Scientists at the University of Colorado have uncovered a new example of the way the Earth, left to its own devices, maintains an equilibrium between itself and climatic conditions. The Earth as a self-regulatory organism is the central idea of James Lovelock's Gaia theory that is gathering credibility with environmental experts. Russell Monson and his colleagues, writing in Nature magazine, show that the amount of snow that falls in winter can critically affect the concentration of carbon dioxide, the principal greenhouse gas, released into the atmosphere by temperate forests. Forests, over the course of a year, absorb more carbon dioxide through photosynthesis than they emit during respiration. Soil micro-organisms, however, which are partly dependent on the trees for their nutrients, release some of this carbon dioxide during respiration in winter.
Snow acts as an insulating layer, warming the soil and encouraging micro-organisms to breathe more rapidly, releasing more carbon dioxide.
A warm winter, however, produces a thinner insulating layer, less respiration and less carbon dioxide. So warmer winters - which intuitively should lead to more carbon dioxide and great global warming - lead, over the course of the year, to less atmospheric carbon dioxide.