July 6, 2022 Reviewed by Alex Smith
A new study of observed temperatures reveals that the Arctic appears to be warming four times faster compared to the global warming rate. The trend has sharply doubled in the last five decades. This is a discovery that has been lost by all but four of the 39 climate models.
Image credit: Shutterstock.com/ Tomas Rebro
Thirty years is considered the minimum to represent climate change. We have reduced the time interval to 21 years. At this smaller time scale, and contrary to previous research that found that the Arctic amplification rate increases smoothly, we observed two different steps, one in 1986 and a 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 Letters.
The decade-to-decade episodic trend determined by Chylek and his collaborators tends to affect sea level and global climate, which projects precisely future climate change in shorter periods of time is necessary to program any mitigation of its effects and develop coping strategies.
The Arctic affects climate and weather, and the melting of the Greenland ice sheet causes sea level rise to endanger several coastal communities.
In this study, the amplification index is the relationship between a 21-year temperature trend in the Arctic and a 21-year global temperature trend.
The study estimated that the Arctic amplification rate is higher compared to 4 in the first decades of the 21st century and is four times faster compared to the global average and significantly faster than research previously reported had identified with the help of 30-40- annual time intervals. These previous studies ranked the index between 2 and 3.
From 39 climate change models in the widely used CMIP6 collection of the Coupled Model Intercomparison Project, the international research group discovered four models that reproduced the first step quite well in 1986. However, none reproduced the second step in 1999.
The CMIP is known as an international collaboration of climate models that use a set of shared parameters. CMIP6 has been used to prepare the new evaluation report of the Intergovernmental Panel on Climate Change.
We have attributed the first step to increasing the concentrations of carbon dioxide and other pollutants in the atmosphere, because several models do it correctly but the second step we believe is due to climate variability because none of the models can reproduce the second step.
Petr Chylek, lead author of the study, physicist and climate researcher, Los Alamos National Laboratory
Typically, climate models have not seen a brief climate variability with their time scales of more than 30 years.
The study does not identify a reason for such sudden increases, but the authors think that the contributing causes are possibly the feedback of sea ice and water vapor integrated with the variations caused in the change of atmospheric and oceanic heat to the ‘Arctic.
Subsequent increases in the Arctic amplification index are likely to be smaller as the temperature variation between the Arctic and the tropics tends 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 the four models that are closest to the observed warming trend, along with the peaks.
Since all four models correctly reproduce at least the first step, we assume they are slightly better for future climate projection. People usually average all models and assume that the set is more reliable than any individual model. We show that the mean does not work in this case.
Petr Chylek, lead author of the study, physicist and climate researcher, Los Alamos National Laboratory
The Arctic research group downloaded publicly available temperature data from the Internet and used climate model simulations in the CMIP6 collection.
Chylek stated: “People are not only interested in long-term climate change, but they are also interested in 10 years, 20, 30 years. For the ten-year prediction, our observation that the amplification rate changed in the past by steps is quite important. “
The study’s research group included members from Los Alamos, the University of East Anglia, PAR Associates, the University of Washington, the Pacific Marine Environmental Laboratory, and Dalhousie University.
Magazine reference:
Chylek, P., et al. (2022) Average annual Arctic amplification 1970–2020: observed and simulated by CMIP6 climate models. Geophysical Research Letters doi.org/10.1029/2022GL099371.
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