Arctic plant growth 'could speed up global warming'

IN A surprise finding, researchers have shown that as trees start to grow closer to the North Pole, replacing once-barren tundra, they release more greenhouse gases than they absorb.

By InvestSMART · 18 Jun 2012

By InvestSMART ·
18 Jun 2012

Comments

IN A surprise finding, researchers have shown that as trees start to grow closer to the North Pole, replacing once-barren tundra, they release more greenhouse gases than they absorb.

The study has global implications for measuring the speed of global warming, because it had previously been thought that when forests colonise the frozen Arctic they might act to slow dangerous climate change by soaking up extra carbon dioxide from the air.

Instead, as temperatures rise and plants take root further north, the barren soils are "primed" by new growth and start to release long-held stocks of carbon. The amount of carbon activated by a change from tundra to forest outweighs that soaked up by the new trees, leading to a net increase in the amount that warms the atmosphere.

"We suggest that, as more productive forest communities colonise tundra, the decomposition of the large [carbon] stocks in tundra soils could be stimulated," the researchers wrote in a paper to be released today in the journal Nature Climate Change.

"Thus, counter-intuitively, increased plant growth in the European Arctic could result in [carbon] being released to the atmosphere, accelerating climate change."

A team of eight researchers from Scotland and England braved frigid conditions in northern Sweden to gather and measure soil samples from patches of forest and tundra.

They carefully peeled the soil into centimetre-thick layers and measured the carbon and organic content of each, using the traces of radioactivity from atomic weapons testing in the 1950s as a marker to distinguish older carbon deposits from those that had been more recently absorbed.

A senior climate change researcher at the CSIRO, Michael Raupach, said the study could be used to refine estimates of how fast the world would warm, but more detail was needed to judge the scale of the phenomenon.

"It's very interesting, it will have ramifications, and it's a process that hadn't been expected, but it's very difficult to say what those ramifications will be on a global scale," Dr Raupach said.

Between 1982 and 2010, the amount of vegetation in the Arctic had increased by 8 per cent, the report said.

Go to Google News, then click "Follow" button to add us.

Share this article and show your support

Frequently Asked Questions about this Article…

What did the new Arctic study find about plant growth and greenhouse gases?

The study found that as trees and other plants move north and replace tundra, the previously frozen soils can be "primed" to release long‑stored carbon. In the research from northern Sweden the carbon released from soils outweighed the carbon absorbed by the new trees, meaning a net increase in greenhouse gases that could speed up global warming.

How did researchers measure carbon release in tundra and new Arctic forests?

Scientists collected soil samples from patches of tundra and forest in northern Sweden, peeled the soil into centimetre‑thick layers and measured carbon and organic content. They used traces of radioactivity from 1950s atomic weapons testing as a marker to distinguish older carbon deposits from more recently absorbed carbon.

Why does the change from tundra to forest cause more carbon to be released than absorbed?

The researchers suggest that when more productive forest communities colonise tundra, decomposition of the large carbon stocks in tundra soils can be stimulated. That stimulated decomposition can activate and release older carbon stores faster than the new vegetation can absorb CO2, producing a net release.

What are the global implications of this finding for the speed of global warming?

The paper says this process could affect estimates of how fast the world will warm because forests colonising the Arctic might accelerate carbon release instead of offsetting it. A senior CSIRO researcher, Michael Raupach, noted the finding could refine warming estimates but stressed more detail is needed to judge the phenomenon's global scale and ramifications.

How much has Arctic vegetation changed in recent decades?

According to the report cited in the article, the amount of vegetation in the Arctic increased by about 8% between 1982 and 2010.

Why should everyday investors pay attention to this Arctic carbon‑release research?

For investors tracking climate risk, this research suggests some carbon‑cycle feedbacks may be different from previous assumptions. That can influence climate projections, policy decisions and the valuation of climate‑sensitive sectors. The article highlights that more research is needed, so investors may want to follow follow‑up studies and updated climate models when assessing long‑term risks.

Who carried out the research and where was the study published?

A team of eight researchers from Scotland and England conducted the field work in northern Sweden. Their paper was released in the journal Nature Climate Change, and the results were commented on by Michael Raupach, a senior climate change researcher at CSIRO.

What further research or information should investors watch for after this study?

The article says more detail is needed to judge how large this effect is globally. Investors should watch for follow‑up field studies, refined climate models that incorporate these findings, and any policy responses tied to updated estimates of Arctic carbon release and global warming projections.