Warming of up to 1.2 degrees Celsius over the next 70 years (0.8 degrees have already occurred), most of which is predicted to happen in cold areas in winter and at night, would extend the range of farming further north, improve crop yields, slightly increase rainfall (especially in arid areas), enhance forest growth and cut winter deaths (which far exceed summer deaths in most places). Increased carbon dioxide levels also have caused and will continue to cause an increase in the growth rates of crops and the greening of the Earth—because plants grow faster and need less water when carbon dioxide concentrations are higher.

Up to two degrees of warming, these benefits will generally outweigh the harmful effects, such as more extreme weather or rising sea levels, which even the IPCC concedes will be only about 1 to 3 feet during this period.

Yet these latest IPCC estimates of climate sensitivity may still be too high. They don’t adequately reflect the latest rash of published papers estimating “equilibrium climate sensitivity” and “transient climate response” on the basis of observations, most of which are pointing to an even milder warming. This was already apparent last year with two papers—by scientists at the University of Illinois and Oslo University in Norway—finding a lower ECS than assumed by the models. Since then, three new papers conclude that ECS is well below the range assumed in the models. The most significant of these, published in Nature Geoscience by a team including 14 lead authors of the forthcoming IPCC scientific report, concluded that “the most likely value of equilibrium climate sensitivity based on the energy budget of the most recent decade is 2.0 degrees Celsius.”