What Is Arctic Amplification? Definition, Causes, and Environmental Implications

Melting Icebergs, Ililussat, Greenland
Paul Souders / Getty Images

Arctic amplification is the increasingly ramped-up warming that’s taking place in the area of the world north of 67 degrees N latitude. For more than four decades, temperatures in the Arctic have risen at two to three times the pace of the rest of the world. High temperatures are melting snow covers and glaciers. Permafrost is thawing and collapsing. Sea ice is disappearing. 

Dismayingly, some or all of these effects of heat trigger further temperature increases. Effect becomes cause, which becomes larger effect, which becomes stronger cause. Arctic amplification is an accelerating feedback loop that accelerates climate change throughout the rest of the world.

The Causes and Mechanisms of Arctic Amplification

While scientists are in general agreement that the Arctic has been warming more quickly than the rest of the world, there is still some debate about why. The almost universal best guess, however, is that greenhouse gases are to blame.

How Arctic Amplification Starts

Greenhouse gases like carbon dioxide (CO2) and methane (CH4) allow the sun’s warming rays in through the atmosphere. A warmed Earth radiates heat back toward space. However, CO2 allows only about half of the heat energy radiating skyward from Earth to escape the troposphere (Earth’s lowest atmospheric layer) into the stratosphere (the next layer up) and eventually out into space. According to the United States Environmental Protection Agency (EPA), CH4 is about 25 times as effective as CO2 in trapping heat.

Together with the sun’s rays, heat trapped by greenhouse gases further warms polar air and thaws significant areas of the Arctic. It decreases the amount of sea ice, which causes more warming. Which decreases even more sea ice. Which causes even more warming. Which puts....

Sea-Ice Melt and Arctic Amplification

Wintery top-down aerial view of cracked ice on Baltic Sea around Helsinki
Wintery top-down aerial view of cracked ice on Baltic Sea around Helsinki. Miemo Penttinen - miemo.net / Getty Images

New research from a team of scientists from the State University of New York at Albany and the Chinese Academy of Sciences in Beijing suggests that the melting of sea ice is the single factor most responsible for the accelerating pace of Arctic warming.

According to the investigative team, the white color of sea ice helps the ice remain frozen. It does this by reflecting about 80% of the sun’s rays away from the ocean. Once ice melts, though, it leaves increasingly large areas of blackish-green ocean exposed to the suns’ rays. Those dark-colored areas absorb the rays and trap the heat. This melts additional ice from below, which exposes more dark water that will soak up the sun’s warmth, which melts even more ice, and so on.

Thawing Permafrost Also Contributes to Arctic Amplification

Permafrost is frozen ground that is composed largely of decayed plants. It is full of carbon because, as part of the photosynthesis process, living plants continuously extract CO2 from the air. 

Melting Ice permafrost near Dempster Highway subarctic tundra Tombstone Territorial Park Yukon
In the subarctic tundra of the Blackstone Uplands, melting permafrost ice is exposed along the gravel Dempster Highway and Ogilvie Mountains in the Tombstone Territorial Park of Yukon Territory. milehightraveler / Getty Images

Carbon

Scientists once thought that the carbon in permafrost binds tightly with iron and is therefore safely sequestered from the atmosphere. However, in a study published in the peer-reviewed journal Nature Communications, a team of international scientists demonstrates that iron doesn’t permanently trap CO2. This is because, as permafrost melts, bacteria frozen inside the soil activate. They use the iron as a food source. When they consume it, once-captive carbon is released. In a process called photomineralization, sunlight oxidizes the released carbon into CO2. (To paraphrase a Biblical phrase: “From CO2 the carbon came, and to CO2 it shall return.”)

Added into the atmosphere, CO2 helps the already-present CO2 melt snow, glaciers, permafrost, and even more sea ice. 

The international team of scientists acknowledges that they do not yet know how much CO2 is released into the atmosphere as permafrost melts. Even so, they estimate the amount of carbon contained in permafrost to be two to five times the amount in the total load of CO2 emitted by human activities annually.

