10 Dec 2007. Nobel Lecture by R. K. Pachauri, Chairman of the Intergovernmental Panel on Climate Change (IPCC), Oslo.
Climate change is likely to lead to some irreversible impacts on biodiversity. There is medium confidence that approximately 20%–30% of species assessed so far are likely to be at increased risk of extinction if increases in global average warming exceed 1.5–2.5 ºC, relative to 1980–99. As global average temperature exceeds about 3.5 ºC, model projections suggest significant extinctions (40%–70% of species assessed) around the globe. These changes, if they were to occur would have serious effects on the sustainability of several ecosystems and the services they provide to human society.