A tractor plows a Sumas Prairie field Wednesday morning. Fields, forests and highway medians are bone dry as the Lower Mainland has seen record dry conditions the past two months.

The Fraser Valley has been warming at a quicker rate than Vancouver. Why?

Implications for agriculture and humans as data suggests region is warming at a rapid rate

Global warming may be having a greater immediate effect on Fraser Valley communities than those cities just an hour’s drive to the west.

It’s well known that different regions will experience climate change in different ways. But seventy years of temperature data compiled by Environment Canada and provided to The News suggests that even within the Lower Mainland’s relatively small area, the effects of global warming are being felt differently depending on where one is.

Since 1950, temperatures have risen more than 50 per cent quicker in Abbotsford, in the Fraser Valley, than in Vancouver, barely 70 kilometres to the east.

A UBC climate scientist says more study is needed to prove the disparity is statistically significant, but that dramatic warming in the Fraser Valley will have repercussions on the area’s billion-dollar agriculture industry. An Environment Canada meteorologist says the numbers are partly the result of the region’s increasingly hot summers, which have been growing so frequent that authorities have upped the the bar for issuing heat warnings.

“That’s a pretty notable trend,” said Douw Steyn, a professor emeritus at University of BC’s earth, ocean and atmospheric sciences department. “There are real consequences for these sorts of changes.”

• • • • •

The figures produced by Environment Canada are simple but show a simple and clear trend: not too long ago Vancouver was once warmer than Abbotsford, and now it is not.

With a new decade upon us, The News requested mean (average) temperatures for each decade for which records are available. Such decadal mean temperatures are simply an accumulation of yearly mean temperatures which themselves are made up of 365 daily mean temperatures. Those daily mean temperatures come from finding the midpoint between one day’s highest temperature and the day’s lowest temperature. That means that a single decadal temperature mean is an average of more than 7,000 data points.

From the 1950s (the first year for which temperature records were kept at Abbotsford International Airport) through to the 1980s, Vancouver’s decadal mean temperature was higher than Abbotsford’s mean, even as both places grew warmer.

In the 1990s, however, that relationship changed and Abbotsford, for the first-time had a warmer decade. The 21st Century has seen that relationship continue, as temperatures in both places continue to rise.

By the 2010s, Abbotsford’s mean temperature was a full 1.5 C warmer than in the 1950s, while Vancouver’s average temperature had increased by 0.9 C – a still-significant, but lesser, rise.

Steyn cautioned that more study was needed to determine whether the changes meet the high bar of being statistically significant. But he said the shift makes sense, given existing knowledge about global warming and its impacts on various climate regions, and warranted more investigation.

“Without having done the careful statistical analysis that one must do, the trend is apparent to the eye,” he said. “This is a fascinating observation.”

He says he suspects regional variations among temperatures likely most pronounced in coastal areas.

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• • • • •

The findings are intuitive, because they reflect the impact that proximity to the Pacific Ocean has on the day-to-day weather.

The vastness of the ocean makes it slow to change temperature. In winter, it’s warmer – and thus helps warm – than the surrounding air. In summer it has the opposite effect. So when Vancouver is cold, Abbotsford tends to be colder. And when Vancouver is warm, Abbotsford and the Fraser Valley are downright hot.

“Vancouver International Airport has a much smaller annual range of temperatures in Abbotsford,” Steyn said.

When Vancouver was warmer, on average, than Abbotsford, the latter’s cold snaps and winters balanced out its summer heat. But as winters have become shorter, with fewer arctic outflow events, and summers have grown longer with more heat waves, the balance has tipped and Abbotsford can now claim to be warmer than the city.

Steyn said further study is needed to make any definite conclusions about the relationship between Vancouver and Abbotsford, but that “the trend is apparent to the eye.”

He noted that manmade global warming has been conclusively proven and the effect of a rapidly warming climate in Abbotsford has a number of implications.

“What does it mean? What it means is that Abbotsford will be less comfortable for humans beings,” he said. Steyn added the pace of warming will also have implications for poultry producers who must cool large barns, greenhouse growers and other agricultural producers. “It will be more amenable for crops that require high temperatures and maybe longer periods of high temperatures to ripen. It will be less-amenable to crops that have a tendency to heat stress.”

• • • • •

Armel Castellan, a warning preparedness meteorologist with Environment and Climate Change Canada, said the data reinforce the changes weather watchers are seeing.

Castellan agreed with Steyn that Vancouver International Airport’s proximity to the Pacific is likely to slow global warming’s impact on the local weather. (University of the Fraser Valley geography instructor Lionel Pandolfo concurred, pointing to a 2012 paper that showed how temperatures will rise faster over land surfaces than those at or near water bodies.)

“It’s indicative of how things are not going to change equally for all locations,” Castellan said.

He pointed to northern communities where animal and fish migration patterns are shifting in hitherto unforeseen ways. In the arctic, for example, salmon are beginning to show up in huge numbers, which is upsetting the local ecosystem and driving out other fish.

“The changes are drastic in some locations and they’re going to be a little bit more subtle in others, but as we’re seeing, there’s already that differentiation between locations that aren’t all that far away from one another – just a few dozen kilometres between YXX and YVR.”

“In the summertime we’re seeing longer and higher amplitude heat waves. We’ve adjusted our heat warming criteria a couple years ago to reflect that. We don’t want to over-alert for heat, but at the same time the implication and impact of heat are so much greater than almost any form of weather.”

He pointed to western Europe’s 2003 heat wave that killed tens of thousands of people.

The changing climate also has a large impact on precipitation and major storm events, Castellan noted.

“It used to be that we would see half the annual precipitation in only 12 days,” he said. Now the region gets half its annual precipitation in just six days.

”That doesn’t sound like very much, but when you think about it … it means that those six days are going to really be almost double what they used to be.”

Steyn and UFV’s Pandolfo each suggested that the topic was worth further exploration by academics and students, with Steyn suggesting an inquiry into the frequency of elderly people being taken to hospital to be treated for heat stress.

Do you have something to add to this story, or something else we should report on? Email:
tolsen@abbynews.com


@ty_olsen
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Photo top from 1950s Abbotsford courtesy The Reach Gallery Museum Archives (P498); File photo (bottom)

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