ARCTIC AMPLIFICATION - GEOGRAPHY

News: The Arctic Is Becoming Wetter and Stormier, Scientists Warn

 

What's in the news?

       As humans warm the planet, the once reliably frigid and frozen Arctic is becoming wetter and stormier, with shifts in its climate and seasons that are forcing local communities, wildlife and ecosystems to adapt, scientists said in an annual assessment of the region.

       Even though 2022 was only the Arctic’s sixth warmest year on record, researchers saw plenty of new signs this year of how the region is changing.

 

Arctic amplification:

       Global warming, the long-term heating of the earth’s surface, expedited due to anthropogenic forces or human activities since pre-industrial times and has increased the planet’s average temperature by 1.1 degrees Celsius.

       Polar amplification: While changes are witnessed across the planet, any change in the surface air temperature and the net radiation balance tend to produce larger changes at the north and south poles is known as Polar amplification.

       When the changes in surface air temperature and net radiation changes are more pronounced at the northern latitudes (especially at poles) is known as the Arctic amplification.

 

Causes of Arctic Amplification:

1. Ice-albedo feedback:

       Sea ice and snow have high albedo (measure of reflectivity of the surface), implying that they are capable of reflecting most of the solar radiation as opposed to water and land.

       In the Arctic’s case, global warming is resulting in diminishing sea ice.

       As the sea ice melts, the Arctic Ocean will be more capable of absorbing solar radiation, thereby driving the amplification.

2. Lapse rate feedback:

       The lapse rate or the rate at which the temperature drops with elevation decreases with warming.

       Studies show that the ice-albedo feedback and the lapse rate feedback are responsible for 40% and 15% of polar amplification respectively.

3. Water vapor feedback:

       Water vapor feedback is the coupling between water vapour and surface air temperature in which a change in radiative forcing perturbs the surface air temperature, leading to a change in water vapor, which could then amplify or weaken the initial temperature change.

4. Ocean heat transport:

       The ocean contributes to regulating the Earth’s climate through its ability to transport heat from the equator to the poles.

       Enhanced ocean heat transport into the Arctic is linked to stronger future Arctic warming and polar amplification.

5. Ice cover:

       Declining sea ice cover and thickness have been great enough to enhance Arctic warming during most of the year.

6. Changing Weather:

       Ocean currents also drive the polar jet stream, which moves hot and cold air masses around the Northern Hemisphere. This happens due to temperature differences between the Arctic and the tropics.

       But as the Arctic warms, the jet stream now undulates wildly north and south due to which the Arctic gets warm air.

 

Consequences of Arctic Amplification:

        The causes and consequences of Arctic amplification are cyclical - what might be a cause can be a consequence too.

1. Melting of ice sheets:

       The Greenland ice sheet is melting at an alarming rate, and the rate of accumulation of sea ice has been remarkably low since 2000, marked by young and thinner ice replacing the old and thicker ice sheets.

       The Greenland ice sheet holds the second largest amount of ice, after Antarctica, and therefore it is crucial for maintaining the sea level. In 2019, this was the single biggest cause for the rise in the sea level, about 1.5 metres.

       If the sheet melts completely, the sea level would rise by seven metres, capable of subsuming island countries and major coastal cities.

2. Changes in nature of water:

       The warming of the Arctic Ocean and the seas in the region, the acidification of water, changes in the salinity levels, is impacting biodiversity, including marine and dependent species.

3. Higher rainfall:

       The warming is also increasing the incidence of rainfall which is affecting the availability and accessibility of lichens to the reindeer.

4. Affecting fauna:

       The Arctic amplification is causing widespread starvation and death among the Arctic fauna.

5. Permafrost thawing:

       The permafrost in the Arctic is thawing and in turn releasing carbon and methane which are among the major greenhouse gases responsible for global warming.

6. Disease outbreak:

       Experts fear that the thaw and the melt will also release the long-dormant bacteria and viruses that were trapped in the permafrost and can potentially give rise to diseases.

       The best-known example of this is the permafrost thaw leading to an anthrax outbreak in Siberia in 2016, where nearly 2,00,000 reindeer succumbed.

 

Impacts on India:

       The link between the changing Arctic and Indian monsoons is growing in importance due to the extreme weather events the country faces, and the heavy reliance on rainfall for water and food security.

       A 2021 by a group of Indian and Norwegian scientists 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.

       The changes in the atmospheric circulation due to diminishing sea ice combined with the warm temperatures in the Arabian Sea contribute to enhanced moisture and drive extreme rainfall events.

       According to the World Meteorological Organization's ‘State of Global Climate in 2021’, sea level along the Indian coast is rising faster than the global average rate due to melting of sea ice in polar regions, especially the Arctic.