No it's global humidity
The atmosphere's water vapour content has a major impact on weather systems, affecting levels of rainfall and the intensity of hurricanes and typhoons. Researchers have observed significant increases in "specific humidity" - a measure of how much water there is in a given volume of air - over the past few decades. However, it has not been clear whether these changes were caused naturally or by human influence. British scientists have now combined observation data with the results of a computer simulation to show that the trend is mainly due to warming caused by human activity. Led by Dr Nathan Gillett, from the University of East Anglia, the researchers warn in the journal Nature that growing humidity could lead to extreme rainstorms and cyclones, and have an adverse effect on human health. They compared data from measurements of humidity between 1973 and 1999 with the predictions made by a climate computer model. Between 1973 and 2002, average specific humidity around the world increased by 0.07 grams per kilogram of air each decade.