Geophysical Phenomena

Introduction:

Climate change has emerged as a critical factor influencing cyclone patterns and frequency globally. Rising global temperatures, warming oceans, and changing atmospheric conditions are contributing to shifts in the intensity, frequency, and geographical distribution of cyclones, posing new challenges for disaster management and coastal communities.

Impact of Climate Change on Cyclone Patterns

1. Increased Sea Surface Temperatures:
   • Cyclones derive their energy from warm ocean waters. As global temperatures rise, sea surface temperatures (SST) increase, providing more heat and moisture to fuel cyclone formation and intensification.
   • Recent Example: In 2023, Cyclone Biparjoy in the Arabian Sea intensified rapidly due to abnormally high SST, demonstrating the impact of warming oceans on cyclone behavior.
2. Higher Frequency of Intense Cyclones:
   • While the overall number of cyclones may not have significantly increased, the proportion of intense cyclones (Category 4 and 5) has risen. Warmer oceans provide more energy, leading to stronger cyclones with higher wind speeds and heavier rainfall.
   • Recent Example: Cyclone Amphan (2020) in the Bay of Bengal rapidly escalated into a super cyclone due to favorable climate conditions, including high SST and low wind shear.
3. Changes in Cyclone Tracks:
   • Climate change is also altering cyclone tracks, with more cyclones forming in unusual regions or deviating from traditional paths. This poses a greater risk to previously unaffected or less-prepared areas.
   • Recent Example: The increasing number of cyclones in the Arabian Sea, such as Cyclone Tauktae (2021), indicates a shift in cyclone activity due to warming waters in the region, which historically witnessed fewer cyclones than the Bay of Bengal.

Impact of Climate Change on Cyclone Frequency

1. Fewer, But More Destructive Cyclones:
   • Some climate models suggest that while the frequency of cyclones may not increase significantly, those that do form will be more destructive due to stronger winds, heavier rainfall, and higher storm surges.
   • Recent Example: Cyclone Fani (2019) was one of the most powerful storms to hit Odisha in decades, and its strength was attributed to the warming of the Bay of Bengal, which fueled its rapid intensification.
2. Longer Cyclone Seasons:
   • Climate change is extending the duration of cyclone seasons, with cyclones forming earlier or later than usual. This increases the window of vulnerability for coastal regions, making disaster management more complex.
   • Recent Example: Cyclone Yaas (2021) hit India towards the end of May, unusually close to the onset of the monsoon season, highlighting the extended cyclone activity period.
3. Rising Sea Levels and Cyclone Intensity:
   • Rising sea levels due to melting polar ice caps and thermal expansion amplify the destructive potential of cyclones by increasing the height of storm surges. This leads to more widespread coastal flooding, even from less intense cyclones.
   • Recent Example: The storm surges during Cyclone Amphan (2020) caused widespread flooding in the Sundarbans, where rising sea levels exacerbated the extent of the damage.

Scientific Consensus and Predictions

1. IPCC Reports on Cyclones:
   • The Intergovernmental Panel on Climate Change (IPCC) in its reports highlights that tropical cyclones are likely to become more intense in the future due to rising global temperatures and changing oceanic conditions.
   • Recent Example: The IPCC’s Sixth Assessment Report (2021) indicates that the frequency of very severe cyclonic storms (VSCS) is projected to increase in the North Indian Ocean, a direct consequence of rising SST.
2. Regional Variations in Cyclone Patterns:
   • Climate change affects different regions in varied ways. The North Indian Ocean is witnessing more frequent and intense cyclones, while other regions may experience fewer storms but with higher intensities.
   • Recent Example: Cyclones like Tauktae and Yaas in 2021 highlight how warming seas in both the Arabian Sea and Bay of Bengal are creating conditions favorable for more destructive storms.

Conclusion:

Climate change is fundamentally altering cyclone patterns and frequency, with cyclones becoming more intense, longer-lasting, and affecting new regions. Governments and communities must adapt to these changing patterns by enhancing early warning systems, resilient infrastructure, and disaster preparedness to mitigate the impacts of these climate-driven events. Continued global efforts to limit global warming are essential to prevent further escalation of cyclonic activity and its associated risks.

Introduction:

Cyclones are intense circular storms that originate over warm tropical oceans and are characterized by low pressure at the center, strong winds, and heavy rainfall. The formation and intensity of cyclones are influenced by several climatic factors such as sea surface temperature, atmospheric moisture, and wind patterns.

Factors Contributing to Cyclone Formation

1. Warm Sea Surface Temperature (SST):
   • Cyclones typically form in tropical regions where sea surface temperatures exceed 26.5°C. Warm water provides the necessary heat and moisture, which leads to the formation of convective clouds and the development of a low-pressure system.
   • Recent Example: The rise in sea surface temperatures due to climate change is linked to an increase in the intensity of cyclones. In 2023, Cyclone Biparjoy in the Arabian Sea intensified rapidly due to abnormally high SST.
2. Atmospheric Moisture:
   • High levels of moisture in the atmosphere, especially in the middle and upper troposphere, contribute to cyclone development by fueling convection. This moisture is crucial for the condensation process, which releases latent heat and powers the cyclone.
   • Recent Example: The Indian Ocean witnessed more intense cyclones in recent years due to enhanced moisture levels, particularly during the post-monsoon period.
3. Coriolis Force:
   • The Coriolis force, caused by the Earth’s rotation, helps cyclones spin and maintain their structure. The force is weakest at the equator and strengthens as one moves toward the poles, which is why cyclones do not form near the equator.
4. Low Wind Shear:
   • Low vertical wind shear (difference in wind speed and direction with height) allows cyclones to grow. High wind shear can disrupt cyclone formation by dispersing the heat and moisture required for intensification.
   • Recent Example: Cyclone Fani (2019), which struck India, was able to sustain its intensity because of favorable low wind shear conditions in the Bay of Bengal.
5. Pre-existing Disturbance:
   • A low-pressure area or tropical disturbance is necessary to kick-start the formation of a cyclone. Without an initial disturbance, cyclonic activity cannot begin.

Climatic Conditions and Cyclone Intensity

1. Ocean Heat Content:
   • The deeper the layer of warm water, the more energy is available for cyclones to intensify. This is referred to as ocean heat content (OHC). Higher OHC results in stronger cyclones with greater intensity and destructive potential.
   • Recent Example: Cyclone Tauktae (2021) rapidly intensified due to extremely high ocean heat content in the Arabian Sea, which has been linked to global warming.
2. Rising Sea Levels:
   • Rising sea levels, caused by melting ice caps and thermal expansion, increase the destructiveness of storm surges associated with cyclones. Higher storm surges lead to more coastal flooding and damage.
   • Recent Example: During Cyclone Amphan (2020), higher sea levels along the Bay of Bengal’s coastline exacerbated flooding in eastern India and Bangladesh.
3. Climate Change and Intensification:
   • Climate change is leading to more frequent and intense cyclones due to rising global temperatures and increasing sea surface temperatures. Studies indicate that the proportion of very severe cyclonic storms (VSCS) has increased in recent decades.
   • Recent Example: The 2020 cyclone season in the North Indian Ocean was particularly severe, with multiple intense cyclones like Amphan and Nivar, attributed to warming oceans and altered wind patterns.

Conclusion:

The interplay between oceanic and atmospheric conditions largely determines the formation and intensity of cyclones. With climate change altering many of these factors, cyclones are becoming more frequent and intense, posing increasing challenges for coastal communities. Effective mitigation and adaptation strategies are crucial to minimize the impact of these climate-driven disasters.