Recent weather patterns across Northern India have shown shift. Heavy rainfall and strong winds struck Delhi and surrounding areas on May 2, 2025. This unusual weather was attributed to an increase in Western Disturbances. The India Meteorological Department (IMD) reported that these disturbances have surged this year due to rising global temperatures. This change has led to severe weather events including flash floods and landslides in the Himalayan region.
What Are Western Disturbances?
Western Disturbances are rain-bearing systems originating from regions beyond Afghanistan and Iran. They gather moisture from the Mediterranean, Black, Caspian, and Arabian Seas. These systems are classified as extra-tropical cyclones. They form due to the interaction of polar and tropical winds. Typically, they are most active during winter months, influencing weather patterns in India and surrounding countries.
Impact of Climate Change on Western Disturbances
Climate change is altering the behaviour of Western Disturbances. Studies indicate an increase in their frequency and intensity in the last 70 years. Warmer global temperatures are believed to strengthen the subtropical westerly jet stream. This results in faster wind currents, allowing disturbances to impact weather outside traditional winter months.
Seasonal Changes
Historically, Western Disturbances were rare in late spring and summer. However, recent trends show an increase in their occurrence during May, June, and July. This shift is linked to the delayed northward retreat of the subtropical jet stream, which has traditionally signalled the onset of the monsoon. Consequently, this has led to more extreme weather events, including heavy rainfall and flooding during the monsoon season.
Moisture Dynamics
The rapid warming of the Arabian Sea is contributing to year-round moisture availability. Studies reveal that sea surface temperatures in this region have risen over the past four decades. This warming enhances moisture release into the atmosphere, subsequently increasing precipitation intensity and frequency during Western Disturbances.
Future Projections
Experts predict that Western Disturbances will continue to evolve due to ongoing climate change. The broadening of the subtropical westerly jet stream allows these disturbances to travel further north and south. This increased oscillation could lead to more unpredictable weather patterns, affecting temperature and precipitation across a wider area.
Implications for the Himalayan Region
The Himalayan states, including Jammu & Kashmir, Himachal Pradesh, and Uttarakhand, are particularly vulnerable. The increased rainfall from Western Disturbances poses risks of flash floods and landslides. As these disturbances become more frequent, the need for effective disaster management strategies becomes critical.
Questions for UPSC:
- Critically analyse the impact of climate change on monsoon patterns in India.
- Estimate the role of sea surface temperature rise in influencing weather systems globally.
- Point out the socio-economic implications of extreme weather events in Himalayan states.
- What are the characteristics of extra-tropical cyclones? How do they differ from tropical cyclones?
Answer Hints:
1. Critically analyse the impact of climate change on monsoon patterns in India.
- Climate change has altered monsoon onset timings, leading to irregular rainfall patterns.
- Increased frequency of extreme weather events, such as heavy rainfall and droughts, disrupt agricultural cycles.
- Warmer temperatures contribute to the intensity of monsoon rains, increasing flood risks.
- Changes in Western Disturbances influence monsoon behavior, causing variability in precipitation.
- Overall, climate change threatens food security and water resources, impacting livelihoods across India.
2. Estimate the role of sea surface temperature rise in influencing weather systems globally.
- Rising sea surface temperatures enhance evaporation, increasing moisture in the atmosphere.
- Warmer oceans can intensify storm systems, leading to more severe weather events globally.
- Changes in temperature gradients affect ocean currents, which play important role in climate regulation.
- Increased SST contributes to altered jet stream patterns, impacting weather systems and climate variability.
- Regions like the Arabian Sea have shown warming, affecting local weather dynamics and precipitation patterns.
3. Point out the socio-economic implications of extreme weather events in Himalayan states.
- Extreme weather events lead to loss of lives and property, straining local economies.
- Flash floods and landslides disrupt infrastructure, affecting transportation and access to services.
- Agricultural losses due to unpredictable weather threaten food security and livelihoods.
- Increased displacement of communities due to natural disasters raises humanitarian concerns.
- Tourism, a vital economic sector, suffers due to environmental degradation and safety concerns.
4. What are the characteristics of extra-tropical cyclones? How do they differ from tropical cyclones?
- Extra-tropical cyclones form in mid-latitudes and are associated with fronts and temperature contrasts.
- They are driven by the interactions of polar and tropical air masses, leading to precipitation and wind.
- Tropical cyclones form over warm ocean waters and are powered by heat from the sea surface.
- Extra-tropical cyclones can occur year-round, while tropical cyclones are seasonal, mainly in summer.
- Extra-tropical cyclones typically have a larger scale and can affect broader areas compared to tropical cyclones.
