Extreme weather is turning the Arctic BROWN - and it could accelerate climate change

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https://www.dailymail.co.uk/sciencetech/article-6431689/Extreme-weather-turning-Arctic-BROWN-accelerate-climate-change.html

Extreme weather is turning the Arctic BROWN - and it could accelerate climate change

Over the last few years Arctic scientists have reported a surprising finding: large areas of the Arctic are turning brown. 

This is in part due to extreme events linked to winter weather, such as sudden, short-lived periods of extreme warmth. 

These events are occurring as the climate warms, which is happening twice as fast in the Arctic compared with the rest of the planet. 

Extreme events are therefore happening more and more often, with increasingly severe effects – including widespread damage and death in Arctic plants.

This 'browning' of plant communities has happened over thousands of square kilometres or more. 

However, until recently we knew very little about what this might mean for the balance between carbon uptake and release in Arctic ecosystems. 

Given that the Arctic stores twice as much carbon as the atmosphere, this is a pressing concern.

Now, our study has shown that extreme climatic events can significantly reduce the ability of Arctic ecosystems to take up carbon – with implications for whether the Arctic will help combat climate change, or accelerate it.

To understand how extreme events are affecting Arctic heathlands, we travelled to the Lofoten Islands in northern Norway where coastal, sub-Arctic plant communities act as a bellwether for future climate change in the far north by exhibiting the effects of warming in the region first.

Here we found the effects of two extreme winter weather events. 

We measured how much carbon dioxide was being taken in and released by the plants in three vegetation types: damaged heathland (where the dominant evergreen species had been killed by frost drought), stressed heathland, and healthy, green heathland which had escaped the effects of either extreme event. 

This was done in three measurement periods across the growing season.

We found that these extreme winter conditions reduced how much carbon was absorbed in heathland ecosystems by up to 50% across the entire growing season.

This is a huge reduction in the ability of a widespread Arctic ecosystem to remove carbon from the atmosphere.

Surprisingly, this was the case both in damaged heathland, where a large part of the vegetation had been killed, and in stressed heathland. 

Although the processes driving this change were different in each type of heathland, this clearly shows that we need to consider the role of plant stress in limiting plant carbon uptake to fully appreciate the consequences of extreme climatic events.