is, in part, a function of how much each strategy is perceived to tamper with nature. Support for bioenergy with carbon capture and storage (BECCS) and direct air capture (DAC) was lower than support for afforestation and reforestation (AR), as BECCS and DAC were perceived to tamper with nature more. These effects were particularly strong among individuals generally opposed to the idea of humans interfering with natural processes. Moreover, we find evidence that describing the risks and benefits of each CDR strategy dampens support; for AR and BECCS, this effect was again mediated through perceptions of tampering, while for DAC, the effect of describing these tradeoffs appeared to operate independently of perceived tampering. We conclude that policymakers and science communicators need to be mindful of how CDR strategies are described to the public, as perceptions of tampering with nature may be an important driver of their acceptance.

Critical Reviews in Environmental Science and Technology, 2019

Low carbon technologies (LCTs) have been widely developed in recent years. However, the classification of LCTs varies across academic studies, business insights, governmental directives and reports from institutions worldwide, and depends on the disciplines. A lack of common knowledge makes it difficult to coordinate and enhance interdisciplinary dialog and multi-level cooperation among scholars, governments, enterprises, and non-governmental organizations (NGOs). This review fills this gap by providing a straightforward classification with analysis on the market potential and opportunities on LCTs. Six categories of LCTs are classified based on two dimensions, which are the emission reduction potential and the technology usage purpose. We further identify the investment strategy for each type of LCT by sectors and stakeholders. Strong signals from the government are necessary to promote the development of LCT via regulation and policy, as it provides an economic incentive for firms to invest properly in LCT market. In addition, we find civil society can act properly as a middleman for multi-level regulations, and boost cooperation at international level across countries.

Sustainability, 2020

Most scenarios on instruments limiting global warming in line with the 1.5 • C temperature limit of the Paris Agreement rely on overshooting the emissions threshold, thus requiring the application of negative emission technologies later on. Subsequently, the debate on carbon dioxide removal (CDR) and solar radiation management (SRM) (frequently subsumed under "geoengineering") has been reinforced. Yet, it does not determine normatively whether those are legally valid approaches to climate protection. After taking a closer look at the scope of climate scenarios and SRM methods compiling current research and opinions on SRM, this paper analyses the feasibility of geoengineering and of SRM in particular under international law. It will be shown that from the perspective of human rights, the Paris Agreement, and precautionary principle the phasing-out of fossil fuels and the reduction in consumption of livestock products as well as nature-based approaches such as sustainable-and thus climate and biodiversity-smart-forest, peatland, and agricultural management strongly prevail before geoengineering and atmospheric SRM measures in particular. However, as all of the atmospheric SRM methods are in their development phase, governance options to effectively frame further exploration of SRM technologies are proposed, maintaining that respective technologies thus far are not a viable means of climate protection.

Sustainability, 2018

The Paris Agreement of December 2015 is subject to much criticism of being inadequate. This however neglects its very ambitious objective, which limits legally-binding global warming to 1.5 to 1.8 degrees in comparison to pre-industrial levels. This article shows, based on the overlap of unanswered questions for prognoses in natural science and the legal precautionary principle, that this objective indicates a legal imperative towards zero emissions globally within a short timeframe. Furthermore, it becomes apparent that policies need to be focused on achieving the 1.5-degree temperature limit. From a legal standpoint with regard to existential matters, only those policies are justified that are fit to contribute to reaching the temperature limit with high certainty, without overshoot, without leaving the 1.5 limit aside and without geoengineering measures, in contrast to the tendencies of the IPCC. This creates a big challenge even for the alleged forerunners of climate policies, G...

Land, 2020

Limiting global warming to well below 2 degrees Celsius and better even to 1.5 degrees Celsius, according to Article 2 paragraph 1 of the Paris Agreement requires global zero emissions in a very short time. These targets imply that not only emissions from degraded peatlands have to be avoided, but conservation and rewetting of peatlands are also necessary to figure as sinks to compensate for unavoidable residual emissions. However, with regard to instruments for meeting these targets, measuring, depicting, and baseline definition are difficult for greenhouse gas emissions from peatlands. In the absence of an easily comprehensible control variable (such as fossil fuels), economic instruments reach their limits. This is remarkable in so far as economic instruments can otherwise handle governance problems and react to various behavioral motivational factors very well. Still, peatlands can be subject to certain regulations and prohibitions under command-and-control law even without prec...

Nature Energy, 2018

Scenarios limiting global warming to 1.5°C describe major transformations in energy supply and everrising energy demand. Here we provide a contrasting perspective by developing a narrative of future change based on observable trends that results in low energy demand. We describe and quantify changes in activity levels and energy intensity in the Global North and South for all major energy services. We project that global final energy demand by 2050 reduces to 245 EJ, around 40% lower than today despite rising population, income and activity. Using an integrated assessment modelling framework, we show how changes in the quantity and type of energy services drive structural change in intermediate and upstream supply sectors (energy and land use). Down-sizing the global energy system dramatically improves the feasibility of low-carbon supply-side transformation. Our scenario meets the 1.5°C climate target as well as many Sustainable Development Goals, without relying on negative emission technologies.

The Anthropocene Review, 2018

For sufficiently fast climate change mitigation, strategies once considered unthinkable have to be discussed. As negative-emission technologies and solar geoengineering are risky, social and economic innovations are needed as well. Working time reduction is a completely neglected strategy that needs urgent attention in climate–economy models and policy.

Nature Climate Change

The role of non-CO 2 effects in future aviation scenarios In Fig. 2, we show the evolution of the different terms of aviation's effective radiative forcing (ERF) according to the two socioeconomic and three technology pathways. While non-CO 2 effects

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2018

A rejection by current generations of more ambitious mitigation of carbon emissions inflicts on future generations inherently objectionable risks about which they have no choice. Any gains through savings from less ambitious mitigation, which are relatively minor, would accrue to current generations, and all losses, which are relatively major, would fall on future generations. This mitigation gamble is especially unjustifiable because it imposes a risk of unlimited losses until carbon emissions cease. Ultimate physical collapses remain possible. Much more ominous is prior social collapse from political struggles over conflicting responses to threatened physical collapse. The two most plausible objections to the thesis that less ambitious mitigation is unjustifiable rely, respectively, on the claim that negative emissions will allow a later recovery from a temporary overshoot in emissions and on the claim that ambitious mitigation is incompatible with poverty alleviation that depends...

Politics, Philosophy & Economics, 2021

With the significant disconnect between the collective aim of limiting warming to well below 2°C and the current means proposed to achieve such an aim, the goal of this paper is to offer a moral assessment of prominent alternatives to current international climate policy. To do so, we’ll outline five different policy routes that could potentially bring the means and goal in line. Those five policy routes are: (1) exceed 2°C; (2) limit warming to less than 2°C by economic de-growth; (3) limit warming to less than 2°C by traditional mitigation only; (4) limit warming to less than 2°C by traditional mitigation and widespread deployment of Negative Emissions Technologies (NETs); and (5) limit warming to less than 2°C by traditional mitigation, NETs, and Solar Radiation Management as a fallback. In assessing these five policy routes, we rely primarily upon two moral considerations: the avoidance of catastrophic climate change and the right to sustainable development. We’ll conclude that ...

