Estimates of future climate based on SRES emission scenarios

Abstract

The preliminary emission scenarios in the Special Report on Emission Scenario (SRES) developed by the Intergovernmental Panel on Climate Change (IPCC), will eventually replace the old IS92 scenarios. By running these scenarios in a simple climate model (SCM) we estimate future temperature increase between 1.7°C and 2.8°C from 1990 to 2100. The global sea level rise over the same period is between 0.33 m and 0.45 m.

Compared to the previous IPCC scenarios (IS92) the SRES scenarios generally results in changes in both development over time and level of emissions, concentrations, radiative forcing, and finally temperature change and sea level rise. The most striking difference between the IS92 scenarios and the SRES scenarios is the lower level of SO2 emissions. The range in CO2 emissions is also expected to be narrower in the new scenarios. The SRES scenarios results in a narrower range both for temperature change and sea level rise from 1990 to 2100 compared to the range estimated for the IS92 scenarios.

Comparison of the B2 scenario with the IS92a scenario show that the effects of lower SO2 emissions will reduce the cooling and result in higher temperature increase in the short run. Near the end of the century this trend is reversed by the effects of the reductions in CO2 emissions earlier in this century, resulting in less temperature increase in B2 than in the old IS92a scenario in 2100.