The science
According to the Intergovernmental Panel on Climate Change (IPCC), warming of the climate system is unequivocal, and is in large part due to an increase in greenhouse gas (GHG) emissions from human activities. The IPCC believes that warming of the climate will probably lead to extreme weather events becoming more frequent and unpredictable. Its latest report makes clear that limiting climate change will require substantial and sustained reductions of GHG emissions.