Nature communications, 2017

The UN Framework Convention on Climate Change aims to keep warming below 2 °C while recognizing developing countries' right to eradicate extreme poverty. Poverty eradication is also the first of the Sustainable Development Goals. This paper investigates potential consequences for climate targets of achieving poverty eradication. We find that eradicating extreme poverty, i.e., moving people to an income above $1.9 purchasing power parity (PPP) a day, does not jeopardize the climate target even in the absence of climate policies and with current technologies. On the other hand, bringing everybody to a still modest expenditure level of at least $2.97 PPP would have long-term consequences on achieving emission targets. Compared to the reference mitigation pathway, eradicating extreme poverty increases the effort by 2.8% whereas bringing everybody to at least $2.97 PPP would increase the required mitigation rate by 27%. Given that the top 10% global income earners are responsible for...

Mitigation and Adaptation Strategies for Global Change, 2016

Stratospheric aerosol injection (SAI) has been receiving increasing attention as a possible option for climate engineering. Its direct cost is perceived to be low, which has implications for international governance of this emerging technology. Here, we critically synthesize previous estimates of the underlying parameters and examine the total costs of SAI. It is evident that there have been inconsistencies in some assumptions and the application of overly optimistic parameter values in previous studies, which have led to an overall underestimation of the cost of aircraft-based SAI with sulfate aerosols. The annual cost of SAI to achieve cooling of 2 W/m 2 could reach US$10 billion with newly designed aircraft, which contrasts with the oft-quoted estimate of Ba few billion dollars.^If existing aircraft were used, the cost would be expected to increase further. An SAI operation would be a large-scale engineering undertaking, possibly requiring a fleet of approximately 1,000 aircraft, because of the required high altitude of the injection. Therefore, because of its significance, a more thorough investigation of the engineering aspects of SAI and the associated uncertainties is warranted.

Acta Agriculturae Scandinavica, Section B — Soil & Plant Science, 2020

In this study, Life Cycle Assessment (LCA) methodology was combined with the agro-ecosystem model DNDC to assess the climate and eutrophication impacts of perennial grass cultivation at five different sites in Sweden. The system was evaluated for two fertilisation rates, 140 and 200 kg N ha −1. The climate impact showed large variation between the investigated sites. The largest contribution to the climate impact was through soil N 2 O emissions and emissions associated with mineral fertiliser manufacturing. The highest climate impact was predicted for the site with the highest clay and initial organic carbon content, while lower impacts were predicted for the sandy loam soils, due to low N 2 O emissions, and for the silty clay loam, due to high carbon sequestration rate. The highest eutrophication potential was estimated for the sandy loam soils, while the sites with finer soil texture had lower eutrophication potential. According to the results, soil properties and weather conditions were more important than fertilisation rate for the climate impact of the system assessed. It was concluded that agroecosystem models can add a spatial and temporal dimension to environmental impact assessment in agricultural LCA studies. The results could be used to assist policymakers in optimising use of agricultural land.

BioScience, 2018

Carbon dioxide must be removed from the atmosphere to limit climate change to 2°C or less. The integrated assessment models used to develop climate policy acknowledge the need to implement net negative carbon emission strategies, including bioenergy with carbon capture and storage (BECCS), to meet global climate imperatives. The implications of BECCS for the food, water, energy, biodiversity, and social systems (FWEBS) nexus at regional scales, however, remain unclear. Here, we present an interdisciplinary research framework to examine the trade-offs as well as the opportunities among BECCS scenarios and FWEBS on regional scales using the Upper Missouri River Basin (UMRB) as a case study. We describe the physical, biological, and social attributes of the UMRB, and we use grassland bird populations as an example of how biodiversity is influenced by energy transitions, including BECCS. We then outline a "conservation" BECCS strategy that incorporates societal values and emphasizes biodiversity conservation.

Justice and food security in a changing climate

Proceedings of the National Academy of Sciences, 2016

Energy & Environmental Science, 2018

Carbon capture and storage (CCS) is vital to climate change mitigation, and has application across the economy, in addition to facilitating atmospheric carbon dioxide removal resulting in emissions offsets and net negative emissions. This contribution reviews the state-of-the-art and identifies key challenges which must be overcome in order to pave the way for its large-scale deployment.

VIII INTERNATIONAL ANNUAL CONFERENCE “INDUSTRIAL TECHNOLOGIES AND ENGINEERING” (ICITE 2021)

Over the entirety of human history, pollution and economic development seem inseparably related. We are now facing unparalleled socioeconomic and environmental stresses and threats across all three dimensions, economic, social, and environmental. When we think about the economy and society, we take note of both the costs and benefits that already occurred. Sustainable development calls for holistic action. Malaysia's growth is based on modest development. Every development requires some cost, like playing the "seesaw" one side goes up the other side goes down, therefore the government need to strike the balance while developing the nation. Development does not necessarily reduce the vulnerability of climate change if it is focused on the right kind of development, investments in the development of economic sustainability, and competitive growth models must involve sound risk management. As we look at the transition of civilization into a circular economy, we need to consider a more integrated structure to overcome the consequences of environmental degradation on social justice. In 2020, more gases have been put into the environment that may contribute to climate change and risk endangering human health. This study explores the connection between economic development, increasing the standard of living, and environmental degradation.

Biology letters, 2017

Restricting future global temperature increase to 2°C or less requires the adoption of negative emissions technologies for carbon capture and storage. We review the potential for deployment of enhanced weathering (EW), via the application of crushed reactive silicate rocks (such as basalt), on over 680 million hectares of tropical agricultural and tree plantations to offset fossil fuel CO2 emissions. Warm tropical climates and productive crops will substantially enhance weathering rates, with potential co-benefits including decreased soil acidification and increased phosphorus supply promoting higher crop yields sparing forest for conservation, and reduced cultural eutrophication. Potential pitfalls include the impacts of mining operations on deforestation, producing the energy to crush and transport silicates and the erosion of silicates into rivers and coral reefs that increases inorganic turbidity, sedimentation and pH, with unknown impacts for biodiversity. We identify nine prio...

Resources, Conservation and Recycling, 2020

Climate change exacerbates the vulnerability of water resources, and water-energy-carbon nexus makes water management more complicated. This paper attempts to explore the water resource synergy management paths within urban metabolic system against the background of human actively respond to climate change. We hold that: (1) Climate change would aggravate water scarcity risk from a supply-based perspective. Meanwhile, the normal metabolism of water consumers and energy consumption and mitigation options against climate change would directly and indirectly respectively, affect the water usage from a demand-based perspective. (2) Agriculture has great water-saving potential resulting from drip irrigation and drought-resistant technologies, but the potentials would be gradually endangered by biomass crop popularization. Industrial water saving mainly lies in energy efficiency, renewable energy, and CO 2-enhanced water recovery (CO 2-EWR). Domestic water-saving depends on sewage source treatment and awareness of water and energy conservation. Ecological water-saving should focus on the circulation of natural ecosystems and hydraulic systems. (3) Synergy management emphasizes the dynamic complementarity among water consumers in the urban metabolic system. Particularly, it is possible to compensate industrial water usage through agricultural water-saving due to fossil energy-based carbon capture and storage (CCS) in the medium to long term, while it is probably reversed due to the biomass crops expansion and bioenergy-based CCS (BECCS) deployment in the future. Additionally, seasonal changes and regional disparities should be fully taken into consideration. Overall, water resource policies should contribute towards effective water allocation within the urban metabolic system and low-carbon technologies deployment against climate change. Huang et al., 2016; Rajsekhar and Gorelick, 2017). Changes in water quantity and spatial distribution will affect the supply of surface water and groundwater for agriculture, industry, hydropower, river ecosystems, and domestic living (Xu and Zeng, 2012), which will further weaken the water availability. Undoubtedly, water are basic conditions for the survival of human beings and are irreplaceable resources for supporting social and economic systems (

