by Robert Maynard
According to a recent article in the Financial Post “In the next five years, the global warming paradigm may fall apart if the models prove worthless.” Here is an excerpt from that article:
There has been a lot of talk lately about the upcoming Intergovernmental Panel on Climate Change (IPCC) report, and whether it will take into account the lack of warming since the 1990s. Everything you need to know about the dilemma the IPCC faces is summed up in one remarkable graph.
The figure nearby is from the draft version that underwent expert review last winter. It compares climate model simulations of the global average temperature to observations over the post-1990 interval. During this time atmospheric carbon dioxide rose by 12%, from 355 parts per million (ppm) to 396 ppm. The IPCC graph shows that climate models predicted temperatures should have responded by rising somewhere between about 0.2 and 0.9 degrees C over the same period. But the actual temperature change was only about 0.1 degrees, and was within the margin of error around zero. In other words, models significantly over-predicted the warming effect of CO2 emissions for the past 22 years.
Chapter 9 of the IPCC draft also shows that overestimation of warming was observed on even longer time scales in data collected by weather satellites and weather balloons over the tropics. Because of its dominant role in planetary energy and precipitation patterns, models have to get the tropical region right if they are credibly to simulate the global climate system. Based on all climate models used by the IPCC, this region of the atmosphere (specifically the tropical mid-troposphere) should exhibit the most rapid greenhouse warming anywhere. Yet most data sets show virtually no temperature change for over 30 years.
The IPCC’s view of the science, consistently held since the 1990s, is that CO2 is the key driver of modern climate change, and that natural variability is too small to count in comparison. This is the “mainstream” view of climate science, and it is what is programmed into all modern climate models. Outputs from the models, in turn, have driven the extraordinarily costly global climate agenda of recent decades. But it is now becoming clear that the models have sharply over predicted warming, and therein lies a problem.
As the gap between models and reality has grown wider, so has the number of mainstream scientists gingerly raising the possibility that climate models may soon need a bit of a re-think. A recent study by some well-known German climate modelers put the probability that models can currently be reconciled with observations at less than 2%, and they said that if we see another five years without a large warming, the probability will drop to zero.