Font size:
Print
Climate Change Impact on Western Disturbances
Storm in Delhi, floods in hill states: Impact of climate change-induced changing patterns of Western Disturbances
Context: A recent analysis by Climate Trends, a Delhi-based climate research group, highlights an increase in the frequency of Western Disturbances in 2024. This increase is directly linked to rising global temperatures, pointing toward a strong climate change connection.
More on News
- Heavy rainfall and strong winds were recorded across Delhi and nearby regions on the morning of May 2 (Friday).
- These weather events led to waterlogging at several locations and flight disruptions at Indira Gandhi International Airport.
- The India Meteorological Department (IMD) attributed the disturbance to a fresh Western Disturbance over northern and northwestern India.
Impact of WDs on Himalayan States
- The behavioural changes in WDs caused: Heavy rainfall, Flash floods, Landslides.
- Affected states included Jammu & Kashmir, Himachal Pradesh, and Uttarakhand in March and April 2024.
- Positive effect: Helped prevent prolonged heatwaves in the northwestern plains.
What are Western Disturbances?
- WDs are east-moving, rain-bearing wind systems originating beyond Afghanistan and Iran.
- They gather moisture from the Mediterranean Sea, Black Sea, Caspian Sea, and Arabian Sea.
- WDs are extra-tropical cyclones, formed due to low-pressure areas created by polar and tropical wind interactions.
- They are embedded in the subtropical westerly jet stream, a fast-moving, high-altitude air current flowing west to east over the Himalayan and Tibetan highlands.
- Typically occur during December to March (boreal winter months).
- Impact weather in India’s northwestern region and Pakistan.
Climate Change and Changing WD Behaviour
- A 2024 study (Weather and Climate Dynamics journal) revealed: Significant increase in winter WDs over the western and central Himalayas and the Hindu Kush over the last 70 years.
- Likely reasons:
- Strengthening of the subtropical westerly jet stream (faster and stronger wind currents).
- Global warming plays a key role in this strengthening.
WDs Expanding Beyond Winter
- WDs are now also appearing in non-winter months like May, June, and July—a rare phenomenon in the past.
- This trend may result from the delayed northward retreat of the subtropical jet stream, which used to occur before the summer monsoon onset.
- Result:
- Increased WDs during monsoon
- Rise in extreme weather events like floods and heavy rains
Moisture Source and Arabian Sea Warming
- A 2022 study (Earth Science Reviews) showed:
- Arabian Sea surface temperatures have increased by 1.2°C to 1.4°C over recent decades (compared to four decades ago).
- This warming has led to increased moisture availability, intensifying WDs and making rainfall more frequent and intense.
Broader Climate Dynamics and Jet Stream Shift
- Soaring temperatures have broadened the subtropical westerly jet stream.
- This enables WDs to:
- Travel in a wider geographical area
- Exhibit more meridional oscillations (north-south movement), affecting temperature and precipitation patterns.
- According to Dimri (Climate Trends):
- Earlier, there was limited space for such oscillations.
Now, WDs can shift toward both the northern and southern boundaries of the jet stream.
Subscribe to our Youtube Channel for more Valuable Content – TheStudyias
Download the App to Subscribe to our Courses – Thestudyias
The Source’s Authority and Ownership of the Article is Claimed By THE STUDY IAS BY MANIKANT SINGH