Land

Negative emissions technologies (NETs) approaches are an essential part of virtually any scenario in which global warming is limited to 1.5 °C in accordance with the Paris Agreement. Discussions often focus on two technologies due to their substantial carbon dioxide (CO2) sequestration potential: bioenergy with carbon capture and storage (BECCS) and direct air carbon capture and storage (DACCS). However, the large-scale deployment of both technologies—especially BECCS—may lead to significant human rights infringements. This paper aims to analyze the impact of both technologies on human rights from the methodological perspective of a legal interpretation of international law. It shows that a large-scale BECCS strategy, which inevitably requires enormous land-use changes, will most likely infringe upon the right to food, the right to water, and the right to a healthy environment. In contrast, large-scale DACCS approaches will likely have a smaller human rights impact, but the energy-i...

Mitigation and Adaptation Strategies for Global Change, 2019

A new process to remove carbon dioxide (CO 2) from the atmosphere, by combining commercial industrial technologies with ocean liming and CO 2 storage, is presented. The process aims to overcome the limiting factors of other negative emission technologies (cost and energy requirements, potential competition for land and freshwater) while simultaneously addressing the problem of ocean acidification. The overall proposed process is based on the following: (a) a gasifier where the biomass is converted to syngas; (b) a thermal steam reformer working at high temperature where the hydrocarbons and tar oils are converted to hydrogen (H 2) and carbon monoxide (CO); (c) a kiln to produce Ca(OH) 2 (slaked lime) from limestone by using the enthalpy of the hot syngas; (d) the spreading, by means of vessels, of the slaked lime into the seawater to achieve ocean liming; (e) the delivery of syngas to a water gas shift reactor producing CO 2 and H 2 that are then separated; (f) the final storage of all CO 2 produced in the process; (g) the use of H 2 , being the valuable by-product of the whole process, for decarbonized energy production as well as for ammonia synthesis, offsetting part of the production cost, thus generating "low-cost" negative emissions. The mass and energy balances show that the total atmospheric CO 2 removed by the process is 2.6 ton per ton of biomass used. By adding an estimated 0.43 ton avoided-thanks to the use of produced H 2-the overall CO 2 benefit of the process increases to 3.0 ton per ton of biomass. A preliminary cost analysis resulted in an average levelized cost of 98 $ per ton of CO 2 removed; when considering the revenues from the produced energy, the cost falls to 64 $/tCO 2. The higher efficiency in carbon removal obtained allows to reduce the amount of biomass required by BECCS (bioenergy with carbon capture and storage) to achieve negative emissions, and thanks to the valuable H 2 produced it lowers the costs of CO 2 removal from the atmosphere.

Environmental Research Letters, 2016

Carbon dioxide removal from the atmosphere (CDR)-also known as 'negative emissions'-features prominently in most 2°C scenarios and has been under increased scrutiny by scientists, citizens, and policymakers. Critics argue that 'negative emission technologies' (NETs) are insufficiently mature to rely on them for climate stabilization. Some even argue that 2°C is no longer feasible or might have unacceptable social and environmental costs. Nonetheless, the Paris Agreement endorsed an aspirational goal of limiting global warming to even lower levels, arguing that climate impactsespecially for vulnerable nations such as small island states-will be unacceptably severe in a 2°C world. While there are few pathways to 2°C that do not rely on negative emissions, 1.5°C scenarios are barely conceivable without them. Building on previous assessments of NETs, we identify some urgent research needs to provide a more complete picture for reaching ambitious climate targets, and the role that NETs can play in reaching them.

Carbon balance and management, 2018

Forests and forest products can significantly contribute to climate change mitigation by stabilizing and even potentially decreasing the concentration of carbon dioxide (CO) in the atmosphere. Harvested wood products (HWP) represent a common widespread and cost-efficient opportunity for negative emissions. After harvest, a significant fraction of the wood remains stored in HWPs for a period that can vary from some months to many decades, whereas atmospheric carbon (C) is immediately sequestered by vegetation re-growth. This temporal mismatch between oxidation of HWPs and C uptake by vegetation generates a net sink that lasts over time. The role of temporary carbon storage in forest products has been analysed and debated in the scientific literature, but detailed bottom-up studies mapping the fate of harvested materials and quantifying the associated emission profiles at national scales are rare. In this work, we quantify the net CO emissions and the temporary carbon storage in fores...

Frontiers in Energy Research

Support for the adoption of climate change mitigation measures in low-income regions depends on how such activities contribute to generating household income and gaining confidence from the local community. The planning of mitigation measures or pro-environmental activities need to consider the cost of deployment, customization of activities according to local conditions, and socio-cultural background and perceptions of people. This paper analyses the incentive induced “agroforestry” or “planting trees in farmland” as part of the Carbon Neutral Programme supported by the Government of Kerala in Meenangadi Grama Panchayath, Wayanad district. An increase in tree cover is proposed as a strategy for increasing carbon sequestration. Planting more trees in farmland (except grain cultivated areas) along with crops, according to farmers, may reduce crop yield and discourage farmers’ participation. The Government of Kerala put forward the concept of a tree banking/tree incentive program to a...

Nature Climate Change, 2016

T he ultimate objective of the United Nations Framework Convention on Climate Change (UNFCCC) is to "prevent dangerous anthropogenic interference with the climate system" 1. This objective can be operationalized by, for example, expressing 'dangerous anthropogenic interference' (DAI) in terms of a global long-term temperature goal (LTTG). However, this translation depends on world-views; on political, legal and other value judgements; and on continuous evaluation 2. Scientific assessments, such as those by the IPCC, are not in the position to recommend specific levels of warming or greenhouse gas (GHG) concentrations. Nevertheless, they provide essential information for science-based political decisions by outlining the impacts, risks and vulnerabilities, as well as technological, economic and feasibility assessments associated with different goals 2. Here we reflect on science and policy aspects relating to the temperature and mitigation goals of the Paris Agreement 3. First, we give a short history of the emergence of 1.5 °C and 2 °C as limits in the policy debate followed by an overview of the current understanding of the differences in impact indicators between these two warming levels. We then examine the mitigation architecture of the Paris Agreement and how it is designed to progressively increase mitigation ambition to meet its global LTTG. In this context, we assess characteristics of emission pathways from the scientific literature. Finally, we outline implications for technological requirements and near-term action, and discuss elements of a post-Paris science agenda. A short history of temperature goals The adoption of the LTTG in the Paris Agreement stems from a long-standing climate policy debate. In 1996, the EU Environment Council was first to identify a global mean temperature (GMT) increase of 2 °C above pre-industrial levels as a limit not to be exceeded, based on the IPCC's Second Assessment Report 4. This was subsequently confirmed by EU heads of government in 2005 and 2007 4 , mainly informed by the IPCC's Third Assessment

Frontiers in climate, 2022

Negative erosion and negative emissions: Combining multiple land-based carbon dioxide removal techniques to rebuild fertile topsoils and enhance food production. Front. Clim. :. doi: .

