Chapter 13

Forcast Calls for Climate Change

Lentils? Gone. Barley? Good as. Canola? Vulnerable. 

That’s a reasonable interpretation of climate change models that foresee much hotter temperatures coming to a summer near you.

Drier dry periods, wetter wet periods and more extreme weather events are in the forecast. That includes more flooding, drought, summer heatwaves, periods of high humidity, stronger winds, but appreciably milder winters, not unlike the 2020-21 winter that was a walk in the park for southern Manitoba.

The big problem with precipitation will be timing. The summer months are forecast to be drier, and the other seasons wetter, which isn’t helpful when you’re a farmer. It means more rainfall at inconvenient times of spring and to a lesser extent in fall. Neither is that additional spring moisture likely to carry crops through the extra heat and decrease in precipitation coming in summers. Drier summers would also mean more frequent and intense droughts.

The Prairie Climate Centre (PCC) at the University of Winnipeg has developed a Climate Atlas of Canada that projects future scenarios by synthesizing data from 24 different climate models from around the globe. Heat stress tops the list of negative impacts due to the rising concentration of atmospheric greenhouse gases that trap heat. Manitoba will see the number of extreme heat days—days of 30 C or more—increase from an average of 14 – 15 per summer, to 25 – 30, the PCC says. That’s between now and 2050.

That has implications for Prairie crop rotations because canola doesn’t like heat. Canola likes cloud cover and damp conditions. Give it a leaky parasol and it’s happy. “‘Heat blasting’ is one of the terms that comes up,” said Matthew Wiens, climate change specialist with Manitoba Agriculture. “Canola does really well with dampness. If it gets a heatwave when flowering, the flowers will fall off and they don’t set the seed.”

The canola industry is putting on a big push to get average yields up to 52 bushels per acre by 2025 because the market is there. But climate change forecasts suggest producers may have trouble just holding onto current production levels. One model cited in federal government literature has canola yields plunging by as much as 20 – 40 per cent in the Brandon area by 2041 – 2070. Wiens said canola may cede ground to soybeans unless plant breeders perform their magic and produce new cultivars with greater heat and drought tolerance. On the plus side, the range for canola production could expand into the northern margins of the agricultural zone.

Barley can’t stand the heat either and that means farmers will be switching.[i] Barley acres are likely to fall even lower than they already have and be replaced with corn. Lentils grew well in Manitoba in the 1980s but wetness starting in the 1990s saw them book passage to Saskatchewan. They could come back again if the current cycle of drier weather of the past three years continues in Manitoba.

Wheat will not fare badly and yields are expected to continue rising, in large part due to elevated carbon dioxide levels in the atmosphere. In one study from 2018 that is often cited by Natural Resources Canada, wheat yields will increase 15 per cent by the 2050s under current conditions, but 26 – 37 per cent under the higher carbon dioxide levels expected with climate change. Yet the prospect of more extreme weather conditions will also mean more variability in yields, too.

These scenarios are not just the next generation’s or the next-next generation’s problems anymore. Significant changes are happening and will become more overt in the next two decades, according to the Prairie Climate Centre.

Agriculture makes up almost a third of total emissions in Manitoba, according to provincial data from the past two decades. That’s a higher proportion than any other province, but part of the reason is low-emission hydro power is so dominant in Manitoba, and there are few large industrial emitters.

FARMERS WILL HAVE to adapt to hotter summers and wetter springs. “One way to get around the increased risk of heat and drought in summer is to get ahead of that by seeding earlier,” said Wiens. That way the crop gets important growth out of the way before the heat stress of summer arrives. Seeding earlier increases the risk of spring frost but there is crop insurance coverage for that and producers would still have time to reseed.

You might also want to plant a cover crop to take up that moisture so you can get on the land earlier for seeding, said Wiens. Plant breeders will be called on to breed more flood-tolerant and heat-resistant cultivars.

Then again, the growing season will be longer.

The Prairie Climate Centre website displays oodles of maps to play with and discover doomsday scenarios for your region. It’s not a map of who’s going to burn up first but rather information to help governments and businesses, like farming, to make plans. The Prairie Climate Centre tries not to sound too alarmist, and prefers to say there will be various “risks and opportunities” to climate change.

The frost-free days maps are of considerable interest to agriculture, as the length of the growing season is the most limiting factor as far as crop selection. The earliest average occurrence of a fall frost (Aug. 27 to Sept. 1) is in the central Interlake, Riding Mountain and southeast part of Manitoba. The latest fall frosts on average (Sept. 16-26) are in the Portage la Prairie, Morden, Pilot Mound, Morris, Winnipeg and Red River Valley areas. Sunflowers are the latest-maturing crop grown in Manitoba requiring 120 to 130 days.

Climate change will likely lengthen the frost-free period. For example, the Rivers area near Brandon could see the average number of frost-free days climb from 120.5 in 1976 – 2005, to 134.7 days in 2021 – 2050, an increase of 14.2 days. That’s the low end of the scale that assumes we make some progress mitigating greenhouse gases. The high end of the scale, also called “the business as usual” model, would see an 18-day increase in frost-free days.

At Hartney in the southwest corner, frost-free days are projected to climb from 128.7 – 143.2 for an increase of 14.5 days, and that’s on the low end of the model. On the high end, frost-free days climb by 17.4 making it 146.1 days in total. The difference from low end to high end on the carbon scale becomes much more pronounced after 2050 for all regions.

