Posted by
Always To The Right on Wednesday, July 05, 2006 4:19:28 PM
According
to Al Gore's new film "An Inconvenient Truth," we're in for "a
planetary emergency": melting ice sheets, huge increases in sea levels,
more and stronger hurricanes, and invasions of tropical disease, among
other cataclysms--unless we change the way we live now.
Bill
Clinton has become the latest evangelist for Mr. Gore's gospel,
proclaiming that current weather events show that he and Mr. Gore were
right about global warming, and we are all suffering the consequences
of President Bush's obtuseness on the matter. And why not? Mr. Gore
assures us that "the debate in the scientific community is over."
That
statement, which Mr. Gore made in an interview with George
Stephanopoulos on ABC, ought to have been followed by an asterisk. What
exactly is this debate that Mr. Gore is referring to? Is there really a
scientific community that is debating all these issues and then somehow
agreeing in unison? Far from such a thing being over, it has never been
clear to me what this "debate" actually is in the first place. The
media rarely help, of course. When Newsweek featured global warming in
a 1988 issue, it was claimed that all scientists agreed. Periodically
thereafter it was revealed that although there had been lingering
doubts beforehand, now all
scientists did indeed agree. Even Mr. Gore qualified his statement on
ABC only a few minutes after he made it, clarifying things in an
important way. When Mr. Stephanopoulos confronted Mr. Gore with the
fact that the best estimates of rising sea levels are far less dire
than he suggests in his movie, Mr. Gore defended his claims by noting
that scientists "don't have any models that give them a high level of
confidence" one way or the other and went on to claim--in his defense--that scientists "don't know. . . . They just don't know."
So,
presumably, those scientists do not belong to the "consensus." Yet
their research is forced, whether the evidence supports it or not, into
Mr. Gore's preferred global-warming template--namely, shrill alarmism.
To believe it requires that one ignore the truly inconvenient facts. To
take the issue of rising sea levels, these include: that the Arctic was
as warm or warmer in 1940; that icebergs have been known since time
immemorial; that the evidence so far suggests that the Greenland ice
sheet is actually growing on average. A likely result of all this is
increased pressure pushing ice off the coastal perimeter of that
country, which is depicted so ominously in Mr. Gore's movie. In the
absence of factual context, these images are perhaps dire or alarming.
They
are less so otherwise. Alpine glaciers have been retreating since the
early 19th century, and were advancing for several centuries before
that. Since about 1970, many of the glaciers have stopped retreating
and some are now advancing again. And, frankly, we don't know why.
The
other elements of the global-warming scare scenario are predicated on
similar oversights. Malaria, claimed as a byproduct of warming, was
once common in Michigan and Siberia and remains common in
Siberia--mosquitoes don't require tropical warmth. Hurricanes, too,
vary on multidecadal time scales; sea-surface temperature is likely to
be an important factor. This temperature, itself, varies on
multidecadal time scales. However, questions concerning the origin of
the relevant sea-surface temperatures and the nature of trends in
hurricane intensity are being hotly argued within the profession. Even
among those arguing, there is general agreement that we can't attribute
any particular hurricane to global warming. To be sure, there is one
exception, Greg Holland of the National Center for Atmospheric Research
in Boulder, Colo., who argues that it must be global warming because he
can't think of anything else. While arguments like these, based on
lassitude, are becoming rather common in climate assessments, such
claims, given the primitive state of weather and climate science, are
hardly compelling.
A
general characteristic of Mr. Gore's approach is to assiduously ignore
the fact that the earth and its climate are dynamic; they are always
changing even without any external forcing. To treat all change as
something to fear is bad enough; to do so in order to exploit that fear
is much worse. Regardless, these items are clearly not issues over
which debate is ended--at least not in terms of the actual science.
A
clearer claim as to what debate has ended is provided by the
environmental journalist Gregg Easterbrook. He concludes that the
scientific community now agrees that significant warming is occurring,
and that there is clear evidence of human influences on the climate
system. This is still a most peculiar claim. At some level, it has
never been widely contested. Most of the climate community has agreed
since 1988 that global mean temperatures have increased on the order of
one degree Fahrenheit over the past century, having risen significantly
from about 1919 to 1940, decreased between 1940 and the early '70s,
increased again until the '90s, and remaining essentially flat since
1998.
