Global average surface temperatures

Fig. 5. Global average surface temperature trend 1850-2000. Scale on y-axis (°C) is indexed to 1970 global average surface temperature. (Adapted from Carbon Dioxide Information Analysis Center 2000.)...

Fig. 1. Global average surface temperatures and atmospheric CO2 levels predicted by models in which CO2 is the only greenhouse gas and the temperature dependence of subaerial silicate weathering is the only effective buffer against changing solar luminosity. One PAL indicates one present atmospheric level of 300 ppm. Curves are labelled by the weathering parameter p (equation (8)). These models are inspired by Walker et al. (1981). Constant CO2 is shown for comparison. Unless silicate weathering is nearly independent of pCQ>2 (P < 0-2), ancient climates are cool.

Observed changes in the global average surface temperature (1850-2005). 

A. Global average temperature of the lowest 8 km of atmosphere has ehanged by + 0.05 0.10 °C per decade but the increase in global average surface temperature has been greater, i.e. by 0.15 0.05 °C per decade. The difference occurs mostly over tropical and sub-tropical regions. ... 

Figure 1.8 (a) Global near-surface temperature averaged over land and ocean,... 

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