Methane

Meanwhile, CH4 is the second most common greenhouse gas. It, too, is frozen in permafrost. According to the EPA, CH4 is about 25 times more powerful than CO2 at trapping heat in Earth’s lower atmosphere.

Wildfires and Arctic Amplification

As temperatures rise and permafrost thaws and dries out, grasslands become tinderboxes. When they burn, the CO2 and CH4 in the vegetation combust. Airborne in smoke, they add to the atmosphere greenhouse gas load.

Nature reports that the Russian Wildfires Remote Monitoring System catalogued 18,591 separate Arctic wildfires in Russia in the summer of 2020; more than 35 million acres burned. The Economist reported that, in June, July, and August of 2019, 173 tons of carbon dioxide were dumped into the atmosphere by arctic wildfires.

The Current and Expected Climate Consequences Beyond the Arctic Circle of Arctic Amplification 

With a new Arctic climate taking hold, higher temperatures and extreme weather events are radiating out into Earth’s middle latitudes. 

Aerial view of gigantic icebergs
Huge icebergs floating in the Arctic ocean, in Ilulissat, Greenland, Unesco World Heritage. Monica Bertolazzi / Getty Images

The Jet Stream

As explained by the National Weather Service (NWS), jet streams are particularly fast-moving currents of air. They are like rivers of strong wind in the “tropopause,” which is the border between the troposphere and the stratosphere.

Like any wind, they are formed by differences in air temperatures. When rising equatorial air and sinking cold polar air move past each other they create the current. The greater the temperature differential, the faster the jet stream. Because of the direction in which Earth rotates, jet streams move from west to east, though the flow can also temporarily shift from north to south. It can temporarily slow down and even reverse itself, as well. Jet streams create and push weather.

Air temperature differences between the poles and equator are shrinking, which means that jet streams are weakening and meandering. This can cause unusual weather as well as extreme weather events. Weakening jet streams can also cause heat waves and cold snaps to linger in the same location for longer than usual.

The Polar Vortex

In the stratosphere at the Arctic circle, cold air currents swirl counterclockwise. Many studies show that warming temperatures disrupt that vortex. The disorder that creates further slows the jet stream. In winter, this can create heavy snows and extreme cold spells in middle latitudes.

What About the Antarctic?

According to NOAA, the Antarctic is not warming as quickly as the Arctic. Many reasons have been offered. One is that winds and weather patterns of the ocean surrounding it may serve a protective function.

The winds in the seas surrounding Antarctica are among the fastest in the world. According to the U. S. National Ocean Service, during the “Age of Sail” (the 15th to 19th centuries), sailors named the winds after the latitude lines near the southern tip of the world, and told tales of wild rides courtesy of the “roaring forties,” “furious fifties,” and “screaming sixties.”

These buffeting winds may divert warm-air jet streams from Antarctica. Even so, Antarctica is warming. NASA reports that, between 2002 and 2020, Antarctica lost an average of 149 billion metric tons of ice per year.

Some Environmental Implications of Arctic Amplification

Arctic amplification is expected to increase in the coming decades. NOAA notes that “the 12-month period of October 2019–September 2020 was the second-warmest year on record for surface air temperatures over land in the Arctic.” The extremities of that year’s temperatures were a continuation of “a seven-year-long streak of the warmest temperatures recorded since at least 1900.”  

NASA also reports that, on September 15, 2020, the area within the Arctic circle covered by sea ice was only 1.44 million square miles, the smallest extent in the 40-year history of satellite record-keeping.

Meanwhile, a 2019 study led by John Mioduszewski of Rutgers University’s Arctic Hydroclimatology Research Lab and published in the peer-reviewed journal The Cyrosphere, suggests that, by the late 21st century, the Arctic will be nearly ice-free.

None of this bodes well for planet Earth.

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