Agriculture and Climate Change

Agriculture image

Robin Tunnicliffe has farmed for almost 20 years, growing a wide range of organic vegetables for local restaurants and farmer’s markets. She remembers that “when I first started farming, my mentor gave me a list of planting dates.” This essential farmer-to-farmer teaching gave her confidence thanks to its hard-won wisdom, and she recalls thinking “Good! Now I know what I’m doing!” But she soon found that the lessons of tradition and experience were expiring, thanks in part to climate change.

Tunnicliffe began to notice that the changing climate was throwing reliable, longstanding patterns and expectations out the window. She notes that unpredictable seasonal weather now means “the map has been wiped clean a little bit,” and says: “I mentor a lot of new growers. I wish I could give them that list of planting dates that I got. But I can’t do that.”

Farmers know all too well that agriculture is highly dependent on weather. Modern methods, techniques, and technologies have made today’s crop and livestock farms increasingly productive, but agricultural success still depends on getting just the right amount of rain and just the right amount of heat at just the right time of year.

  • The planting, maturing, and harvesting of crops all depend on consistent seasonal patterns.
  • Livestock depend on feed, water, and a tolerable range of heat and humidity for healthy, productive growth.
  • Climate helps determine which pests and diseases will spread, and so how much time, effort, and money farmers must spend on herbicides, insecticides, and other defences.
  • Beyond the harvest, patterns of temperature and weather affect the entire supply chain of storage and transportation that brings food from the field to the dinner plate.

From the largest farm to the smallest market garden, from planting to eating, and at every stage in the cycle of production –from choosing seed to transporting livestock – agriculture and agri-business thoroughly depend on climate. And the climate is changing.

Farming in a hotter climate

Seasonal temperatures are very important to farming. The length of the growing season, typical average temperatures, and the timing and severity of hot and cold spells all work together to determine what crops can be grown. Climate models show that Canada’s cold season will shrink, leaving a longer growing season. But with that possibly good news comes a huge increase in high temperature events and changes in precipitation patterns – especially the increasing likelihood of flooding and drought in the same year – which will require farmers to make significant changes.

The Climate Atlas map of very hot days shows large increases in heat coming to many of Canada’s agricultural regions, including the Okanagan Valley, the Prairies, southern Ontario, and the Maritimes.

Roy McLaren has a long lifetime of farming experience – he’s farmed in southern Manitoba for over 70 years – and looks at these projections with concern. “That is pretty bad,” he says. “With that kind of heat,” McLaren concedes, “we’d have to change our farming methods. We’d have to adopt new crops.”

Temperature changes don’t just affect crops. Hot temperatures also reduce weight gain and milk production in cattle. Heat can even be deadly: in 2002, for example, heat waves in Quebec killed half a million poultry, despite the use of modern shelter and ventilation systems [1], and during 2010-2012 hundreds of dairy cattle died in Ontario because of extreme heat [2].

Farming and changes in precipitation

Water supply and water management are fundamental to farming. McLaren is plain-spoken on the topic: “Without water, you don’t have anything. I don’t care where you farm.”

Climate models show that Canada’s agricultural regions will likely see drier summers from coast to coast, but increased winter and spring precipitation. This means that farmers may have to deal with both too much water during the seeding season and too little water during the growing season, all in the same year. Projections also show that although much of southern Canada will be drier overall in the summer, it could also face an increase in short-lived but very intense rainfall events.

august-april delta precip_1.jpg

The projected change in monthly precipitation for April and August (for the “high carbon” climate scenario) shows that much of southern Canada is expected to become much wetter during the spring, but drier during the summer. These maps show the percent difference in total monthly precipitation between the 2051-2080 and 1976-2005 time periods.

Canada’s prairie provinces have recently experienced the consequences of such seasonal shifts in precipitation: in 2016 a hot, dry spring caused widespread drought. This extended dry weather was followed by torrential rains in the late summer that caused flooding in many areas, from northern Alberta to eastern Manitoba. And in 2017, southern Saskatchewan experienced the driest July in over 130 years of record-keeping. For farmers in the region the heat and dryness was especially damaging because it followed a rainy spring that had been so wet that they’d been unable to properly seed their fields [3].

In addition to the increased threat of drought and flooding, wet springs and autumns may make it challenging for farmers to take advantage of the longer growing season promised by rising temperatures. Early or late rain can simply make the land too wet to support farm machinery, and can hinder important seeding, maturing, or drying phases of many crops.

