Worldwide, the net result of climate change has been slightly good for rice and soybeans and slightly bad for wheat (above) and corn. (Rob Gillies/Associated Press)

Research suggests Canadian farmers seem to be dodging the worst impacts of climate change and may even benefit from it as crop prices increase.

Stanford University researcher David Lobell concludes in a paper published online in Science Express that climate change has already begun to slow harvest growth rates almost everywhere in the world — except in the United States and Canada.

"In some sense, Canada has gained relative to a lot of other countries because Canada has not seen significant trends so far and other countries have, on average, been hurt by climate change which has driven up prices," Lobell said.

He and his co-authors asked a simple question: how has the average increase in global temperatures of .13 C per decade since 1950 affected yields of wheat, corn, rice and soybeans? Those crops account for about 75 per cent of the world's calories.

"That in itself is a simple bit of analysis," Lobell said. "Where it gets complicated is in trying to translate those changes in weather into changes in production and changes in food prices."

The team had to find a way to filter out factors such as different farming practices, different soils, exceptional years and technology change.

They also had to take into account the fact other research shows that high levels of carbon dioxide in the atmosphere act, to some extent, as fertilizer.

"There's all kinds of stuff that changes in agriculture and it's a challenge trying to understand any one factor," Lobell said. "We're pretty conservative in not invoking temperature or precipitation as an explanation for changes in yields if we can explain it some other way."

Analysis showed that two-thirds of countries in the world have already experienced statistically significant temperature increases for corn and rice cropland. Three-quarters of the world's wheat lands and about half its soybean acreage have experienced similar warming.

Eastern Europe, Mexico, China worst-affected

The worst-affected countries include those in Eastern Europe, Russia, Turkey, Mexico and China. Canada and the U.S. had little temperature shift, so there's been little effect on crops.

The net result of climate change has been slightly good for rice and soybeans and slightly bad for wheat and corn. Because wheat and corn account for a greater proportion of the world's food supply, the overall effect is negative.

"Production is still going up for almost every region in every crop," Lobell said. "This is just a matter of it not going up as fast as it would have had climate not changed."

The study suggests the economic effects are already evident.

"You have demand rising quickly and supply rising, historically, as quickly," said Lobell. "But climate has been like a headwind for that increase in food production trying to keep up with demand."

Anything that impedes world agriculture's ability to keep up to demand is going to goose prices.

6.4% of price increase

The paper calculates that about 6.4 per cent of global price increases for agricultural commodities is due to climate change.

Because Canadian yield gains aren't being slowed yet, Canadian farmers get to reap the benefits without paying the price.

"Canadian farmers are probably a little bit better off than they would have been without climate change," Lobell said. "That doesn't in any way say that that will continue, but it does point to the fact that there are winners and losers in any situation where you're affecting agriculture differentially across the world."

Lobell said his study is an example of the kinds of things decision-makers will need to consider as the world changes.

"The general idea is that at the global scale we can already see a need to adapt to climate change. It's not just something that's in the future."