Farther north, Swan River could go from 116.3 – 131, or 14.8 more frost-free days. On the high end of the carbon scale, it will add 20 days for 136.3 total frost-free days.

Over at Morris, south of Winnipeg, frost-free days will increase from 130.3 – 147.1 days, for an increase of 16.8 days. If we carry on in ignorant bliss, the number increases by 19.3 frost-free days to 149.5.

At Arborg in the Interlake, low-end projections are for the number climbing from 121.8 – 137.2, for a total of 15.4 extra frost-free days. Under the business as usual model, there will be 19 more frost-free days for a total of 140.8.

To summarize, Manitoba farmers have good reason to expect the average number of frost-free days to increase by 14 – 20 days over the next three decades, climbing to about 130 – 150 days in total depending on location.

The number of frost-free days today is already several days more than a century ago, according to various studies, and that has already allowed farmers to grow crops that require more heat. That has helped corn and soybeans emerge as new crops in Manitoba in this century, although breeding has been a much larger factor.

Fewer frost-free days should allow crop production to move farther north, too. Warmer temperatures and less soil moisture in summer would see forests transformed into a more open ecosystem. Boreal forest will transition to aspen parkland and grassland, but that movement will lag decades behind climate changes. When it does occur, it will be patchy, following the path of fires, insect outbreaks and windstorms, rather than a uniform retreat of forest land.

We’re already seeing what excess moisture is like in Manitoba. From 1993 – 2005 was the wettest period going back more than a century. In 2010, more than 1.6 million acres were drowned out or went unseeded, resulting in crop insurance payments of $200 million. In 2011, the drowned acres more than doubled to over 3.4 million acres and $283 million in crop insurance payments. In 2014, 1.6 million acres were lost to flooding, costing $126 million in crop insurance payments.

Actual losses are much higher than insurance payments. Flooding of agricultural lands cost almost $700 million in Manitoba in 2011, according to provincial documents. Extreme rain events also generate runoff with heavy nutrient loads.

Manitoba has gone through a wet phase generally since the 1990s but the last three years have been on the dry side. In fact, the province was categorically in a drought heading into the spring of 2021 according to the North American Drought Monitor, which operates under the United States Department of Agriculture. Decreases in water, whether in groundwater or rivers, are a concern to all farmers, including those who irrigate.

Multi-year droughts occurred in Manitoba, as well as Alberta and Saskatchewan, in the 1810s, 1890s, 1930s, and 1980s. In fact, there were nine years of continuous drought in the 1890s. There was a continuous drought and hordes of grasshoppers in Manitoba from 1816 – 1819, and crop failures from drought in 1846 and 1868. Western Manitoba is most commonly affected by drought.

The drought of 1988 was the last bad general drought across Manitoba and caused crop failures, yield losses, feed shortages and other financial hardship. In 2011, there was the bizarre case of a summer drought following spring flooding, or a “weather whiplash” as meteorologists called it. So while compensation was being paid for flooding, it also had to be paid for drought losses to the tune of $81.7 million.

And there’s always potential for another Dirty Thirties, or worse, according to climate change forecasts. That drought lasted from 1929 and into the early 1940s. The 1936 census recorded 500 abandoned farms. The most intense heatwave was in 1936. From July 5 – 17 that year, temperatures broke 44 C in Manitoba and Ontario, claiming the lives of 1,180 Canadians. Four hundred of the deaths were people who drowned trying to cool off from the heat. It was so hot, says Environment Canada, “that steel rail lines and bridge girders twisted, sidewalks buckled, crops wilted and fruit baked on trees.”

It can always be worse. Tree ring analyses have built a record of dry and wet cycles over the past 1,000 years and show the worst drought in the Upper Assiniboine River Watershed—worse even than the 1930s drought—occurred in the late 1500s. The Red River Basin also suffered a multi-decade drought—that is multi-decade, not multi-year—in the mid-to-late 1500s.

At the opposite end of the pole, winters are projected to be much milder. Western Canada is already seeing considerably warmer winters, on average. That may lower feed costs for livestock left outside during the winter, and lower heat costs for indoor operations like hogs and chicken. But warmer winters may not be all they are cracked up to be because the cold keeps out plagues and pests. So we should expect more vector-borne diseases and new invasive species.

The forecast from the Prairie Climate Centre, with which the province works closely, is there will be increased storms from greater heat and humidity, and potentially more tornadoes. There are differing projections on that: one, that there will be more tornadoes, and another that there will be no change in tornado frequency. The former theory is that “tornado alley,” which encompasses Kansas and Oklahoma, may migrate further north because of warming here, and increase the rates and severity of tornadoes. Manitoba is currently only on the northern fringe of that tornado range. The other theory is that temperature differences between north and south that clash to form tornadoes will more or less even out and not increase the severity or frequency of such events.

In summary, all signs point to the need for farmers to prepare for climate change. The Prairies are already known to have among the greatest weather extremes in the world. You ain’t seen nothing yet, say climate forecasters, and the Prairies are expected to only add to that reputation in the coming decades.

The primary risks are farmland that is too wet to seed, crop failures from drought and yield loss to heat stress. Water management will become increasingly important and strategies will continue to be talked about. That includes retaining water from winter and spring runoff for use during growing seasons.

[i] “Growing Conditions Are Changing – Here’s How Agriculture Can Respond,” Manitoba Agriculture and Resource Development document, posted online, 2019.