The atmosphere is becoming more humid in a pattern consistent with man-made climate change, researchers have found.

They say that the pattern of humidity increases in various parts of the world resembles that projected by computer models of man-made global warming. Water vapour is a greenhouse gas, and it is thought that having more of it in the air could amplify temperature rise. The major report released earlier this year by the Intergovernmental Panel on Climate Change (IPCC) said that this amplification was the largest “positive feedback” mechanism they had identified.