IPCC WGIIAR5 focused on the climate change related impacts of various sectors and regions in the risk and its management. Based on comprehensive analysis and consideration of risk of climate change-related hazards, exposure and vulnerability, it proposed the framework for assessing risk associated with climate change. Risk may not only come from climate change itself, but also from development and the governance process of the human society. The report identified of a variety of emergent risks that were not previously assessed or recognized, summarized eight kinds of key risks, and evaluated climate change related risk levels of five reasons for concern on the different levels of tempreture rise. Due to limitations of adaptation and mitigation, the residual risk is unavoidable in risk management process. The risk of severe, extensive and irreversible impacts of the human and socio-ecological systems will exacerbate when future global temperature rise in excess of 4 ℃ relative to preindustrial levels.