Cold region tipping point now inevitable

September 11, 2017, University of Exeter
Cold region tipping point now inevitable
Intense soil frost churning at Kilpisjärvi, northwestern Finland, at 800 metres above sea level. Credit: uha Aalto

The decline of cold regions called periglacial zones is now inevitable due to climate change, researchers say.

Periglacial zones, where there is often a layer of frozen ground known as permafrost, make up about a quarter of the Earth's land surface and are mostly found in the far north and south, and at high altitudes.

Scientists from the universities of Exeter and Helsinki and the Finnish Meteorological Institute examined natural processes caused by frost and snow which take place in these zones.

Their findings suggest that – even with optimistic estimates of future carbon emissions – areas covered by periglacial zones will reduce dramatically by 2050, and they will "almost disappear" by 2100.

This would have a major impact on landscapes and biodiversity, and could trigger climate "feedbacks" – processes that can amplify or diminish the effects of .

"The results suggest that profound changes can be expected in current periglacial zones regardless of policies," said Dr Juha Aalto, of the University of Helsinki and the Finnish Meteorological Institute.

"Unfortunately, it seems that many of the frost-driven processes we studied are already at the margin of the climate in which they can exist."

The scientists studied four processes which take place in periglacial zones, including snow accumulation sites and "frost churning" – which refers to mixing of materials caused by freezing and thawing.

"Our results forecast a future tipping point in the operation of these processes, and predict fundamental changes in ground conditions and related atmospheric feedbacks," Dr Aalto added.

Dr Stephan Harrison, of the University of Exeter's Penryn Campus in Cornwall, said: "The project used very high-resolution climate and land surface models to demonstrate that geological processes and ecosystems in high latitudes (the far north and south) will be fundamentally altered by climate change during this century."

Even based on the optimistic RCP2.6 estimate for future carbon emissions, the researchers predict a 72% reduction in the current periglacial zone in the area of northern Europe they studied.

By 2100, periglacial zones in will only exist in high mountain regions, they say.

Professor Miska Luoto, of the University of Helsinki, said: "The anticipated changes in processes can feedback to the regional system via alterations in carbon cycle and ground surface reflectance (light reflected by snow and ice) caused by the increase of shrub vegetation to alpine tundra.

"Our results indicate significant changes in Northern European plant life. Many rare species can only be sustained in areas of intense frost activity or late-lying snow packs, so the disappearance of such unique environments will reduce biodiversity."

The paper, published in the journal Nature Communications, is entitled: "Statistical modelling predicts almost complete loss of major periglacial processes in Northern Europe by 2100." 

Explore further: Monitoring changes in wetland extent can help predict the rate of climate change

More information: Juha Aalto et al. Statistical modelling predicts almost complete loss of major periglacial processes in Northern Europe by 2100, Nature Communications (2017). DOI: 10.1038/s41467-017-00669-3

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6 comments

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Turgent
1 / 5 (2) Sep 11, 2017
Paper is Open Access (OA)

As has been issue other papers is the degree of uncertainty:
"We use an ensemble modelling approach, where methodology-related uncertainty can be controlled by merging predictions from multiple statistical algorithms (regression and machine learning) to a single agreement map.*27"

Ref. 27 - Invasive species distribution models-how violating the equilibrium assumption can create new insights. (2012)

"Even with the most optimistic CO2 emissions scenario (Representative Concentration Pathway (RCP) 2.6) we predict a 72% reduction in the current periglacial climate realm by 2050 in our climatically sensitive northern Europe study area."

It is limited to northern Fennoscandia. It is interesting that the Gulf Stream is not mentioned as a variable.
Turgent
1 / 5 (2) Sep 11, 2017
Cont.

Additionally read refs. 32, 60, and 61

32. Accelerated thawing of subarctic peatland permafrost over the last 50 years (2004)

60. J. F. A review of methods for the assessment of prediction errors in conservation presence/absence models. (1997)

61. Assessing the accuracy of species distribution models: prevalence, kappa and the true skill statistic (TSS) (2006)

I did not see how these explained "the uncertainty can be controlled by merging predictions".

Three Representative Concentration Pathways (RCPs) or greenhouse gas concentration (not emissions) trajectories adopted by the IPCC were used which in themselves contain large ranges of uncertainty.

Paper acknowledged lag time was not addressed.

Turgent
1 / 5 (2) Sep 11, 2017
Cont.

Paper states "further decreasing albedo in a positive feedback loop." This I believe basically refers to a true runaway GHG, as permafrost is a CO2 and CH4 sink. However, some papers have argued that GHG will not act as source for GHG.

Ref. 32 provided no predictive value; however, it would be neat to see how an update of the years forward of 2003 would compare with the trend lines of the paper.
Shootist
2.3 / 5 (3) Sep 13, 2017
Call me when barley, wheat, and cattle have been raised for 300-400 years on Greenland as did happen during the Medieval Climate Optimum. Or commercially viable vineyards in Caledonia (Scotland) and Scandinavia, too cold today, you know?
PTTG
4.2 / 5 (5) Sep 14, 2017
A reminder to the sane: Insane people spend their entire lives posting nonsense because they can't come to terms with reality.

The important thing to remember -- and the thing I sometimes forget -- is that the insane part is not why they post, but that they waste so much time at all.

Don't argue with the wind, as tempting as it may be.
barakn
5 / 5 (3) Sep 14, 2017
"The find also substantiates a well-known text from about 1250, 'King's mirror (Konungs skuggsjá)', which mentions in passing that the Vikings attempted to grow grain on Greenland. It is the only report about cultivating barley that we have from that time and says: "As to whether any sort of grain can grow there, my belief is that the country draws but little profit from that source. And yet there are men among those who are counted the wealthiest and most prominent who have tried to sow grain as an experiment; but the great majority in that country do not know what bread is, having never seen it.""https://ancientfo...eenland/

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