back into space. However, the statistical distribution of volcanic eruptions is well-known, and the climate modelers should have evaluated the odds of bunching together of volcanic eruptions, and adjusted their range of uncertainty. Yet another is that the sun is currently undergoing a quiescent period of solar activity, and the earth’s heating would resume once the sun reverts to a more active phase. However, once again, the fact that the sun would be relatively quiet over this period should have been factored in by the climate modelers.
The explanation, that to my mind is the most plausible, is as follows: The direct warming effect of carbon dioxide which results from burning fossil fuels, and other man-made greenhouse gases (GHGs) such as methane is actually quite modest. However, water vapour is a strong GHG in itself, and accounts for the natural greenhouse effect which is what, after all, gives the earth its hospitable climate. An initial warming due to carbon dioxide and other man-made GHGs would increase evaporation of water from the oceans, and this would, at first blush, increase the initial warming due to man-made GHGs. However, the increased water vapour in the atmosphere may also induce increased cloud cover which reflects solar radiation back into space. The net effect may thus be either increased heating or cooling, and neither is inconsistent with thermodynamics. It is possible that the parameter capturing the positive feedback from water vapour in the atmosphere was incorrectly estimated by earlier researchers, and in a startling demonstration of ‘groupthink’ most modelers adopted these incorrect estimates. The result is forecasts of the earth’s future temperature that are significantly higher than actually recorded. However, this is but one candidate explanation, and the true explanations may lie elsewhere. The problem with all the explanations on offer is that they are ex post, and beg the question of why the modelers did not take them into account before publishing their models’ forecasts.
What is to be done? First, the IPCC. The scientific method involves not ignoring uncertainty, but in being explicit about it. Climate scientists need to acknowledge that there is