There
is also little disagreement that levels of carbon dioxide in the
atmosphere have risen from about 280 parts per million by volume in the
19th century to about 387 ppmv today. Finally, there has been no
question whatever that carbon dioxide is an infrared absorber (i.e., a
greenhouse gas--albeit a minor one), and its increase should
theoretically contribute to warming. Indeed, if all else were kept
equal, the increase in carbon dioxide should have led to somewhat more
warming than has been observed, assuming that the small observed
increase was in fact due to increasing carbon dioxide rather than a
natural fluctuation in the climate system. Although no cause for alarm
rests on this issue, there has been an intense effort to claim that the
theoretically expected contribution from additional carbon dioxide has
actually been detected.
Given
that we do not understand the natural internal variability of climate
change, this task is currently impossible. Nevertheless there has been
a persistent effort to suggest otherwise, and with surprising impact.
Thus, although the conflicted state of the affair was accurately
presented in the 1996 text of the Intergovernmental Panel on Climate
Change, the infamous "summary for policy makers" reported ambiguously
that "The balance of evidence suggests a discernible human influence on
global climate." This sufficed as the smoking gun for Kyoto.
The
next IPCC report again described the problems surrounding what has
become known as the attribution issue: that is, to explain what
mechanisms are responsible for observed changes in climate. Some
deployed the lassitude argument--e.g., we can't think of an
alternative--to support human attribution. But the "summary for policy
makers" claimed in a manner largely unrelated to the actual text of the
report that "In the light of new evidence and taking into account the
remaining uncertainties, most of the observed warming over the last 50
years is likely to have been due to the increase in greenhouse gas
concentrations."
In
a similar vein, the National Academy of Sciences issued a brief
(15-page) report responding to questions from the White House. It again
enumerated the difficulties with attribution, but again the report was
preceded by a front end that ambiguously claimed that "The changes
observed over the last several decades are likely mostly due to human
activities, but we cannot rule out that some significant part of these
changes is also a reflection of natural variability." This was
sufficient for CNN's Michelle Mitchell to presciently declare that the
report represented a "unanimous decision that global warming is real,
is getting worse and is due to man. There is no wiggle room." Well, no.
More
recently, a study in the journal Science by the social scientist Nancy
Oreskes claimed that a search of the ISI Web of Knowledge Database for
the years 1993 to 2003 under the key words "global climate change"
produced 928 articles, all of whose abstracts supported what she
referred to as the consensus view. A British social scientist, Benny
Peiser, checked her procedure and found that only 913 of the 928
articles had abstracts at all, and that only 13 of the remaining 913
explicitly endorsed the so-called consensus view. Several actually
opposed it.
Even
more recently, the Climate Change Science Program, the Bush
administration's coordinating agency for global-warming research,
declared it had found "clear evidence of human influences on the
climate system." This, for Mr. Easterbrook, meant: "Case closed." What
exactly was this evidence? The models imply that greenhouse warming
should impact atmospheric temperatures more than surface temperatures,
and yet satellite data showed no warming in the atmosphere since 1979.
The report showed that selective corrections to the atmospheric data
could lead to some warming, thus reducing the conflict between
observations and models descriptions of what greenhouse warming should
look like. That, to me, means the case is still very much open.
So what, then, is one to make of this
alleged debate? I would suggest at least three points. First,
nonscientists generally do not want to bother with understanding the
science. Claims of consensus relieve policy types, environmental
advocates and politicians of any need to do so. Such claims also serve
to intimidate the public and even scientists--especially those outside
the area of climate dynamics. Secondly, given that the question of
human attribution largely cannot be resolved, its use in promoting
visions of disaster constitutes nothing so much as a bait-and-switch
scam. That is an inauspicious beginning to what Mr. Gore claims is not
a political issue but a "moral" crusade.
Lastly,
there is a clear attempt to establish truth not by scientific methods
but by perpetual repetition. An earlier attempt at this was accompanied
by tragedy. Perhaps Marx was right. This time around we may have
farce--if we're lucky.
Mr. Lindzen is the Alfred P. Sloan Professor of Atmospheric Science at MIT.