What Pause in Global Warming?
I have recently been engaged in frankly a rather pointless online debate with a Climate Change Denier that took too much of my time and showed no signs of being read by anyone else but the pair of us and he seemed entirely brainwashed by Denial propaganda, incapable of engaging with the basic science behind the issue and much preferred to just regurgitate the classic Denial nonsense. However it did prompt me to look again at one of the most important Climate Change Denial claims – the claim that there has been a pause in global warming since 1998. Now I thought this was just a case of one of those statistical blips and deviations from the trend line that you would expect in a set of scientific data covering over a century but on digging deeper I found that it is in fact such a mendacious misrepresentation of scientific data that it amounts to a huge lie by the Denial propagandists. Let me explain why.
The measurements cited by the Deniers are those that show that the mean surface temperature of the planet in 1998 is very much the same as it was in 2011-2013 based on findings by Prof Matt England of the University of New South Wales. Now, at first glance this seems very reasonable as a bit of data suggesting a pause in global warming but this is not the case.
Firstly is the surface temperature in isolation a reliable measure of “global warming”? No it is not. The planet can also warm as the deep oceans absorb heat, as the upper atmosphere absorbs heat and as heat is absorbed as the latent heats of fusion and vapourisation when ice decreases and the atmosphere carries more water vapour. These combined effects vary in their relative contribution to the overall global warming and therefore to claim that a pause or even a reversal in the data for any one of them in isolation means that global warming has stopped is false.
Secondly, it has always seemed to me odd that the Deniers are often so specific about there not having been any global warming since 1998. Not since the late 90s, not since 1997 and not since 1999. Why is 1998 special? It turns out it is. Not only can the deep oceans absorb heat, it appears that under certain conditions relating to winds and currents they can push heat back to the surface. This means that over and above the sort of natural spread of data discussed earlier some years can be warmer in terms of surface temperature than others regardless of the presence or absence of global warming. 1998 was a warm year. Therefore, if you specifically take 1998 as your base-line then the 15 years after it give data that either shows lower or broadly similar surface temperatures. If however you don’t cheat in this way the trend line, even in surface temperature in isolation, is in keeping with the predictions of climate change science.
Finally if you google “prof Matt England University of New South Wales” you will find some Climate Change Denial websites slagging him off because, much to their annoyance, he has spent quite a bit of time since publishing his data (perfectly good data in itself it turns out) telling people that Global Warming has not stopped and his data is being misrepresented.
So next time some Denier or wind NIMBY tells you that there has been no Global Warming in the last 15 years tell them they are talking rubbish!
I will leave the last word to Prof England in a quote I found on-line:
“Global warming has not stopped. People should understand that the planet is a closed system. As we increase our emissions of greenhouse gases, the fundamental thermal dynamics tells us we have added heat into the system. Once it’s trapped, it can go to a myriad of places – land surface, oceans, ice shelves, ice sheets, glaciers for example.”