One of climate skeptics’ favourite arguments is that climate models are unreliable and that you can’t really predict what’s going to happen. Two of RealClimate’s contributors have now dug up a projection by James Hansen et al. from 1981 and compared it to what actually happened. The result: the agreement is quite good, and it actually underestimated the actual warming.
To conclude, a projection from 1981 for rising temperatures in a major science journal, at a time that the temperature rise was not yet obvious in the observations, has been found to agree well with the observations since then, underestimating the observed trend by about 30%, and easily beating naive predictions of no-change or a linear continuation of trends. It is also a nice example of a statement based on theory that could be falsified and up to now has withstood the test. The “global warming hypothesis” has been developed according to the principles of sound science.