How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic


Thirty-Five Years of Climate Change in Antarctica
Reference
Doran, P.T., Priscu, J.C., Lyons, W.B., Walsh, J.E., Fountain, A.G., McKnight, D.M., Moorhead, D.L., Virginia, R.A., Wall, D.H., Clow, G.D., Fritsen, C.H., McKay, C.P. and Parsons, A.N. 2002. Antarctic climate cooling and terrestrial ecosystem response. Nature advance online publication, 13 January 2002 (DOI 10.1038/nature710).

What was done
Between 1986 and 2000, the authors measured a number of meteorological parameters in the McMurdo Dry Valleys of Antarctica, while they simultaneously measured various characteristics of the region's indigenous life forms. They also compared what they learned about climate change over this period with what happened concurrently over the rest of the continent, the climatic record of which stretches two additional decades back in time.

What was learned
Over the 14 years of the authors' intensive measurements, the McMurdo Dry valleys cooled - that's right, cooled - and at the phenomenal rate of approximately 0.7C per decade. This dramatic cooling, in the words of the authors, "reflects longer term continental Antarctic cooling between 1966 and 2000." In addition to sharing the same cooling trend, most of the 14-year cooling in the dry valleys occurred in the summer and autumn, just as most of the 35-year cooling over the continent as a whole (which did not include any data from the dry valleys) also occurred in the summer and autumn. The authors note that this multi-faceted "compatibility with the dry valley data increases the validity of the analysis."

Ecosystem response to the observed cooling was not good. In fact, it was - for lack of a better word - bad. Since the thickness of ice on the perennially ice-covered lakes in the McMurdo Dry Valleys increased by an average of 1.5 meters over the 14-year period, underwater irradiance declined so much that the primary productivities of the region's lakes decreased at rates of 6-9% per year. Likewise, on the adjacent land, soil moisture gradually dropped - from 2.2% by weight to 1.4% by weight - between 1993 and 1999, which decline is equivalent to a relative drop of 6% per year. Hence, it was not surprising that the group of scientists determined that the numbers of soil invertebrates (the largest animals around) simultaneously declined by "more than 10% per year."

What it means
In the words of the authors, the continental Antarctic cooling documented in their paper "poses challenges to models of climate and ecosystem change." Climate models, as they note, not only predict that global warming should have been occurring over the period of their study, but that there should have been "amplified warming in polar regions." To instead find dramatic cooling - which is about as different from amplified warming as one can get - especially in one of the two places on earth where the climate models are thought to be most correct, represents about as clear-cut a refutation of the predictions of the climate models as one can imagine. Likewise, we keep hearing how bad global warming will be for the biosphere, when for Antarctica it is cooling that is decimating its meager ecosystems.

Yes, there's nothing like a reality check now and then to set the record straight. And what the real-world record tells us about the future of this part of the world, in the words of the authors, is that "prolonged summer cooling will diminish aquatic and soil biological assemblages throughout the valleys, and possibly in other terrestrial Antarctic ecosystems."

So where are the placard-carrying activists who will march on behalf of Antarctic tardigrades and nematodes? Who will protest in the name of Scottnema lindsayae, which could well disappear from the realm of the living if current trends continue? Don't strain your eyes, because you simply won't see them. They are blinded to the truth by the political Juggernaut that paints white black and black white with respect to CO2 and its impacts on climate and biology.


Reviewed 30 January 2002