CO2 GLOBAL WARMING AND CORAL REEFS: PROSPECTS FOR THE FUTURE

Authors: IDSO, SHERWOOD; IDSO, CRAIG - CTR...GLOBAL CHANGE TEMPE; IDSO, KEITH - CTR...GLOBAL CHANGE TEMPE

Submitted to: Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: A disturbing perturbation of earth's biosphere that has become increasingly pronounced over the past two decades is the phenomenon of coral bleaching. Because global temperatures are believed to have risen over this same time period, it has been postulated that rising temperatures have been responsible for the increasing frequency of bleaching episodes. It has also been postulated that the increasing concentration of atmospheric carbon dioxide (CO2) is altering the chemistry of seawater in such a way as to reduce coral calcification rates. In a comprehensive review of these subjects, we find that these highly publicized threats have been generally oversimplified, often exaggerated, and sometimes even misinterpreted. The scientific literature reveals, for example, that (1) there is no simple linkage between high temperature and coral bleaching, (2) bleaching may, in fact, be an adaptive mechanism that helps corals survive increasing temperatures, (3) reefs will likely benefit from the rising sea levels thought to result from global warming, and (4) atmospheric CO2 enrichment may actually enhance coral calcification rates. It is clear, however, that local human influences can severely weaken coral reefs, making them more susceptible to changes in the global environment. Consequently, well-thought-out local solutions to well-defined local problems may well do more to protect earth's coral reefs from pervasive environmental changes than anything we could ever do in the global arena. This information should help everyone concerned about reef health to better maintain these important ecosystems.

Technical Abstract: Reconstructions of surface air temperature and atmospheric CO2 concentration derived from Antarctic ice cores reveal that air temperature always rose or fell in advance of similar changes in the air's CO2 content throughout all major climate transitions between glacial and interglacial periods of the past half-million years, thereby demonstrating that changes in atmospheric CO2 concentration cannot be the principal cause of climate change. A review of the literature also reveals there is no simple linkage between high temperatures and coral bleaching. Indeed, scientists are beginning to realize that bleaching may be an adaptive mechanism for surviving high temperatures. Many reef specialists also suggest that reefs may not only tolerate rising sea levels but actually benefit from them. On the other hand, the rising CO2 content of the atmosphere may induce changes in ocean chemistry that could slightly reduce coral calcification rates; but potential positive effects of hydrospheric CO2 enrichment may more than compensate for this modest negative phenomenon. The geologic record reveals that earth's coral reefs are well equipped to deal with major environmental changes, the most immediately threatening of which could well be a rapid global cooling instead of the catastrophic warming that has been predicted for several years. Currently, however, a number of local or place-specific anthropogenic activities are rendering reefs more susceptible to the deleterious effects of all potential climatic and/or environmental fluctuations. It is imperative, therefore, that these local problems be immediately addressed in order to help coral reefs better withstand the vagaries of natural global change.