How does rising atmospheric CO2 affect marine organisms?

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The Opposing Impacts of Intensified Human Activities
Reference
Krebs, J.R., Wilson, J.D., Bradbury, R.B. and Siriwardena G.M.  1999.  The second silent spring?  Nature 400: 611-612.

What was done
The authors discuss how "the drive to squeeze ever more food from the land has sent Europe's farmland wildlife into a precipitous decline."

What was learned
The British Trust for Ornithology's annual censuses of 42 species of breeding birds shows that 13 species living exclusively in farmland declined by an average of 30% between 1968 and 1995, while 29 species of habitat generalists increased by an average of 23%.  The authors attribute the 13-species decline to the intensification of agriculture, particularly those aspects of it that have led to the massive monoculture of but a few crops, resulting in the loss of the "heterogeneous landscapes [that] are beneficial for birds."

What it means
We have no reason to doubt the data presented or the conclusions of the authors.  What is most interesting, however, is what is left unsaid.  What about the 29 species of non-farmland or generalist bird species that increased in numbers between 1968 and 1995?  What caused this phenomenon?

In multiple places throughout our website, we have reported on the tendency for the ongoing rise in the air's CO2 content to stimulate vegetative productivity, expand plant and animal ranges, and promote ecosystem biodiversity, even in the face of regional or global warming; and we believe that this consequence of anthropogenic CO2 emissions is what is responsible for the very important benefits (such as the one described here for generalist bird species in Britain) that are beginning to be recognized in the world of nature.  Clearly, the activities of Industrial Man are like those of a two-edged sword; they cut both ways, for good and for evil.  Moreover, they do so at one and the same time.  If we could but blunt one edge of this marvelous instrument, we could be a tremendous source of good, for both ourselves and nature, and we could be such simultaneously.


Reviewed 1 September 1999