Climate change and extreme rainfall
Why in News?
Climate change and extreme rainfall are in the news due to a compounding series of record-breaking global deluges, catastrophic flash floods, and new climate models showing that the extreme weather patterns of recent years could become the planet's "new normal" by 2050.
The Science: How Climate Change Causes Extreme Rain
- The Clausius-Clapeyron Law (The Atmospheric Sponge): For every 1°C rise in global temperatures, the atmosphere's capacity to hold moisture increases by 7%. This creates a massive "sponge effect" where the air holds more water vapor, leading to heavier, larger clouds and more intense downpours when it finally rains.
- Shift from Snow to Rain: Warmer winters mean that high-altitude precipitation is shifting from snow to rain. Mountainous regions are experiencing a 15% increase in high-altitude rainfall extremes per degree of warming, causing rapid runoff rather than slow-melting snowpacks.
- The "Dry-to-Wet" Contrast: Climate change is polarizing seasonal weather. Wet seasons are becoming significantly wetter with concentrated torrential downpours, while dry seasons are growing longer and harsher.
- Disrupted Monsoons and Ocean Currents: Extreme Ocean warming fuels more intense tropical cyclones and disrupts atmospheric rivers, dumping massive amounts of water in a matter of hours.
Severe Impacts and Consequences
- Urban and Infrastructure Collapse: Most global cities feature aging drainage systems designed for historical weather patterns. Torrential downpours quickly overwhelm stormwater networks, causing flash floods, power grid failures, and severe transportation shutdowns.
- Agricultural Disruption: Saturated soils block sunlight and drown root systems, killing crops, altering river flows, and accelerating soil erosion, which triggers devastating landslides.
- Aggravated Runoff from Wildfires: Climate-induced wildfires strip vegetation and alter the soil texture. When extreme rain hits these scarred landscapes, it creates highly destructive mudslides and instant runoff.
Mitigation and Climate Resilience
- Engineering and Infrastructure Defences: Cities are forced to adapt through large-scale engineering. For example, cities are building deep tunnel projects to capture massive storm runoff, separating wastewater from stormwater systems, and enforcing strict, climate-resilient building codes.
- Nature-Based Solutions: Environmental agencies are advocating for "sponge cities" that limit non-permeable concrete surfaces and instead utilize green flood-control infrastructure, wetlands, and natural zoning barriers to absorb excess water safely.
