In the video above from Oct. 6, 2015, Sen. Ted Cruz aggressively questions the head of the Sierra Club (Dr. Aaron Mair) on the alleged “pause” in global warming. My friend Joe posted it on Facebook; I responded with a link to an article on RealClimate.org by Dr. Stefan Rahmstorf refuting the claim that the “pause” disproves global warming. Note that other rebuttals have been written by Phil Plat, NOAA, the World Meteorological Organization, a joint statement by the U.S. National Academy of Sciences and the Royal Society, and Dr. Mair himself.
Why do I want to add to this list? Joe asked me to:
…could I invite you to put it in your own word[s], Luke? Honestly. I read it and I’m not the brightest bulb in the scientific data batch. What did you hear Cruz say and how does this article refute or clarify. And why do you suspect the high level environmental spokesperson went mute on the point and talked in a broken record manner about ‘the majority of the scientists’? I’ll bet you can summarize it quickly, and I’d read you.
18 years is simply too short a period from which to draw conclusions for climate change. The system has so much noise that longer time periods are needed to see the long-term trends. When we consider the long-term data sets (centuries or more), I think the influence of humanity becomes clear.
I am a physicist, not a climatologist, and I write this because Joe asked me to. He and others might find my words more convincing than Dr. Rahmstorf’s. I realize that I have, at best, a 6% chance of succeeding in this task. Let us begin with a graph of the data.
This is the official NASA GISS data set, which varies slightly from others mainly due to interpolations over the polar regions. In all cases, the upward trend since roughly 1960 is quite clear, especially with the addition of the final point, representing 2015. Senator Cruz is talking about the relatively flat region from 1998 and 2014. I admit that I could be wrong, but I don’t see any pause in this data.
Dr. Rahmstorf’s article starts with the truth that this system has a great deal of variability around this trend, much like a baseball player’s batting average will vary wildly from game to game around his season average. With such variability, one can expect times where the trend might seem flat or even negative if one zooms in enough. Dr. Rahmstorf explores this with mathematical rigor and shows that the “pause” is well within the natural variability one would expect in the midst of a warming trend.
As for Dr. Mair’s response, I agree that it was lacking, but I also agree with Dr. Plat that “it’s easy to be an armchair quarterback,” and I don’t know if I would have done any better in his position.