Paris Agreement does not rule out ice-free Arctic

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Research published in this week's issue of Nature Communications reveals a considerable chance for an ice-free Arctic Ocean at global warming limits stipulated in the Paris Agreement. Scientists from South Korea, Australia and the U.S. used results from climate models and a new statistical approach to calculate the likelihood for Arctic sea ice to disappear at different warming levels.

Future climate projections are usually obtained from global climate computer models. These models are based on several hundred thousand lines of computer code, developed to solve the physical equations of the atmosphere, ocean, sea-ice and other climate components. Applying future greenhouse gas concentrations, each computer model produces a version of what the future of the Earth's climate might look like. Transforming this information into practical decisions is not easy, because of the remaining uncertainties in the magnitude of future climate change on regional scales. Decision making in a world requires an understanding of the probabilities of certain climatic events to occur.

Up to now, it has been difficult to extract meaningful probabilities from climate models, because these models sometimes share common computer code or make similar assumptions regarding the implementation of less well understood processes, such as clouds or vegetation. To obtain more accurate estimates for future climate change in the Arctic region, the research team has developed a novel which translates results from a suite of climate computer model simulations to probabilities. This method ranks the models in terms of how well they agree with present-day observations and accounts also for inter-dependencies amongst the models.

"Translating model dependence into mathematical equations has been a long-standing issue in climate science. It is exciting to see that our method can provide a general framework to solve this problem," said coauthor Won Chang, assistant professor in the department of Mathematical Sciences at the University of Cincinnati, U.S..

The researchers applied the new statistical method to climate model projections of the 21st century. Using 31 different climate models, which exhibit considerable inter-dependence, the authors find that there is at least a 6% probability that summer sea ice in the Arctic Ocean will disappear at 1.5 °C warming above preindustrial levels—a lower limit recommended by the Paris Agreement of the United Nations Framework Convention on Climate Change (Figure 1). For a 2°C warming, the probability for losing the ice rises to at least 28%. Most likely we will see a sea ice-free summer Arctic Ocean for the first time at 2 to 2.5°C warming.

"Our work provides a new statistical and mathematical framework to calculate change and impact probabilities," commented Jason Evans, professor at the Climate Change Research Center in UNSW Australia in Sydney.

"Up to now, there was no established mathematical framework to assign probabilities on non-exclusive theories. While we only tested the new approach on , we are eager to see if the technique can be applied to other fields, such as stock market predictions, plane accident investigations, or in ," says Roman Olson, the lead author and researcher at the Institute for Basic Science, Center for Climate Physics (ICCP) in South Korea.


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More information: R. Olson, S.-I. An, Y. Fan, W. Chang, J. P. Evans. A novel method to test non-exclusive hypotheses applied to Arctic ice projections from dependent models. Nature Communications. DOI: 10.1038/s41467-019-10561-x
Journal information: Nature Communications

Citation: Paris Agreement does not rule out ice-free Arctic (2019, July 9) retrieved 21 October 2019 from https://phys.org/news/2019-07-paris-agreement-ice-free-arctic.html
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Jul 09, 2019
So much for models.

Jul 09, 2019
the Paris Agreement.


LOLOL

Jul 09, 2019
The abstract reads:
Most likely, September Arctic sea ice will effectively disappear at between approximately 2 and 2.5 K of global warming. Yet, limiting the warming to 1.5 K under the Paris agreement may not be sufficient to prevent the ice-free Arctic.


Error: Units must be in degree Celsius, not Kelvin! Did Nature let this paper go through full peer-review?

Jul 10, 2019
Kelvin is correct.
In any case, 2 K warming is the same as 2 C warming.

Jul 10, 2019
https://www.ameri...pse.html

Global warming should be thought of as nature aborting unwanted people. Abortion is politically acceptable.

Jul 10, 2019
Interestingly enough, an ice-free Arctic ocean will allow significant evaporation, which will fall as rain, then snow, on the land masses around the perimeter. There will be enough snow that it won't all melt before the following winter. The snow will turn to ice - more and more ice. The beginning of the next ice age - as predicted back in the 1950's.

A part of that prediction is a major change in the weather patterns around the world. I might have to start looking to buy a couple of thousand square miles of the Sahara Forest.

Jul 10, 2019
Error: Units must be in degree Celsius, not Kelvin! Did Nature let this paper go through full peer-review?
Errrr, Kelvin is the unit of temperature in the SI system. Where have you been hiding for the last 50 or 60 years?

Jul 10, 2019
Meter, kilogram, second, candela, ampere, kelvin, and mole. These are the units of SI. This has been established since 1960.

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