Despite having been debunked numerous times, the global cooling myth still lives on, most recently as part of a column by George Will. Hopefully a new paper by David R. Easterling and Michael F. Wehner published in Geophysical Research Letters will finally kill this myth. Of course given the outright dishonesty of deniers, I don’t have high hopes for this, but at least this paper will serve as a direct rebuttal of anyone foolish and dishonest enough to continue to claim that global warming has stopped or that the earth is now cooling.
Here is the paper abstract:
Numerous websites, blogs and articles in the media have claimed that the climate is no longer warming, and is now cooling. Here we show that periods of no trend or even cooling of the globally averaged surface air temperature are found in the last 34 years of the observed record, and in climate model simulations of the 20th and 21st century forced with increasing greenhouse gases. We show that the climate over the 21st century can and likely will produce periods of a decade or two where the globally averaged surface air temperature shows no trend or even slight cooling in the presence of longer-term warming.
And here are three figures from the paper that make this point abundantly clear. The first two figures highlight periods of no warming in both the instrumental record (fig 1) and model predictions (fig 2).
The third figure shows the probability distributions of decadal trends for the pre-industrial era, the instrumental record and various model runs. Notice how the bell curve moves to the right (thus making decadal warming trends more likely) as we move forward into the future, but that there still exists the possibility for a decadal cooling trend.
The authors conclude that:
The reality of the climate system is that, due to natural climate variability, it is entirely possible to have a period as long as a decade or two of ‘‘cooling’’ superimposed on the longer-term warming trend due to anthropogenic greenhouse gas forcing… [and] it is clear that the models can and do produce sustained multi-year periods of ‘‘cooling’’ embedded within the longer-term warming produced in the 21st century simulations. Therefore, it is reasonable to expect that the natural variability of the real climate system can and likely will produce multi-year periods of sustained ‘‘cooling’’ or at least periods with no real trend even in the presence of long-term anthropogenic forced warming. Claims that global warming is not occurring that are derived from a cooling observed over such short time periods ignore this natural variability and are misleading.
This isn’t a particularly difficult concept to grasp, given that the weather ‘noise’ is much larger than the climate ‘signal’, over short time scales the signal can be completely overwhelmed by the noise. Or as James Hrynyshyn puts it:
We all know that it gets warmer in the summer and cooler in the winter in the Northern Hemisphere, so no one would dare use a temperature trend of half a year to reach a conclusion about global warming. Looking at five or even 10 years can lead to similar errors. Yet otherwise intelligent critics continue to do just that, even after the problem has been pointed out to them.
It is foolish for anyone to claim that models expect global temperatures to increase monotonically, they don’t. Cooling trends that last for a decade or more are not only completely consistent with global warming, they are to be expected, and anyone who assigns any importance to these short term fluctuations is either dishonest or ignorant (George Will I am looking at you). Either way they shouldn’t be listened to.