The Global Warming Hiatus

Ted Cruz invited a conservative radio host to testify about climate change.  As one of the members of that Committee, Senator Ed Markey (D-MA), noted,  

“The only thing that requires a serious scientific investigation is why we are holding today’s hearing in the first place,” 

Why indeed is a radio host testifying on climate change?  At an earlier convocation of the Committee on Commerce, Science, and Transportation, Sen. Cruz pressed upon the President of the Sierra Club about the evidence for a hiatus, i.e., no change in global temperatures over an 18 year period.  Mr. Mair is not a climate scientists, but Sen. Cruz took that opportunity to press for the conclusion of a hiatus on essentially a defenseless man without the scientific background to counter Sen. Cruz's conclusion.

Sen. Cruz is almost certainly getting his information from a blog publication by the 3rd Viscount Brenchley, a British public speaker and hereditary peer. that is someone with no training whatsoever in statistical methods or climate science.  This man has presented an analysis at a well known climate change denial blog purporting to show no change in global temperatures over an 18 year period.  His analysis is simple, fit a linear regression to Satellite data.  A t-test fails to support a nonzero coefficient.  Aside from the fact this is the most simplistic type of model one could propose, it turns out that he has to choose which Satellite data to use because another set shows a clear increase in global temperatures, his reasoning being that it "much-altered".   Well, there's no question the one he's looking at is also "much-altered", that is the nature of preparing data for analysis to render it "clean".

Well, climate scientists have studied the so-called "hiatus" and declared it nonexistent.

In 2008, a paper was published in the journal Nature predicting that global surface temperatures would cool slightly in the years 2005–2015 as compared to 1994–2004. The authors of that paper thought that during that time, the cool phase of natural ocean cycles would be enough to more than offset warming from the increased greenhouse effect, before human-caused global warming caught up again thereafter. At the time, the paper and its cooling prediction received a tremendous amount of media attention.

There was some truth to the prediction. From about 1999 to 2012, there were more La Niña than El Niño events, with the former having a short-term cooling influence on global surface temperatures, and the latter having a short-term warming effect. So, it’s true that natural ocean cycles had a temporary cooling effect during that time period. 

the authors of the paper predicted that global surface temperatures would fall. The climate scientists who blog at RealClimate were so confident that temperatures would continue to rise that they offered the authors a bet.

If the average temperature 2000-2010 (their first forecast) really turns out to be lower or equal to the average temperature 1994-2004, we will pay them € 2500. If it turns out to be warmer, they pay us € 2500. This bet will be decided by the end of 2010. We offer the same for their second forecast: If 2005-2015 turns out to be colder or equal compared to 1994-2004, we will pay them € 2500 – if it turns out to be warmer, they pay us the same. 

The authors of the paper note it’s particularly interesting that global warming keeps winning the bet despite ocean cycles, solar activity, and human aerosol pollution all acting in the cooling direction over the past 15 years. Human-caused global warming has become so strong that it’s consistently overcoming these natural short-term cooling factors.

Despite the temporary cooling influence of natural ocean cycles and low solar activity since 1999, temperatures have continued to rise due to the strength of the increased greenhouse effect. They have risen more slowly than they would have otherwise, but temperatures have continued to rise nevertheless. As the climate scientists at RealClimate wrote,

It is clear that prediction of global cooling or even stasis was way off the mark, with global warming continuing and observations running more than 0.15ºC warmer than the Keenlyside et al forecast 

There is no hiatus.  In fact, what appears to be happening is that the people Sen. Cruz are relying on for his information may not have been looking for a static global temperature but were comparing the the increase they did see against some models or predictions of increasing temperatures.  But models are scientific speculation not scientific results. Beating out a model prediction has no implications for policy except to reject that model.  The fact is global temperatures have been increasing over the last 20 years. slowly maybe, but increasing.  So why is Sen Cruz pushing a nonexistent hiatus? What Sen. Cruz is doing is propagandizing.  Is he really interesting in what is happening?/ No.  He has a forgone conclusion he is peddling for political purposes.

The great tragedy of our species is that such peddling can have more of an effect on solving our problems than science.