Arctic temperatures are rising four times faster than global warming rates: Study
Temperatures in the Arctic have been increasing four times faster than the current rate of global warming, a chilling new study has revealed.
Analysis of observed temperatures also found two jumps over the past 50 years that were missed by most climate tracking models, the Los Alamos National Laboratory said in a statement.
“Thirty years is considered the minimum to represent climate change,” lead author Petr Chylek, who is also a physicist and climate researcher at the institute, said.
“We decreased the time interval to 21 years. At that smaller time scale and, contrary to previous investigations that found the Arctic amplification index increases in a smooth way, we observed two distinct steps, one in 1986 and a second one in 1999.”
The researchers said that it was necessary to accurately project future climate change in smaller timeframes to take action to mitigate the impact of climate change and develop adaptation strategies.
This is particularly crucial because the Arctic influences the world’s climate and weather, and the melting of the Greenland ice sheet causes sea levels to rise which in turn threatens many coastal communities.
The amplification index in the study is the ratio of an Arctic 21-year temperature trend versus an overall global 21-year temperature trend.
The research team calculated the Arctic amplification index to be greater than four within the early decades of the 21st century, four times faster than the global mean and much more rapid than previously published research indicated through the use of 30 to 40-year timeframes.
From 39 climate-change models in the widely used CMIP6 collection of the Coupled Model Intercomparison Project, the international research team found four that reproduced the first step reasonably well around 1986, but none that reproduced the second step in 1999, the institute said in a statement.
CMIP is an international collaboration of climate models using a shared set of parameters. CMIP6 has been used to create a recent Intergovernmental Panel on Climate Change Assessment Report.
“We attributed the first step to increasing concentrations of carbon dioxide and other pollutants in the atmosphere because several models do it correctly… but the second step we think is due to climate variability because none of the models can reproduce the second step,” Chylek said.
While the new study does not specifically identify a cause for these relatively sudden increases in temperatures, the authors speculated that contributing causes are probably sea-ice and water-vapor feedbacks combined with changes in how atmospheric and oceanic heat move into 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, the team said.
Head researcher Chylek said the team will study future arctic climate projections next using the four models that came closest to matching the observed global warming trends.
“Because the four models correctly reproduce at least the first step, we assume they’re a little better for future climate projection,” Chylek said.
“People usually average all models and assume the ensemble is more reliable than any single model. We show the average does not work in this case.”
The researchers downloaded publicly available Arctic temperature data and used simulation output from climate models in the CMIP6 collection.
“People are not only interested in long-term climate change, but they are also interested in 10 years ahead, 20 years, 30 years. For decadal prediction our observation that the amplification index changed in the past in steps is quite important,” Chylek added.
The team’s findings were published in the journal Geophysical Research Letters.
Aside from Los Alamos, the research team included members from the University of East Anglia, Dalhousie University, PAR Associates, the University of Washington, the Pacific Marine Environmental Laboratory.
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