The Great Canadian desert

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Forecast for Prairies: drier than a dust bowl

Droughts worse than 1930s are on the way if history is an indication,

study warns

MARTIN MITTELSTAEDT

 

>From Tuesday's Globe and Mail

 

TORONTO - The Prairies are almost certain to experience future

droughts far worse than the dry period that turned the region into a

dust bowl during the 1930s, warns a new study by one of Canada's most

prominent water experts.

 

Dr. David Schindler says he expects such arid conditions that

immigration into Alberta should be restricted in light of looming water

shortages.

 

The study, co-authored by Dr. Schindler, an ecology professor at the

University of Alberta, and published on-line yesterday in the

Proceedings of the National Academy of Sciences, says " a crisis in

water quantity and quality with far-reaching implications " is likely to

hit the Prairies because of global warming and evidence indicating the

20th century was a climatic fluke, the only extended period of moist

conditions the region has had during the past 2,000 years.

 

The drought of the 1930s was " relatively mild when considered in the

historical context " because previous dry periods occurred several times

a century and typically lasted several decades, the study said.

 

Dr. Schindler said that if the climate reverts back to drier

conditions, and global warming trends continue, parts of the Prairies

that are already dry will probably begin to resemble the near-desert

conditions of the U.S. West.

 

" In the long term, looking ahead a century, that could happen, " he

said. " Historically, it's been a dry place already without climate

warming and without millions of people clamouring for water for

everything from industry to recreation. It's pretty clear that things

are going to get worse. "

 

Given the likelihood of a severe water crunch, Dr. Schindler suggests

people in the West should consider some radical steps, such as limiting

the number of industries and residents, to avoid the problems of the

U.S. Southwest, where millions of people are living in what is

basically a desert.

 

" I think it's also time in this country we started adopting a

philosophy to put our industries and our people where the water is, not

to let the people settle where they want and then go through all the

expense of piping the water to them. "

 

The areas around both Calgary and Edmonton already have more than a

million residents each, and in the paper, Dr. Schindler and co-author

W. F. Donahue, a consultant at Freshwater Research Ltd. of Edmonton,

said " continued development has caused rapid immigration from other

parts of Canada and abroad and even more rapid increases in freshwater

use. Unfortunately, this rapid growth, which is expected to continue,

has rendered Alberta the most vulnerable [part of the Prairies] to

water shortages. "

 

Although Canada as a whole is blessed with an abundance of fresh water,

the Prairies lie in the rain shadow of the Rocky Mountains and are the

largest dry area of southern Canada.

 

It is not known why the climate of the past hundred years has been

relatively moist, but using clues such as tree rings and the types of

algae remains found in sediments, researchers have developed strong

evidence that conditions on the Prairies were generally more arid in

the past than they were during the 20th century.

 

For those living on the Prairies, one of the most disturbing findings

from the study was that summertime river flows have been falling

precipitously and are 20 per cent to 84 per cent lower than they were

in the early 20th century.

 

The worst hit -- with the 84-per-cent drop -- has been the South

Saskatchewan River, at Saskatoon, where the river is a fraction of its

former size, in part because of heavy withdrawals for irrigation,

industry, and municipal uses on its major tributaries, the Oldman, Bow,

and Red Deer rivers.

 

The river flows are also falling because temperatures have risen

anywhere from 1 degree to 4 degrees between the early 20th century and

2003, causing more water to evaporate and less to be available as

groundwater to feed rivers.

 

When water is removed from rivers to use as irrigation for crops, only

about 20 per cent eventually returns to the streams through

groundwater.

 

The temperature changes were recorded at 10 sites removed from built-up

areas so the results wouldn't be skewed by the so-called urban heat

island effect, or the tendency for darkly coloured cityscapes to absorb

heat. At these sites, almost half received 14 per cent to 24 per cent

less precipitation than in the early 20th century, and none has

experienced an increase.

 

 

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