A new temperature analysis shows that the Arctic is warming four times faster than the rate of global warming. The trend has risen sharply twice in the past 50 years, a finding that all but four of the 39 climate models have missed, a finding.
“Thirty years are considered the minimum to represent climate change,” said Peter Chielke, a physicist and climate researcher at Los Alamos National Laboratory and lead author of the study published in Geophysical Research Letters.
“We have reduced the time to 21 years. At this smaller time scale, and in contrast to previous investigations that found the Arctic amplification index to increase smoothly, we observed two distinct phases, one in 1986 and the second in 1999.
As the decade-to-decade trend identified by Chylek and his collaborators affects global weather and sea level, accurate prediction of future climate change over shorter periods is essential for planning any mitigation and developing adaptation strategies. The Arctic affects global climate and weather, and melting Greenland’s ice sheet is causing sea levels to rise, threatening many coastal communities.
The warming trend has risen sharply twice in the past 50 years
The study’s amplification index represents the ratio between the 21-year Arctic temperature trend and the 21-year global temperature trend.
The study calculated that the Arctic amplification index would be above 4 in the early decades of the 21st century, four times faster than the global average and much faster than previously published research, using time periods of 30 to 40 years. These previous studies set the index at 2 to 3.
Of the 39 widely used climate change models in the CMIP6 Conjugate Model Comparison Project’s ensemble, the international research team found four that reproduced the first stage fairly well around 1986, but none of them were reproduced. Phase two in 1999. CMIP is an international collaboration of climate models that use a common set of criteria, Phys.org writes.
“We attribute the first stage to increased concentrations of carbon dioxide and other pollutants in the atmosphere because more models are doing it right,” Celik said, but the second stage we think is due to climate variability, because none of the models can do that. Second stage reproduction.
A discovery missed by most climate models
Climate models usually do not detect short-term climate variability, on time scales greater than 30 years.
The study did not identify a reason for these relatively abrupt increases, but the authors speculate that the most likely contributing causes are sea ice and water vapor reactions, along with changes in how the atmosphere and ocean heat move in the Arctic. Future increases in the Arctic amplification index are likely to be smaller as the temperature difference between the Arctic and the tropics decreases.
Celik said the team will continue to study future projections for Arctic climate using the four models closest to the observed warming trend, with those peaks.
“People are not only interested in long-term climate change, but also in those over 10, 20 or 30 years old. For 10-year projections, our observation that the amplification index has changed in steps in the past is very important,” Schilk said.
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