TORONTO -- A new study suggests that the Arctic was once lush and green, and may eventually return to this state as the region continues to warm from climate change.
According to research out of the University of Colorado Boulder, the Arctic was covered with vegetation and woody shrubs as far north as the Canadian coast about 125,000 years ago.
The study, published this week in the journal Proceedings of the National Academy of Sciences, looked at plant DNA from lake sediment that was from the last interglacial period in the Arctic. In the lake sediment, which was more than 100,000 years old, researchers found evidence of a native Canadian shrub 400 kilometres farther north than previously recorded.
Since the Arctic warms much faster in response to climate change than anywhere else on Earth, the study’s authors suggest their findings may "not only be a glimpse of the past, but a snapshot of our potential future."
"We have this really rare view into a particular warm period in the past that was arguably the most recent time that it was warmer than present in the Arctic. That makes it a really useful analogue for what we might expect in the future," Sarah Crump, who conducted the study with the Institute of Arctic and Alpine Research, said in a press release.
While other studies have analyzed older DNA samples from Arctic permafrost, the study noted that lake sediments are kept cool, but not frozen, which keeps the DNA more intact.
The lake sediment was analyzed at an organic geochemistry lab in Boulder, Colo., and at a lab dedicated to decoding ancient DNA at Curtin University in Perth, Australia.
By extracting the plant DNA directly from the sediment and sequencing the DNA, the research team said they were able to get a "local snapshot" of what plant species were living in the Arctic between 116,000 and 125,000 years ago.
The plant DNA researchers found and analyzed was a taller shrub known as dwarf birch. According to the study, dwarf birch is a "key species" of the low Arctic tundra, but doesn’t currently survive past the southern part of Baffin Island in Nunavut.
While the study says there may be "many potential ecological effects" of the dwarf birch being found farther north, the researchers looked at the climate feedbacks related to these shrubs covering more of the Arctic.
The study acknowledged that climate models don’t typically include these kinds of changes in vegetation, but reported that these taller shrubs can stick out above snow in the spring and fall, making the surface of the region dark green instead of white.
Crump said this vegetation change would cause the area to absorb more heat from the sun.
"It's a temperature feedback similar to sea ice loss," Crump said in the release.
According to the study, these shrubs had "thousands of years" to adjust and move during the last interglacial period in response to warmer temperatures. With today's rate of warning, the researchers warn that the vegetation likely won't keep the same pace.
However, Crump says the plants will still have a role in impacting the region's changes, including thawing permafrost, melting glaciers and rising sea levels.
"As we think about how landscapes will equilibrate to current warming, it's really important that we account for how these plant ranges are going to change," Crump said.
With the Arctic seeing a possible temperature increase of 5 C by 2100 -- the same temperature it was in the last interglacial period -- researchers say their findings can help to better understand how Earth's landscapes will change with global warming.
The team also plans to expand their research beyond plants in future studies as their DNA samples from the lake sediment signal a "whole range of organisms" that once lived in and around the Arctic.
"We're just starting to scratch the surface of what we're able to see in these past ecosystems," Crump said. "We can see the past presence of everything from microbes to mammals, and we can start to get much broader pictures of how past ecosystems looked and how they functioned."