RSC Advances, 2023

The increasing concentration of carbon dioxide (CO 2) in the atmosphere has compelled researchers and policymakers to seek urgent solutions to address the current global climate change challenges. In order to keep the global mean temperature at approximately 1.5°C above the preindustrial era, the world needs increased deployment of negative emission technologies. Among all the negative emissions technologies reported, direct air capture (DAC) is positioned to deliver the needed CO 2 removal in the atmosphere. DAC technology is independent of the emissions origin, and the capture machine can be located close to the storage or utilization sites or in a location where renewable energy is abundant or where the price of energy is low-cost. Notwithstanding these inherent qualities, DAC technology still has a few drawbacks that need to be addressed before the technology can be widely deployed. As a result, this review focuses on emerging trends in direct air capture (DAC) of CO 2 , the main drivers of DAC systems, and the required development for commercialization. The main findings point to undeniable facts that DAC's overall system energy requirement is high, and it is the main bottleneck in DAC commercialization.

Energies, 2021

According to EU goals and the Paris Agreement, an urgent need exists for reducing CO2 emissions while still securing energy supply. Thus, the timely deployment of carbon capture and storage (CCS) is seemingly unavoidable, especially for the cement and steel industries. However, diverse perceptions of CCS among stakeholders such as experts, politicians, and laypeople exist that could hinder the deployment of the technology. Hence, it is worthwhile to recognise these diverse perceptions and their roots. In the studies on risk perceptions, the emphasis has been mostly on the public, as well as factors that influence the public, such as knowledge dissemination and trust. Although these are crucial elements, they are not enough to explain the complexity of risk perceptions. In contrast to the mainstream research, this paper hypothesises that both laypeople and experts are affected by common cultural denominators, therefore, might have similar patterns of risk perceptions. This research s...

Cambridge Review of International Affairs, 2020

An apocalyptic zeitgeist infuses global life, yet this is only minimally reflected in International Relations (IR) debates about the future of world order and implications of climate change. Instead, most approaches within these literatures follow what I call a "continuationist" bias, which assumes that past trends of economic growth and intercapitalist competition will continue indefinitely into the future. I identify three key reasons for this assumption: 1) a lack of engagement with evidence that meeting the Paris Agreement targets is incompatible with continuous economic growth; 2) an underestimation of the possibility that failure to meet these targets will unleash irreversible tipping points in the earth system, and 3) limited consideration of the ways climate change will converge with economic stagnation, financial instability, and food system vulnerabilities to intensify systemic risks to the global economy in the near-term and especially later this century. I argue that IR scholars should therefore explore the potential for "post-growth" world orders to stabilize the climate system, consider how world order may adapt to a three or four degree world if Paris Agreement targets are exceeded, and investigate the possible dynamics of global "collapse" in case runaway climate change overwhelms collective adaptation capacities during this century.

Climatic Change, 2020

This paper explores the potential role of bioenergy coupled to carbon dioxide (CO 2) capture and storage (BECCS) in long-term global scenarios. We first validate past insights regarding the potential use of BECCS in achieving climate goals based on results from 11 integrated assessment models (IAMs) that participated in the 33rd study of the Stanford Energy Modeling Forum (EMF-33). As found in previous studies, our results consistently project large-scale cost-effective BECCS deployment. However, we also find a strong synergistic nexus between CCS and biomass, with bioenergy the preferred fuel for CCS as the climate constraint increases. Specifically, the share of bioenergy that is coupled to CCS technologies increases since CCS effectively enhances the emissions mitigation capacity of bioenergy. For the models that include BECCS technologies across multiple sectors, there is significant deployment in conjunction with liquid fuel or hydrogen production to decarbonize the transportation sector. Using a wide set of scenarios, we find carbon removal to be crucial to achieving goals consistent with 1.5°C warming. However, we find earlier BECCS deployment but not necessarily greater use in the long-term since ultimately deployment is limited by economic competition with other carbon-free technologies, especially in the electricity sector, by land-use competition (especially with food) affecting biomass feedstock availability and price, and by carbon storage limitations. The extent of BECCS deployment varies based on model assumptions, with BECCS deployment competitive in some models below carbon prices of 100 US$/tCO 2. Without carbon removal, 2°C is infeasible in some models, while those that solve find similar levels of bioenergy use but substantially greater mitigation costs. Overall, the paper provides needed transparency regarding BECCS' role, and results highlight a strong nexus between bioenergy and CCS, and a large reliance on not-yet-commercial BECCS technologies for achieving climate goals. Keywords Bioenergy. Negative emissions. Carbon capture and storage. CCS. BECCS. Carbon dioxide removal. Integrated assessment. Model comparison. EMF

PLOS Climate

Carbon dioxide removal (CDR) has become a focal point for legislators and policymakers who are pursuing strategies for climate change mitigation. This paper employs a policy framework of collective biophysical need to examine two broad categories of CDR methods being subsidized and advanced by the United States and other countries: mechanical capture and biological sequestration. Using published data on these methods, we perform a biophysical input-outcome analysis, focusing on the U.S., and compare methods on the basis of three criteria: effectiveness at net carbon removal, efficiency at a climate-relevant scale, and beneficial and adverse co-impacts. Our findings indicate that biological methods have a superior return on resource inputs in comparison to mechanical methods. Biological methods are both more effective and more resource efficient in achieving a climate-relevant scale of CO2 removal. Additionally, the co-impacts of biological methods are largely positive, while those o...

PLOS Biology, 2023

AU : Pleaseconfirmthatallheadinglevelsarerepresentedcorrectly: Antarctic terrestrial biodiversity faces multiple threats, from invasive species to climate change. Yet no large-scale assessments of threat management strategies exist. Applying a structured participatory approach, we demonstrate that existing conservation efforts are insufficient in a changing world, estimating that 65% (at best 37%, at worst 97%) of native terrestrial taxa and land-associated seabirds are likely to decline by 2100 under current trajectories. Emperor penguins are identified as the most vulnerable taxon, followed by other seabirds and dry soil nematodes. We find that implementing 10 key threat management strategies in parallel, at an estimated present-day equivalent annual cost of US$23 million,

Frontiers in Forests and Global Change

Several key international policy frameworks involve forests, including the Paris Agreement on Climate Change and the Convention on Biological Diversity (CBD). However, rules and guidelines that treat forest types equally regardless of their ecosystem integrity and risk profiles in terms of forest and carbon loss limit policy effectiveness and can facilitate forest degradation. Here we assess the potential for using a framework of ecosystem integrity to guide policy goals. We review the theory and present a conceptual framework, compare elements of integrity between primary and human-modified forests, and discuss the policy and management implications. We find that primary forests consistently have higher levels of ecosystem integrity and lower risk profiles than human-modified forests. This underscores the need to protect primary forests, develop consistent large-scale data products to identify high-integrity forests, and operationalize a framework of ecosystem integrity. Doing so w...

