Climate change increasing chance of crop failure, UBC researchers say
Climate-driven heat and drought are increasing the frequency of low yields or failure for some of the world’s most important food crops, according to a University of B.C.-led study.
The study, published this week in Science Advances and involving researchers from UBC and Harvard University, is the first to show how changes in temperature and soil moisture will likely affect yields for three main summer crops: corn, soybean and sorghum.
Using modelling data, the researchers project that for every degree of warming, year-to-year variability in yields rises by seven per cent for corn, 19 per cent for soybeans and 10 per cent for sorghum.
Jonathan Proctor, an assistant professor at UBC’s faculty of land and food systems and the study’s lead author, said they combined historical data on harvests at a global scale with historical data on temperature and soil moisture, a key indicator of water supply, measured by satellite.
Once the scientists understood how the crops responded to temperature and soil moisture year-to-year, they combined that data with scientific models that project how temperature and soil moisture are affected by climate change.
For instance, soybean crop failures that strike once every 100 years would happen every 25 years with 2 C of warming, according to the study. Corn failures would happen every 49 years, and sorghum failures every 54 years.
Increased crop failure hits farmers hard
“A lens that we took on this study is that farmers don’t live off of average harvests, they live off of the harvests from each year, and so understanding yield and stability is really important,” said Proctor. “A large loss in harvests can lead to reduced livelihoods for farmers and higher prices for consumers and these challenges are arguably largest for farmers with the least resources to deal with that.”
While this study didn’t look at the consumer costs associated with crop variability, Proctor said that is something they will look at next.
He said an increase in crop failure is linked to “a double whammy” of heat and drought.
“Under climate change, both of those are intensified, which means that droughts become hotter and heat waves can become drier, and it’s that intensification which leads to large yield losses, which in turn leads to instability of yield,” he said.
Irrigation can solve the problem, but many regions already face water shortages or lack irrigation infrastructure, according to the study.
Researchers are calling on governments for urgent investment in heat- and drought-resistant crop varieties or “tougher” seeds that are bred to produce higher yields in drought conditions, better soil management and increasing crop insurance.
However, Proctor said the most pressing thing for communities is to reduce greenhouse-gas emissions to limit global warming.
Farmers around the world face unique climate challenges, so solutions to mitigate crop failure differ. But better irrigation is a top priority for many, he added.
For example, in the B.C. Interior ranchers have asked the province to consider reducing red tape around building and expanding water-storage dams to help them cope with the continuing drought. Three persistent years of drought in B.C. has led to the need for more water storage, either by expanding existing dams or building new ones.
How climate change is causing drought and water shortages
Hotter air dries out the soil, while dry soil causes the air to heat up, said Proctor.
“If you go for a run and you’re really well-hydrated, your body will sweat and that will cool you down, because the evaporation of water cools your body in the same way a wet field can cool by evaporating some of that water,” he said. “If you’re dehydrated and you go for a run, you can get a heat stroke because your body can’t cool itself down by sweating. And in the same way, a dry crop field will get much hotter than a wet crop field.”
The B.C. drought summary in July shows about 60 per cent of the province is rated as “abnormally dry” or worse. Drought conditions continue to deteriorate in parts of the southern Interior, notably the Similkameen, Slocan-Lower Columbia and Creston basins, the summary said.
A warming planet means snowmelts are happening earlier in the year, reducing summer flows. It also leads to glacier loss. Glaciers contribute to summer water flow, but they’re disappearing at an alarming rate, according to scientists.
With files from The Canadian Press