Severity and sweep of Prairie droughts to spiral as climate changes | CBC News
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Climate change will profoundly affect our water supply as summers grow hotter and winters shorter.
While precipitation is predicted to increase overall, so will the duration and severity of droughts.
The good news is that over the last century our ability to deal with drought conditions has improved. Crop types, tillage, even the timing of fertilizers can help plants get the moisture they need.
What is a drought?
The Prairies are considered to be in the midst of severe drought, though the definition of a drought is not specific.
“It’s just when you get a long period of below normal precipitation, and this has some impact either on humans or environmental needs,” says Barrie Bonsal, a research scientist with Environment and Climate Change Canada.
The longer the dry conditions last, the worse things get.
Droughts go through phases, Bonsal says. They start as meteorological droughts, as hot dry weather, but can have much more far-reaching impact.
“Generally, if it’s dry during the summer and at critical times for agriculture, this will turn into an agricultural drought and we’ll start to see deficits in soil moisture,” he says.
“Once we start to see the impacts on society, these droughts become socioeconomic droughts and, as you can imagine, the longer a drought proceeds the harder it is to undo.”
Droughts to worsen
As we continue to warm and see more variability in our weather, the chance for longer and more severe droughts grows.
While we will likely see more precipitation overall, the nature of the precipitation will differ, with more of it falling in winter or spring or in short bursts with bigger storms, according to Canada in a Changing Climate: Regional Perspectives Report.
“When we get the water, it might come all at once as opposed to where we’ve had nice gentle storms that will occur over two or three days and really soak the soil that needs it,” Bonsal says.
In the winter, we can expect more rain instead of snow.
The loss of snow, which replenishes soils in the spring, will be critical.
Despite the odd snowy winter like this one, the snowpack is declining, says John Pomeroy, professor and Canada Research Chair in water resources and climate change at the University of Saskatchewan.
“The snowfall as a percentage of total precipitation has dropped from around one-third to down to one-fifth of the total over the many parts of the Prairies now,” Pomeroy said.
And while midwinter rains may seem like a nice break from cold weather, they cause other moisture issues.
“That water percolates down and refreezes at the top of the frozen ground and can seal it off,” Pomeroy says. “It creates a restricted infiltration capacity, we call it. So very little water can enter the soil.”
Recent drought worst in 60 years
Not every year however will be a drought year, as droughts are cyclical, Bonsal says.
“Those cycles, you know, they’re still going to continue,” he said. “But the nature and character of those cycles has a big potential to change with climate warming.”
The area affected by last summer’s drought was the largest we’ve seen, says Trevor Hadwen, agroclimate specialist with Agriculture and Agri-Food Canada.
“The drought that we just went through in 2021, it was as severe and as extensive as 1961.
“So many of us remember the 2001-2002 drought and the 1988-1989 drought as being the recent extreme droughts. The one we just had surpasses those by far,” Hadwen says.
Going back even further, the geographical extent of this drought puts the Dirty ’30s to shame, Pomeroy says.
“The 1930s drought was patchy. At that time, farmers could go up into northern Saskatchewan or settle the Peace River district and find adequate moisture conditions,” he says.
In this recent drought, that wouldn’t be possible, he says.
“Last summer, almost the whole Prairie region at one point was down below 40 per cent of soil moisture,” Pomeroy says. “And in the growing season, almost everywhere was subject to drought, even up to the Peace River district in Alberta.”
And though the current winter did bring with it some much needed snow, the drought continues in parts of Western Canada.
“The snowpack, at least in eastern, central and northern Saskatchewan are looking very, very good,” Pomeroy says.
“Unfortunately, they’re not good in southern Alberta and the southwestern tip of Saskatchewan, where they won’t alleviate that drought at all.”
What can be done?
Luckily we have seen improvements in drought management over the last 100 years.
“We have much better crop varieties in terms of their ability to survive dry conditions and extract moisture from soils,” Pomeroy says. “And we have better tillage systems and others to control dust storms.”
Minimum tillage is effective and has been heavily adopted in Saskatchewan but, according to Pomeroy, could be used more in Alberta and Manitoba.
“It’s quite useful because the crack development allows any rains, even heavy rains to enter the soils.”
Leaving fields in stubble and re-introducing shelter belts will help reduce the effects of snow loss due to wind, Pomeroy says.
Research is underway to develop management practices for farms to support optimum nutrient and water-use efficiency.
“There are sustainable fertilizer management practices — many of which are in use on farms across the Prairies right now — like placing fertilizer in soil at the time of seeding, which promotes good use of that fertilizer and water because it’s being taken up by the plant,” says Blake Weiseth, a Ph.D student at the University of Saskatchewan.
Weiseth hopes further research in snowpack melt will help farmers on the land.
“I think they can be used potentially across all these situations, maybe targeting the use of them in certain areas of the field that are particularly at risk of being impacted by suboptimal moisture conditions on either end of the spectrum.”
Our planet is changing. So is our journalism. This story is part of a CBC News initiative entitled Our Changing Planet to show and explain the effects of climate change and what is being done about it.