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.