Tuesday, January 24, 2006

Trees, Methane and Global Warming

The BBC reports that scientists have just discovered that trees produce methane, a major greenhouse gas:
Scientists in Germany have discovered that ordinary plants produce significant amounts of methane, a powerful greenhouse gas which helps trap the sun's energy in the atmosphere.

The findings, reported in the journal Nature, have been described as "startling", and may force a rethink of the role played by forests in holding back the pace of global warming.
This came as something of a shock:
To their amazement, the scientists found that all the textbooks written on the biochemistry of plants had apparently overlooked the fact that methane is produced by a range of plants even when there is plenty of oxygen.

The amount of the gas produced increased when the air was warmer, and when there was more sunlight. The paper estimates that this unexplained phenomenon could account for 10-30% of the world's methane emissions.

The possible implications are set out in Nature by David Lowe of New Zealand's National Institute of Water and Atmospheric Research, who writes: "We now have the spectre that new forests might increase greenhouse warming through methane emissions rather than decrease it by sequestering carbon dioxide."

Researchers warn it is too early to make assumptions
If this turned out to be true, it would have major implications for the rules of the Kyoto Protocol on climate change, which allows countries and companies to offset emissions from the burning of fossil fuels like coal and oil by funding the planting of new forests or the restoration of deforested areas.
This should be a warning to those who think that "global warming" is settled science. The earth's environment is a complicated system that is not easily reducible to a powerpoint presentation. Politicized scientists have time and again issued dire warnings about the latest and greatest calamity to befall mankind, only to have those claims look irresponsible a few years later (see Michael Crichton's piece, Fear, Complexity, & Environmental Management in the 21st Century). We should try to understand things a little better before we jump to conclusions.