Science and Technology for Energy Transition

Bioenergy with Carbon Capture and Storage (BECCS) is a negative emissions technology that allows the removal of CO2 from the atmosphere while producing energy or goods. This technology has been increasingly pictured as key to reaching the Paris Agreement targets. But with only a few demonstration projects currently in operation, its deployment is far from projected. The large-scale deployment of BECCS is hindered by economic, social, and environmental barriers that have been subject to an increasing number of studies. As most research on BECCS tends to adopt a central planning perspective, the barriers related to strategic interactions and coordination issues within the BECCS value chain are often overlooked. Based on a systematic literature review, we identify coordination-related challenges for BECCS deployment. We describe three challenges to BECCS deployment that should be further examined through the lens of coordination: (i) trading biomass and ensuring its sustainability; (ii...

Communications Earth & Environment

Natural revegetation, afforestation, and lignocellulosic crops for bioenergy, possibly coupled with a developing technology like carbon capture and storage, are the most common land-based climate change mitigation options. However, they can compete for land and threaten food security or nature conservation. Using abandoned cropland for their deployment can minimize these risks, but associated potentials are unclear. Here, we compare alternative land-based mitigation options by integrating historical and future (up to 2050) abandoned cropland with site-specific biomass yields and life-cycle emissions. Considering natural revegetation in biodiversity priority areas and different measures in the remaining land can achieve a mitigation potential of 0.8–4.0 GtCO2-equivalents yr−1 (2–11% of 2021 global CO2 emissions). Afforestation generally provides larger climate benefits than bioenergy, but bioenergy with carbon capture and storage delivers the highest mitigation in most locations. Ove...

CATENA, 2021

The Mediterranean mountainous landscapes have undergone large-scale exploitation for millennia. In the Central Pyrenees, land abandonment has occurred since the 1950s, leading to a process of woody encroachment. The main objective of this paper is to shed light on the effects of different land use and land covers (LULCs) on soil organic carbon (SOC) and nitrogen (N) stocks, and on the composition of soil organic matter (SOM) after land abandonment in the Central Pyrenees. Five LULCs (8 specific sites) were selected through detailed land use change mapping. Soil and litter samples (n = 160) were collected and analyzed, including Tetramethylammonium hydroxide pyrolysis-gas chromatography. Organic carbon (Corg)/N ratios, Carbon Preference Index and Average Chain Length indices were calculated based on the distribution of fatty acids in order to determine the molecular composition and degradation of SOM. The results showed: (i) an increase in the dominance index and forest cover, at the expense of shrublands and agricultural fields, and a decrease in Shannon's Diversity and Evenness indexes; (ii) LULC and depth had significant effects on SOC and N contents and stocks; (iii) SOC and N contents and stocks were higher in the meadows and young forests; (iv) significant differences were observed between meadows and young forests and the first stages of land abandonment considering the soil profile; (v) total decomposition of lignins and an omnipresence of unsaturated and saturated straight-chain fatty acids; and (vi) Corg/N values indicate that the origin of SOM is microbial. This study confirms that SOC accumulation after abandonment is a slow process, and the first stages of the woody encroachment decrease SOC stocks. Woody encroachment should be managed with measures based on scientific knowledge, but also considering the historic adaptation of agro-pastoral activities to the environment to ensure the proper functioning of ecosystem services and promote SOC storage in Mediterranean mountain soils.

Energies

Bioenergy with Carbon Capture and Storage (BECCS) technologies are fundamental to reach negative CO2 emissions by removing it from the atmosphere and storing it underground. A promising solution to implement BECCS is pressurized Chemical Looping Combustion (CLC), which involves coupling a pressurized CLC reactor system to a turboexpander. The typical configuration chosen is to have an air reactor and a fuel reactor based on coupled circulating fluidized beds. The fluidization regime in both reactors is preferred to be fast fluidization to enhance gas particle contact and solids circulation among reactors. To design the two reactors, Aspen Plus software was used, given that the new version has a module for fluidized bed modeling. At first, the oxygen carrier was designed ex novo, but given that it is a composite compound mainly made by nickel oxide freeze-granulated on alumina (Ni40Al-FG), the molecular structure has been inserted in Aspen Plus. Then, based on the power of the gas tu...

Sustainability

Carbon capture and storage (CCS) is an essential greenhouse gas removal (GGR) technology used to achieve negative emissions in bioenergy plants using biomass feedstock (Bio-CCS). In this study, the climate mitigation potential of a novel GGR technology consisting in the production of renewable-derived plastics from municipal solid waste (MSW) refuse has been evaluated. This novel GGR technology allows for carbon storage, for variable periods, in stable materials (plastics), and thus overcomes the technical limitations of CCS. A time-dependent carbon cycle assessment has been conducted based on the Absolute Global surface Temperature change Potential (AGTP) metric. This new method to assess carbon emissions is presented against a traditional life cycle assessment (LCA). The production of renewable-derived plastics proves to be an effective GGR technology for both landfill- and incineration-dominant countries in Europe. The results obtained encourage the implementation of renewable-de...

Forests, 2018

We simulated Austrian forests under different sustainable management scenarios. A reference scenario was compared to scenarios focusing on the provision of bioenergy, enhancing the delivery of wood products, and reduced harvesting rates. The standing stock of the stem biomass, carbon in stems, and the soil carbon pool were calculated for the period 2010–2100. We used the forest growth model Câldis and the soil carbon model Yasso07. The wood demand of all scenarios could be satisfied within the simulation period. The reference scenario led to a small decrease of the stem biomass. Scenarios aiming at a supply of more timber decreased the standing stock to a greater extent. Emphasizing the production of bioenergy was successful for several decades but ultimately exhausted the available resources for fuel wood. Lower harvesting rates reduced the standing stock of coniferous and increased the standing stock of deciduous forests. The soil carbon pool was marginally changed by different ma...

Nature, 2018

The United Nations' Paris Agreement includes the aim of pursuing efforts to limit global warming to only 1.5 °C above pre-industrial levels. However, it is not clear what the resulting climate would look like across the globe and over time. Here we show that trajectories towards a '1.5 °C warmer world' may result in vastly different outcomes at regional scales, owing to variations in the pace and location of climate change and their interactions with society's mitigation, adaptation and vulnerabilities to climate change. Pursuing policies that are considered to be consistent with the 1.5 °C aim will not completely remove the risk of global temperatures being much higher or of some regional extremes reaching dangerous levels for ecosystems and societies over the coming decades.

Energies

In these last decades, especially after the Russia–Ukraine war, the impact of energy related to issues, such as energy poverty, energy transition, and energy security have been heavily debated. To comprehend the conceptual development of this subject in the academic literature, few studies tackle the problems above by reviewing earlier research on the subject. Inspired by this interest and literature ago in this field, this study aimed to address the past, present, and future advancements of critical issues in this regard. Thus, in this review paper performed during February–April 2023, we employed the PRISMA method selecting and checking the review papers articles indexed in the three databases of Web of Science (WoS), Scopus, and JSTOR. Then, the research was followed by extending it and adding some other articles discovered on the gray literature. After a detailed classification of articles, a total of 2615 review articles were deemed valid for this analysis. The study’s key cont...

