Explained: How extreme rainfall events in India have been steadily increasing over the past decade or so
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Context
Recent data and analysis reveal a steady increase in extreme rainfall events across India over the past decade, despite fluctuations in overall monsoon rainfall. This rising frequency and intensity of heavy downpours, often triggering severe localized and urban flooding, highlight the growing impact of climate change on India's weather patterns and the urgent need for improved disaster preparedness and urban planning.
UPSC Perspectives
Geographical
The , a complex meteorological phenomenon, is characterized by significant regional and intra-seasonal variations. The 's forecast of 'below-normal' overall rainfall does not negate the rising frequency of localized extreme rainfall events (defined by IMD as >21 cm in 24 hours). This highlights a shift in precipitation patterns where rain occurs in shorter, more intense spells rather than being evenly distributed throughout the season. The science of meteorology grapples with predicting these highly localized events due to the chaotic nature of weather systems, where minor initial changes cause massive variations. This unpredictability, exacerbated by climate change altering atmospheric circulation and moisture-holding capacity, poses significant challenges for early warning systems. UPSC candidates must understand the mechanisms of the monsoon, the parameters defining 'extreme rainfall,' and the inherent limitations in forecasting highly granular weather events.
Environmental
The increasing frequency and intensity of extreme weather events, including heavy rainfall, heatwaves, and droughts, are directly linked to global . A warmer atmosphere holds more moisture (Clausius-Clapeyron relationship), leading to heavier downpours when precipitation occurs. This trend is a global phenomenon, underscoring the severe consequences of global warming on regional weather patterns. The article notes that while the threshold for 'extreme' rainfall was slightly lowered in 2016 (from 244.5 mm to 204.5 mm), the upward trend remains evident even at higher thresholds, confirming the escalating severity. The implications are profound, shifting the primary monsoon concern from agricultural drought to localized, devastating floods. This requires a transition in environmental policy from merely reacting to disaster to proactive climate adaptation and building resilient infrastructure to withstand extreme weather shocks.
Governance
The shift in disaster profiles from widespread droughts to localized demands a reevaluation of urban governance and municipal planning. While unprecedented rainfall is the trigger, the severity of urban disasters is often compounded by unregulated development, encroachment on floodplains and water bodies, and inadequate drainage infrastructure. The economic and human cost is staggering, with floods accounting for over 55% of state disaster expenditure, according to the , and resulting in massive economic disruption in major metropolitan hubs like Mumbai, Chennai, and Bengaluru. Effective now requires a multi-pronged approach: improving granular weather forecasting capabilities, implementing strict land-use regulations to protect natural drainage systems, and investing heavily in climate-resilient urban infrastructure. The UPSC often tests the interplay between natural hazards and systemic governance failures in exacerbating disasters.