Assessment of uncertainty in climate diagnostics and projections
One of the conclusions of the 5th IPCC assessment report is that “the principal driver of long-term warming is total emissions of CO2. Therefore, for any given warming target, higher emissions in earlier decades imply lower emissions later. Many aspects of climate change will persist for many centuries even if emissions of greenhouse gases are stopped. This represents a substantial multi-century commitment created by past, present and future emissions of CO2“. The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts. The Fifth Assessment Report (AR5) provides a clear and up to date view of the current state of scientific knowledge relevant to climate change. This opening presentation will highlight some of the conclusions concerning the evidence of global warming and of the relationship between human activity and climate change. A particular focus will be put on future climate projections and their credibility, so as to put into perspective the different time scales involved, the magnitude of the global and regional changes and the implications for the carbon mitigation needs.