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Wed Oct 23, 2019, 07:37 AM

Nature: Arctic May Now Emit More Carbon In Winter Than It Absorbs In Summer, But More Data Needed

The Arctic is unraveling before our eyes. As our understanding of the changes continues, scientists have been fine-tuning models to give us a sense of how quickly we can expect tipping points to arrive. One of the most terrifying is the permafrost feedback. A new study finds that the feedback just may have arrived. The reason? Winter permafrost carbon emissions are now greater than what can be stored in the summer. To be clear, not all scientists believe that the tipping point has arrived. But regardless, the rapid changes we see in the Arctic, which has warmed 3 times faster than the rest of the earth, are glaringly obvious.

Global impacts of thawing Arctic permafrost may be imminent

It’s here now, according to research published today by a large team of scientists in Nature Climate Change. By pooling observations from more than 100 Arctic field sites, scientists from the Permafrost Carbon Network estimate that permafrost released an average of 1662 teragrams of carbon each winter from 2003 to 2017—double that of past estimates. Meanwhile, during the summer growing season, other surveys have found that the landscape absorbs only 1032 teragrams—leaving an average of more than 600 teragrams of carbon to escape to the atmosphere each year.

The study remains limited by the paucity of Arctic observations; the overall uncertainty of Arctic winter emissions, for example, is 813 teragrams, nearly half the total emissions. The study also found no rise in emissions since 2003. Still, researchers say, it’s a sign that the permafrost feedback—which would see carbon emissions from permafrost lead to warming that would in turn thaw more permafrost—is already underway.



Recent warming in the Arctic, which has been amplified during the winter1,2,3, greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (CO2)4. However, the amount of CO2 released in winter is not known and has not been well represented by ecosystem models or empirically based estimates5,6. Here we synthesize regional in situ observations of CO2 flux from Arctic and boreal soils to assess current and future winter carbon losses from the northern permafrost domain.

We estimate a contemporary loss of 1,662 TgC per year from the permafrost region during the winter season (October–April). This loss is greater than the average growing season carbon uptake for this region estimated from process models (−1,032 TgC per year). Extending model predictions to warmer conditions up to 2100 indicates that winter CO2 emissions will increase 17% under a moderate mitigation scenario—Representative Concentration Pathway 4.5—and 41% under business-as-usual emissions scenario—Representative Concentration Pathway 8.5.

Ed. - Emphasis added

Our results provide a baseline for winter CO2 emissions from northern terrestrial regions and indicate that enhanced soil CO2 loss due to winter warming may offset growing season carbon uptake under future climatic conditions.



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Reply Nature: Arctic May Now Emit More Carbon In Winter Than It Absorbs In Summer, But More Data Needed (Original post)
hatrack Oct 2019 OP
Boomer Oct 2019 #1
The_jackalope Oct 2019 #2

Response to hatrack (Original post)

Wed Oct 23, 2019, 12:33 PM

1. All together now....

"We are so screwed."

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Response to Boomer (Reply #1)

Wed Oct 23, 2019, 06:47 PM

2. "Estamos tan jodidos!" Nt

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