This figure shows climate model predictions for global warming under the SRES A2 emissions scenario relative to global average temperatures in 2000. The A2 scenario is characterized by a politically and socially diverse world that exhibits sustained economic growth but does not address the inequities between rich and poor nations, and takes no special actions to combat global warming or environmental change issues. This world in 2100 is characterized by large population (15 billion), high total energy use, and moderate levels of fossil fuel dependency (mostly coal). At the time of the IPCC Third Assessment Report, the A2 scenario was the most well-studied of the SRES scenarios.
The IPCC predicts global temperature change of 1.4-5.8 degrees C due to global warming from 1990 to 2100 (IPCC 2001a). As evidenced above (a range of 2.5 degrees C in 2100), much of this uncertainty results from disagreement among climate models, though additional uncertainty comes from different emissions scenarios.
