How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Is there scientific consensus on the causes of glacial periods. Looking at the history of glacial periods, it looks as if we should be pouring CO2 and methane into the atmosphere in the hope that we could forestall the next big chill.  Is the solar radiation variable enough to cause cooling, or is it possible that interplanetary dust clouds could block solar radiation from the earth on a cyclic basis?

Submitted by: Edward Riffle

There is indeed a general consensus that the cyclical glaciations of the past million years [Climate History (Overview - The Last 2,000,000 Years)] are driven by phenomena related to the receipt of solar radiation at the surface of the earth, and that cyclical variations in the accretion of interplanetary dust may play a role in this regard.

Standard Milankovitch (1920, 1941) theory, which relates changes in insolation to changes in the eccentricity of earth's orbit, has been the dominant force in studies of this subject for the past few decades.  The past few years, however, have seen a challenge arise in the form of a number of pesky problems that continue to gnaw at it.  These deficiencies have been described by Muller and MacDonald (1995, 1997), who first elucidated the potential interactive role of cyclical variations in the inclination of the earth's orbit relative to the invariable plane of the solar system, whereby meteoroids and dust concentrated in the invariable plane are accreted at greater rates when the earth passes through the invariable plane.  Although they have not been able to calculate quantitatively the effects of various mechanisms of accretion on climate, they claim that their hypothesis resolves a number of problems associated with the Milankovitch theory.

As to whether we should be "pouring CO2 and methane into the atmosphere" in an effort to forestall the next expected glaciation, which is not that far distant in terms of geologic time, you could perhaps make a good case for such a program.  It would seem to be no more farfetched than the current designs of many governments to do just the opposite and dramatically reduce CO2 emissions to stave off predicted global warming.  With apparent reasons to pull strongly in both directions, perhaps the course of wisdom would be to not unduly meddle in the normal progression of human affairs.


Milankovitch, M.  1920.  Theorie Mathematique des Phenomenes Produits par la Radiation Solaire.  Gauthier-Villars, Paris, France.

Milankovitch, M.  1941.  Canon of Insolation and the Ice-Age Problem.  Royal Serbian Academy, Belgrade, Yugoslavia.

Muller, R.A. and MacDonald, G.J.  1995.  Glacial cycles and orbital inclination.  Nature 377: 107-108.

Muller, R.A. and MacDonald, G.J.  1997.  Spectrum of 100-kyr glacial cycle: Orbital inclination, not eccentricity.  Proceedings of the National Academy of Sciences, USA 94: 8329-8334.