major-impact-on-climate-due-to-extension-of-amery-ice-shelf-ais

Context: The National Centre for Polar and Ocean Research (NCPOR) predicts that there would be a 24% increase in the expansion of Amery Ice Shelf (AIS) boundaries by 2021 and another 24% expansion by 2026 from its 2016 positions. 

More on News:

  • The prediction made by NCPOR is based on a 16-year-long satellite-based observation that covered an area of 60,000 sq. km across the AIS. 
  • Scientists feel that this study would help understand the ongoing changes in the ocean and atmospheric forces better.

About Amery Ice Shelf:

  • The AIS is one of the largest glacier drainage basins in the world, located on the east coast of Antarctica, at about 70ºS Latitude, 70ºE Longitude. 
  • The AIS dynamics and mass balance help in understanding the changes in the global climate scenario.

Study area map showing the AIS extent positions from 2001 to 2016 (Source: pib)

About the study:

  • NCPOR carried out this study based on the satellite data collected from 2001 to 2016.
  • The data were collected during the austral (relating to the southern hemisphere) summer months of January to March to understand the advancement of AIS extension and the influence of ocean atmospheric forcing in East Antarctica. 

Understanding the study:

  • The floating sheets of ice called the ice shelves play a multi-faceted role in maintaining the stability of a glacier
  • Ice shelves connect a glacier to the landmass. 
  • The ice sheet mass balance, sea stratification, and bottom water formation are important parameters for the balancing of a glacier. 
  • Latent and sensible heat processes do play important roles here.
  • The insulation of ice shelves from atmospheric forcing is dependent on a temperature gradient that the ocean cavity beneath the ice shelves provides. 
    • It is the pressure exerted by the ice shelves upon the ocean cavity that determines this temperature gradient.
  • There is always a stress on the sea ice and ice sheets themselves play an indirect role in reducing the amplitude of the ocean swell. 
  • This is assisted by the freezing atmospheric temperature, which is capable of promoting a change in the morphology of ice shelves.

Observations and Inference:

  • The NCOPOR scientists observed a spatio-temporal change in the ice shelf as reflected
    • By the extension of the Pridze and Mackenzie and 
    • By the extension of a 200-km stretch between Mackenzie Bay (68.5ºS Latitude; 70.2ºE Longitude) and the Sandefjord Bay (69.65ºS Latitude; 74.3ºE Longitude), which is a part of the AIS.
    • Inference: It becomes clear from the study that the AIS is losing its stability owing to the impact of a downstream giant glacial drainage system over the past 19 years, thereby advancing the ice shelf boundaries due to higher freezing rates than basal melting.
  • It also estimated the rate at which ice shelves have extended for the last three years (2017-2019). 
    • The AIS extended by about 550 m in 2017, 1470 m in 2018, and 2200 m in 2019. 
    • Inference: If this continues, it is entirely possible that in the next six years (2021 to 2026), the positions of the ice shelf would closely coincide with the actual boundary conditions.
  • The observations also revealed a critical cooling of the sea surface temperature (SST), resulting in an advancement of the ice shelf by 88% in the past 15 years. 
    • Inference: These changes would contribute in a major way to climate variability.

 Conclusion:

  • The study clearly demonstrated the application of satellite observations and statistical techniques methods for the determination and validation; the reconstruction of the past; and the prediction of the future dynamism of ocean heat fluctuation and Antarctic Amery ice shelf mass shifting-extent. 
  • These are some of the groundbreaking methods crucial for monitoring and quantification of climate change effects and its consequences. 

 

NATIONAL CENTRE FOR POLAR AND OCEAN RESEARCH:

  • National Centre for Polar and Ocean Research (NCPOR) is India’s premier R&D institution responsible for the country’s research activities in the Polar and Southern Ocean realms.
  • It is an Indian research and development institution, situated in Vasco da Gama, Goa.
  • The mandate of NCPOR is multi-dimensional:
  • Leadership role in niche areas of scientific research in the domain of polar and ocean sciences.
  • Lead role in - 
    • the geoscientific surveys of the country’s EEZ and its extended continental shelf beyond 200M, 
    • deep-sea drilling in the Arabian Sea basin through the Integrated Ocean Drilling Program, 
    • exploration for ocean non-living resources such as the gas hydrates and multi-metal sulphides in mid-ocean ridges.
  • Facilitatory role in the scientific research activities being undertaken by several national institutions and organizations in Antarctica, the Arctic and in the Indian Ocean sector of the Southern Ocean.
  • Management role in implementing all scientific and logistics activities related to the Annual Indian Expeditions to the Antarctic, Arctic and Southern Ocean.
  • Management and upkeep of the Indian Antarctic Research Bases “Maitri” and “Bharati”,  and the Indian Arctic base “Himadri”
  • Management of the Ministry’s research vessel ORV Sagar Kanya as well as the other research vessels chartered by the Ministry
  • It is an autonomous Institution of the Department of Ocean Development (DOD), Ministry of Earth Sciences.
  • It was formerly known as the National Centre for Antarctic and Ocean Research (NCAOR). 

 

Key Terms:

  • Mass balance of a glacier or ice sheet:  It is the net balance between the mass gained by snow deposition, and the loss of mass by melting (either at the glacier surface or under the floating ice shelves or ice tongues) and calving (production of icebergs).
  • Sea Stratification: It is the division of the water column into layers with different densities caused by differences in temperature or salinity or both as the different densities act as barriers to water mixing.

Source:

https://pib.gov.in/PressReleaseIframePage.aspx?PRID=1629172#:~:text=NCPOR observations also revealed a,major way to climate variability.