The scientists said their finding is important for understanding the link between global warming and a rise in greenhouse gases. It could also have implications for the Kyoto Protocol, which calls for developed countries to cut their emissions of greenhouse gases by 5.2% below 1990 levels by December, 2008. 　　It was discovered that living plants emit 10 to 100 times more methane than dead plants. Scientists had previously thought that plants could only emit methane in the absence of oxygen. 　　David Lowe, of the National Institute of Water and Atmospheric Research in New Zealand, thinks the findings are startling and controversial. According to David Lowe, Keppler and colleagues' finding helps to account for observations from space of incredibly large plumes of methane above tropical forests. But the study also poses questions, such as how such a potentially large source of methane could have been overlooked and how plants produced it. There will be a lively scramble among researchers for the answers to these and other questions.