The most recent prairie drought may be a taste of things to come, says the head of the Prairie Adaptation Research Collaborative based at the University of Regina.
Dave Sauchyn told a recent water conference sponsored by the research support organization Alberta Ingenuity that as the earth warms, the greatest impact may be felt in the centre of continents, subjecting the great northern plains to more drought.
He said Alberta, Saskatchewan and Montana are among the driest regions in North America, with some areas receiving less than 331 millimetres of precipitation a year.
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“The least precipitation on the continent is on the northern great plains with increasing distance from the Gulf of Mexico,” he said.
The centres of the continents are apt to experience warmer winters and longer growing seasons because these areas are the farthest from the moderating effects of oceans.
Temperatures are predicted to increase between 1.5 and 5.5 C over the next century.
While warmer weather may be welcome, it also means longer periods with no precipitation and more evaporation and drier soil.
“The dominant impact of global warming on the Prairies will be the decrease in water in the soil and an increase in the variability of water resources,” Sauchyn said.
A period of no precipitation for 50 consecutive days is not common, but in 2001, the Medicine Hat region in Alberta experienced this extended drought.
Sauchyn said 1999-2001 was the driest period for this region since records started 130 years ago.
He expects this could happen with increasing frequency within 50 years.
Drought is actually the norm for the Prairies, he added.
The years between 1960 and 1990 were among the wettest in the last millennium, despite the region’s semi-arid description.
“During the period 1961-1990, nowhere did the data indicate a semi-arid landscape,” he said.
The driest region of southeastern Alberta and southwestern Saskatchewan is actually considered dry, sub-humid.
However, the small semi-arid region is expected to expand within 20 years.
These models do not take all climate factors into consideration, but Sauchyn is confident the predictions are reasonably accurate.
“Based on the best scientific evidence we have, we’re able to plot a future scenario for the climate of Canadian plains that shows the progressive drying out of the Prairies,” he said.
Research shows that the Prairies have historically been extremely dry for decades at a time.
Geological records and tree rings from the Cypress Hills and Havre, Montana, regions indicate that extended periods of drought lasting several decades were common. Archival records from explorers and Hudson’s Bay Company fur traders in the 18th century describe a “want of water,” providing more evidence of dry conditions.
In the 1850s, the John Palliser expedition travelled through the Prairies at the end of a 30-year drought. Palliser declared the area unsuitable for farming.
Farmers came anyway, settling the Prairies during a benign period.
As the climate continues to change at an unprecedented rate, water supplies are in jeopardy.
“All of the cities in Alberta and Saskatchewan derive their water from glaciers and snow melt in the Rocky Mountains,” Sauchyn said.
Runoff declines as the glaciers shrink and less snow falls in the mountains.
Part of the problem is that governments are unsure how to plan for this uncertain future, although agriculture tends to adapt to new and changing situations.
There are two approaches.
- Slow the increase in climate change by reducing greenhouse gases
- Accept that climate change is happening and adjust practices and develop infrastructure to store water in years of plenty.
“Water conservation is a no regrets adaptation strategy because even if the climate doesn’t change like we expect, it is still a good idea to conserve water,” he said.
However, water conservation can be difficult to achieve during periods of severe and sustained drought.