Nature Communications, 2019

A major uncertainty in the land carbon cycle is whether symbiotic nitrogen fixation acts to enhance the tropical forest carbon sink. Nitrogen-fixing trees can supply vital quantities of the growth-limiting nutrient nitrogen, but the extent to which the resulting carbon–nitrogen feedback safeguards ecosystem carbon sequestration remains unclear. We combine (i) field observations from 112 plots spanning 300 years of succession in Panamanian tropical forests, and (ii) a new model that resolves nitrogen and light competition at the scale of individual trees. Fixation doubled carbon accumulation in early succession and enhanced total carbon in mature forests by ~10% (~12MgC ha−1) through two mechanisms: (i) a direct fixation effect on tree growth, and (ii) an indirect effect on the successional sequence of non-fixing trees. We estimate that including nitrogen-fixing trees in Neotropical reforestation projects could safeguard the sequestration of 6.7 Gt CO2 over the next 20 years. Our res...

Biology Letters, 2017

Negative emission technologies (NETs) target the removal of carbon dioxide (CO 2 ) from the atmosphere, and are being actively investigated as a strategy to limit global warming to within the 1.5–2°C targets of the 2015 UN climate agreement. Enhanced silicate weathering (ESW) proposes to exploit the natural process of mineral weathering for the removal of CO 2 from the atmosphere. Here, we discuss the potential of applying ESW in coastal environments as a climate change mitigation option. By deliberately introducing fast-weathering silicate minerals onto coastal sediments, alkalinity is released into the overlying waters, thus creating a coastal CO 2 sink. Compared with other NETs, coastal ESW has the advantage that it counteracts ocean acidification, does not interfere with terrestrial land use and can be directly integrated into existing coastal management programmes with existing (dredging) technology. Yet presently, the concept is still at an early stage, and so two major resear...

Nature plants, 2018

The magnitude of future climate change could be moderated by immediately reducing the amount of COentering the atmosphere as a result of energy generation and by adopting strategies that actively remove COfrom it. Biogeochemical improvement of soils by adding crushed, fast-reacting silicate rocks to croplands is one such CO-removal strategy. This approach has the potential to improve crop production, increase protection from pests and diseases, and restore soil fertility and structure. Managed croplands worldwide are already equipped for frequent rock dust additions to soils, making rapid adoption at scale feasible, and the potential benefits could generate financial incentives for widespread adoption in the agricultural sector. However, there are still obstacles to be surmounted. Audited field-scale assessments of the efficacy of COcapture are urgently required together with detailed environmental monitoring. A cost-effective way to meet the rock requirements for COremoval must be ...

Environmental Research Letters, 2016

Communications Earth & Environment

Both carbon dioxide uptake and albedo of the land surface affect global climate. However, climate change mitigation by increasing carbon uptake can cause a warming trade-off by decreasing albedo, with most research focusing on afforestation and its interaction with snow. Here, we present carbon uptake and albedo observations from 176 globally distributed flux stations. We demonstrate a gradual decline in maximum achievable annual albedo as carbon uptake increases, even within subgroups of non-forest and snow-free ecosystems. Based on a paired-site permutation approach, we quantify the likely impact of land use on carbon uptake and albedo. Shifting to the maximum attainable carbon uptake at each site would likely cause moderate net global warming for the first approximately 20 years, followed by a strong cooling effect. A balanced policy co-optimizing carbon uptake and albedo is possible that avoids warming on any timescale, but results in a weaker long-term cooling effect.

Energy & Environmental Science, 2022

This comprehensive review appraises the state-of-the-art in direct air capture materials, processes, economics, sustainability, and policy, to inform, challenge and inspire a broad audience of researchers, practitioners, and policymakers.

Nature Climate Change, 2017

Here we describe how the treatment of agriculture has evolved over the course of the IPCC, as tracked across the five Assessment Reports (ARs). From the First (in 1990) to the Fifth (in 2013/14) IPCC Assessment Report, both the level of detail and quantification of the impacts and adaptation, and mitigation potential of the agriculture sector has grown enormously, reflecting the almost exponential increase in available literature on the topic. For example, using the search terms '(agriculture or ghg or greenhouse gas) and climate and mitigation' for mitigation, '(agriculture or ghg or greenhouse gas) and climate and (adaptation or impact)' for adaptation and impacts, about 600 and 1800 papers were published on the Web of Knowledge (WoK) database in 2016, compared with 0 and 7 papers in 1990, for mitigation and impacts/adaptation, respectively.

GCB Bioenergy, 2018

Scientific Reports, 2018

Non-food biomass production is developing rapidly to fuel the bioenergy sector and substitute dwindling fossil resources, which is likely to impact land-use patterns worldwide. Recent publications attempting to factor this effect into the climate mitigation potential of bioenergy chains have come to widely variable conclusions depending on their scope, data sources or methodology. Here, we conducted a first of its kind, systematic review of scientific literature on this topic and derived quantitative trends through a meta-analysis. We showed that second-generation biofuels and bioelectricity have a larger greenhouse gas (GHG) abatement potential than first generation biofuels, and stand the best chances (with a 80 to 90% probability range) of achieving a 50% reduction compared to fossil fuels. Conversely, directly converting forest ecosystems to produce bioenergy feedstock appeared as the worst-case scenario, systematically leading to negative GHG savings. On the other hand, convert...

Global Environmental Politics, 2020

Most scenarios that achieve present climate targets of limiting global heating to 1.5°-2.0°C rely on large-scale carbon dioxide removal (CDR) to drive net emissions negative after mid-century. Scenarios that overshoot and return to a future temperature target, or that aim to restore some prior climate, require CDR to be rapidly deployed, operated for a century or so, then greatly reduced or phased out. This need for future phasedown presents challenges to near-term policies that have been underexamined. A CDR enterprise of climate-relevant scale will require financial flows of billions to trillions of dollars per year. The enterprise and supporting policies will create risks of lock-in via mobilized actors whose interests favor continuance as well as other mechanisms. The future phasedown need implies suggestive guidance for near-term decisions about removal methods and design of associated policy and business environments. First, variation among methods' scale constraints and cost structures suggests a rough ordering of methods by severity of future phasedown challenges. Second, of the three potential means to motivate removals-profitable products incorporating removed carbon, extended emissionspricing policies, or public procurement contracts-public procurement appears to present the fewest roadblocks to future phasedown.

Nature Climate Change, 2018

In the framework of the Scenario Model Intercomparison Project 1 (ScenarioMIP) of the Sixth Phase of the Coupled Modelling Intercomparison Project 2 (CMIP6) a total of eight scenarios will be run. Four scenarios are included in Tier 1 of ScenarioMIP and four more in Tier 2. A very low emission scenario with forcing significantly below 2.6 Wm-2 is part of Tier 2. Based on the scenario results presented in this paper, a first selection of two candidates has been proposed initially: the marker implementations of SSP1-1.9 and SSP2-1.9, each with their particular characteristics (see Suppl. Material "ScenarioMIP Proposal"). Based on this information, the ScenarioMIP Scientific Steering Committee selected the SSP1-1.9 scenario for inclusion as the very low emission scenario in ScenarioMIP. Supplementary Text 2: Feasibility of scenarios in models Under the scenario protocol for this study, modelling frameworks attempted to limit total anthropogenic radiative forcing by 2100 to 1.9 Wm-2 (within rounding precision), by globally adjusting a CO2-equivalent carbon price. In several cases models were not able to provide a scenario under this stringent forcing constraint (see Supplementary Table 1). In such cases, the scenario is referred as an "infeasible" scenario in the model. "Feasibility" or "infeasibility" of scenarios in models is determined in different ways, depending on the modelling framework.

