How does rising atmospheric CO2 affect marine organisms?

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Question:
On August 10, 1998, the Office of the Vice President of the United States of America issued an official press release that stated that "we are warming the planet and, unless we act, we can expect even more extreme weather - more heat waves, more flooding, more powerful storms, and more drought."  Prominently reported by national and local television media, the Vice President's pronouncement was set to images of catastrophic environmental destruction typical of the apocalyptic view shared by alarmists who are quick to associate heat waves, droughts, floods, storms and various other devastating weather phenomena with CO2-induced global warming.  But are such claims correct?  Are they grounded in scientific truth?  Or are they merely suppositions?

Answer:

To answer these questions, we turn to the latest report (Houghton et al., 1996) of the Intergovernmental Panel on Climate Change (IPCC), where it is noted that interannual temperature variability has shown no consistent trend in recent decades, while in some regions it has actually decreased (Karl et al., 1995).  This highly-touted "consensus of scientists" report also indicates that there is no evidence of changes in interannual rainfall variability, although only a few regions have been carefully examined.  The report does state that evidence of a trend towards fewer low-temperature and frost events has been reported in a number of widely-separated areas in recent decades but that "widespread significant changes in extreme high temperature events have not been observed, even in areas where the mean temperatures have increased."

There is also solid evidence that as earth's CO2 concentration has risen over the last few decades, intense tropical cyclone activity has actually decreased in the North Atlantic (Gray, 1990; Landsea et al., 1996).  In fact, even the climate models are beginning to point in this direction.  In a recent model experiment, for example, Bengtsson et al. (1996) used a GCM to estimate the likely changes in hurricane intensity and frequency that would result if the concentration of atmospheric CO2 were to double.  Their results indicate that the number of hurricanes would be "significantly reduced, particularly in the Southern Hemisphere" and that "most tropical storm regions indicate reduced surface windspeeds and a slightly weaker hydrological cycle."

Hurricane financial damage in the U.S. has also dropped in recent decades.  Particularly revealing in this regard is the study of Pielke and Landsea (1997), who examined U.S. hurricane damage trends over the last 70 years, estimating the damage likely to occur if past hurricanes were to hit today.  Incorporating relative inflation, wealth statistics and population, they found that the most damaging hurricane (relatively speaking) occurred in Florida in 1926, causing almost twice the damage of hurricane Andrew.

To summarize, the consensus of scientists expressed in the 1996 IPCC report states bluntly that "there is no evidence that extreme weather events, or climate variability, has increased, in a global sense, through the 20th century."  Consequently, if there has not been an increase in extreme weather events over the past century, and the mean global temperature has increased over this period, the Vice President's claim that more heat causes more extreme weather would appear to have no basis in climatological fact.  It would thus appear that his pronouncement of August 10 must be climatological fiction.

References

Bengtsson, L., Botzel, M. and Esch, M.  1996.  Will greenhouse gas-induced warming over the next 50 years lead to a higher frequency and greater intensity of hurricanes?  Tellus 48A: 57-73.

Gray, W.M.  1990.  Strong association between West African rainfall and U.S. landfall of intense hurricanes.  Science 249: 1251-1256.

Houghton, J.T., Miera Filho, L.G., Callander, B.A., Harris, N., Kattenberg, A. and Maskell, K (Eds.).  1996.  Climate Change 1995: The Science of Climate Change.  Cambridge University Press, Cambridge, UK.

Karl, T.R., Knight, R.W. and Plummer, N.  1995.  Trends in high-frequency climate variability in the twentieth century. Nature 377: 217-220.

Landsea, C.W., Nicholls, N. and Avila, L.A.  1996.  Downward trends in the frequency of intense Atlantic hurricanes during the past five decades.  Geophysical Research Letters 23: 1697-1706.

Pielke, R.A. and Landsea, C.W.  1997.  Normalized hurricane damages in the United States: 1925-1995.  22nd Conference on Hurricanes and Tropical Meteorology, Fort Collins, CO.