Canadian Reactions To Sir David King
by Richard S. Lindzen

Neither the IPCC, nor the NAS, confirmed that human-caused climate change is a serious problem, says MIT professor

The Hill Times Ottawa
Monday, Feb 23 - March 1, 2004

In recent issues of The Hill Times there have been some seriously misleading comments made about the current state of climate science and the conclusions of the scientific review bodies assigned to study the situation. These misrepresentations are crucially important to correct if Canadians are to come to sensible decisions regarding climate-change policy.

Sir David King (Feb 9, "Kyoto Protocol a key part of international response") and Environment Minister David Anderson (Jan 19, "Anderson is currently working on Kyoto implementation plan") cite the reports of the Intergovernmental Panel on Climate Change (IPCC) and the U.S. National Academy of Sciences (NAS) as substantiation for proceeding with implementation of the Kyoto Accord. As one of 11 scientists who took part in the 2001 evaluation of the IPCC for the NAS and as a lead scientific author of the IPCC WG I report, I can assure readers of The Hill Times that neither of these studies warrant the actions being promoted by Dr. King and Mr. Anderson.

Specifically, it is quite wrong to say that our NAS study endorsed the credibility of the IPCC assessment report. We were asked to evaluate the IPCC "Summary for Policymakers" (SPM), the only part of the IPCC reports that is ever read or quoted by media and politicians. The SPM, which is seen as endorsing Kyoto, is commonly presented as the consensus of thousands of the world's foremost climate scientists. In fact, it is no such thing. Largely for that reason, the NAS panel concluded that the SPM does not provide suitable guidance for the U.S. government. There is no reason why it should be considered as an appropriate foundation for the decision-making of any other government either, including that of Canada.

The full IPCC report, most of which is written by scientists about specific scientific topics in their areas of expertise, is an admirable description of research activities in climate science. It is however not directed at policy. The SPM is, of course, but it is also a very different document. It represents a consensus of government representatives (many of whom are also their nations' Kyoto representatives), rather than of scientists. As a consequence, the SPM has a strong tendency to disguise uncertainty, and conjures up some scary scenarios for which there is no evidence.

Similarly, in the case of our NAS report, far too much attention was paid to the hastily prepared summary rather than to the body of the report. The [NAS}summary claimed that greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise [especially during the past twenty years]. Yet, the full text noted that 20 years was too short a period for estimating long-term trends, a crucial point that the summary neglected to mention. Our primary conclusion was that despite some knowledge and agreement, the science is by no means settled.

In reality, scientists are only confident that:

(1) global mean temperature is about 0.6 degrees Celsius higher than it was a century ago; (2) atmospheric levels of carbon dioxide have risen about 30 percent over the past two centuries; and, (3) carbon dioxide is a greenhouse gas (one of many, the most important being water vapour and clouds) whose increase is likely to warm the earth

Nevertheless, Mr. Anderson and his fellow Parliamentarians should understand that we are not in a position to confidently attribute past climate change to carbon-dioxide variations or to forecast what the climate will be in the future. In other words, agreement with the three basic statements above tells us almost nothing relevant to policy discussions.

One reason for this uncertainty is that, as our NAS report states, Earth's climate is always changing. Two centuries ago, much of the Northern Hemisphere was emerging from a little ice age. A millennium ago, during the Middle Ages, the same region was in a warm period. Thirty years ago, we were concerned with global cooling. Distinguishing the small recent changes in global mean temperature from the natural variability, which is unknown, is not a trivial task. All attempts so far, are based on crude "curve fitting" using the hopelessly na´ve assumption that existing computer climate models simulate natural variability in detail.

We simply do not know what relation, if any, exists between global climate changes and water vapour, clouds, storms, hurricanes, and other factors, including regional climate changes, which are generally much larger than global changes and not well correlated with them. Nor do we know how to predict changes in greenhouse gases. This is because we cannot forecast economic and technological change over the next century, and also because there are many man-made substances whose properties and levels are not well known, but which could be comparable in importance to carbon dioxide.

Actually, the impact of greenhouse gases on climate is nonlinear in the amount of greenhouse gases. That is to say, each added unit of greenhouse gas has less impact than its predecessor. Although we are far from a doubling of the amount of carbon dioxide, the climate impact of the current level of anthropogenic (human-induced) greenhouse gases is almost 3/4 of what we expect from a doubling of carbon dioxide. Thus, if all the observed increase in globally averaged temperature over the past century were due to anthropogenic greenhouse gases (probably a gross exaggeration since much of the temperature rise occurred before significant increases in carbon dioxide, while significant decreases in temperature occurred between 1940 and the early 70's), we would have little reason to expect serious warming over the next century. This should not be surprising: a doubling of carbon dioxide by itself would produce a modest temperature increase of only one degree Celsius. Predictions of greater responses depend critically on water vapour and clouds acting in models to greatly amplify any other changes, but water vapour and clouds are acknowledged to be major areas of uncertainty in the models. Indeed, the IPCC showed that the treatment of clouds is universally wrong among models [judging by comparisons with observations].

Quite apart from such serious difficulties, there is general scientific agreement that the Kyoto Protocol, even if fully implemented, would not change global mean temperature over the next hundred years by more than a few tenths of a degree regardless of what one believes about climate sensitivity to greenhouse-gas levels.

Our NAS report made it clear that there is no consensus in the scientific community about long-term climate trends and what causes them. Mr. Anderson and Dr. King would do well to discuss this with any one of the many non-governmental climate experts who signed the open letter to Mr. Martin referenced in Dr. Tim Ball's piece in The Hill Times on February 2 ["Government Climate Science Scandal Continues"].

Sadly, the reports of both the IPCC and the NAS have been used by Kyoto supporters as a source of authority with which to bludge on political opponents and propagandize uninformed citizens. A fairer view of the science will show that there is still a vast amount of uncertainty - far more than advocates of Kyoto would like to acknowledge.

It is crucially important that we preserve the integrity of science as a tool for effective assessment and understanding of nature. Policymakers such as Mr. Anderson should devote their ingenuity to designing a system of support for science that encourages problem resolution and discourages alarmism. Equating climate change with global terrorism, as both the environment minister and Dr. King have done recently, is precisely the sort of statements that all concerned, thinking citizens should condemn.


Richard S. Lindzen is the Alfred P. Sloan Professor of Atmospheric Science in the Department of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology (MIT). Readers may write him at 54-1720, MIT, Cambridge, MA 02139 or e-mail him at

Source:  04 April 2004       red highlighting by meteoLCD