Adaptation

Farmers are used to planning for uncertainty, but climate change is bringing new extremes, seasonal shifts, and increased variability that are likely to push the boundaries of our climate beyond anything they are used to managing.

Some aspects of climate change look promising for farming: longer frost-free seasons, increases in growing degree days, and even increased atmospheric CO2 can, in theory, lead to better crop yields and productivity. However, as Natural Resources Canada warns: “An increase in climate variability and the frequency of extreme events would adversely affect the agricultural industry. A single extreme event (later frost, extended drought, excess rainfall during harvest period) can eliminate any benefits from improved ‘average’ conditions” [1].

Some of the existing tools the farming sector uses to handle climate risks (such as crop insurance or sprinkler irrigation) mostly rely on poor conditions being unusual and intermittent. But short-term and one-off crisis management strategies aren’t sustainable responses to the enduring effects of climate change.

The Food and Agriculture Organization of the United Nations cites research that identifies six major classes of agricultural climate adaptation [4]:

  • seasonal changes and sowing dates;
  • different varieties or species;
  • water supply and irrigation systems;
  • inputs (fertilizer, tillage methods, grain drying, other field operations);
  • new crop varieties; and
  • fire risk management.

Tunnicliffe reflects on her farm’s adaptation to climate change and notes that “our strategy now is just being more resilient.” She is experimenting with new varieties of produce, over-planting in expectation of higher losses, and breeding plants that are adapted to local conditions. “Your best strategy is diversity” she says, so that “a crop failure isn’t a disaster.” Asked to define resilience, she laughs and says “many layers of backup!”

Mitigation

Agriculture has an important part to play in reducing the severity of climate change.

Modern agriculture – like most modern industry – relies on high-carbon energy. Farming generates about 8% of Canada’s greenhouse gas emissions [5]. These greenhouse gases come from a variety of sources. Diesel- and gas-powered machinery is used to till fields, plant seeds, apply fertilizers, harvest crops and transport the food to market. Manufacturing nitrogen fertilizer uses large quantities of natural gas, and when this fertilizer is applied to fields it produces nitrous oxide, a greenhouse gas that is 300 times more potent than carbon dioxide. Industrial-scale livestock operations can release large volumes of both nitrogen and methane (another powerful greenhouse gas).

The agricultural sector has begun to look at inventive ways to reduce these emissions and to pursue land-use practices that can help mitigate climate change. Strategies range widely, and include different crop cultivation and rotation strategies, using conservation tillage, transitioning to lower-carbon fuel sources, improving fertilizers and fertilizer application approaches, improving soil carbon sequestration, and using gas-capture systems for livestock and manure. There are many opportunities in this sector for technical innovation that can help ensure both climate mitigation and economic benefits.

Of course, the agricultural sector cannot singlehandedly mitigate climate change. Mitigation is ultimately a society-wide problem, and climate solutions and possibilities developed in any one sector will benefit everyone.

The vulnerability of farming to climate change could threaten food security for millions upon millions of people [6]. This essential yet threatened sector means that agricultural producers have a unique opportunity to demonstrate climate leadership. Agricultural adaptation and mitigation are necessary to create a sustainable future for Canada’s farms, and the rest of society has a fundamental role to play in supporting the development of the resilient agricultural systems so necessary to us all.

References

  1. Natural Resources Canada. From Impacts to Adaptation: Canada in a Changing Climate 2008
  2. Bishop-Williams , Katherine E. Et al. “Heat stress related dairy cow mortality during heat waves and control periods in rural Southern Ontario from 2010–2012.” BMC Veterinary Research (2015) 11:291. Accessed online.
  3. CBC News. “Sask. farmers say drought conditions worst in decades”.
  4. Food and Agriculture Organization of the United Nations. Adaptation to climate change in agriculture, forestry and fisheries: Perspective, framework and priorities.
  5. Environment and Climate Change Canada. “Greenhouse gas emissions by Canadian economic sectorGreenhouse gas sources and sinks”
  6. Porter, J.R., L. Xie, A.J. Challinor, K. Cochrane, S.M. Howden, M.M. Iqbal, D.B. Lobell, and M.I. Travasso, 2014: Food security and food production systems. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Accessed online.

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