A Distant Pacific Pattern May Be Influencing Dry Conditions in North India: Study

Context

A study conducted by the India Meteorological Department (IMD) and the Indian Institute of Tropical Meteorology (IITM) examines how the Pacific Ocean’s Victoria Mode phenomenon may influence rainfall distribution and contribute to the expansion of semi-arid regions in northwestern India.

Key Highlights

• The study indicates that the semi-arid steppe region in northwestern India expanded from 25.7% (1951 – 80) to 33.1% (1991 – 2020).
• The tropical savannah region in northeastern India contracted from 18.4% to 11.8%, accompanied by an expansion of the temperate climatic zone.
• Victoria Mode (VM): It is a recurring pattern of relatively warm and cool sea surface temperatures across the North Pacific Ocean. It is distinct from the more widely recognised Pacific Decadal Oscillation.
• Variations in Pacific Ocean temperatures are associated with changes in Indian monsoon rainfall patterns and the transportation of atmospheric moisture.
• The growing extent of semi arid regions may have implications for food security, water resources and population displacement.

Key Concepts

• Indian Summer Monsoon: A seasonal reversal of wind direction that brings most of India’s annual rainfall during the June – September period.
• Pacific Decadal Oscillation (PDO): A long term pattern of variations in sea surface temperatures across the North Pacific Ocean, influencing regional and global climate patterns.
• El Niño and La Niña: These represent opposite phases of the El Niño – Southern Oscillation (ENSO), influencing global atmospheric circulation and contributing to variations in the Indian monsoon.
• Aridity and Desertification: Reduced moisture availability can alter existing climatic zones, accelerate land degradation and adversely affect agricultural productivity.

Way Forward

• Improve climate modelling by incorporating ocean atmosphere interactions into Indian monsoon forecasting systems.
• Encourage climate resilient agricultural practices to reduce the vulnerability of farming communities to changing rainfall patterns.
• Strengthen water conservation measures and sustainable groundwater management in regions experiencing increasing aridity.
• Develop region specific adaptation strategies based on local climatic conditions, changing rainfall trends and the vulnerability of communities.