Volume 5, Number 26: 26 June 2002
The Kyoto Protocol is based on the premise that the ongoing rise in the air's CO2 content must be slowed as soon as possible, and ultimately stopped altogether, in order to avoid an increase in mean global air temperature of sufficient magnitude to inflict serious damage on the biosphere. Consequently, those who believe in the conceptual foundation of the Protocol - as well as some who don't (but who promote its adoption for political or philosophical reasons) - would like to see its provisions implemented as soon as is practicable, in order to prevent the presumed deleterious consequences (or, alternatively, to foist their political philosophy upon the world).
Within this context, it is important to know what the proponents of the Protocol consider a dangerous climate impact worthy of immediate action. Taking the Intergovernmental Panel on Climate Change as their guide, O'Neill and Oppenheimer (2002) say it is an impact that either imposes a risk upon unique and threatened ecosystems or engenders a risk of some large-scale discontinuity in earth's climate system. On this basis, they claim there are three warming-related risks that are serious enough to implement the Kyoto Protocol with all due haste. These risks are the potentials for (1) the infliction of extreme damage to earth's coral reefs, (2) the disintegration of the West Antarctic Ice Sheet, and (3) the virtual shutdown of the marine thermohaline circulation.
The basis for the first of these supposedly dangerous risks - which draws its inspiration from the work of Hoegh-Guldberg (1999) - is, in the words of O'Neill and Oppenheimer, the presumption that "sustained global warming in excess of 1°C would cause bleaching [of coral reefs] to become an annual event in most oceans," plus the further presumption that "sustained bleaching over consecutive warm seasons increases the risk of permanent loss of the reefs."
The melding of these two assumptions sounds a lot like a prescription for extinction. But could a temperature increase of just a little over 1°C really produce such a catastrophic consequence?
Perhaps the best way to settle this question is to consider earth's climatic past. If, for example, it can be demonstrated that within the time frame required for the evolution of extant coral species, there were sustained periods when the planet's mean surface temperature was more than 1°C warmer than it was in 1990 (the baseline date employed by O'Neill and Oppenheimer from which to measure temperature departures), there can be no question but what their presumptions are wrong; for such temperatures, if they truly occurred, were obviously not a detriment to the continued existence of the host of coral species that currently inhabit the world's oceans.
In this regard, we note that the scleractinian corals, which are the major builders of the reefs of today (Achituv and Dubinsky, 1990), appeared in the mid-Triassic some 210 million years ago (Wells, 1956), when the earth was considerably warmer than it is currently (Chadwick-Furman, 1996). They were also present throughout the Cretaceous, when temperatures were as much as 10-15°C higher than at present (Chadwick-Furman, 1996). Last of all, they survived the numerous warm interglacials that have punctuated the great Pleistocene ice ages (Pandolfi, 1999).
Of these latter warm periods, the most pertinent, of course, are the most recent, as their thermal conditions would have impacted the most immediate predecessors of today's corals; and we are fortunate in this regard to have a 420,000-year record of Antarctic temperatures that was derived from the Vostok ice core by Petit et al. (1999). Their extensive data set clearly indicates that all four interglacials that preceded the current interglacial were warmer than the one in which we presently live by an average thermal increment in excess of 2°C. Furthermore, the most recent of the prior four interglacials was fully 3°C warmer.
Of course, one can always say these data pertain to Antarctica, which is not the part of the world where most corals are apt to be found. Just recently, however, Muhs et al. (2002) published a review of a vast array of globally-dispersed faunal records - including marine invertebrates, such as mollusks, ostracodes and corals themselves - from which Last-Interglacial ocean temperatures can be inferred. Beginning with their own work, they note that both Oahu, Hawaii and Bermuda, which they studied in great detail, exhibit evidence of a number of "extralimital southern species of mollusks, suggesting warmer-than-present waters during the Last Interglacial period." Warmer Last-Interglacial waters are similarly suggested for localities around North America, including Alaska, Greenland, Baffin Island, Nantucket Island, southern Florida, Baja California, California and Oregon. In addition, Muhs et al. note that "studies in Japan, the Mediterranean Basin and Western Australia also show evidence of warmer-than-modern Last-Interglacial waters." And in many of the cases of high-temperature-induced latitudinal displacement of species, the distances involved spanned hundreds - and in some instances even thousands - of kilometers. Also, in a study of marine sediment cores obtained along the western coast of North America from the southern tip of the Baja Peninsula to Oregon, Herbert et al. (2001) determined that "the previous interglacial produced surface waters several degrees warmer than today," such that "waters as warm as those now at Santa Barbara occurred along the Oregon margin."
Even the several-thousand-year-long central portion of the current interglacial was considerably warmer than it has been recently. On the basis of temperature reconstructions derived from studies of latitudinal displacements of terrestrial vegetation (Bernabo and Webb, 1977; Wijmstra, 1978; Davis et al., 1980; Ritchie et al., 1983; Overpeck, 1985) and vertical displacements of alpine plants (Kearney and Luckman, 1983) and mountain glaciers (Hope et al., 1976; Porter and Orombelli, 1985), it has been concluded (Webb et al., 1987; COHMAP, 1988) that mean annual temperatures in the Midwestern United States were about 2°C warmer than those of the past few decades (Bartlein et al., 1984; Webb, 1985), that summer temperatures in Europe were 2°C warmer (Huntley and Prentice, 1988), as they also were in New Guinea (Hope et al., 1976), and that temperatures in the Alps were as much as 4°C warmer (Porter and Orombelli, 1985; Huntley and Prentice, 1988). In the Russian Far East, temperatures are also reported to have been from 2 °C (Velitchko and Klimanov, 1990) to as much as 4-6°C (Korotky et al., 1988) higher than they were over the past few decades; while the mean annual temperature of the Kuroshio Current between 22 and 35°N was 6°C warmer (Taira, 1975).
These several observations, as well as a host of others not cited, bear witness to the fact that many times in the past, the coral species that currently inhabit the planet have successfully endured temperatures well in excess of what O'Neill and Oppenheimer claim should pretty much spell their doom; and the fact that they are still with us speaks volumes about their resiliency. For the past several centuries, however, a number of direct and localized human activities have degraded coastal environments the world over to the point where today's corals can no longer respond to rising temperatures with the resiliency that served them so well in the past, being subject, as they are, to so many other anthropogenic-induced stresses (Idso et al., 2000). Thus, it is becoming more and more commonplace that periods of higher-than-usual temperatures do indeed result in deadly episodes of coral bleaching; and this synergism is showing signs of reaching mammoth proportions.
So what should we do about it? We should do what we know will relieve the stress, not what we incorrectly speculate will alleviate it. For example, what if the sun is largely responsible for 20th century warming? If it is - as we truly believe is the case [see our Editorials of 28 November 2001 and 12 June 2002] - no cutback in CO2 emissions, however large, will have any impact on global temperature. And even if the rise in the air's CO2 content is responsible for the temperature rise - for which proposition we find no compelling evidence - even O'Neill and Oppenheimer openly admit that "the emissions limits required by the Kyoto Protocol would reduce warming only marginally."
So, if you want to see earth's coral reefs go the way of the dodo bird, follow the advice of "O and O." But if you want to have any hope at all of truly preserving these unique marine ecosystems for generations yet to come, fight the good fight against human activities that either physically, chemically or biologically end up polluting specific coral reefs. Do what works, and do it locally ... everywhere.
Dr. Sherwood B. Idso
Dr. Keith E. Idso
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