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Table |. Terrestrial and marine archives and proxies in southern Africa that cover the Last Glacial Maximum, giving some key example data sets. 'c = carbonate, * o = organic, ? = orbital tuning of Total Inorganic Carbon signal, 5'°O-t* = orbital tuning of oxygen isotope signal, ° corr = correlation of Total Organic Carbon and CaCO3 records with another marine core.

Table 1 |. Terrestrial and marine archives and proxies in southern Africa that cover the Last Glacial Maximum, giving some key example data sets. 'c = carbonate, * o = organic, ? = orbital tuning of Total Inorganic Carbon signal, 5'°O-t* = orbital tuning of oxygen isotope signal, ° corr = correlation of Total Organic Carbon and CaCO3 records with another marine core.

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Figure |. Modern-day climatology in southern Africa. (a) Mean annual rainfall and rainfall regimes and major oceanic surface currents (modified from Gasse et al., 2008). ABF = Angola-Benguela front; DRM = double rainfall maximum; SRZ = summer rainfall zone; YRZ = year-round rainfall zone; WRZ = winter rainfall zone. (b) Subdivision of southern Africa using the regions of Gasse et al. (2008) (I is western Africa north of the ABF; Il is Benguela Coastal Current and Agulhas Zone; Ill is equatorial and tropical East Africa; IV is the summer rainfall domain) and the three axes used by Chase and Meadows (2007) and also showing country outlines. Schematic representation of major atmospheric circulation features over southern Africa in (c) austral winter and (d) austral summer (RH side) (modified from Tyson, 1999, and Gasse et al., 2008).
Figure |. Modern-day climatology in southern Africa. (a) Mean annual rainfall and rainfall regimes and major oceanic surface currents (modified from Gasse et al., 2008). ABF = Angola-Benguela front; DRM = double rainfall maximum; SRZ = summer rainfall zone; YRZ = year-round rainfall zone; WRZ = winter rainfall zone. (b) Subdivision of southern Africa using the regions of Gasse et al. (2008) (I is western Africa north of the ABF; Il is Benguela Coastal Current and Agulhas Zone; Ill is equatorial and tropical East Africa; IV is the summer rainfall domain) and the three axes used by Chase and Meadows (2007) and also showing country outlines. Schematic representation of major atmospheric circulation features over southern Africa in (c) austral winter and (d) austral summer (RH side) (modified from Tyson, 1999, and Gasse et al., 2008).
Table 2. Summary of contrasting conceptual climate models for the southern African subcontinent at the LGM (Last Glacial Maximum), and what 1 informed by. 'Palaeoenvironmental data from southern Africa to support these ideas is limited to ocean core evidence for increased upwelling off the SW coast (Giresse et al., 1976), palaeocean temperatures (Burckle and Clarke, 1977; Hays et al., 1974) and a northward shift of the Kalahari desert (Heine, 1978).
Table 2. Summary of contrasting conceptual climate models for the southern African subcontinent at the LGM (Last Glacial Maximum), and what 1 informed by. 'Palaeoenvironmental data from southern Africa to support these ideas is limited to ocean core evidence for increased upwelling off the SW coast (Giresse et al., 1976), palaeocean temperatures (Burckle and Clarke, 1977; Hays et al., 1974) and a northward shift of the Kalahari desert (Heine, 1978).
Figure 3. Palaeoclimatic reconstructions from proxy syntheses. Palaeotemperature patterns: (a) from Partridge (1997) (who also depicts isolines for precipitation as percentage of present); (b) from Gasse et al. (2008), where numbers are estimated anomalies compared to modern (mean and extreme in parentheses). Hydroclimatic patterns (precipitation, or wetter/drier than present), where (c) is two panels from Thomas and Shaw (2002) for time-slices |8—21 ka and 21—23 ka, where horizontal lines represent dune construction, and vertical lines represent calcrete formation (d) from Chase and Meadows (2007) showing a spatial interpolation of sites with evidence for wetter or drier conditions than present at 24—18 ka (panels illustrate that the broad spatial pattern is largely insensitive to excluding proxies that have been highlighted as having questionable reliability — see details in Chase and Meadows, 2007), (e) from Gasse et al. (2008) where AMAP and AP-E are difference in mean annual precipitation and precipitation minus evaporation between the LGM (23-19 ka) and present, where numbers are estimated anomalies compared to modern (mean and extreme and parentheses), see the online colour version for depiction of sites representing wetting (blue) and drying (red).
Figure 3. Palaeoclimatic reconstructions from proxy syntheses. Palaeotemperature patterns: (a) from Partridge (1997) (who also depicts isolines for precipitation as percentage of present); (b) from Gasse et al. (2008), where numbers are estimated anomalies compared to modern (mean and extreme in parentheses). Hydroclimatic patterns (precipitation, or wetter/drier than present), where (c) is two panels from Thomas and Shaw (2002) for time-slices |8—21 ka and 21—23 ka, where horizontal lines represent dune construction, and vertical lines represent calcrete formation (d) from Chase and Meadows (2007) showing a spatial interpolation of sites with evidence for wetter or drier conditions than present at 24—18 ka (panels illustrate that the broad spatial pattern is largely insensitive to excluding proxies that have been highlighted as having questionable reliability — see details in Chase and Meadows, 2007), (e) from Gasse et al. (2008) where AMAP and AP-E are difference in mean annual precipitation and precipitation minus evaporation between the LGM (23-19 ka) and present, where numbers are estimated anomalies compared to modern (mean and extreme and parentheses), see the online colour version for depiction of sites representing wetting (blue) and drying (red).
able 3. Key numerical model simulation outputs for southern African palaeoclimate (temperature, precipitation and mid-latitude westerlies).