Nature, 2019

Environmental Research Letters, 2021

Climate science provides strong evidence of the necessity of limiting global warming to 1.5 °C, in line with the Paris Climate Agreement. The IPCC 1.5 °C special report (SR1.5) presents 414 emissions scenarios modelled for the report, of which around 50 are classified as ‘1.5 °C scenarios’, with no or low temperature overshoot. These emission scenarios differ in their reliance on individual mitigation levers, including reduction of global energy demand, decarbonisation of energy production, development of land-management systems, and the pace and scale of deploying carbon dioxide removal (CDR) technologies. The reliance of 1.5 °C scenarios on these levers needs to be critically assessed in light of the potentials of the relevant technologies and roll-out plans. We use a set of five parameters to bundle and characterise the mitigation levers employed in the SR1.5 1.5 °C scenarios. For each of these levers, we draw on the literature to define ‘medium’ and ‘high’ upper bounds that deli...

Energy Sources Part B-economics Planning and Policy, 2020

Separations

CO2 capture from air is crucial in achieving negative emissions. Based on conventional or newly developed high-enriching processes, we investigated the rough enrichment of CO2 from air via an externally heated or cooled adsorber (temperature-swing adsorption, TSA), along with air purge using double-pipe heat exchangers packed with low-volatility polyamine-loaded silica. A simple adsorption–desorption cycle was attempted in a TSA experiment, by varying the temperature from 20 °C to 60 °C using moist air, yielding an average CO2 concentration of product gas that was ~17 times higher than the feed air, but the CO2 recovery rate was poor. A double-step adsorption process was applied to increase CO2 adsorption and recovery simultaneously. In this process, substantial-CO2-concentration gas was used as the product gas, and the remaining gas was used as the reflux feed gas for adsorber. This method can provide a product gas with ~100 times higher CO2 concentration than raw gas, with a recov...

Nature Energy, 2017

The Paris Agreement provides an international framework aimed at limiting average global temperature rise to well below 2°C, implemented through actions determined at the national level. As the Agreement necessitates a 'net-zero' emissions energy system prior to 2100, decarbonisation analyses in support of national climate policy should consider the post-2050 period. Focusing solely on mitigation objectives for 2030 or 2050 could lead to blindsiding of the challenge, inadequate ambition in the near term, and poor investment choices in energy infrastructure. Here we show, using the UK as an example, that even an ambitious climate policy is likely to fall short of the challenge of net-zero, and that analysis of the post-2050 period is therefore critical. We find that the analysis of detailed, longer term national pathways which achieve net-zero is important for future reassessment of ambition under Nationally Determined Contributions (NDCs). Global ambition to limit anthropogenic warming to 2°C requires a radical transformation of the energy system to one that produces 'net-zero' GHG emissions before 2100 1. For a 1.5°C limit, action has to be even more rapid, with net-zero emissions achieved much earlier 2. The goal of net-zero GHG emissions is expressed in the Paris Agreement as a system that achieves 'a balance between anthropogenic emissions by sources and removals by sinks' 3. In

Nature Communications, 2018

Current mitigation efforts and existing future commitments are inadequate to accomplish the Paris Agreement temperature goals. In light of this, research and debate are intensifying on the possibilities of additionally employing proposed climate geoengineering technologies, either through atmospheric carbon dioxide removal or farther-reaching interventions altering the Earth’s radiative energy budget. Although research indicates that several techniques may eventually have the physical potential to contribute to limiting climate change, all are in early stages of development, involve substantial uncertainties and risks, and raise ethical and governance dilemmas. Based on present knowledge, climate geoengineering techniques cannot be relied on to significantly contribute to meeting the Paris Agreement temperature goals.

Geoderma, 2021

We compiled information from different sources in order to establish a comprehensive map of the stock of soil organic carbon (SOC) in the upper 30 cm under different forms of land use for Austria. The information serves as a baseline for the evaluation of the potential of climate-change mitigation measures. SOC sequestration plays an important role in the discussion of terrestrial carbon (C) sinks and the size of the SOC pool is one of several quality measures for crop production and the national and regional food security. The baseline serves also for the evaluation of the effectiveness of adaptive land management in order to cope with climate change. Austrian croplands, grasslands, forests, and settlements contain 300 Mt SOC. Peatlands have the highest SOC density (220 t C/ha), yet cover only about 2% of the country. Forest soils store 106 t C/ha and comprise the largest pool due to the coverage of more than 4 Mha (48% of the country). Intensively and extensively managed grasslands cover 0.8 Mha (10%) and contain between 91 and 113 t C/ha, and cropland on 1.28 Mha (15%) hold on average 62 t C/ha. Due to the geographic heterogeneity of Austria with respect to climatic conditions, geology and soils, and topography the regional differences in SOC stocks are large. Measures to increase the SOC stock in cropland have been applied for 25 years within agri-environmental and climate-smart strategies. An increase of the total SOC pool is expected due to the afforestation and reforestation of marginal agricultural land and to a smaller extent due to the restoration of peatlands. A decline of the SOC stock is a consequence of land development for settlements and infrastructure.

Soil Systems, 2022

Repeated soil surveys provide opportunities to quantify the effect of long-term environmental change. In recent decades, the topics of forest soil acidification as a consequence of acidic deposition, the enrichment of forest ecosystems with nitrogen, and the loss of carbon due to climate change have been discussed. We used two forest soil surveys that were 20 years apart, in order to establish the direction and magnitude of changes in soil carbon, nitrogen, and soil acidity. Soils have been initially sampled in the late 1980s. The plots were revisited twenty years later. Archived soil samples from the first survey were reanalyzed with the same protocol as the new samples. We found changes in the stocks of soil organic carbon, soil nitrogen, and soil pH. However, the changes were inconsistent. In general, as many sites have gained soil organic carbon, as sites have lost carbon. Most soils have been slightly enriched with nitrogen. The soil pH has not changed significantly. We conclud...

Environmental Research Letters, 2016

Simulating the Earth system response to negative emissions C D Jones, P Ciais, S J Davis et al. Detlef P van Vuuren, Heleen van Soest, Keywan Riahi et al. Global economic consequences of deploying bioenergy with carbon capture and storage (BECCS)

Global Environmental Change, 2021

Greenhouse gas removal (GGR) approaches are considered essential in several projections to meet the climate mitigation ambition of the Paris Agreement. Biomass Energy with Carbon Capture and Storage (BECCS) and afforestation are included extensively in mitigation scenarios but there are concerns about the feasibility of these approaches. This was explored with stakeholders from industry, non-governmental organisations (NGOs) and policy who were involved in interviews and a one-day participatory workshop. Multicriteria mapping (MCM) methodology was used to appraise the 'real-world' feasibility of four specific greenhouse gas removal supply chains at a granular level in the UK context. The MCM analysis shows that afforestation performs better in comparison to three BECCS supply chains, on criteria such as business model, social acceptability, and environmental sustainability. This innovative application of the MCM methodology enables the abstract representations of GGR in integrated assessment models to be explored at a more granular level through a supply chain analysis and thus gain a deeper understanding of the issues facing these approaches. The data gathered allows a wide range of technical, environmental, social and political criteria to be systematically applied in appraising the practical performance of different future implementation options for afforestation and BECCS. If these GGR supply chains are to become a reality on the scale required for 1.5 • C global warming, factors such as global cooperation, land availability, and the longevity of policies and incentives were found to be major challenges.

