Welcoming an early spring? Chill out — it's not necessarily a good thing
Warm weather that arrives too soon can harm birds, trees — and people
While colder temperatures are making their way into some parts of Canada this week, warm weather swept across most of the country in February. By the end of the month, several cities had seen warmer than usual temperatures, some in the extreme.
In Calgary, the temperature rose to 16.4 C on Feb. 16. In Toronto, where temperatures at time of year should be around 1 C, 15 out of 28 days were above normal, with a record of 17.7 C set on Feb. 23.
That warm weather travelled east, and parts of Nova Scotia saw temperatures in the double digits.
While there are a few chilly days ahead, temperatures in cities like Toronto, Montreal and Halifax are all expected to climb at least 4 C above normal within the week.
A few days of warmer than usual temperatures occur frequently, but it's the trend that is most concerning.
The U.S. National Phenology Network, which studies seasonal and natural changes, has found that this year, leaves are appearing about 20 days early in many parts of the southeastern U.S. stretching north into Ohio.
Jake Weltzin, an ecologist and the executive director of the network, says that in the east and west — in the U.S. and Canada — "there is definitely a trend towards earlier spring, although there's some spatial variation … and a stronger effect the further north you go."
David Phillips, Environment Canada's senior climatologist, said this is occurring straight across the country.
"We know that the winter and spring periods are showing the greatest change of temperatures since the 1940s," he said.
The birds and the buds
The warmer weather provides signals to species far and wide. Insects emerge. Buds appear on trees. Birds begin to breed. But if this process begins earlier than normal, it can throw off the whole ecosystem.
Take birds, for example. Birds that migrate short distances are able to respond to a signal that indicates warmer weather at their breeding site.
However, those that have wintered thousands of kilometres away are unable to respond. They rely on longer days as their signal. One bird in particular, the wood thrush, arrives on almost the same date each year.
Kevin Fraser, assistant professor at the Avian Behaviour and Conservation Lab at the University of Manitoba, studies the migration patterns of birds.
"When birds arrive late, and they're mismatched with the peak productivity, they produce fewer young, and that actually is correlated in population declines," Fraser said. It's these birds that are facing the biggest challenges caused by climate change.
The purple martin, for instance, which Fraser studies, migrates thousands of kilometres from Canada to the Amazon basin.
"We know that long-distance migratory birds are declining more steeply than any other kind of bird," Fraser said. The decline varies between one and three per cent annually.
Interestingly, birds have been seen to respond to cooler weather by halting their migration or even retreating.
"My concern is that long-distance migrants aren't going to have the flexibility and plasticity that they need to respond to the rapid rate of environmental change that we have," Fraser said.
"Particularly with our springs; with earlier and warmer springs, we have birds that are trying to cue to this from great distances away and don't seem to be keeping up with the pace of climate change."
Earlier springs also greatly affect the ground, the consequences of which can carry on far past the season.
Earlier snowmelt means the ground may dry out earlier, which can be particularly problematic to farmers, who may not receive enough precipitation to account for the loss. That can raise prices at the grocery store.
Not only that, unseasonable temperatures can affect the quality of foods, even the beloved Canadian maple syrup.
Phillips said if warm weather starts earlier, too much maple syrup can be collected. It can't be processed quickly enough, and the quality can suffer.
As well, maple syrup production in trees relies on a thaw-freeze cycle that warmer weather can break.
People are worried about agricultural production, crop production, with the change in climate.— Ecologist Jake Weltzin
Overall, there is a concern about what warmer winters and earlier springs can mean to farmers. "People are worried about agricultural production, crop production, with the change in climate," Weltzin said.
Then there are fire concerns.
Persistent dry conditions greatly increase the fire risk, as was demonstrated in Fort McMurray last year. The drier winter and early spring helped create a type of tinder box that resulted in the rapid spread of flames throughout the city.
Winners and losers
Phillips said that while we may enjoy hitting that patio a week or two earlier, there are consequences we might want to consider, such as allergies. People allergic to pollen may begin to feel their symptoms earlier or could see their runny noses and watery eyes stick around for longer.
Some argue there are positives to earlier springs: some farmers may have longer growing seasons or may be able to grow new crops. We may see songbirds that are usually found farther south. And, of course, there may be more weekends at the cottage.
However, each of those positives could also have a negative consequence. New birds might push out native birds, for example. The scourge of spring and summer — mosquitoes and blackflies — might arrive earlier and stick around longer.
Already there have been more cases of Lyme disease seen farther north than normal, such as in Newfoundland and Labrador.
Not all the consequences of climate change are known, but they will come.
"Part of it is the sad story of seeing who are going to be the climate change winners and who are going to be the climate change losers," Fraser said.