Arctic warming turns the bushes in the trees

On the slopes of Polar Urals (Photo BC Forbes).

Tundra, by definition, cold treeless terrain. But Mark Macias-Faure from Oxford University (UK) and colleagues found that in some places in the Eurasian Arctic dwarf willow and alder in the last decade were turned into trees.

The reason — the warming.

About 30 years ago, the trees there almost was not. Now 10-15% of the southern part of the north-west of the Eurasian tundra, which stretches from Finland to Western Siberia, occupied shrubs, rising by more than two meters.

The change was first attracted the attention of scientists when Nenets, nomadic shepherds were told that they lose sight of their reindeer for new trees. Until recently, the height of the bush does not exceed m.

The researchers examined the evidence shepherds, temperature readings, tree rings and satellite data, including monitoring of vegetation density during the growing season. It turned out that most of all the bushes grew in years with particularly warm July.

Satellites indicate that shrubs are common in the southern part of the treeless tundra, they displace grasses, mosses and lichens further north.

This part of the Eurasian Arctic has a relatively mild climate, so she became the first. Soon, the same process will start in other places.

If the tree-shrub is widely used, it could exacerbate global warming due to the albedo effect, the scientists. When the snow falls on the tundra shrubs, he goes to a continuous white blanket that reflects sunlight back into space. Trees also rise above the snow, creating darker areas. As a result, less energy is reflected back into space and more is absorbed.

Finally warming will lead to the fact that the southern forests will spread to the north, but the process will take much longer.

The study is published in the journal Nature Climate Change.

On materials: LiveScience
Source: Kompyulenta


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