A (Oliver Morton, a staff writer for "Nature"): Our planet is not in mortal peril.
...The planet-in-peril idea persists through widespread ignorance of earth history. The current carbon/climate crisis is small beer. The change in mean global temperatures seems quite unlikely to be much greater than the regular cyclical change between glacial and interglacial climates. Land use change is immense, but it's not clear how long it will last... If fossil fuel use goes unchecked, CO2 levels may rise as high as they were in the Eocene, and do so at such a rate that they cause a transient spike in ocean acidity. But they will not stay at those high levels, and the Eocene was not such a terrible place.[Most of the land was covered by lush forests, where flyless predatory birds, eg Gastornis were hunting the ancestors of horses-S.]
...The earth doesn't need ice caps, or permafrost, or any particular sea level. Such things come and go and rise and fall as a matter of course. The planet's living systems adapt and flourish, sometimes in a way that provides negative feedback, occasionally with a positive feedback that amplifies the change. A planet that made it through the late Permian [one of the great mass extinctions-S.] is in little danger from a doubling, or even a quintupling, of the very low CO2 level that preceded the industrial revolution, or from the loss of a lot of forests and reefs, or from the demise of half its species, or from the thinning of its ozone layer at high latitudes.
...Since the 1970s the environmental movement has based much of its appeal on personifying the planet and making it seem like a single entity, then seeking to place it in some ways "in our care". The idea that the planet is not in peril could thus come to undermine the movement's power. This is one of the reasons people react against the idea so strongly. One respected and respectable climate scientist reacted to Andrew C. Revkin's [a NYT science reporter who published an article "Past Hot Times Hold Few Reasons to Relax About New Warming," in December 27, 2005 issue - S.] recent use of the phrase "In fact, the planet has nothing to worry about from global warming" in the New York Times with near apoplectic fury. http://www.edge.org/q2006/q06_11.html#morton
excerpt from the "controversial" article in question:
[Andrew C. Revkin is a science reporter on climate issues for NYT; his reports can be read here http://www.nytimes.com/pages/science/sciencereport]
[David G. Barber holds the Canada research chair in Arctic systems science at the U. Manitoba]
...Even for polar bears, there are reasons to think the end is not necessarily nigh. There was at least one significant period - the last gap between ice ages 120 kya - when the global climate was several degrees warmer than it is today and they clearly squeaked through. Dr. Barber said he was confident that biology would endure much of what humans throw at it. His concern is for the effects on people and the things they rely on or cherish."All of global warming has nothing to do with the planet," Dr Barber said. "The planet will go on through its normal cycles, and it will do its own thing. It only has to do with us - as people. Our economic side of things and our political side of things are really what are being affected by climate change. The planet could care less." [See also Update 1 below]
More thoughts about the decimation of coral reefs (another favorite of the doomsayers) from the evolutionary perspective, from Rachel Wood (Cambridge; In Annu. Rev. Ecol. Syst. 29 (1998) 179):
...the fossil record of reef-building shows that both the acquisition of photosymbiosis and the appearance of modern predator, herbivore, and bioeroding groups are relatively recent occurrences: Many ancient reefs clearly grew under profoundly different ecological controls than those that govern the functioning of modern coral reefs. Moreover, the global distribution of reefs has varied considerably through geological time, determined largely by sea-level, geochemical, and climatic fluctuations. Present day sea level is relatively low compared to that in much of the geological record such that the area of shallow water tropical seas is small, resulting not only in a reduced volume of shallow-water carbonates being formed, but also in an absence of analogs for the very extensive shallow seas (known as epeiric or epicontinental seas) that were common when sea levels were high. The extensive carbonate platform reefs and atolls of today are also the product of an unusually prolonged period of stable sea level, which, together with relict topography, have exerted a strong influence over modern reef form and style of sedimentation. Present-day climate is also relatively cool, with well-developed polar ice caps. During significant periods of geological time, ice caps were not present, and at times such as the mid-Cretaceous, northern hemisphere mean annual surface temperatures may have been 15 to 25 C warmer than today. In addition, 60% of modern carbonate production is accounted for by calcareous plankton that produce pelagic ooze deposited on the deep ocean floor, but before the evolution of such plankton during the mid-Mesozoic, shallow marine carbonate deposits represented up to 90% of global production. Consequently, for much of geological time, marine carbonate distribution, and possibly carbonate saturation levels, were very different from those found in modern seas. http://web.macam98.ac.il/~biology/courses/aquat_biol/evolution%20of%20coral%20reefs.pdf
Yes, if anything, it is the present situation which is rare and "unhealthy."
We should worry about ourselves, rather than the mystical "health of the planet," polar bears, and reefs. They endured much more than we can offer as far as the climatic upheaval is concerned. Furthermore, one cannot have evolution without extinction. The planet will take care of itself.
Why is this self-obvious idea dangerous?
PS: There are more "dangerous ideas" on that site, from physics to psychology to biology, most of which are but speculative drivel. For some reason, string theory landscape and anthropic principle are discussed a lot. Susskind claims that this favorite idea of his "spreads like cancer." So far, the cancer is largely contained to the West Coast. The majority of these "dangerous ideas" have been articulated countless times before without doing much harm; I'd say, all in all I did not learn much new or "dangerous." In Pauli's words: "Harmless, harmless."
Update 1: 5/2/06 More thoughts on the demise of polar bears:
...Flannery says polar bears typically gave birth to triplets, but now they usually have just one cub. That is wrong. Triplets, though they do occur, are very infrequent and are by no means typical. Polar bears generally have two cubs — sometimes three and sometimes one. He says the bears' weaning time has risen to 18 months from 12. That is wrong. The weaning period has not changed. Polar bears worldwide have a 3-year reproduction cycle, except for one part of Hudson Bay for a period in the mid-1980s when the cycle was shorter. One polar bear population (western Hudson Bay) has declined since the 1980s and the reproductive success of females in that area seems to have decreased. We are not certain why, but it appears that ecological conditions in the mid-1980s were exceptionally good. Climate change is having an effect on the west Hudson population of polar bears. Of the 13 populations of polar bears in Canada, 11 are stable or increasing in number. They are not going extinct, or even appear to be affected at present. It is noteworthy that the neighbouring population of southern Hudson Bay does not appear to have declined, and another southern population (Davis Strait) may actually be over-abundant. Dr. Mitchell Taylor, Polar Bear Biologist, Department of the Environment, Government of Nunavut, Igloolik, Nunavut; from "Toronto Star."