2007 | IPCC AR4 Climate Change 2007: Synthesis Report

Global warming is now a scientific fact. To limit the warming to a maximum of 2°- 2.4°C, the greenhouse gas emissions of the Annex I countries of the UNFCCC (1992) must be reduced by 25-40% compared to 1990 by 2020.

The temperature increase can only reasonably be limited to 2°C if the concentration of greenhouse gases in the atmosphere stabilises at a maximum of about 450ppm CO2eq.

This report calls for the establishment of a long-term global warming goal.

It forms the basis for The Copenhagen Accord (2009) which states that global warming must be limited to 2°C, given current scientific evidence.