Global change biology. Bioenergy, 2018

Perennial bioenergy crops have significant potential to reduce greenhouse gas (GHG) emissions and contribute to climate change mitigation by substituting for fossil fuels; yet delivering significant GHG savings will require substantial land-use change, globally. Over the last decade, research has delivered improved understanding of the environmental benefits and risks of this transition to perennial bioenergy crops, addressing concerns that the impacts of land conversion to perennial bioenergy crops could result in increased rather than decreased GHG emissions. For policymakers to assess the most cost-effective and sustainable options for deployment and climate change mitigation, synthesis of these studies is needed to support evidence-based decision making. In 2015, a workshop was convened with researchers, policymakers and industry/business representatives from the UK, EU and internationally. Outcomes from global research on bioenergy land-use change were compared to identify area...

Proceedings of the National Academy of Sciences of the United States of America, 2018

Bioenergy with carbon capture and storage (BECCS) is a negative-emissions technology that may play a crucial role in climate change mitigation. BECCS relies on the capture and sequestration of carbon dioxide (CO) following bioenergy production to remove and reliably sequester atmospheric COPrevious BECCS deployment assessments have largely overlooked the potential lack of spatial colocation of suitable storage basins and biomass availability, in the absence of long-distance biomass and COtransport. These conditions could constrain the near-term technical deployment potential of BECCS due to social and economic barriers that exist for biomass and COtransport. This study leverages biomass production data and site-specific injection and storage capacity estimates at high spatial resolution to assess the near-term deployment opportunities for BECCS in the United States. If the total biomass resource available in the United States was mobilized for BECCS, an estimated 370 Mt CO⋅yof negat...

Heliyon, 2020

Existing mitigation strategies to reduce greenhouse gas (GHG) emissions are inadequate to reach the target emission reductions set in the Paris Agreement. Hence, the deployment of negative emission technologies (NETs) is imperative. Given that there are multiple available NETs that need to be evaluated based on multiple criteria, there is a need for a systematic method for ranking and prioritizing them. Furthermore, the uncertainty in estimating the techno-economic performance levels of NETs is a major challenge. In this work, an integrated model of fuzzy analytical hierarchy process (AHP) and interval-extended Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is proposed to address the multiple criteria, together with data uncertainties. The potential of NETs is assessed through the application of this hybrid decision model. Sensitivity analysis is also conducted to evaluate the robustness of the ranking generated. The result shows Bioenergy with Carbon Capture and Storage (BECCS) as the most optimal alternative for achieving negative emission goals since it performed robustly in the different criteria considered. Meanwhile, energy requirement emerged as the most preferred or critical criterion in the deployment of NETs based on the decision-maker. This paper renders a new research perspective for evaluating the viability of NETs and extends the domains of the fuzzy AHP and interval-extended TOPSIS hybrid model.

Nature Communications

Using engineered wood for construction has been discussed for climate change mitigation. It remains unclear where and in which way the additional demand for wooden construction material shall be fulfilled. Here we assess the global and regional impacts of increased demand for engineered wood on land use and associated CO2 emissions until 2100 using an open-source land system model. We show that if 90% of the new urban population would be housed in newly built urban mid-rise buildings with wooden constructions, 106 Gt of additional CO2 could be saved by 2100. Forest plantations would need to expand by up to 149 Mha by 2100 and harvests from unprotected natural forests would increase. Our results indicate that expansion of timber plantations for wooden buildings is possible without major repercussions on agricultural production. Strong governance and careful planning are required to ensure a sustainable transition to timber cities even if frontier forests and biodiversity hotspots are...

The British Journal of Politics and International Relations, 2019

The distinction between subsistence emissions and luxury emissions was originally devised in 1992 to guard people so poor as to be able to afford only fossil fuels from being priced out of energy by market mechanisms like cap-and-trade that were proposed to assist with limiting climate change. Non-carbon energy can now be made as affordable and accessible as fossil fuel, but tensions remain between measures to support sustainable development and measures to control climate change. Consequently, the distinction between subsistence energy and luxury energy continues to be surprisingly relevant to current international political struggles. The most fully justified method for normative assessment of Nationally Determined Contributions under the Paris Agreement, the Climate Equity Reference Framework, presupposes the distinction. Normative evaluation of the choice between maximally ambitious ratcheting-up of Nationally Determined Contributions in the immediate future and lazy reliance up...

Geoscientific Model Development, 2018

The recent IPCC reports state that continued anthropogenic greenhouse gas emissions are changing the climate, threatening "severe, pervasive and irreversible" impacts. Slow progress in emissions reduction to mitigate climate change is resulting in increased attention to what is called geoengineering, climate engineering, or climate intervention -deliberate interventions to counter climate change that seek to either modify the Earth's radiation budget or remove greenhouse gases such as CO 2 from the atmosphere. When focused on CO 2 , the latter of these categories is called carbon dioxide removal (CDR). Future emission scenarios that stay well below 2 • C, and all emission scenarios that do not exceed 1.5 • C warming by the year 2100, require some form of CDR. At present, there is little consensus on the climate impacts and atmospheric CO 2 reduction efficacy of the different types of proposed CDR. To address this need, the Carbon Dioxide Removal Model Intercomparison Project (or CDRMIP) was initiated. This project brings together models of the Earth system in a common framework to explore the potential, impacts, and challenges of CDR. Here, we describe the first set of CDRMIP experiments, which are formally part of the 6th Coupled Model Intercomparison Project (CMIP6). These experiments are designed to address questions concerning CDR-induced climate "reversibility", the response of the Earth system to direct atmospheric CO 2 removal (direct air capture and storage), and the CDR potential and impacts of afforestation and reforestation, as well as ocean alkalinization.

Biomass & Bioenergy, 2023

Softwood and organosolv lignin were pyrolized in a fluidized bed reactor. In each case, fractional condensation was achieved through two cyclonic condensers, maintained at different temperatures, and separated by an electrostatic precipitator. The produced oil was analyzed for liquid yield, water content, acidity, calorific value, carbon-hydrogen-nitrogen-oxygen content, viscosity, and rheology. To assess the effects of aging on the quality of the bio-oil, these tests were repeated after one-, two-, three-and nine-month intervals. The organosolv lignin is found to provide lower oil yields (30%) than softwood (50%). It is shown that higher carbon and lower oxygen content in the feedstock correlates to better bio-oil quality. Lignin, with a higher carbon and lower oxygen content than softwood, results in bio-oil with less water, lower acidity, higher heating values, and higher dynamic viscosities. Increasing the condensing temperature of the first condenser delays the condensation of water and light organics in the condensing train, affecting the properties of bio-oil, especially for the softwood. Tests on aging of the bio-oil demonstrate that viscosity is the only property significantly affected by the shelf life of the oil. Present data are favorably compared with available published data, for both feedstock types.

Mitigation and Adaptation Strategies for Global Change, 2019

Environmental Chemistry Letters

Rising adverse impact of climate change caused by anthropogenic activities is calling for advanced methods to reduce carbon dioxide emissions. Here, we review adsorption technologies for carbon dioxide capture with focus on materials, techniques, and processes, additive manufacturing, direct air capture, machine learning, life cycle assessment, commercialization and scale-up.