able 3. Key numerical model simulation outputs for southern African palaeoclimate (temperature, precipitation and mid-latitude westerlies).
moistening on the southwest tip (Figure Sa). UGAMP shows no change in winter and a slight drying in the southeast during the summer (Wyrwoll et al., 2000) (Figure 5b). By contrast, the PMIP2 ensemble-mean indicates increases of 0-0.25 mm/d over most of the region and of 0.25—0.5 mm/d in the east, with reductions in precipitation toward the equator (Braconnot et al., 2007a; Figure 5c). Individual PMIP2 model precipitation outputs are not presented by Rojas et al. (2009). Simulation of precipita- tion minus evaporation in NCAR CCM3 yields no change along the west coast, a drying (of 0.1— 0.4 mm/d) in a central southern band and part of the southeast coast, and moistening in Angola, east of Lake Malawi and in northern Madagas- car (Kim et al., 2008; Figure 5d). A HadCM3 simulation testing the hydrological feedback of megalake-Magkadigadi using LGM _ boundary conditions (although the lake high stand is later than the LGM, centred on 19 + 2 ka) indicates a localized increase in both precipi- tation and precipitation minus evaporation (Burrough et al., 2009). Model simulations Namibia and in an arc back up around 30°E (Kim et al., 2008; Figure 4b). Model reconstructions of LGM precipitation patterns are much more variable than those of temperature (Figure 5 shows some exam- ples). This reflects the lower model confidence in simulating precipitation than temperature Braconnot et al., 2012; Solomon et al., 2007), and suggests that regional-scale palaeoclimate simulations using models still have large areas for improvement. The PMIPII and II bench- marking activities seek to investigate whether inclusion of additional components in models (e.g. ice sheets, vegetation, biochemical cycles) improve the simulation of regional climates (Braconnot et al., 2012). Harrison et al. (2013) highlight that while the direction and large- scale gradients of climate change at the LGM and mid-Holocene are depicted fairly well in models, there are limitations to their ability to simulate the amplitude of change and reproduce smaller-scale spatial patterns. The HadAM3 model simulates some drying in the central and eastern part of southern Africa with some
moistening on the southwest tip (Figure Sa). UGAMP shows no change in winter and a slight drying in the southeast during the summer (Wyrwoll et al., 2000) (Figure 5b). By contrast, the PMIP2 ensemble-mean indicates increases of 0-0.25 mm/d over most of the region and of 0.25—0.5 mm/d in the east, with reductions in precipitation toward the equator (Braconnot et al., 2007a; Figure 5c). Individual PMIP2 model precipitation outputs are not presented by Rojas et al. (2009). Simulation of precipita- tion minus evaporation in NCAR CCM3 yields no change along the west coast, a drying (of 0.1— 0.4 mm/d) in a central southern band and part of the southeast coast, and moistening in Angola, east of Lake Malawi and in northern Madagas- car (Kim et al., 2008; Figure 5d). A HadCM3 simulation testing the hydrological feedback of megalake-Magkadigadi using LGM _ boundary conditions (although the lake high stand is later than the LGM, centred on 19 + 2 ka) indicates a localized increase in both precipi- tation and precipitation minus evaporation (Burrough et al., 2009). Model simulations Namibia and in an arc back up around 30°E (Kim et al., 2008; Figure 4b). Model reconstructions of LGM precipitation patterns are much more variable than those of temperature (Figure 5 shows some exam- ples). This reflects the lower model confidence in simulating precipitation than temperature Braconnot et al., 2012; Solomon et al., 2007), and suggests that regional-scale palaeoclimate simulations using models still have large areas for improvement. The PMIPII and II bench- marking activities seek to investigate whether inclusion of additional components in models (e.g. ice sheets, vegetation, biochemical cycles) improve the simulation of regional climates (Braconnot et al., 2012). Harrison et al. (2013) highlight that while the direction and large- scale gradients of climate change at the LGM and mid-Holocene are depicted fairly well in models, there are limitations to their ability to simulate the amplitude of change and reproduce smaller-scale spatial patterns. The HadAM3 model simulates some drying in the central and eastern part of southern Africa with some
Figure 5. Examples of precipitation simulations for the LGM from numerical models. (a) Precipitation change (LGM minus pre-industrial values, divided by pre-industrial) using HadAM3 (Sime et al., 2013); box highlights southern Africa. (b) LGM minus present-day precipitation (mm/day) using UGAMP (Valdes and Hall, 1994) where RH is JJA and LH is DJA (from Wyrwoll et al., 2000). (c) PMIP2 OA (coupled ocean- atmosphere model) ensemble mean precipitation (LGM minus pre-industrial) (mm/day). (d) Annual-mean precipitation minus evaporation (LGM minus modern) in the NCAR CCM3 high-resolution (T 170) model (Kim et al., 2008).
Figure 5. Examples of precipitation simulations for the LGM from numerical models. (a) Precipitation change (LGM minus pre-industrial values, divided by pre-industrial) using HadAM3 (Sime et al., 2013); box highlights southern Africa. (b) LGM minus present-day precipitation (mm/day) using UGAMP (Valdes and Hall, 1994) where RH is JJA and LH is DJA (from Wyrwoll et al., 2000). (c) PMIP2 OA (coupled ocean- atmosphere model) ensemble mean precipitation (LGM minus pre-industrial) (mm/day). (d) Annual-mean precipitation minus evaporation (LGM minus modern) in the NCAR CCM3 high-resolution (T 170) model (Kim et al., 2008).
Related topics:
PalaeoclimatologyPalaeoenvironmentQuaternary GeologyClimate modelingQuaternary environmentsQuaternary geochronology
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