As polar ice melts, seabed life is working against climate change

September 21, 2015
Icefish swimming over bryozoans on the Weddell Seabed. Credit: Thomas Lundalv

When it comes to climate change, it's rare to get any good news. But a researcher who's reported evidence in the Cell Press journal Current Biology on September 21, after more than two decades of study, has some: the loss of sea ice over Antarctic waters in some areas has led to the increased growth of creatures living on the seafloor. Those underwater assemblages are acting as an important and unexpected carbon sink.

"It was a surprise that life had been invisibly responding to for more than a decade below one of the most obviously visible impacts of climate change: the 'blueing' poles," says David Barnes of the British Antarctic Survey (BAS). "We've found that a significant area of the planet—more than three million square kilometers—is a considerable carbon sink and, more importantly, a negative feedback on climate change."

In fact, most of the known consequences of climate change have made matters worse instead of better. For example, Barnes says, as the polar climate warms, sea ice melts. As sea ice has melted, the Earth's surface has turned from reflective white to a much darker blue at the poles, absorbing more heat and melting even more ice.

Scientists knew that arctic forests and new algal blooms where ice shelves disintegrated were, to some extent, working against climate change. They now say, based on studies of West Antarctic bryozoans—organisms sometimes referred to as "moss animals"—that other organisms living on the seafloor "could be more important than both" when it comes to accumulating and burying carbon.

RRS James Clark Ross in Bellingshausen Sea. Credit: British Antarctic Survey

Antarctica has not experienced a net loss of sea ice in the way the Arctic has. The ice has melted over more-productive continental shelves as ice has formed over less-productive, deeper waters. In the new study, Barnes and his colleagues collected specimens across West Antarctic seas and used high-resolution images to calculate the density of life on the seabed.

The data, collected over more than 20 years, reveals strong increases in annual production of shelf seabed carbon in the bodies of West Antarctic bryozoans. The researchers calculate that growth of the bryozoans has nearly doubled, with the animals taking in more than 2 ? 105 tons of carbon per year since the 1980s. Extrapolating from the data to account for other undersea species suggests an increased drawdown of carbon of about 2.9 ? 106 tons per year, equivalent to about 50,000 hectares of tropical rainforest. Even better is the suggestion that this carbon may be more likely to become trapped and buried at the bottom of the ocean, given the depth of the polar .

Barnes says that the surprising differences in the amount of carbon taken up in different regions in Antarctica linked closely to the losses at each location. In more encouraging news, they found that the South Orkney Islands—the world's first High Seas Marine Protected Area—"is bang on a carbon hotspot, without us realizing!"

Captain Scott, who got collection of key bryozoans off to an early start. Credit: SPRI

A new international, BAS-lead scientific cruise to the South Orkney Islands MPA in early 2016 should give researchers a close-up look at why that particular location is so important. More generally, the findings are a reminder of the importance of ocean life for understanding our changing climate.

"The forests you can see are important with respect to the cycle and climate change, but two-thirds of our planet is ocean, and below it the life you can't see is also very important in climate responses as well," Barnes says.

It will now be important to find out whether similar things are happening in the Arctic.

Explore further: Climate change affects marine animals on Antarctica's seabed

More information: Current Biology, D.K.A. Barnes: "Antarctic sea ice losses drive gains in benthic carbon drawdown" dx.doi.org/10.1016/j.cub.2015.07.042

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2 comments

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denglish
2 / 5 (4) Sep 21, 2015
No wonder the models were wrong, they didn't account for this.

Another discovery abut climate! Life adapts to what is happening in the climate; it always has and always will. Humans can do nothing about it; be it accelerating or slowing the process.

It is impossible to know all of the factor at play in our climate; despite what the taxman and Population Control say.
mememine69
1 / 5 (2) Sep 21, 2015
This garbage reporting is criminal level exaggeration and lazy copy and pasting journalism.

Science is smart enough to say; 'PROVEN' before it's to late to say it's "PROVEN" to be a CO2 Armageddon for certain.
32 years of 97% certainty was not a crime but exaggerating vague science was.

*Is THIS how you want your kids remembering you because what is stopping another 34 MORE years of climate action failure and disbelief?*

Get up to date, it's over;
Occupywallstreet does not even mention CO2 in its list of demands anymore because of the bank-funded and corporate run carbon trading stock markets ruled by politicians.

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