Arctic Melt May Dry Out US West Coast - New Scientist

Cities and towns along the west coast of the US could be suffering from a serious water shortage by 2050, thanks to global warming. As Arctic sea ice melts, annual rainfall may drop by as much as 30 per cent from Seattle to Los Angeles, and inland as far as the Rocky Mountains.

As temperatures rise over the next 50 years, the area of Arctic sea ice is predicted to shrink by as much as 50 per cent in some areas during the summer. To find out what this would mean for climate, Jacob Sewall and Lisa Cirbus Sloan from the University of California at Santa Cruz first used a climate model to work out how sea ice cover was likely to change through the rest of the year.

Then they took these values for sea ice cover and the resulting sea surface temperatures, and plugged those into a global climate model to see which areas of the world would be most affected. While Europe got off quite lightly, they found that the sea ice changes are likely to mean significantly fewer storms will pass over the west coast of the US.

EDIT

Towers of warm air form above areas where sea ice has been lost, and that disturbs the flow of air in the atmosphere around them, "like the supports under a bridge alter the flow of water in a river." In their model Sewall and Cirbus Sloan found that such towers formed between Norway and Greenland, deflecting winter storms that would otherwise have passed over the west coast of the US towards northern British Columbia and southern Alaska. These areas received six per cent more rain, while southern British Columbia down to southern California suffered a 30 per cent drop. The researchers will publish their results in a future issue of Geophysical Research Letters. "Given that water resources in this region are currently stretched close to their limit, a 30 per cent drop would have a serious impact," says Sewall."

EDIT

http://www.newscientist.com/news/news.jsp?id=ns99994856

other posters have pointed out that fairly recent stories from Woods Hole Oceanographic Institute have theorized that increased fresh water melt at high latitutes may lead to severe disruptions in the thermohalene circulation, particularly in the North Atlantic, but elsewhere as well. The disruptions are thought to possibly cutting off the Gulf Stream/North Atlantic drift, leading to serious cooling in the North Atlantic, and IIRC, adjoining arctic areas north of Canada, Greenland, Iceland and Scandinavia. Perhaps that's why Europe gets off quite lightly in the model used, according to the article. It would be more helpful if the article were more explicit on that point.

Nonetheless, this is very bad news. If there is sufficient energy from a useable source available at that time, I would imagine that there would be a call to construct diversions into the Saskachewan River and perhaps the Columbia basins from Eastern British Columbia for agricultural purposes. The western U.S., though, sounds like it will become toast, literally. I wonder just how far east the toaster will go.


Amanda

You can't make climate predictions about coastal areas without sophisticated ocean modeling, and the current models thay have are very primitive.

I'd say it'll be 5 years before they start getting what the need to make these predictions.