Debates of climate changed picked up
traction with ignoble US president announcing the withdrawal of America from
the Paris Climate Accord. Protesting the indifference of politicians towards
the climate change environmentalists expressed their discontentment with
massive protests at Hamburg where G-20 leaders assembled for the summit meet.
Days after conclusion of the summit, European Space Agency, Sentinel-1 mission,
announced that Larsen C ice-shelf, the fourth largest in the World (5800 sq km)
comprising of 12% of total area of Antarctica broke off from the frozen
continent.
Ice-shelves are humongous
repositories which are formed when glaciers on land begin to spread out over
the sea. They essentially prevent the drifting of glacial ice into sea and
thereby regulate sea level rise. In general, glacial ice, chips off to form
icebergs. Now snapping of 12 trillion cubic meters of ice, larger than Haryana,
is believed to change the landscape of Antarctica. While the immediate effects
of this event are not ominous, scientists are carefully monitoring rest of the
ice-shelf closely. The ice shelf which looks like a crooked finger is pointing
towards tip of the South America is an extension of huge West Antarctic Ice
Sheet (WAIS). The ice-shelf when ripped off completely will exist as a
190-meter-thick iceberg nearly four times the height of Qutub Minar.
Indeed, fissures in the Larsen C
ice-shelf first appeared in 2010. The tear which spread 10 meters per day
gradually accelerated to 36 mt before finally snapped away on July 12th.
Splintering of ice shelf has already begun and the smaller ice bergs are now
heading towards Weddell Sea. Experts at Scripps Institute of Oceanography said that
ice fragments might eventually move further north towards South Georgia and
South Sandwich Islands.
Breaking of ice-shelf is a natural
process. Antarctica ice is tightly compressed at the edges of its rocky base
and under the weight of huge ice accumulations, ice shelves break off from time
to time. Hence breaking of ice shelves can’t be attributed to global warming
directly. But what caught the attention of the scientists is the shortened
frequency of the calving (breaking of ice-shelves) process. Ice shelves which
form 75% of coastal Antarctica are susceptible to changes in atmospheric
temperature from above and ocean warming from below. Though the role of warm
climates in triggering calving is not scientifically established as of now,
experts believe don’t belie its role.
Gigantic Icy continent is firmly
edged by ice-shelves which form the coastal region while glaciers impound
inlands. Thwaites glaciers, a gigantic bulk of ice part of the West Antarctica
Ice Sheet, located further inland has become cause of intense concern. Rapidly
changing climates led to melting and sliding of the glaciers into sea pushing
up sea levels. Unchecked greenhouse gas emissions accentuate melting of
glaciers. It is estimated that melting of West Antarctica Ice Sheet can increase
sea level by 3 meters. On the contrary, ice-shelf breaking may not increase the
sea-level since this portion of ice was already in water. Volume of water
produced after the ice shelf melting is equal to volume of ice that was
displaced. But calving of ice-shelf and its gradual melting will greatly
destabilize the land ice. Though scientists are hopeful that ice-shelf will
regrow but chipping away of huge chunks of ice-shelves at regular intervals
will inadvertently make Antarctica less stable. If the newly calved iceberg
drifts into warm oceans, it can just long for few decades. Ice shelves act as
sinks for glaciers and their calving will eventually hasten melting of glaciers
leading to increase in sea-level. In 2015, a report in reputed journal Science warned that ice-shelves in
Antarctica are thinning at an accelerated pace and that ice-shelves ceased to
gain volume.
Larsen Shelf is named after the
Norwegian explorer Carl Anton Larsen who in 1890, sailed along the 1000km
western coastal stretch. The Larsen shelf comprises of distinct shelves- Larsen
A, B, C and D. In 1995, Larsen A broke away and melted completely in seven
years. The 10,000 years old Larsen B
separated from Antarctica in 2002 and became an iceberg. Reports showed that
Larsen B calving speeded up glacier collapse by 300 to 800%. Larsen C is five
times the size of Larsen B. NASA scientist Cavin Schmidt said that complete
melt down of Larsen C might increase sea level by 0.1mm.
Intergovernmental Panel on Climate Changes
Fifth Assessment Report (5AR), indicated that temperatures in Antarctic
peninsula where Larsen-C is located, are rising four to six times that of
global average. Though role of global warming wasn’t scientifically established
as of now, reputed scientific journal, Nature,
opined that increased human (anthropogenic) activity in Antarctica is posing
new threat. Surge in number of tourists visiting Antarctica is drastically
changing the delicate ecosystem of Antarctica. Especially visitors to coastal
regions has increased from 1.5 million in 2004-05 to 2.6 million in 2013-14. Interestingly,
Antarctica is in news recently for being the venue for first ever wedding
ceremony of expedition leaders of British Antarctica Survey (BAS).
As per IPCC reports twentieth century
witnessed a linear increase of sea-level caused by warmer oceans and melting
glaciers. In 21st century rise of sea-level is exponential because
of melting of fast flowing glaciers and subsequent breaking of ice-shelves of
Greenland and Antarctica. Already islands in the Pacific Ocean, Indian Ocean
and countries with huge coasts are facing the inimical effects of global
warming. Besides the impending threats of inundation, rising sea-levels are
critically endangering livelihoods of thousands of people living along the
coasts. Fertile cultivable lands are rendered barren by salty depositions.
Fresh water resources are becoming salty.
Mounting evidences unequivocally
indicate that unscrupulous human activity has irrevocably disturbed delicate
balance of nature. The irreversible damage can be controlled through collective
action and committed nurture. It is time international collaboration be ramped
up to tame the disastrous cycle of events triggered by global warming. But
sadly, overpowered by ritualistic nationalism, America, the biggest emitter of
greenhouse gases is dragging its feet. Abdicating responsibilities towards
environment will push us closer to a brink of self-inflicted catastrophic
consequences. Calving of Antarctic ice-shelf is an inimical distress signal
lest the World choses to brush it off at its own peril.
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