The Arctic Amplification will Affect Tropical Monsoon Circulation

KOCHI:
A prominent climate change phenomenon happening around the Polar Regions characterized by a change in net-radiation balance inducing a much larger change in surface temperature near the poles relative to lower latitudes and the global mean, is becoming a universal threat in the recent decades, said Dr M. Ravichandran, Union Secretary of the Ministry of Earth Sciences (MoES), Govt. of India. There is a deluge of studies showing that even the extremes in the Indian summer monsoon, either flood/drought, have teleconnections with arctic processes – he added.

He was delivering the plenary session talk of the INTROMET-2021 Symposium held at the Cochin University of Science and Technology, Kerala. The polar region is warming at a rate of 2⸰C per decade while the global rate is 1⸰C/decade. This unprecedented warming, almost twice that of the global mean has catastrophic consequences in the form of enhanced sea ice melt and global sea level rise.

As the result of melting, the impact is materialized in the form of complex feedback processes both in the local atmosphere as well as in the ocean, world-wide. The Arctic amplification is a self-reinforcing phenomenon and through increased warming together with sea-level rise poses looming crisis in the form of extreme climate variability, loss of coastal habitat and indigenous communities, catch loss of fishery sector, coastal erosion and increased environmental pressures.

Besides the biota, the non-living sectors such as maritime industries, oil and natural gas sectors, and international ship routes are affected. This has colossal impacts on the global GDP. The local atmospheric feedbacks arise when the albedo (ability of ice surface to reflect off sunlight incident on it) of the sea ice reduces due to coating of aerosols such as black carbon onto the ice. The black carbon aerosols have great potential in absorbing heat energy from the incoming solar radiation.

The absorption of excess heat leads to accelerated ice melt which in turn leads to enhanced absorption of heat due to loss of ice. This positive (but unwanted) feedback continues as a cyclic process and makes the situation even more complex. The second response in the form of oceanic processes makes the problem worser due to supply of additional fresh water because of enhanced ice melt which can alter the stability of the oceanic density stratification.

The ocean circulation pattern is then affected which can trigger dramatic weather/climate changes world-wide. Any change in the polar surface temperature can have global consequences irrespective of latitudes. The ozone depleting polar stratospheric vortex, mid-latitude jet-streams, tropical monsoon circulation etc. are all remotely connected with the extent of arctic sea ice – Ravichandran warned.