If melting sea ice and glaciers weren’t enough, now climate change is producing what researchers call a “structurally novel ecosystem” in the northwestern Eurasian tundra.
Warmer weather and precipitation changes in the region, which covers western Russia into Finland, has allowed shrubs of willow and alder to grow into sparse forests within just forty years, according to a new study in Nature Climate Change.
The new ecosystem could have global implications as researchers say it is likely to worsen global warming due to a decline in the region’s albedo, i.e. the sunlight reflected back into the atmosphere due to snow cover.
“It’s a big surprise that these plants are reacting in this way,” lead author Marc Macias-Fauria of Oxford University said in a press release. “Previously people had thought that the tundra might be colonized by trees from the boreal forest to the south as the Arctic climate warms, a process that would take centuries.
But what we’ve found is that the shrubs that are already there are transforming into trees in just a few decades.”
The scientists write that the new ecosystem of tree thickets, with stands over two meters high, may be similar to an ecosystem that once existed along the Bering land bridge 12,000 years ago; the very same land bridge that early humans used to cross from Asia and into the Americas for the first time.
But today that extinct ecosystem may be returning: using satellite data, fieldwork, and on-the-ground observation by reindeer herders, the scientists believe the open woodland ecosystem now covers about 8-15 percent of the northwestern Eurasian tundra.
“This is just one small part of the vast Arctic tundra and an area that is already warmer than the rest of the Arctic, probably due to the influence of warm air from the Gulf Stream,” explains Macias-Fauria. “However, this area does seem to be a bellwether for the rest of the region.”
One of the biggest concerns is that these sudden forests will decrease the albedo (literally “whiteness”) of the tundra where snow cover bounces solar radiation back into the atmosphere creating a cooling effect. But as warming turns tundra shrubs, which can be covered by snow, into tall trees, researchers fear that less light will be bounced back creating a feedback loop that will worsen climate change.
Previously, scientists have estimated that if forest covered the entire Arctic tundra it could raise global temperatures another 1 to 2 degrees Celsius (1.8 to 3.6 degrees Fahrenheit) by 2100. To date, the Earth has warmed 0.8 degrees Celsius.
Even as shrubs becomes trees in Siberia, researchers last year reported that boreal forests had begun shifting northward into the Alaskan tundra.