Opinion: Concerned Scientists Reply on Global Warming

Editor's Note: The authors of the following letter, listed below, are also the signatories of "No Need to Panic About Global Warming," an op-ed that appeared in the Journal on January 27. This letter responds to criticisms of the op-ed made by Kevin Trenberth and 37 others in a letter published Feb. 1, and by Robert Byer of the American Physical Society in a letter published Feb. 6.

The interest generated by our Wall Street Journal op-ed of Jan. 27, "No Need to Panic about Global Warming," is gratifying but so extensive that we will limit our response to the letter to the editor the Journal published on Feb. 1, 2012 by Kevin Trenberth and 37 other signatories, and to the Feb. 6 letter by Robert Byer, President of the American Physical Society. (We, of course, thank the writers of supportive letters.)

We agree with Mr. Trenberth et al. that expertise is important in medical care, as it is in any matter of importance to humans or our environment. Consider then that by eliminating fossil fuels, the recipient of medical care (all of us) is being asked to submit to what amounts to an economic heart transplant. According to most patient bills of rights, the patient has a strong say in the treatment decision. Natural questions from the patient are whether a heart transplant is really needed, and how successful the diagnostic team has been in the past.

In this respect, an important gauge of scientific expertise is the ability to make successful predictions. When predictions fail, we say the theory is "falsified" and we should look for the reasons for the failure. Shown in the nearby graph is the measured annual temperature of the earth since 1989, just before the first report of the Intergovernmental Panel on Climate Change (IPCC). Also shown are the projections of the likely increase of temperature, as published in the Summaries of each of the four IPCC reports, the first in the year 1990 and the last in the year 2007.

These projections were based on IPCC computer models of how increased atmospheric CO2 should warm the earth. Some of the models predict higher or lower rates of warming, but the projections shown in the graph and their extensions into the distant future are the basis of most studies of environmental effects and mitigation policy options. Year-to-year fluctuations and discrepancies are unimportant; longer-term trends are significant.

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From the graph it appears that the projections exaggerate, substantially, the response of the earth's temperature to CO2 which increased by about 11% from 1989 through 2011. Furthermore, when one examines the historical temperature record throughout the 20th century and into the 21st, the data strongly suggest a much lower CO2 effect than almost all models calculate.

The Trenberth letter tells us that "computer models have recently shown that during periods when there is a smaller increase of surface temperatures, warming is occurring elsewhere in the climate system, typically in the deep ocean." The ARGO system of diving buoys is providing increasingly reliable data on the temperature of the upper layers of the ocean, where much of any heat from global warming must reside. But much like the surface temperature shown in the graph, the heat content of the upper layers of the world's oceans is not increasing nearly as fast as IPCC models predict, perhaps not increasing at all. Why should we now believe exaggerating IPCC models that tell us of "missing heat" hiding in the one place where it cannot yet be reliably measured—the deep ocean?

Given this dubious track record of prediction, it is entirely reasonable to ask for a second opinion. We have offered ours. With apologies for any immodesty, we all have enjoyed distinguished careers in climate science or in key science and engineering disciplines (such as physics, aeronautics, geology, biology, forecasting) on which climate science is based.

Trenberth et al. tell us that the managements of major national academies of science have said that "the science is clear, the world is heating up and humans are primarily responsible." Apparently every generation of humanity needs to relearn that Mother Nature tells us what the science is, not authoritarian academy bureaucrats or computer models.

One reason to be on guard, as we explained in our original op-ed, is that motives other than objective science are at work in much of the scientific establishment. All of us are members of major academies and scientific societies, but we urge Journal readers not to depend on pompous academy pronouncements—on what we say—but to follow the motto of the Royal Society of Great Britain, one of the oldest learned societies in the world: nullius in verba—take nobody's word for it. As we said in our op-ed, everyone should look at certain stubborn facts that don't fit the theory espoused in the Trenberth letter, for example—the graph of surface temperature above, and similar data for the temperature of the lower atmosphere and the upper oceans.

What are we to make of the letter's claim: "Climate experts know that the long-term warming trend has not abated in the past decade. In fact, it was the warmest decade on record." We don't see any warming trend after the year 2000 in the graph. It is true that the years 2000-2010 were perhaps 0.2 C warmer than the preceding 10 years. But the record indicates that long before CO2 concentrations of the atmosphere began to increase, the earth began to warm in fits and starts at the end of the Little Ice Age—hundreds of years ago. This long term-trend is quite likely to produce several warm years in a row. The question is how much of the warming comes from CO2 and how much is due to other, both natural and anthropogenic, factors?