Clouds reflect heat back into space. Knowing how clouds form tells us about how sensitive the atmosphere is to heating. Professor Steven Sherwood, from UNSW Australia's Climate Change Research Centre, has just released a paper in the prestigious "Nature" journal explaining that research and observations show fewer clouds will form than demonstrated in existing climate models. The low warming predicted for an expected doubling of C02 in the atmosphere is now out of the question. Expect warming of more than 3 degrees.