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OTTAWA (Reuters) - Alarmingly low snow levels in the Rocky Mountains will cut water supplies to Canada's Prairies and could help trigger a river drought in the important farming region, a leading expert said on Thursday.
The predictions by University of Saskatchewan hydrologist John Pomeroy were particularly gloomy, given that 2009-2010 was a record dry winter for the western Prairies.
"It's clear that we have serious problems and will have more serious problems in the future," Pomeroy said in a presentation at Parliament in Ottawa.
The three Prairie provinces produce most of the country's grain and cattle. Canada is the world's sixth largest producer of wheat and third-biggest grower of canola, a variant of rapeseed.
After severe drought in parts of Saskatchewan and Alberta last year, many farms have seen too much moisture this spring, setting back planting in both provinces.
But parts of the region depend heavily on rivers that extend across the Prairies, fed by snow, rain, glaciers and lakes in the mountains.
"There is a severe drought in the western mountains and if it carries on it will be a river drought extending across the Prairies," said Pomeroy, a specialist in both Prairie droughts and predicting snow changes in the Rockies.
The scientist said he had visited a research site some 900 meters (2,950 feet) up a mountain in the Alberta Rockies this week to check for snow.
"What horrified me when I struck the tree line was that I could see the trees. Normally they're buried," he said.
"They were brown and red because they'd been killed off by the dry Chinook winds over the winter ... the snow packs are really low this year, the lowest I've ever seen."
Separately, the U.S. space agency NASA said the North American snow cover this April had retreated to its smallest extent for the month since records began in 1967.
NASA said unusual warmth had caused low snowfalls and rapid melting of existing snow.
Pomeroy said models show that a temperature increase of 3 degrees Celsius in the mountains would be "a tipping point -- we have the collapse of the alpine snowpack".
He added: "We did the simulation last fall and I said 'Yeah, we might see this I guess in 20, 30 years' time' ... we're seeing that this spring and I hope it's just an aberration."
Pomeroy said Prairie farmers have already begun to adapt to the drier conditions, in part by using more efficient methods and by growing pulse crops, such as beans and peas, which require less water.
"One of the triumphs we had is that (although) this last drought meteorologically was very very severe, we did not have a collapse of the Prairies economy," he said.
Other simulations show that, by 2080, global warming means the amount of spring runoff available in the southern prairies would be 37 percent less than now, Pomeroy added.
"This is a bit of a hint of what's to come and it suggests an inherent unreliability in these water supplies," he said.
Additional reporting by Rod Nickel in Winnipeg; editing by Rob Wilson