GLOBAL WARMING: ARE WE ENTERING THE GREENHOUSE CENTURY? by Stephen H. Schneider, San Francisco: Sierra Club Books, 317 pp., $18.95.
FOR climatologist Stephen H. Schneider, a few degrees of global warming can be ``a very big deal.''
It's a big deal scientifically to try to foretell the climatic effect of the carbon dioxide (CO2) and other heat-trapping gases that human activity pours into the air.
It's a big deal politically to try to figure out what to do about it.
Dr. Schneider, happily, is one of those rare scientists who operates effectively in each of these contentious arenas and who knows the boundaries between them. When he speaks (or writes) of the science involved, he is clear, accurate, and objective.
When he lets his opinions fly in the free-for-all arena of politics and public policy, he takes pains to note that he is expressing personal value judgments, for which he has no special claim to authority.
Would that more of the ``visible'' scientists who provide quotable quotes for newspapers and dramatic warnings for television were as clearheadedly honest about their passions.
That's why I unreservedly recommend this book as background reading for anyone interested in the subject, even though the publisher is well known for environmental activism.
Schneider leads the Interdisciplinary Climate Systems research group at the National Center for Atmospheric Research in Boulder, Colo. He has world-class scientific status as a climate modeler - that is, a scientist who studies climate processes mathematically on a computer. He has also brought that expertise to enough lay audiences to know how to put climate science across, without either oversimplification or sensationalism. This has given him the experience needed to make the explanatory chapters of this book a good laymen's primer.
There is a clear account of the celebrated greenhouse effect in which certain gases, such as CO2, let sunshine through to the ground but absorb some of the heat the ground would radiate back to space. Earth would be unliveably cold without this effect.
The central question this part of the book asks is: What may be the effect of man-made greenhouse gas pollution?
Schneider shows how studies of past climate changes finger atmosphere CO2 content as a key pacing factor. Computer climate models predict that the additional CO2 from burning fossil fuels would raise Earth's average surface temperature several degrees Celsius. This could translate into such regional catastrophes as sea-level rises that flood coastal cities, crop-searing droughts, and intensified hurricane activity.
But the models have weaknesses that make their predictions uncertain. Schneider spells these out candidly. He also warns that, if governments are to begin limiting CO2 pollution, they can't rely only on scientific knowledge to justify that decision.
This is the crux of what the book has to offer. Even though the author himself wants such action now, he advises: ``We must turn to our own values in order to make the decision whether hedging against potential future changes is worthy of the investment of present resources. Don't let anyone tell you that technical knowledge or uncertainty provides a `scientific' basis for policy choice, for science can only contribute to policy analysis, not to policy choice.''
Schneider states his own position in his politically oriented chapters. Is global warming a reality? He says ``I believe we've been in it for a while already.'' But he admits he can't prove this scientifically just yet. Should we act as though global warming is likely? He says unambiguously ``yes.''
The action he would like to see would attempt in a variety of ways to slow and eventually stabilize the rise of heat-trapping gases. This would involve many kinds of action, including aggressive development of efficient energy use and alternative energy sources. It would promote forest conservation. Most important, it would emphasize cooperation between industrial nations and developing countries to curb pollution in the former and encourage nonpolluting economic development in the latter.
One of the book's weaknesses is the author's accounts of various forums in which he has discussed such action. He sometimes goes on about these experiences to an extent that becomes repetitive and a bit boring.
In spite of this, the book is a gold mine of insight and information. If it awakens readers to the global warming challenge and gives them sufficient understanding to think meaningfully about it, Schneider says, he will have succeeded whether readers agree with his political agenda or not. I wish him well.