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25 Dec 2025·Source: The Hindu
3 min
Environment & EcologyEnvironment & EcologyEnvironment & EcologyEXPLAINED

North Indian Ocean's Storm Cycle: Four Alarming Trends Emerge

Climate change is reshaping North Indian Ocean cyclones, with four critical trends emerging.

North Indian Ocean's Storm Cycle: Four Alarming Trends Emerge

Photo by Andres Ayala s.

पृष्ठभूमि संदर्भ

Historically, the Bay of Bengal has been more prone to tropical cyclones, accounting for a significant portion of global cyclone-related fatalities. However, recent decades have shown a clear shift in patterns, with the Arabian Sea experiencing a notable increase in cyclone activity.

वर्तमान प्रासंगिकता

These changing cyclone patterns have critical implications for coastal states in India and neighboring countries, affecting disaster preparedness, infrastructure planning, and the livelihoods of millions. Understanding these trends is crucial for effective climate adaptation and mitigation strategies.

मुख्य बातें

  • •The Arabian Sea is becoming a new hotspot for intense cyclones, challenging historical trends.
  • •Increased intensity and duration of cyclones mean greater destructive potential and longer periods of impact.
  • •Shifting cyclone tracks make prediction and preparedness more complex.
  • •Climate change is the primary driver behind these changes, necessitating urgent global and national action.

विभिन्न दृष्टिकोण

  • •Some studies attribute the changes primarily to anthropogenic climate change, while others also consider natural climate variability cycles.

संबंधित अवधारणाएं

Climate Change ImpactsOcean WarmingTropical Cyclone FormationDisaster Risk Reduction (DRR)Indian MonsoonSea Surface Temperature (SST)

The North Indian Ocean (NIO) is experiencing significant changes in its storm cycle, driven by climate change and ocean warming. Four key trends are redefining cyclone activity: an increase in the frequency and intensity of cyclones, particularly in the Arabian Sea; a shift in cyclone tracks, with more storms moving towards the west and northwest; a rise in the number of very severe cyclonic storms (VSCS) and extremely severe cyclonic storms (ESCS); and an increase in the duration of cyclones.

These changes pose heightened risks to coastal regions, impacting disaster management strategies and necessitating urgent adaptation measures. The Bay of Bengal, historically a cyclone hotspot, and the Arabian Sea are both showing these alarming shifts, with the latter seeing a disproportionate increase in severe storms.

मुख्य तथ्य

1.

North Indian Ocean (NIO) includes Bay of Bengal and Arabian Sea.

2.

Bay of Bengal accounts for 5-6% of global tropical cyclones but 80% of fatalities.

3.

Arabian Sea cyclone frequency has increased by 52% in the last two decades (2001-2020) compared to 1980-2000.

4.

Very Severe Cyclonic Storms (VSCS) and Extremely Severe Cyclonic Storms (ESCS) are increasing.

5.

Cyclone duration is increasing, with storms lasting longer over the ocean.

UPSC परीक्षा के दृष्टिकोण

1.

Impact of climate change on extreme weather events.

2.

Geographical distribution and characteristics of tropical cyclones.

3.

Disaster management strategies and coastal vulnerability.

4.

Oceanography and atmospheric science concepts (e.g., SST, vertical wind shear, IOD).

5.

Policy implications for climate adaptation and mitigation.

दृश्य सामग्री

North Indian Ocean Cyclone Activity: Shifting Trends (2015-2025)

This map illustrates the changing dynamics of tropical cyclones in the North Indian Ocean, highlighting the increased activity and intensity in the Arabian Sea and the general shift in cyclone tracks towards the west and northwest. Coastal regions most vulnerable to these changes are marked.

Loading interactive map...

📍Arabian Sea (Increased Activity)📍Bay of Bengal (Historical Hotspot)📍Gujarat Coast📍Maharashtra Coast📍Odisha Coast📍West Bengal Coast

बहुविकल्पीय प्रश्न (MCQ)

1. Consider the following statements regarding the recent trends in the North Indian Ocean's storm cycle: 1. There has been an increase in the frequency and intensity of cyclones, particularly in the Arabian Sea. 2. Cyclone tracks are increasingly shifting towards the west and northwest. 3. The number of Very Severe Cyclonic Storms (VSCS) and Extremely Severe Cyclonic Storms (ESCS) has risen. 4. Tropical cyclones typically form over ocean waters with a sea surface temperature (SST) below 26.5°C. Which of the statements given above is/are correct?

उत्तर देखें

सही उत्तर: A

Statements 1, 2, and 3 are explicitly mentioned in the article as alarming trends in the North Indian Ocean's storm cycle. Statement 4 is incorrect. Tropical cyclones require warm ocean waters, typically with a sea surface temperature (SST) of 26.5°C or higher, extending to a depth of at least 50 meters, to provide the necessary energy for their formation and intensification.

2. In the context of tropical cyclogenesis in the North Indian Ocean, which of the following statements is/are correct? 1. Ocean warming provides more latent heat, contributing to increased cyclone intensity and duration. 2. A positive phase of the Indian Ocean Dipole (IOD) generally suppresses cyclogenesis in the Arabian Sea. 3. Reduced vertical wind shear in the atmosphere is conducive for the intensification of tropical cyclones. Select the correct answer using the code given below:

उत्तर देखें

सही उत्तर: C

Statement 1 is correct. Warmer ocean waters (due to ocean warming) provide more energy (latent heat) for cyclones, leading to their intensification and longer duration. Statement 2 is incorrect. A positive IOD phase is characterized by warmer sea surface temperatures in the western Indian Ocean (including the Arabian Sea) and cooler temperatures in the eastern Indian Ocean. This condition generally *enhances* cyclogenesis in the Arabian Sea. Statement 3 is correct. Low vertical wind shear allows the storm's vertical structure to remain intact, facilitating the organization and intensification of the cyclone. High wind shear, conversely, can tear the storm apart.

3. Which of the following statements is NOT correct regarding tropical cyclones in the North Indian Ocean?

उत्तर देखें

सही उत्तर: D

Statement D is NOT correct. Increased duration of cyclones, even with slower movement, generally *increases* the risk of coastal inundation, prolonged heavy rainfall, and storm surge. Slower movement means a particular area is exposed to the storm's destructive forces (wind, rain, storm surge) for a longer period, exacerbating impacts like flooding and erosion. Statements A, B, and C are correct. IMD has its own 7-step classification (Depression to Super Cyclonic Storm). A VSCS is indeed 118-165 kmph. The Bay of Bengal has historically been a cyclone hotspot.

4. Assertion (A): The observed changes in the North Indian Ocean's storm cycle necessitate a significant overhaul of India's existing coastal disaster management strategies. Reason (R): The shift in cyclone tracks towards the west and northwest, coupled with increased frequency of severe storms in the Arabian Sea, poses novel challenges for early warning systems and infrastructure resilience. In the context of the above two statements, which one of the following is correct?

उत्तर देखें

सही उत्तर: A

Both Assertion (A) and Reason (R) are individually true. The changing patterns (increased intensity, duration, and track shifts, especially in the Arabian Sea) indeed demand a re-evaluation and overhaul of disaster management strategies, as traditional preparedness might not be adequate for these new threats. Reason (R) correctly explains why this overhaul is needed, by highlighting the specific challenges posed by altered cyclone tracks and increased severity in previously less-affected regions like the Arabian Sea coast.

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