Our arctic polar region is traditionally associated with predominantly treeless permafrost and a vast cover of snow and ice during the winter period in the northern hemisphere. However, researchers at the University of Colorado discovered that it was covered with green vegetation stretching as far north as the arctic ocean during the last so-called interglacial period.

This last interglacial period took place approximately 125,000 years ago. During that time, the earth would have looked quite different if observed from space, and the Colorado researchers think this could happen again. The team analyzed 100,000-year-old plant DNA that they obtained from ancient lake sediment in the Canadian Arctic polar region. They uncovered evidence of woody shrubs growing a whopping 400 kilometers farther north than their contemporary descendants.

Arctic region in Norway - Image Credit: azgek via iStock/Getty images - HDR tune by Universal-Sci

Due to climate change, the average temperature on our planet is rising, but the Arctic region, in particular, seems to be warming up a lot faster than any other area. Scientists think that the evidence found of a green past may not just be a look back at a long-gone past but also a picture of our potential future.

Sarah Crump, one of the researchers, explained in a press release that their research provided a rather scarce view into a specifically warm period in our planet's recent history. According to Chump, this was arguably the most recent time that it was warmer than present in the Arctic.

The specific DNA that the researchers analyzed what that of ancient dwarf birch, a hardy shrub that grows to about 30cm tall. Even though it is a robust plant capable of surviving in relatively inhospitable regions, no dwarf birch is found as far north as the Canadian Arctic (where the researchers found the DNA) in modern times.

Although one could think of several possible ecological consequences of the dwarf birch edging farther north, Crump and her colleagues examined the climate feedbacks associated with these shrubs covering more of the Arctic. It is uncommon for contemporary climate models to this type of vegetation change, but these taller types of plants are capable of sticking out above snow in the spring and fall, making rendering the surface of our planet darker green instead of white. A darker surface absorbs more light while snow and ice coverage reflects light. A darker surface would therefore make our planet warmer.

Typical forest-tundra. Scientists think we would have encountered this type of landscape much further up north, 125,000 years ago - Image Credit: Evgenii Mitroshin via iStock/Getty Images - HDR tune by Universal-Sci

According to Crump, it is vital to account for plant coverage if we think about how landscapes will balance and adapt to current climate change. It is not unlikely that our arctic region will warm up with 5 degrees Celcius by the year 2100 compared to pre-industrial levels. The Colorado research helps scientists improve their understanding of changing landscapes in the artic and their influence on global climate change.

The Colorado team used a new high-end method that allowed them to extract plant DNA directly from sediment, sequence the DNA and induce what plant species existed there in the past. In lieu of a regional snapshot, sedimentary DNA analysis gives scientists a local picture of the plant species living there thousands of years ago. Chump: "Your best shot is getting fresh mud," said Crump. "Once it's out of the lake, the DNA is going to start to degrade."

As it is now possible to extract and analyze DNA that is more than 100,000 years old, many new possibilities for future research lay open, looking at far longer timescales. On top of the plant DNA, the scientists found a range of signals from organisms that lived in and around the lake, where they subtracted the sample.

As a whole, researchers are just starting to scratch the surface of what they are able to see in these past ecosystems. As reported by Crump, researchers can see the past presence of everything from microbes to mammals. They can begin to perceive far broader pictures of how ancient ecosystems looked and how they functioned.

If you are interested in a more detailed picture of the research we talked about in this article, be sure to check out the paper published in the science journal: Proceedings of the National Academy of Sciences (PNAS), listed below.

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