"According to an international team of scientists from the Canadian Center for Climate Modeling and Analysis that has provided the first empirical evidence that humans have indeed been affecting rainfall patterns around various regions of the planet for the past century."

"After analyzing rainfall pattern data going back over 8 decades side-by-side with an array of climate change simulations taking into account two types of anthropogenic emissions — sulfate aerosols and greenhouse gases — they found that human activity caused up to two-thirds of the extra rain observed in northern temperate regions (Canada, Europe, U.S., etc), all of the extra rain in the southern tropics and subtropics and removed close to a third of the rain once seen in the northern tropics and subtropics. "

"The next step for the scientists will be to differentiate the individual contributions of greenhouse gases and aerosols to determine which are exerting the strongest influence on rainfall patterns. This study could help scientists and policymakers forecast future precipitation within specific regions more accurately and allow them to better prepare for fluctuations in the weather regimes."

(Quotes and image from http://www.treehugger.com under artcle "Call Me Rainmaker").