Syllabus
GS Paper 1 – Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc.,
GS Paper 3 – Disaster and disaster management.
Context
According to a new study, human induced climate change is causing more frequent and intense cyclones in the Eastern Arabian Sea.
About Cyclones:
- Cyclones are rapid inward air circulation around a low-pressure area.
- Classification –
- Tropical Cyclones: Originate between the Tropics of Capricorn and Cancer
- Extra Tropical/ Temperate Cyclones: Originate in the Polar Regions
Cyclone vs Anticyclone –
| Pressure System | Pressure Condition at the Centre | Pattern of Wind Direction | |
| Northern Hemisphere | Sothern Hemisphere | ||
| Cyclone | Low | Anti-clockwise | Clockwise |
| Anti-cyclone | High | Clockwise | Anti-clockwise |
About Tropical Cyclones:
- An intense circular storm that originates over warm tropical oceans.
- Characteristic features –
- Eye, a central region of clear skies, warm temperatures, and low atmospheric pressure.
- Low atmospheric pressure, high winds, and heavy rain.
- Conditions for Formation –
- Large sea surface with temperature >27° C.
- Presence of the Coriolis force
- Small variations in the vertical wind speed
- A pre-existing weak low- pressure area
- Upper divergence above the sea level system
- Nomenclature –
- Nodal Authority – World Meteorological Organization (WMO)
- Indian Ocean Region – 13 member countries of WMO/ESCAP Panel on Tropical Cyclones (Bangladesh, India, Iran, Maldives, Myanmar, Oman, Pakistan, Qatar, Saudi Arabia, Sri Lanka, Thailand, United Arab Emirates and Yemen)
- Cyclones in India
- Bi-annual Cyclone Season – March to May and October to December
- Recent Cyclones –
- Arabian Sea: Tauktae, Vayu, Nisarga and Mekanu
- Bay of Bengal: Asani, Amphan, Fani, Nivar, Bulbul, Titli, Yaas and Sitrang
Different Names for Tropical Cyclones
- Typhoons – Southeast Asia and China
- Hurricanes – North Atlantic and eastern Pacific
- Tornados – West Africa and southern USA
- Willy-willies – Northwest Australia
- Tropical Cyclones – Southwest Pacific and Indian Ocean
Cyclones in Arabian Sea:
- The Bay of Bengal and the Arabian Sea, constituting the North Indian Ocean, contribute around 6% of the global annual count of tropical cyclones.
- Research published in the Nature journal in 2021 observed a significant rise in the intensity, frequency, and duration of cyclones in the Arabian Sea between 1982 and 2019.
- According to a 2022 paper in Elsevier’s Earth Science Reviews, sea surface temperatures in the Arabian Sea have escalated by approximately 1.2°C to 1.4°C in recent decades.
- During the period of 2001 to 2019, there was a recorded 52% increase in the frequency of cyclones in the Arabian Sea, while the Bay of Bengal saw an 8% decrease.
- Notably, the total duration of cyclones in the Arabian Sea has surged by 80% over the past two decades.
Factors for increasing cyclones in Arabian Sea:
- Global Warming and Sea Surface Temperatures: Global warming induces a rise in surface sea temperatures, directly impacting the Arabian Sea’s characteristics.This change contributes to the increased formation and sustenance of more severe cyclones in the region.
- Vertical Shear and Cyclone Formation: Vertical shear measures the variance in winds from the Earth’s surface to the upper atmosphere.Lesser vertical shear conditions promote the creation of cyclones.
- Positive Indian Ocean Dipole (IOD) Phase: A positive IOD phase signifies warmer sea surface temperatures in the western Indian Ocean relative to the eastern areas.The warming of the Arabian Sea could intensify both the frequency and strength of tropical cyclones in the North Indian Ocean.
Impacts:
- Impact on Western India’s Coastline: Changes in the eastern Arabian Sea pose an increasing risk to the coastlines of western India. The evolving scenario heightens the vulnerability of densely populated regions from Thiruvananthapuram to Gujarat’s coast.
- Increased Cyclone Intensity: The heightened intensity of cyclones amplifies the potential for severe consequences such as high winds, storm surges, and heavy rainfall.
- Population Vulnerability: Densely populated coastal areas along the western coast face an escalating threat due to these cyclones.
- Effects on Coastal Communities and Fishers: The lives and livelihoods of indigenous coastal communities and artisanal fishers are significantly impacted.
- Influence on Southwest Monsoon: The alterations caused by these cyclones raise concerns about their impact on the southwest monsoon, which the country heavily relies upon for drinking water and agricultural needs.
Way Forward:
- Adjustment in Development Strategies: The report advocates for the adaptation of development strategies to consider the threats presented by increasingly intense and frequent cyclones.
- Necessity for Policy and Technology Advancements: There is a pressing need to implement new policy and technology initiatives, particularly in the domains of storm warning systems, impact-oriented local weather services, and dependable localized weather forecasting.
Source: Indian Express
Practice Question
Examine the causes behind the rising occurrence of cyclones in the Arabian Sea. Evaluate the influence of climate change on tropical cyclones. (Answer in 250 words)