Agro-climate data is a ‘mismatch’ with overall trends

Farmers need improved data on agro-climate to make sense of climate change, says U of M soil scientist

Numbers don’t lie but they’re presently a real puzzle when it comes to making sense of climate change and what’s happening on the farm, says a University of Manitoba professor.

Despite warming trends of recent years and forecasts of a continued increase, analysis of agro-climate data shows the last spring frosts are only marginally earlier, and there is no consistent pattern of increases to corn heat units nor lengthening of frost-free periods across the Prairies, says Professor Paul Bullock, head of the university’s department of 
soil science.

In other words, agro-climate data and broader climate data are a bit of a mismatch right now, he told St. Jean Farm Days.

“Climate change is very important and it affects us all,” he said. “But what I’m finding trying to relate what we see with climate change to what you experience on the farm as agro-climate may not always match up.”

To illustrate Bullock cited various agro-climate analysis using data from weather stations collected from across Southern Canada including some dating back as far as the 1900s.

Overall, it points to an average air temperature increase of about 1°, related more to overnight lows than daytime highs, he said. Researchers have also crunched data looking at dates of the last spring frosts. After last year’s widespread damage to crops from frosts May 29 and 30, the question arose, “Is this unusually late?” he said. The conclusion: “Yes, a little bit later than normal but not off the charts or anything like that.”

Variable across the Prairies

Other work looking at the length of frost-free days does show there has been an almost two-week increase in average length, but also shows considerable variability across Western Canada. Some areas are even seeing a decrease, Bullock said. As for corn heat units, a student who reviewed average CHU accumulation also found inconsistent trends, with some areas showing upward, but others showing declining or statistically insignificant trends.

“It’s a mixed message depending where you are,” he said.

“If you had to generalize based on what we’re seeing, you’re going to see this increase in frost-free period on average… but there’s going to be a lot of variability year to year,” he told his farm audience. “It depends on where your boots are on the ground.”

Bullock said later in an interview he thinks this perplexing data, plus our individual experiences or recollections of weather contribute to “the disconnect” we can feel when it comes to grasping climate change.

Farmers need meaningful information that will help them assess their weather-related crop production risks, he said.

Right now we don’t have enough of it. To date, work done to gather and analyze agro-climate is being done by graduate students at universities, he said.

“Without them we’d have no assessment at all,” he said.

“The agro-climate needs to be evaluated on an ongoing basis the same way we do with climate change,” he said.

“And what really matters is to translate that into something that’s meaningful on the farm.”

About the author


Lorraine Stevenson is a reporter and photographer for the Manitoba Co-operator with 25 years experience writing news and features. She was previously a reporter with the Farmers Independent Weekly and has also written for community newspapers in Winnipeg and Manitoba's Interlake.


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