On Science, Politics and Climate Change

global temperature trends
Avoiding "overheated rhetoric" on climate change is important. So is getting the science right. For example, while the rate of warming in the atmosphere in the 2000s has slowed, the oceans continue to absorb heat, and some of that heat will undoubtedly eventually find its way into the atmosphere. (


U.S. Representative Lamar Smith's strutting his science cred.

Smith, a Republican, represents the 21st District of Texas, which includes his hometown of San Antonio, and chairs the House Committee on Science, Space and Technology. I met him a few weeks ago at a hearing on climate held by the Subcommittee on the Environment. He was the consummate gentleman. Despite the fact that I was testifying as a witness for the Democratic Party, he was cordial and gentle in his questions. I thought, Now there's a reasonable man.

That impression of reasonableness was soon undercut when I learned that Smith is leading the charge in new legislation that would mandate a new layer of political review at the National Science Foundation (NSF) before granting funding for research projects. This is a bad and radical idea for any number of reasons, including its violation of a tried-and-true conservative maxim: if it ain't broke, don't fix it.

The U.S. R&D program is the envy of the world. The United States receives more patents than any other country, and families from all over the globe spend huge sums of money to send their sons and daughters to American universities to study with our researchers and work in our labs. Much of that effort is grounded in the funding of grants by the NSF. Smith's legislation would undermine all that.

Another reason you don't want to have politicians mucking around in the nuts and bolts of science is that they often have a shaky grasp of the science at best. A case in point, Rep. Smith's understanding of the state of climate science.

Lamar Smith's Take on Climate Science

On Sunday the Washington Post published an op-ed written by Congressman Smith entitled "Overheated rhetoric on climate change doesn't make good politics." Can't argue with that premise. Nor can one argue with his conclusion that we "think critically about the challenge before ... [d]esigning an appropriate public policy response" to climate change.

What one can argue with is the spin he puts on climate science to justify his conclusion that there is no urgency to begin that response. How so? Here are three examples.

No Recent Warming

Rep. Smith rolls out the well-worn -- but factually incorrect -- meme floating out there that "global temperatures have held steady over the past 15 years." It is true that the rate of warming in the 2000s has slowed, but concluding that global warming has halted would be a misread of the evidence. While warming in the atmosphere has slowed, the oceans continue to absorb heat, and some of that heat will undoubtedly eventually find its way into the atmosphere.

Secondly, the statement that temperatures have held steady is not strictly true. As illustrated below, a simple linear regression of average global temperatures running from 1996, 1997, 1998, 1999 or 2000 to 2012 all produce a positive trend -- that is, the temperatures have not held "steady" but have tended to increase over time. Depending upon whether you start the regression on a relatively warm or cool year, the trend is smaller or larger, but they are all positive.

global temperature trends
Temperature data from the

However, there is a problem. The time period used to calculate the trends is quite short (< 20 years), while the natural variability from year to year is quite large. As a result, it is not possible to establish the statistical significance of these trends. And so, we cannot statistically eliminate the possibility that there has been no temperature change. This is very different from saying there has been no temperature increase. A subtle point that a politician might miss, but significant nonetheless.

So what's going on? A lot of the slowdown in warming is likely related to the changing cycles of La Ninas and El Ninos. For a nice explanation of this, check out this Skeptical Science post.

U.S. Emissions Irrelevant

Then there's the argument that the United States is simply not a player in the global carbon emissions game and thus doesn't need to be a contributor to lowering global emissions. Hard to swallow given that the United States is one) the second largest emitter of carbon, accounting for about 17 percent of global emissions, and two) the largest contributor to the current stock of global warming carbon dioxide (CO2) in the atmosphere.

How hard to swallow? Well, open wide -- here's how Smith makes the argument. U.S. emissions in the coming decade are projected to be relatively flat while emissions from developing countries, and especially China, are projected to increase significantly. It's those other countries, the argument goes, that will be responsible for most of the future global warming, and so there's no need for countries like the United States to do anything.

To bolster such an argument, Rep. Smith refers to a white paper [pdf] published by Paul Knappenberger of the Science and Public Policy Institute, a nonprofit that discounts the role of humans in and challenges the scientific consensus on climate change.

Using model simulations (which Smith himself discounts as unreliable), Knappenberger concludes that "If the U.S. as a whole stopped emitting carbon dioxide (CO2) emissions immediately, the ultimate impact on projected global temperature rise would be ... approximately 0.08°C by the year 2050." Yikes, only 0.08 degrees Celsius! That's tiny! Great news, Americans, the United States is off the hook, right? Well, that's what Smith would have you believe.

The problem is that such calculations focusing on a single country are misleading. Global warming is a global problem requiring participation of all major emitters. No single country can do it alone. And from the opposite point of view, any country can justify not participating by looking only at its contribution to global warming. For example, take the big bad carbon emitter China. Extrapolating from Knappenberger's calculations and emissions projections for China from a report [pdf] by the Lawrence Berkeley Laboratory, I estimate that if China completely stopped its emissions in 2050, global warming would decrease in 2050 by about 0.1 to 0.2 degrees Celsius depending on the emissions scenario.*

That's larger than the U.S. contribution but not by all that much. One could imagine a Chinese official, perhaps even one who chairs the Politburo's version of the Committee on Science, Space and Technology, using this argument to similarly argue that there is no need for China to lower its emissions.

As I have previously written:

"As long as individual countries focus on their own little contribution, nothing will ever happen. It's sort of like this:

You're at a party with 29 other revelers. The beer just ran out and $30 is needed to get more beer. The hat is passed around for contributions, but each person thinks, ‘If I put in a dollar all it will add is 1/30th or 3 percent of what is needed. That's a tiny amount, too small to worry about ... I think I'll just pass.’ And no one adds to the hat, and no beer gets bought."

IPCC Says No Severe Weather Effect?

Finally there's Rep. Smith’s statement that "last year's IPCC report stat[es] that there is 'high agreement' among leading experts that trends in weather disasters, floods, tornados and storms cannot be attributed to climate change." I presume by last year's IPCC report, Smith is referring to: "Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation."

While it’s true that the report discusses a number of weather-related trends in which scientists have yet to see a global warming signature -- such as hail, tornadoes and river flooding -- there are others -- including temperature and extreme precipitation -- where they noted high or medium confidence that the impact of global warming was already visible. Looks like Rep. Smith got that one wrong as well.

In summary I'm all for avoiding "overheated rhetoric," but how about we include misstatements about and misrepresentations of science in that category? And oh yeah, leave NSF out of politics.


End Note

* China's avoided contribution was calculated to a first approximation by using the maximum and minimum emissions scenarios in the Lawrence Berkeley Lab report [pdf] between 2015 and 2050. The avoided temperature rise stemming from eliminating that estimate of cumulative CO2 emissions was calculated using a metric developed in a paper by H. Damon Matthews and co-authors discussed here.

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