In response to:

In the Climate Casino: An Exchange from the April 26, 2012 issue

Why the Global Warming Skeptics Are Wrong from the March 22, 2012 issue

To the Editors:

Readers may have followed the ongoing debate between a group of prominent scientists and the nation’s leading environmental economist, Yale professor William D. Nordhaus [“Why the Global Warming Skeptics Are Wrong,” NYR, March 22; “In the Climate Casino: An Exchange,” NYR, April 26]. I have not been involved so far but will comment briefly on the provocative questions Nordhaus has put forward. For detail, please see

I raise here two crucial points that may have been overlooked in the debate:

1. Evidence for anthropogenic global warming (AGW) is problematic.

2. A modest warming is likely to be beneficial—not damaging.

First, Professor Nordhaus asks three related fundamental questions: Is the planet in fact warming? Are human influences an important contributor to warming? Is carbon dioxide a pollutant? Most thermometers at weather stations indeed report rising temperatures during the crucial interval 1978 to 2000. The UN’s climate science panel, the IPCC (Intergovernmental Panel on Climate Change), considers this warming trend as its main evidence for AGW. But we don’t see any significant warming of the atmosphere; observations from radiosondes carried in weather balloons are backed up by completely independent temperature data from weather satellites. The oceans, covering 71 percent of the earth’s surface, show no appreciable warming either. Also, non-thermometer data from so-called “proxies” (tree rings, stalagmites, etc) show mostly no warming during this period.

So in spite of rising CO2 levels, undoubtedly anthropogenic, most observations show no warming trend. That’s a real scientific puzzle—all climate models calculate major warming. Do weather stations simply report local warming and cooling rather than global trends? Yet the IPCC reaches its conclusion based on surface thermometers; its Summary for Policymakers ignores contrary evidence (“inconvenient truths”—to paraphrase Al Gore). The debate among scientists now centers on the validity of various climate data.

Nordhaus also asks: Are we seeing a regime of fear for skeptical climate scientists? Being fairly senior, I am not much affected. My concern would be for younger scientists just trying to establish their professional careers.

Are the views of mainstream climate scientists driven primarily by the desire for financial gain? This is a leading question; but I would assume that scientific curiosity is the main driving force.

Finally, Nordhaus asks: Is it true that more carbon dioxide and additional warming will be beneficial? Briefly, my answer is: Yes. Here I tend to rely mainly on the published studies of two dozen resource economists, led by Nordhaus’s Yale colleague Professor Robert Mendelsohn.

Overall then, I mostly support the arguments of the scientist-debaters, but I applaud Professor Nordhaus for not surrendering to climate alarmism and for resisting drastic mitigation policies to “save the climate.”

S. Fred Singer
Professor Emeritus
University of Virginia
Director of the Science and Environmental Policy Project

William D. Nordhaus replies:

This month marks two decades since the Rio Earth Summit. That meeting resulted in the first international agreement on climate change, the UN Framework Convention on Climate Change (UNFCCC). Under the Framework Convention, countries agreed on a goal of “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.” The Framework Convention was signed by US President George H.W. Bush and ratified unanimously by the US Senate. In the two decades since the signing of the Framework Convention, earth scientists have confirmed the basic climate science through both modeling and observations. Warming and other changes to the earth system are underway, and the dangers look even more grave than they did two decades ago.

All this time, a small band of contrarian scientists had been fighting a rear-guard action to undermine the scientific research and findings in this area. I discussed one example—an article by “sixteen scientists”—in these pages in the March 22, 2012, issue. The letter from S. Fred Singer takes the baton from the sixteen and restates their major arguments in a conclusory fashion, but he provides no new evidence.

Among the standard arguments used by climate contrarians and echoed by Singer is: “So in spite of rising CO2 levels, undoubtedly anthropogenic, most observations show no warming trend.” Singer uses the data selectively to support his argument. As I showed in my earlier pieces, if we use the standard statistical techniques for examining trends, then it is clear that the globe is warming, and in fact it has warmed faster over the period of the rapid growth in CO2 concentrations than in earlier periods. However, with a volatile series, such as the stock market or global temperatures, there are always periods of decline. But in both cases the trend has been upward and significantly so.

The other point Singer makes is that “a modest warming is likely to be beneficial.” If he means a “modest warming” of 1/2 or 1°C, then there is evidence that the combination of CO2 accumulation and warming will have benefits in some sectors and in some regions. But we need to take into account the scientific evidence for “realistic warming” projected to be 3–4°C along with other geophysical changes—such as potential melting of the major ice sheets, rapid sea-level rise, and hurricane intensification—by the end of this century, if nations fail to take significant steps to slow climate change. The evidence from hundreds of scientific and economic studies finds serious to grave impacts on agriculture, coastlines and associated settlements, and ecosystems, as well as increasing acidification of the oceans and threats to many species around the world.

Science progresses, the earth warms, glaciers melt, the oceans become increasingly acidic, but the climate contrarians change not.