"Neither the IPCC, nor the NAS, confirmed that human-caused
is a serious problem, says MIT professor"
The Hill Times Ottawa
Monday, Feb 23 - March 1, 2004
By: Richard S. Lindzen
In recent issues of The Hill Times there have been some seriously
misleading comments made about the current state of climate science and
conclusions of the scientific review bodies assigned to study the
situation. These misrepresentations are crucially important to correct
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
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
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
does not provide suitable guidance for the U.S. government. There
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
policy. The SPM is, of course, but it is also a very different document.
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
a century ago; (2) atmospheric levels of carbon dioxide have risen about
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
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 naïve 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
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
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
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
uncertainty in the models. Indeed, the IPCC showed that the treatment
clouds is universally wrong among models [judging by comparisons with
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
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
["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 bludgeon 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
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
54-1720, MIT, Cambridge, MA 02139 or e-mail him at email@example.com