© Elisabeth Kruger / WWF-US
Predicting tipping points in the Arctic

Picturing life in a warmer, climate-altered Arctic is far from straightforward. As the Far North heats up more than twice as fast as the rest of the planet, it’s easy to imagine that, in the future, plants and animals to the south will merely march northward together as an orderly group: nature on Baffin Island in a few decades, say, might resemble nature found in northern Quebec today. It’s not that simple.

“Plant populations shift and probably form new [plant community] zones that didn’t exist before in different combinations,” explained Don McLennan, a senior scientist at Polar Knowledge Canada. “How we think about it is important … to get at the complexities.”

Dr. McLennan was speaking in late April as one of more than a dozen Arctic experts gathered at the second workshop of WWF’s new Arctic Conservation Forecast Initiative. The initiative, which held its first virtual expert workshop in January, is a new, experimental approach to explore options for supporting the resilience of Arctic organisms and ecosystems in a rapidly changing climate.

© / Doug Allan / WWF

Its aim is to better understand what Dr. McLennan described as the “complexities” of Arctic change, both on land and at sea, by bringing together climate scientists, oceanographers, biologists and conservationists in a unique consensus-building forum. The group is asked to consider together how new Arctic projections of temperature, snow, ice and other changes derived from the latest computer climate models—known as the Coupled Model Intercomparison Project Phase 6, or CMIP6—might affect Arctic ecosystems and species. These, in turn, will help direct conservation groups like WWF to conserve these species and systems into the climate-altered future.

© Germund Sellgren / WWF-Sweden

It’s not easy.

Models of future climate-affected changes come with their own uncertainties, and, for biologists, it’s critical to avoid oversimplifying how these changes—such as warming summer temperatures—affect the life histories of Arctic plants or animals.

People leap to conclusions about how biota will change in response to changes in climate. There are obviously correlations but correlations, like all correlations, are not perfect.

said Nancy Fresco, associate research professor at the University of Alaska Fairbanks and another expert participant in the workshop.

Some plants and animals may simply shift north as the tundra or northern seas warm, for example. But in many parts of the Arctic northern coastlines or the shelf edge of shallow seas constitute a hard stop for such shifts and endangers the survival of plants and animal. For others, the temperature rise may mean changes to the landscape or marine world that completely transform existing ecosystems—edging them past their so-called “tipping points” and paving the way for new wildlife communities.

Still other plants may respond by simply changing form—their so-called physiognomy – like a shrub species that may have existed as part of low-lying vegetation, growing instead to be several meters tall. Transforming how they look, in turn, can change their role in the environment and even influence what other animals and plants surround them.

© Wild Wonders of Europe / Orsolya Haarberg / WWF

“If we talk about physiognomy, then we can talk about what it means for habitat for, for example, songbirds,” said Dr. McLennan. “There’s good evidence from Labrador where dwarf birch can respond quite rapidly to changes in summer temperature to grow much taller—the famous ‘shrubification’ that’s happening in the Arctic. Then, that produces shrubby habitat for songbirds that wasn’t available before.”

© Peter Ewins / WWF-Canada

Importantly, what’s true for the dwarf birch in Labrador—and its wider impacts on birds and other species there—isn’t necessarily true for other Arctic life. The logic that informs how climate change affects vegetation, for example, is different from the thinking required to understand its impacts on caribou herds, explained Martin Sommerkorn, head of conservation with the WWF Global Arctic Programme and one of the workshop organizers.

“It’s really difficult to engage the caribou in the same case study logic that makes sense to vegetation people,” he said. For caribou, for example, climate changes that cause more incidents of rain freezing on snow, preventing the animals from scraping through to food beneath, can decimate herds within months or years. Climate impacts on plants are typically far slower and more complicated. "The whole science logic is set up differently," Dr. Sommerkorn said.

The aim of the Arctic Conservation Forecast Initiative is to find a “meeting in the middle” of these separate logics, he said, to find the best region-specific, geography specific and biodiversity-specific approaches to conserving Arctic nature.

© Wild Wonders of Europe / Munier / WWF

The objective of what we are trying to do here is to test what we can say on the basis of [climate] models in terms of biological consequences across all of these different logics. It needs dedicated discourse and dedicated processes. It needs these dedicated workshops coming together, etc., because the logics are distinct and don’t fit otherwise.

Dr. Sommerkorn said.