Why Arctic temperature is increasing, and Why that's so alarming?

A new analysis of recorded temperatures shows that the Arctic is warming more than four times faster than the rate of global warming. The trend has increased dramatically twice in the last 50 years, a finding overlooked by 35 of the 39 climate models in use today.

A new study shows that the Arctic is warming more than four times faster than the rate of global warming. Scientists have used time models of 21 years, instead of 30 like the rest of the studies, which allows more precision in the estimates

"Thirty years is considered the minimum to represent climate change," explains Petr Chylek, a physicist and climate researcher at Los Alamos National Laboratory and lead author of the study published in Geophysical Research Letters. “We shortened the time interval to 21 years. On that smaller time scale, and contrary to previous research that found the rate of Arctic amplification to increase smoothly, we observed two distinct steps, one in 1986 and one in 1999."

Because the episodic decade-by-decade trend identified by Chylek and colleagues affects global climate and sea levels, it is essential to accurately project future climate change in smaller time frames to plan for any mitigation of its impacts and to develop strategies. of adaptation. . The Arctic influences the climate of the entire planet, and the melting of the Greenland ice sheet causes a rise in sea levels that threatens many coastal communities.

The study calculated that the Arctic amplification rate was greater than 4 in the first decades of the 21st century, four times faster than the global average and considerably faster than previously published research had determined using time intervals from 30 to 40 years. These earlier studies pegged the index between 2 and 3.

Of 39 climate change models in the Coupled Model Intercomparison Project's widely used CMIP6 collection, the international research team found four that reproduced the first step reasonably well around 1986, but none that reproduced the second step in 1999. CMIP is an international collaboration of climate models using a shared set of parameters. CMIP6 has been used to create the recent Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).

"We attribute the first step to increased concentrations of carbon dioxide and other pollutants in the atmosphere because several models get it right," Chylek said, "but the second step we think is due to climate variability because none of the models can play the second step."

Short-term climate variability is generally not detected by climate models with their time scales of more than 30 years.

The study doesn't identify a cause for these relatively sudden increases, but the authors speculate that the contributing causes are likely feedbacks from sea ice and water vapour combined with changes in the way atmospheric and oceanic heat moves toward the Arctic. Future increases in the Arctic amplification rate are likely to be smaller as the temperature difference between the Arctic and the tropics decreases.

Effects of Arctic warming

One of the most significant effects of Arctic amplification is the weakening of west-east jet streams in the Northern Hemisphere. As the Arctic warms at a faster rate than the tropics, this results in a weaker atmospheric pressure gradient and thus lower wind speeds.

Links between Arctic amplification, slowing (or meandering) jet streams, blocking highs, and extreme weather events in the mid- and high-latitude Northern Hemisphere are controversial. One view is that the link is strong and the main driver behind the recent summer heat waves and winter cold snaps. But more recent research questions the validity of these links for mid-latitudes.

Here we look at the largest body of evidence supporting the relationship between Arctic warming and slowing jet streams.

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