Scientists at the Max Plank Institute in Germany have discovered that living trees are a major source of methane in the Earth's atmosphere. Methane is a major "greenhouse gas," implicated in global warming.
Before this study, scientists thought plants only released small amounts of methane, and then only when they decomposed (as in swamps). The new research shows that plants release methane throughout their lives, and in large amounts—up to 30% or more of the planet's total methane production may come from plants.
This forces us to re-think environmental efforts. Strategies for dealing with climate change, such as the Kyoto Protocols, often call for planting more trees. And it's true that trees do take a lot of carbon dioxide out of the atmosphere—the most prevalent greenhouse gas. But now it turns out trees also release methane, so their benefit is not quite as great as once thought.