Climate change, generally perceived as rising global temperature and changing rainfall patterns, has a large impact on crop production. Canada is a high-latitude country in Northern Hemisphere, whose major croplands originated from the three Prairie Provinces, Alberta, Saskatchewan, and Manitoba. Thus, climate effects, potentially, could have significant opportunities and challenges to the crop production in the Prairie region, hence, to the entire country. As such, (how much, if any) are we prepared for the coming change as well as climate mitigation strategies?
Longer growing seasons with possible northward croplands expansion
There have been rising waves of discussion that Canada, as the second-largest country in the world, whose majority of its croplands are located in high latitude, will benefit from a warmer climate. Currently, major crop growing season in Canadian Prairies, such as wheat and canola, starts planting in May and harvesting in Sep. This four-month period, allowing only one season of cropping, is much shorter compared to other temperate and tropic countries, that can support two- or even three-season croppings. Moreover, during this period, the crops are usually delayed by cool-wet spring in May and disturbed by early frost in Sep, which are both detrimental to the final production.
However, climate change may bring fundamental shifts to the growing season weather that we are currently accustomed to. Canadian farmers may presumably expect warmer seasonal temperatures, and longer growing seasons, hence, larger heat accumulation under climate change. Crops are less likely disturbed by frost or insufficient heat accumulation and warmer/longer growing seasons may even allow two croppings each year. What’s more, the vast extension of northern boreal regions, currently covered by forests and peatland, may become suitable for cropland expansion due to temperature increases. Thus, optimistic and hopeful opportunities can be perceived amidst future climate change in Canadian agriculture.
Elongated drought events mixed with extreme heat and floodings
Despite the optimistic opinions described above, the counterparty would argue that droughts may become more frequent and last longer under climate change. For Canadian Prairies, where snowpacks from last winter would remain until April and snowmelt contribute a significant amount of water budget, restored soil moisture, groundwater, and surface wetlands. So that croplands, which has access to these stored water source, can be less reliant on rainwater supply and be more resilient to drought.
The rising average temperature will cut the future water supply from two ends. The winter snowpack may start melting earlier contributing to surface runoff that drains away instead of being stored in the soil, whereas the vapor pressure deficit (VPD) will soar together with the temperature that demands a larger amount of water from soils and vegetations. These two factors both contribute to elongating possible drought in Canadian Prairies and making crops exposed to water stress, a major reason for crop failure.
Moreover, the growing season weather becomes more volatile and is a challenge to future agricultural practices. People may find it surprising to see both extreme flooding and heatwaves may occur in the same year. For example, the wet and snowy-rainy spring of 2022 has poured much water into the soggy soil in Apr and May, the usual planting season, leading to both delaying in planting and shrinking in planting areas. On the other hand, the unexpected heatwaves can join together in concurrence with droughts, contributing to compound drought heatwave (CDHW) events. Under this detrimental condition, the crops are exposed to both water stress as well as heat stress, to two of the most important growing stages, anthesis, and grain-filling.
What’s more, the potential northward expansion of croplands will inevitably disturb boreal forest and peatland, the major carbon sink and store in the globe. Land-use conversion will release a tremendous amount of greenhouse gases (GHGs) into the atmosphere, exacerbating the continuously rising CO2 level and global climate change.
Strengthening climate resilience and preparing for climate adaptation
The first consideration would be irrigation. Irrigation is a common approach to ensure crop yield from water stress under adverse environmental conditions. Irrigation is largely applied in the U.S., for example in Nebraska corn-soybean rotation, California Central Valley for fruit and nuts, and along the Mississippi river for soybean and cotton. However, it is not very popular in the Canadian Prairies, except in southern Alberta. There has been emerging discussion about implementing irrigation in southern Saskatchewan from conventional rainfed agriculture. At the same time, there are ongoing concerns about charges from infrastructure investment and water levies outweighing agricultural production, adding doubts on the efficiency of irrigation plans. (Another presentation clearly outlined this new plan)
In addition to incorporating irrigation, another potential mitigation strategy is to change the current planting schedule. The current planting season spanning from May to Sep may shift to an early start, depending on future warming conditions in springs. This new strategy has two obvious advantages – it can first enjoy an early start in prolonged growing seasons and then avoid the driest and hottest months in late summers. However, the realistic situations are not as simple as described above, further research is needed to investigate when and where would this “early planting” strategy succeed.
Canadian Prairies, as the breadbasket for the whole country and the world, its role has never been more important and cannot be overstated, amidst climate change, water security, and global food market volatility. Global climate models provide general negative responses to crop yield with large uncertainties. Regardless of the above optimistic or pessimistic opinions, what all stakeholders – local farmers, government decision-makers, climate scientists – could do, is to “hope for the best and prepare for the worst”.
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