The IPCC, in the AR4 working group one, stated what could be called the central claim of global warming, the estimate of the net radiative forcing. "The understanding of anthropogenic warming and cooling influences on climate has improved since the TAR, leading to very high confidence that the effect of human activities since 1750 has been a net positive forcing of +1.6 [+0.6 to +2.4] W m–2." Remember a forcing is an imbalance that causes heating, like a hot plate heating a saucepan of water. Read more [...] 25 com