With the threat of an imminent nuclear exchange behind us, there is now only the prospect of global warming to keep us awake at nights. And that threat is not all that distant. By the middle of the next century, we shall all be uncomfortably warmer than now unless we live in Manitoba or Siberia-by which time it will be too late to do much about a further worsening of the climate.
That is what the intergovernmental panel on climate change (IPCC) has been saying since 1990, when it produced its first assessment of the prospects. (Others, Roger Revelle of Harvard University in particular, began the refrain more than four decades earlier.) The success of the UN framework convention on climate change negotiated at Rio in 1992 suggests that governments in general believed what the IPCC had said, although the Bush administration in the US was more than hesitant.
The IPCC is now in the throes of producing its second assessment, the most important part of which has just appeared (Climate Change 1995, CUP 1996). The earlier version, timed to precede the Earth summit at Rio, was widely lampooned on several grounds, not least because the second and third parts of the exercise were inconsistent with each other and were manifestly na?ve as well. This time round, part one has drawn the flak, perhaps because the other two have yet to appear.
Part one? Parts two and three? What is this? You need to know that the IPCC is a creature of two UN agencies, the World Meteorological Organisation (WMO) and the UN Environmental Program (Unep) and that it was founded in anticipation of the Rio summit to make an assessment of global warming. The concept was grandiose and old- fashioned.
There were to be three working groups (WG1, WG2 and WG3), working simultaneously; the first would deal with the science, the second with the economic and social aspects and the third would make recommendations to governments. The trouble with the first assessment was that nobody had considered how WG3 could make intelligent recommendations without seeing the reports of WG1 and WG2 and how WG2 could say what the socio-economic consequences of global warming would be without seeing WG1's conclusions.
But it is all in a good cause. If it is relevant, my own belief is that the middle ground projections of global warming, if proved correct, will be as big a threat to international peace and quiet half a century from now as nuclear weapons ever were. I also believe that the IPCC, already a substantial bureaucracy in its own right, is at risk of being imprisoned by political correctness, to which all too many UN offshoots eventually succumb; and that precisely because global warming is a potentially serious problem, the scientific assessment of the risk should be in more robust hands.
To say that is not to imply that this year's document is anything but excellent. Its 570 pages are packed with technical information. CUP can fairly claim, on the IPCC's behalf, that it is the "most comprehensive and up-to-date assessment available of current scientific understanding..." There are 11 separate chapters on topics such as climate modelling (by computer), sea level changes and the need for more research, all of which are preceded by a "Technical Summary" and a "Summary for Policymakers." The tone of the document is that of a high-level textbook, perhaps one designed to help graduate students to read their way into a new subject. With the help of copious references to the literature, the text covers the ground from A to Z.
With all that said, it is not entirely clear to whom the document is addressed. Certainly not to the research community of atmospheric scientists, which is entirely proper; they have their own research journals anyway, and this volume does not pretend to be a compendium of original research but a review of material already published. To judge from the tone of the text, with its blend of explanatory and critical material, the intended audience is interdisciplinary, a little like that of the weekly journal Nature.
That may be thought only right; if global warming is a risk, a first priority must surely be to alert the whole research community to the dangers. But the policymakers are also in there, with a summary all to themselves. (The IPCC's top brass, when asked why this or that technical point has not been dealt with, often takes the line that documents like this are meant for policymakers anyway and have to be simple.)
The scale of the effort is gargantuan. The document claims that there were 78 "lead authors" from 20 countries, 400 contributors from 40 countries and no fewer than 500 reviewers from as many countries. Just think of all those e-mail messages and per diem forms! In reality, the IPCC's network includes most of the world's well known atmospheric scientists, while the leadership consists of stars from the same firmament: the overall chairman is Bert Bolin from Stockholm; the co-chairmen of WG1 are John Houghton (former director of the UK Meteorological Office) and L Gilvan Meira Filho who holds a similar position in Brazil.
So how, with all that care taken, could there have been so much trouble about the content of Climate Change 1995? It is a curious story, which came to light during the summer when Frederick Seitz, president emeritus of the Rockefeller University in New York, wrote an article in the Wall Street Journal complaining that the IPCC had tampered with the text of Climate Change 1995 after its final approval by WG1 at a meeting in Madrid in November last year. Seitz used strong language; "corruption of the peer review process" was one phrase.
The argument is about the difference of meaning between phrases such as "point towards a detectable..." and "... balance of evidence suggests a discernible" human influence on global climate. The second, considered the weaker statement, survived. But the oddest feature of the story is that the main text was changed to match the summary, not the other way around.
John Houghton has explained, in the correspondence columns of Nature last month, that the IPCC's agreed procedures distinguish between documents which are "accepted" and "approved." In the new assessment, only the "Summary for Policymakers" was "approved" line for line; after that, evidently only the "accepted" documents could feel the weight of the chairman's red pencil.
None of this can be counted as a scandal; if such there is, it must surely be that grown men have spent so much time arguing about it. The real trouble will come a few years from now, when estimates of what the future holds will presumably be more accurate than they are now, and when there may also be substantial rather than marginal evidence that the climate is indeed changing.
The issue of peer review is also interesting. The IPCC routinely defends its conclusions by insisting that all its documents have been peer reviewed. It is a standard procedure much used by learned journals and grantmaking bodies. It entails asking experts in a field what they think of a proposed publication or research grant application. Replies are usually careful, and geared to the purpose.
But perhaps the real worry about the IPCC is that the scientific part of it has become a kind of club. People who regularly meet at working groups inevitably become pally and, eventually, exclusive. There is nothing to suggest that WG1 is anything but meticulous in its treatment of the data it handles, but it also wears its search for consensus prominently on its sleeve. There is nothing like that to bring on a bout of political correctness.
To be fair, there are not many who are both knowledgeable and who dissent from the IPCC's conclusions so far: that the computer models predict warming over the next half century or so and that there is a steady deepening of understanding about past climatic fluctuations, which also test the models and provide a yardstick for what would be unnatural warming. The big development since 1990 is that the integration between the atmosphere and the oceans is better understood. On the other hand, the computers cannot yet deal with real clouds, only average cloudiness.
So what should be changed in the IPCC's way of working? It is surely essential that WG1 should be detached from its social, economic and political partners. In the long run, they will have the more difficult job to do-devising a quota system that taxes countries with rapid population growth, listening to China's comment on the proposition that it is no longer a developing country and thus exempt from restraints, and so on. But those are also the entanglements that turn political correctness into compromise and fudge.
WG1 should also be more open to the scientific community at large. At present, researchers who dissent from its findings are merely advised to write to one of the lead authors. In fact, WG1 would be surprised at the response if it asked the research community at large for help. (I have a physics professor friend in the US who is wondering whether he should spend his retirement persuading the IPCC that particle physicists know how best to use data to answer questions such as "Does global warming exist or not?") But a little proselytising would also help dispel the envious impression (false, I have no doubt) that the IPCC exists to raise public funds for atmospheric research.
On what may seem a technical point, but which is not, it is to be hoped that the IPCC does not see its task as that of updating its present textbook every four or five years. It should be reviewing all the literature and giving its assessment. It should also make an explicit statement about the current uncertainties in the global climate problem and update that. The result would be more persuasive-and less dull.
The danger is not that we or our grandchildren will die from drought or drowning as the sea level rises. Survival is always possible, but at a price: taxes, high taxes.
