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. And the BBC News Website has learned that the research, based on observations in the laboratory, appears to be corroborated by unpublished observations of methane levels in the Brazilian Amazon. Until now, it had been thought that natural sources of methane were mainly...