So concludes a group of nearly two dozen scientists in a paper appearing this week in the journal Bioscience. The lead author is Ted Schuur, an associate professor of ecology at the University of Florida.
Previous studies by Schuur and his colleagues elsewhere have estimated the carbon contained in permafrost in northeast Siberia. The new research expands that estimate to the rest of the permafrost-covered northern latitudes of Russia, Europe, Greenland and North America. The estimated 1,672 billion metric tons of carbon locked up in the permafrost is more than double the 780 billion tons in the atmosphere today.
"It's bigger than we thought," Schuur said.
Permafrost is frozen ground that contains roots and other soil organic matter that decompose extremely slowly. When it thaws, bacteria and fungi break down carbon contained in this organic matter much more quickly, releasing it to the atmosphere as carbon dioxide or methane, both greenhouse gases.
Scientists have become increasingly concerned about this natural process as temperatures in the world's most northern latitudes have warmed. Just last week, it was announced that the amount of sea ice covering the Arctic may reach a new low this summer. Meanwhile, there is widespread consensus that the highest latitudes will warm the fastest, a process already visible in the accelerated thawing of glaciers worldwide.
Two years ago, Schuur and two colleagues authored a paper in the journal Science estimating that 400,000 square miles of northeast Siberian permafrost contained 500 billion metric tons of carbon. For this new paper, scientists combined an extensive database of measurements of carbon content in different types of permafrost soils with the estimated spatial extent of those soils in Russia, Europe, Greenland and North America.
Schuur said the researchers estimated the carbon contained in permafrost to a depth of three meters, two meters deeper than many earlier estimates. Although permafrost depths vary greatly with location, basing the estimate on three-meter depth "better acknowledges the true size of the permafrost carbon pool," Schuur said.
The new estimate is important because it mirrors other climate change science suggesting that at a certain tipping point, natural processes could contribute significant amounts of greenhouse gases, supplementing human-influenced, industrial processes that release fossil fuel carbon, Schuur said.
"There are relatively few people living in the permafrost zone," Schuur said. "But we could have significant emissions of carbon from thawing permafrost in these remote regions."
How fast the permafrost would release its carbon is a hugely important question.
Schuur said the burning of fossil fuels contributes about 8.5 billion tons of carbon dioxide each year. Deforestation of the tropical forests and replacement of the forest with pasture or other agriculture is thought to add about 1.5 billion tons per year. How much permafrost will add will depend on how fast it thaws, but Schuur said his research indicates the figure could approach .8-1.1 billion tons per year in the future if permafrost continues to thaw.
With the Arctic warming and permafrost thawing, shrubs and trees are likely to grow on ground formerly occupied by tundra – indeed, such a transformation has already been observed in parts of Alaska, where some arctic tundra is becoming shrub land.
Because plants take in carbon dioxide and release oxygen, it might appear they could compensate for whatever carbon is released by the thawed permafrost. But Schuur said the amount of carbon stored in the permafrost is far greater than what is found in shrubs or trees.
For example, he said, a mature boreal forest may contain five kilograms per meter squared of stored carbon. But the same area of permafrost soil can contain 44 kilograms, and 80 percent of that could be lost over long-term warming. "The bottom line," he said, "is that you can't grow a big enough forest to offset the carbon release from the permafrost."
Ted Schuur | EurekAlert!
Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter
17.08.2017 | Swansea University
Climate change: In their old age, trees still accumulate large quantities of carbon
17.08.2017 | Universität Hamburg
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences