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Who’s Gerrymandering Evidence on Global Warming?

“Employing actual facts is not nearly as effective a tactic as gerrymandering evidence.”

This phrase, appearing on page 107 of The Politically Incorrect Guide to Global Warming and Environmentalism (Regnery Press 2010), is one of the few in Christopher Horner’s book that hits the mark.

Horner means for you to apply that statement to the climate science he’s been paid to denigrate. But he’s projecting. On the very next page of his book, Horner “gerrymanders evidence” himself as he writes about global temperature:

If you set your baseline somewhere else — say 1998 or 1934 — the planet appears to be in a cooling trend. These are obnoxious points for the greens and the media, who — to borrow a phrase — “don’t do nuance.” They know we’re warming, and so they try to present the information in such a way to convince us. [page 108]

Let’s look at global temperature to decide who is and who isn’t “gerrymandering evidence.” Let’s decide which parties “don’t do nuance.”

The following is the annual global temperature record from 1880-2009 over the land masses of the Earth, measured as anomalies departing from the 1951-1980 average. The data, available here, comes from the NASA Goddard Institute for Space Studies:

Annual Global Land Temperature Anomaly Data from NASA for 1880 to 2009, with 1934 and 1998 highlighted and a best fit trend with high R squared included

I’ve drawn arrows to the data points for the years 1934 and 1998, years that Christopher Horner doesn’t just happen to point out. They are years that mark short-term high points occurring just before a series of years that hit lower points. By restricting his vision to 1934 and 1998, Christopher Horner is gerrymandering evidence in just the way he says climate scientists do: he’s picking two very particular years that make it temporarily appear as if global cooling is taking place — if you only look at those years and the years immediately following them, if you cover up the rest of the graph, and if you squint really, really hard.

What happens if you don’t gerrymander the evidence? The graph above contains the full breadth of data in NASA’s dataset over time from 1880 onward, the point at which the dataset begins because that’s the point when enough direct temperature measurements began to be made. The year 2010 isn’t included yet only because the year isn’t over yet. When you look at ALL the years, not just the years Christopher Horner likes, what does your eye see? It sees an increase over time. That’s global warming.

If you don’t want to believe your eyes, believe the best-fit trend line, drawn graphically in black above and also included in equation form with an accompanying statistic, R squared. Multiplied by 100, this R-squared statistic tells us how much of the variation in temperature over the period can be explained simply as a progression of the years. The answer is that 73.65% of global temperature variation can be explained by the progression of the years. For a complicated phenomenon like climate change, affected potentially by so many things, to explain 73.65% of it with one variable is pretty impressive, and an indication that we’re not just seeing random variation unconnected to time. Furthermore, the best-fit line indicates that the increase in temperature is accelerating over time.

That’s the story you get when you don’t “gerrymander the evidence.”

If you must read Horner’s “Politically Incorrect Guide to Global Warming,” check Horner’s assertions. And please, pick up a copy at the library, not the bookstore. Don’t give him the reward of a royalty payment for projecting his failures onto climate scientists. Don’t reward him for lying to you.

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