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11:01:00 AM EDT
Study Shows People Affect How Much It Rains
First Evidence That Human Activity Has Altered Rainfall Patterns: A story published online by the journal Nature ("Rainfall Changes Linked to Human Activity") details a new study that shows how greenhouse gases from human activity contributed to changes in rainfall patterns around the world during the 20th century. Reuters covered the story here, "Humans to Blame for Global Changes in Rain: Study."
Rainfall increased in northern latitudes (including much of Canada and Northern Europe) and decreased in the northern tropics and subtropics (including Mexico and the Sahara and Sahel regions of Africa). Rain also increased in Brazil and regions just below the equator. View a chart and a map from the study, portraying the changes in rainfall.
Scientists arrived at their conclusions by comparing "observed changes in rainfall during the twentieth century with those predicted by 14 climate models, divided into three groups. One group contained estimates of human greenhouse-gas emissions, one included only natural factors such as volcanic aerosols, and a third contained both.
The models including both human and natural influences gave the best fit to the observed trends." (quoted from the Nature article)
In the northern band including part of Canada and Northern Europe, rainfall increased 62 millimeters (6.2 centimeters or about 2.5 inches). The researchers used data from 1925 to 1999. They estimated that between 50 and 85 percent of the increase can be attributed to human activity.
Regions that get more rain could experience more flooding; regions with less will find it harder to grow crops.
There are more questions to be answered: What are the long-term natural patterns of drought and recovery? How big is the impact of greenhouse gases on precipitation, versus aerosols? (See the bottom of this story for more of the uncertainties.)
This seems like a landmark study to me. What do you think? Have rain and snow amounts changed over the long haul where you live? Post your comments here.
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Governments should do what they can to soften the blows of global warming, construct green houses with sprinkle systems at high altitudes, and a waterplant that converts salt water into fresh water, might be somethings worth looking into.we have the know how ,we can control our environment no matter flood or drought if we have the resources in place
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get a clue this is all b.s. where are all the huricanes and why are temps so moderate than normal you cant believe everything you read you need to think a little.
8/5/07 3:37 PM
Wyoming, where I live, is suffering from long-term drought. That is, compared to our normally arid condition. The occasional blizard or flood does not make up for a steady amount of rainfall, no matter how little, year in and year out.
We are "passed over" by so many cross-country airplane flights each day, our clear blue sky often looks like a tic-tac-toe game. You'd think we'd ge t more rain, not less. Who knows what the answers are? I still don't think we have the big picture.