A recent study conducted by Finnish Meteorological Institute researchers notes that the Arctic is heating four times faster than the rest of the planet.
It takes note that this arctic warming is all the more concentrated in the Eurasian part of the Arctic, consisting of the Barents Sea north of Russia and Norway. This region is found to be warming at almost seven times faster than the global average.
- Multiple studies have observed this trend of differential rate of heating and this has been described as polar amplification or arctic amplification.
- The Inter-governmental Panel on Climate Change in its ‘Special Report on the Ocean and Cryosphere in a Changing Climate’ in 2019, noted this arctic warming.
- The Arctic Monitoring and Assessment Programme (AMAP) in its 2021 report noted the faster Arctic warming as compared to the global average. The report noted that the average annual temperature in the region increased by 3.1 degrees Celsius compared to the 1 degree Celsius for the planet.
Polar amplification and arctic amplification:
- Polar amplification is the phenomenon that any change in the surface air temperature and the net radiation balance contributing to global warming, tends to produce a larger change in temperature near the poles than in the planetary average. This is commonly referred to as the ratio of polar warming to tropical warming.
- Notably, these changes are more pronounced at the northern latitudes and are known as Arctic amplification.
Causes of arctic amplification:
- Sea ice has a high albedo.
- Albedo is the fraction of light that is reflected by a body or surface and is thus a measure of the reflectivity of the surface.
- Notably, Arctic sea ice cover has been declining owing to global warming. Open water reflects less sunlight than sea ice and absorbs more incoming solar radiation, thereby driving the amplification.
Lapse rate feedback:
- The atmosphere’s temperature decreases with height in the troposphere. This is referred to as the lapse rate.
- Since the emission of infrared radiation varies with temperature, longwave radiation escaping to space from the relatively cold upper atmosphere is less than that emitted toward the ground from the lower atmosphere. Thus, the strength of the greenhouse effect depends on the atmosphere’s rate of temperature decrease with height.
- The lapse rate or the rate at which the temperature drops with elevation decreases with warming.
- However, in regions with strong inversions, such as the polar regions, one observes positive lapse rate feedback because the surface warms faster than at higher altitudes, resulting in inefficient longwave cooling. This contributes to polar amplification.
- Studies show that the ice-albedo feedback and the lapse rate feedback are responsible for 40% and 15% of polar amplification respectively.
Water vapour feedback:
- A lot more water vapour is being transported northward by big swings in the jet stream. Since water vapour is a greenhouse gas that traps heat in the atmosphere, this is contributing to polar/arctic amplification.
- Also, water vapour in the atmosphere can condense into droplets and form clouds. Since clouds also trap more heat than a cloudless sky, this is also contributing to polar amplification.
Ocean heat transport:
- Changes in atmospheric and ocean circulation have been noted due to global warming. A more pronounced poleward flow of ocean currents has been noted which could be contributing to arctic amplification.
Decreasing sea ice:
- Global warming in general and the arctic amplification can result in the disappearance of sea ice from the region in summers. This can lead to a vicious cycle of further temperature rise through the ice-albedo feedback mechanism.
Melting of Greenland ice sheet:
- The Greenland ice sheet is melting at an alarming rate. The melting of the Greenland ice sheet is a big contributor to the global rise in sea level. If the sheet melts completely, the global sea level would rise by seven metres. This would lead to the submergence of island countries and major coastal cities.
- The Greenlandic ice sheet holds the second largest amount of ice, after Antarctica.
- This is all the more critical for a country like India with a long coastline and major cities with substantial populations along its coastal borders. According to the World Meteorological Organization’s report, ‘State of Global Climate in 2021’, the sea level along the Indian coast is rising faster than the global average rate.
Impact on flora and fauna:
- Polar warming also affects many ecosystems, including marine and terrestrial ecosystems. This will have an adverse impact on the fauna of the region, including both the marine species and land species and the dependent species. This will impact the biodiversity of the region.
- Due to the polar amplification, the permafrost in the Arctic is thawing.
- This will result in the release of greenhouse gases like methane which will further increase global warming.
- The thaw and the melt may also release the long-dormant bacteria and viruses that were trapped in the permafrost and can potentially give rise to new diseases.
Impact on climate systems:
- The arctic amplification can change the existing climate systems like monsoons in the Indian subcontinent.
- A study by a group of Indian and Norwegian scientists has found that the reduced sea ice in the Barents-Kara sea region can lead to extreme rainfall events in the latter half of the monsoons, in September and October.
- This can have serious consequences for India due to the likelihood of more frequent and more intense extreme weather events and their impact on water and food security.
- SeIndARC is India’s first underwater moored observatory in the Arctic region. It was deployed in 2014 at Kongsfjorden fjord, Svalbard, Norway which is midway between Norway and the North Pole. Its research goal is to study the Arctic climate and its influence on the monsoon.