More Cyclones in Arabian Sea

Why in news?

According to a new study, human induced climate change is causing more frequent and intense cyclones in the Eastern Arabian Sea.

Cyclone - Any large system of winds that circulates about a centre of low atmospheric pressure in a counter-clockwise direction north of the Equator and in a clockwise direction to the south.
Occurrence - Cyclonic winds move across nearly all regions of the Earth except the equatorial belt.
Cause - By atmospheric disturbances around a low-pressure area distinguished by swift and often destructive air circulation.
Eye of the cyclone - Low-pressure center of the cyclone
- The lower the pressure in the eye, the more intense is the cyclone.
Eye-wall - Surrounds the eye with the strongest winds and heaviest rain and is the most destructive part of the cyclone.

The Bay of Bengal and Arabian Sea which make up the North Indian Ocean, accounts for 6% of all global tropical cyclones annually.
In 2021, a research paper in Nature journal said that there is a significant increasing trend in the intensity, frequency, and duration of cyclones observed over Arabian Sea during 1982 to 2019.
According to a 2022 paper in Elsevier’s Earth Science Reviews, the sea surface temperatures over the Arabian Sea increased by 1.2°C to 1.4°C in recent decades.
The paper highlighted that there is a 52% increase in the frequency of cyclones during 2001–2019 in the Arabian Sea, while there is a decrease of 8% in the Bay of Bengal.
There has been an 80% increase in the total duration of cyclones in the Arabian Sea during the last two decades.

Important cyclones in Arabian Sea
- Cyclone Tej - 2023
- Cyclone Biparjoy - 2023
- Cyclone Tauktae – 2021
- Cyclone Nisarga – 2020
- Cyclone Kyarr- 2019
- Cyclone Maha
- Cyclone Maha
- Cyclone Vayu

Global warming - It is causing surface sea temperatures to rise and causing a change in the Arabian Sea’s character.
This is leading to more severe cyclones forming and sustaining over it.
Vertical shear - It refers to how strongly the winds can change from the surface to the top of the atmosphere.
Weak vertical shear promotes the formation of cyclones.
Positive Indian Ocean dipole (IOD) phase – It refers to warmer sea surface temperatures in the western Indian Ocean relative to the east.
Warming of Arabian Sea can increase the frequency and intensity of tropical cyclones in the North Indian Ocean.

West India- As the eastern Arabian Sea changes, the coastlines of western India are increasingly at risk.
Intensity- Increase in intensity of cyclones increases their potential to cause high wind, storm surges, severe rainfall, etc.
Population- The cyclones could pose more and more of a threat to all densely populated coastal regions along the western coast, from Thiruvananthapuram to the coast of Gujarat.
Impact on fishers- It will affect the lives and livelihood of the indigenous coastal communities and artisanal fishers.
Impact on southwest monsoon – Its impact on southwest monsoon is concerning which as the country relies upon heavily for its drinking water and agricultural needs.

This report calls for changes to development strategies to account for the dangers posed by more intense and frequent cyclones.
There is also a need to develop new policy and technology initiatives in the areas of storm warning, impact-based local weather services and reliable localised weather services.

Related links- Monsoon Mayhem

Quick facts

Indian Metrological Department

It is the national meteorological service of the country and the principal government agency in all matters relating to meteorology and allied subjects.
Established- 1875
Headquarters- New Delhi
Aegis- Ministry of Earth Science
Mandate-
- To take meteorological observations and to provide current and forecast meteorological information for optimum operation of weather-sensitive activities like agriculture, irrigation, shipping, aviation, offshore oil explorations, etc.
- To warn against severe weather phenomena like tropical cyclones, norwesters, duststorms, heavy rains and snow, cold and heat waves, etc., which cause destruction of life and property.
- To provide meteorological statistics required for agriculture, water resource management, industries, oil exploration and other nation-building activities.
- To conduct and promote research in meteorology and allied disciplines.

References