Abstract: The Synthesis Report of the IPCC Fourth Assessment Report (AR4) was launched in Spain on November 17, 2007. The report synthesizes the recent advances in physical sciences, impacts, adaptation and mitigation of climate change by interlinking the greenhouse gas (GHG) emission, atmospheric GHG concentration with surface temperature. The report indicates whether the negative impacts of climate change could be minimized largely depends upon the efforts and investment in global GHG emission control in the future 20 to 30 years. It is urgent for mankind to take prompt actions in reducing the GHG emission. The synthesis report of IPCC AR4 promotes scientific guidance to the social-economy policies made by governments worldwide and the international negotiation regarding climate change.