Extreme climatic events turning the Arctic regions brown

The increasing number of extreme events is causing dieback of Arctic plants or 'browning' across Arctic regions, a study has found.

Scientists from the University of Sheffield in the UK studying the Arctic—which is warming twice as fast as the global average—found that plant dieback following these events could significantly reduce the ability of Arctic ecosystems to help combat climate change.

Previously, scientists had found that increasing summer warmth in the Arctic was encouraging vegetation to grow, turning areas green.

"Despite the scale of Arctic browning, until now we knew very little about its impacts on ecosystem carbon balance; the balance between carbon uptake by vegetation and its release from vegetation and soils," said Rachael Treharne, a PhD student at the University of Sheffield.

"This information is critical to understanding the role of Arctic ecosystems in regulating global climate, both now and in the future," Treharne said.

The study, published in the journal Global Change Biology, assessed the impacts of Arctic browning driven by extreme climatic events.

Researchers looking at heathland in the Lofoten archipelago of Arctic Norway found the area had been affected by two extreme climatic events.

One of the events caused death of the dominant evergreen vegetation, and the second caused an extensive 'stress response', visible as high levels of protective anthocyanin (red) pigments in shoots and leaves.

Researchers found Arctic browning driven by extreme climatic events nearly halves the ability of widespread Arctic heathlands to take up carbon dioxide.

"Many climate models assume an arbitrary level of greening (and therefore increasing CO2 uptake) across the Arctic," Treharne added.

"The scale of the browning we have seen in recent years suggests the reality may be more complex— calling into question our understanding of the role the Arctic plays in global climate, and whether we should expect Arctic ecosystems to slow or accelerate future climate change," she said.