A recent study has shed light on the effects on Indian Monsoon by seasonal changes in the Arctic sea ice levels.

About the Study

• Published In: The Study is published in the journal Remote Sensing of Environment 
• Conducted By: The research is a collaboration between India’s National Centre for Polar and Ocean Research (NCPOR), under the Ministry of Earth Sciences, and South Korea’s Korea Polar Research Institute.
• Subject: To check how the Arctic sea ice levels affect atmospheric circulations that in turn influence the Indian Summer Monsoon Rainfall.
• Data Source: Observational data from the period of  1980 to 2020 were used along with climate models (specifically Coupled Model Intercomparison Project Phases 5 and 6)
• Findings:
  • Role of Climate Change: Climate Change accelerates the reduction of Arctic sea ice and exacerbates the variability and unpredictability of the ISMR
    • Lower Arctic sea ice can lead to more frequent and severe droughts in western and peninsular India regions while causing excessive rainfall and flooding in central and northern India.
  • Influence Monsoon Onset: Lower sea ice levels in the upper latitudes (mainly in the Barents-Kara Sea region encompassing the Hudson Bay, the Gulf of St. Lawrence and the Sea of Okhotsk) delay the monsoon’s onset rendering it more unpredictable.
  • Changes in Several Atmospheric Systems: 
    • Increased Sea Ice Levels in the Central Arctic: It results in the heat transfer from the ocean to the atmosphere triggering a cyclonic circulation at slightly lower latitudes (North Atlantic)
    • Rossby Waves:The cyclonic circulation bolsters the Rossby waves resulting in high pressure over northwest India and low pressure over the Mediterranean region.
      • These are fast-flowing streams of air high in the atmosphere created by the earth’s rotation and differences in temperature and weather systems that move west to east.
    • Strengthening Jet Stream: The circulation strengthens the Asian jet stream over the Caspian Sea, causing the subtropical easterly jet (a jet stream blowing over the Indian subcontinent during summer to shift northward)
    • An anomalous high pressure region is created over Central Asia as a result disrupting atmospheric stability over the Indian landmass and bringing more rain over western and peninsular India.
  • Low sea ice over the Barents-Kara Sea region:
    • It triggers a series of air currents that produce an anomalous high pressure over southwest China.
    • The heat from the Barents-Kara sea creates an anticyclonic circulation (calm, clear skies) over northwest Europe disturbing the upper atmospheric region over subtropical Asia and India.
    • The instability along with high surface temperature of the Arabian Sea promotes high rainfall over northeastern India while leaving central and northwest regions of the country with deficient rainfall.

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