What on Earth

How climate change is leading to 'a redistribution of life on Earth'

Scientists have documented more than 12,000 species worldwide that are moving to more hospitable regions, including everything from fish to bees to caribou to grasses to berries to trees.

Scientists say more than 12,000 species experiencing 'range shift'

Caribou are among the species that are currently experiencing what scientists call 'range shift.' (Mike Bedell/CPAWS/Canadian Press)
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Pacific salmon used to be so unfamiliar in Arctic waters that many communities don't have local words for the fish, and there are stories of harvesters feeding them to their dogs.

But in recent years, chum, pink and sockeye salmon have been showing up in so many fishing nets that Fisheries and Oceans Canada has been keeping track.

Michelle Gruben works at the Hunters and Trappers Committee (HTC) in Aklavik, N.W.T., a small community near the Mackenzie delta on the Beaufort Sea, collecting salmon from harvesters in order to pass them on to scientists with the Arctic Salmon project.

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Most summers, Gruben takes in a couple of salmon each week. But last year, 30 arrived in one day and 180 over the entire summer.

"For the salmon, it was crazy busy," said Gruben.

Across the western Arctic, nearly 2,500 were turned in — more than the previous 18 years combined.

"There were so many salmon that we had to switch from accepting whole salmon to heads only," because the freezers were full," said DFO biologist Karen Dunmall, who heads the Arctic Salmon project. "Every community in the Northwest Territories was experiencing more salmon than they'd ever experienced before."

The Arctic Salmon Project collected more than 2,400 salmon samples in 2019. (Submitted by Kevin Chan)

This is not normal. The influx of salmon in the Arctic is such that Fisheries and Oceans Canada has published an identification guide in Inuktitut and a cookbook of community recipes.

While the arrival of Pacific salmon might bring a new food source to the North, it's an uncertain and possibly ominous sign for the species, whose populations are suffering at the southern end of their range, as waters warm and Arctic salmon runs in B.C. and Washington state decline.

It's not clear if the salmon are spawning successfully yet in Arctic streams, but the northern arrivals look like the start of what scientists call "range shift." 

As a result of climate change, species are finding their traditional geography uninhabitable and are moving elsewhere.

'A redistribution of life on Earth'

Scientists have documented more than 12,000 species worldwide that are experiencing range shift — everything from fish to bees to caribou to grasses to berries to trees.

"We're literally living through a redistribution of life on Earth," said Gretta Pecl, a marine ecologist at the University of Tasmania and lead author on a recent study of range shift in the journal Science. "Even though this is my bread and butter that I work on, it really does blow my mind ... the extent of this phenomena."

Pecl said the way this is playing out, in broad strokes, is that in the Northern Hemisphere, plants and animals are moving north, while in the Southern Hemisphere, they're moving south. 

Gretta Pecl, a marine ecologist at the University of Tasmania, said, 'we're literally living through a redistribution of life on Earth.' (Submitted by Gretta Pecl)

Seeking cooler homes, plants and animals are also "going to higher elevations on mountains and deeper in the ocean, and it really is a pervasive movement of the geography of life." 

Ultimately, these species are seeking what scientists call climate change "refugia" — areas where they can survive at a time of environmental instability. 

Species seeking 'slow lanes' to survive 

Diana Stralberg, a research associate at the University of Alberta, said the concept of refugia has been around for a while as a way to examine where species escaped during major changes in climate in the past, such as ice ages.

Stralberg said that in the current era, many scientists think of climate change refugia "as a slow lane for species in a rapidly changing world."

The "slow lane" refers to "areas that are changing more slowly with respect to the surrounding landscape," said Stralberg. "These are areas where species and ecosystems can bide time while they adapt to change — or we can figure out how to slow down the process of climate change."

In their research, Stralberg and her colleagues have identified certain slow lanes for climate change in Canada, including mountain ranges. 

"Mountains have different micro-climates — some with less sunlight, for example," Stralberg said.

These micro-climates stay cooler, becoming a safe haven for animals pushed out of their ranges due to warming temperatures. Stralberg said that in seeking sanctuary, species in these areas could, for example, move higher up mountains or along river corridors, areas that they "can more readily shift to."

Canada's boreal peatlands are one of the areas scientists are looking to preserve as the climate changes. (Submitted/ Michel Rapinski)

By mapping out these slow lanes, Stralberg and her colleagues want to show the parts of Canada that have the most value in preserving biodiversity, in the hopes they can "protect those areas in parks or conservation areas, or work with industry to manage them."

Varying pace of adaptation

The effects of range shift are not restricted to the plants and animals themselves. As the Science review points out, "The well-being of human societies is tied to the capacity of natural and altered ecosystems to produce a wide range of goods and services."

In the example of Pacific salmon in the Canadian Arctic, the disappearance of some species and the emergence of others is changing consumption habits. 

Pecl said that what is complicating matters is that the species engaging in range shift are not doing so at the same pace. 

"If we had this neat system where entire ecosystems were marching collectively in the one direction and staying intact, it probably would be less of an adjustment that ecosystems and humans that depend on them need to make," Pecl said.

She said that if the supply lines of species traditionally required for food or other human uses are broken, it could lead to conflict among people.

"I think that's why as a society we need to be having discussions now about how we should be approaching this challenge of this redistribution of life on Earth, and in particular, how do we do that in an equitable, legitimate way."

Written by Andre Mayer, with files from Lisa Johnson and Molly Segal

Listen to What on Earth on CBC Radio 1 every Sunday at 10:30 a.m., 11 a.m. in Newfoundland.

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