The Arctic is heating four times faster than the rate of global warming
A new study of observed temperatures reveals that the Arctic appears to be warming four times faster than the rate of global warming. The trend has increased sharply twice in the last five decades. This is a finding that all but four of the 39 climate models missed.
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Thirty years is considered the minimum time to represent climate change. We reduced the time interval to 21 years. On a smaller time scale and, contrary to previous investigations which found that the Arctic amplification index increased smoothly, we observed two distinct steps, one in 1986 and the second in 1999..
Petr Chylek, Lead Author of the Study, Physicist and Climate Researcher, Los Alamos . National Laboratory
The study was reported in the journal Geophysical Research Letter.
Decade-by-decade episodic trends defined by Chylek and his collaborators tend to have an impact on global sea levels and weather, which precisely projecting future climate change in smaller time frames is needed to schedule any mitigation of their impacts and develop adaptation strategies.
The Arctic has an impact on climate and weather, and the melting of the Greenland ice sheet is causing sea level rise that is endangering some coastal communities.
In this study, the amplification index is the ratio of the 21-year Arctic temperature trend versus the overall global 21-year temperature trend.
This study estimates the Arctic amplification index to be greater than 4 in the early 21 decadest century and four times faster than the global average and significantly faster than previously reported studies have identified with the help of 30 to 40 year time intervals. Previous studies like the index rank between 2 and 3.
Of the 39 climate change models in the widely used CMIP6 collection of the Pairwise Model Intercomparison Project, the international research group found four models that reproduced the first step fairly well in 1986. However, none reproduced the second step in 1999.
CMIP is known as an international collaborative climate model that uses a common set of parameters. CMIP6 has been used to create the new Intergovernmental Panel on Climate Change Assessment Report.
We attribute the first step to an increase in the concentration of carbon dioxide and other pollutants in the atmosphere, because few models get it right but the second step in our opinion is due to climate variability as no model can reproduce the second step.
Petr Chylek, Lead Author of the Study, Physicist and Climate Researcher, Los Alamos . National Laboratory
Typically, brief climate variability is not seen by climate models with a time span of more than 30 years.
The study did not identify a reason for such a relatively sudden increase, but the authors contemplated that a contributing cause may be a sea ice and water vapor feedback integrated with variations caused by how the heat of the atmosphere and ocean shifts towards the Arctic.
Future increases in the Arctic amplification index are likely to be smaller as temperature variations between the Arctic and the tropics are likely to decrease.
Valuable for Projecting Change in the Arctic
Chylek stated that the research group will study future Arctic climate projections with the help of four models that are closest to the recorded warming trend, along with spikes.
Since all four models reproduce correctly at least the first step, we consider them slightly better for future climate projections. People usually average all models and consider ensembles to be more reliable than single models. We show averaging does not work in this case.
Petr Chylek, Lead Author of the Study, Physicist and Climate Researcher, Los Alamos . National Laboratory
The publicly available temperature data was downloaded by the research group for the Arctic from the internet and made use of the simulation output from climate models in the CMIP6 collection.
Chylek stated, “People are not only interested in long-term climate change, they are also interested in the next 10 years, 20 years, 30 years. For decade prediction, our observation that the amplification index changed in the past gradually is quite important.”
The research group of the study included members from Los Alamos, University of East Anglia, PAR Associates, University of Washington, Pacific Ocean Environment Laboratory and Dalhousie University.
Journal Reference:
Chylek, P., et al. (2022) Average Annual Arctic Amplification 1970–2020: Observed and Simulated by the CMIP6 Climate Model. Geophysical Research Letter doi.org/10.1029/2022GL099371.
Source: https://www.lanl.gov/
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