Monday, January 18, 2010

11. Effects of Warming II

Former VP Al Gore calls CO2 "an urgent and unprecedented threat to the existence of our civilization." The most authoritative source for information about exactly why this might be so is presumably the report on Impacts, Adaptation and Vulnerability by Working Group II in the current edition of the gospel according to the Intergovernmental Panel on Climate Change (IPCC), its Fourth Assessment Report. Unfortunately, this document is a morass of misrepresentation and equivocation.

The general principle seems to be that any deviation at all from the present situation is necessarily detrimental – or, in other words, that we now live in the best of all possible worlds. The major conclusions that are highlighted in the report are mostly meaningless, weasel-worded platitudes, such as "A global assessment of data since 1970 has shown it is likely that anthropogenic warming has had a discernible influence on many physical and biological systems." The apparent implication is that any "discernible" effect of human activities is a major global disaster that we must resist at any cost.

Where specific effects are "projected" (a word that, in IPCC NewSpeak, apparently means "conjectured"), misleading caveats are usually added, presumably as a defense against accusations of outright falsehood. An example: "Increases in sea surface temperature of about 1-3°C are projected to result in more frequent coral bleaching events and widespread mortality, unless there is thermal adaptation or acclimatisation by corals" (emphasis added). The phrase in italics is the only indication that corals first appeared some 500 million years ago, and have in fact evolved through much greater climate changes than anything "projected" by the IPCC. A presentation less biased might have mentioned that the largest coral colony on Earth, the Great Barrier Reef off the coast of Queensland, dates from 25 million years ago, and has survived the temperature maximum of the Miocene epoch as well as the savage ice ages of the Pleistocene. It stretches over 18ยบ of latitude, and thus accommodates a range of sea temperatures. The active region of the reef might migrate north or south when the climate changes, but it is ridiculous to suggest that anthropogenic global warming (AGW) would endanger its survival, or even that its effects would be noticeable compared to other environmental threats, such as predation by the Crown of Thorns starfish.

The few clear declarative statements in the report are remarkably one-sided: for example, it is claimed that the "frequency of heatwaves… will increase rapidly, causing increased mortality, crop failure, forest die-back and fire, and damage to ecosystems," without noting that warming would also alleviate cold spells, which are much more dangerous to people, crops, and many species of plants and animals. This is clumsy propaganda, not objective scientific analysis.

It is true, of course, that significant warming would disrupt some human activities. Most ski resorts would presumably face a shorter season, and some at lower latitudes might go out of business. Devotees of ice fishing in the northern United States and in Canada would face thinner ice or a shorter season – but, on the other hand, they would enjoy better weather all year, lower winter heating bills, lower costs for snow removal, fewer cold-related diseases, and fewer accidents on icy roads.

It is also true that climate change could affect the habitats of many native plant and animal species. Some would thrive, some would adapt, some would migrate, and some might face extinction. In time, new species might evolve, better adapted to the new conditions. There is however no evidence that anthropogenic CO2 poses an ecological threat comparable to those from many natural changes, and from other human activities. In fact, the most cursory comparison of the variety of species in the Tropics with those in the Arctic shows conclusively that warming will increase overall biological diversity.

The US Endangered Species Act (ESA) of 1973 is based on the proposition that we must protect every species, no matter how insignificant, and no matter what the cost, "other than a species of the Class Insecta determined by the Secretary to constitute a pest whose protection under the provisions of this Act would present an overwhelming and overriding risk to man." Of course we should not casually destroy existing species, but this formulation agrees with the IPCC in the implication that the present suite of species is somehow the best possible. The idea that we can or should interfere with nature by preventing evolution is insane human hubris.

It is simply not true that all changes due to human activities are deleterious. Some actions (for example, deforestation that creates farmland or prairie) may exterminate some species, but it also creates new habitat for other species. It is not obvious a priori that it is better to preserve a threatened species than to extend the range of some other species, or to encourage evolution of new species.  

Severe climate changes can certainly cause difficulties for many species, including us, but they are a major evolutionary force. Eventual extinction has been the common fate of all species: 97% of those that once existed have disappeared. The history of life on Earth has been one of repeated catastrophes – but without them, primitive pond scum would be the only life there is. In particular, it was probably the selective stresses due to the brutal ice ages of the Pleistocene that led to the evolution of Homo sapiens. If our ancestors had not been exposed to severe glaciation, interrupted every thousand centuries by brief warm interglacials, we would still be primitive homini, mere prey animals for the big cats that roamed the Rift Valley in East Africa. 

Even if we could prevent global warming or protect all species from its effects, it would be only a temporary reprieve. The relatively benign climate that we have enjoyed throughout recorded human history is merely a transient interglacial: the ice will surely come again. When it does, it will take only 20 years for ice sheets a mile thick to cover most of Europe and all of North America, as far south as Kansas. The transition could begin tomorrow, or not for a thousand years or more. The threat to the survival of many species will be much more extreme than anything AGW could do.

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