why-the-bay-of-bengal-breeds-cyclones

Cyclone Remal's destructive rampage across West Bengal, Assam, Meghalaya, Mizoram, and Bangladesh serves as a stark reminder of the Bay of Bengal's perilous reputation.

 

While the full extent of the devastation is yet to be fully assessed, West Bengal alone has mourned at least six lives lost to electrocution from fallen power lines.

 

The storm's wrath ripped through coastal districts, uprooting over 2,140 trees and snapping 337 electricity poles, particularly in southern areas like Kakdwip, Namkhana, Sagar Island, Diamond Harbour, Fraserganj, Bakkhali, and the Sundarbans.

 

This vulnerability to cyclones is nothing new for the Bay of Bengal, which holds the dubious distinction of being one of the most cyclone-prone regions globally.

 

Dr. Jeff Masters, a renowned hurricane scientist writing for Yale Climate Connections, reveals a chilling truth – 22 of the 30 deadliest cyclones in history have churned within the Bay of Bengal over the past two centuries.

 

Storm surges, a hallmark of these tropical cyclones, inflict the most severe damage.

 

Research published in 2009 highlights the Bay of Bengal's dominance in both cyclone formation and the frequency of storm surges compared to  neighbouring Arabian Sea. 

A similar research also highlights that the Bay of Bengal, which covers only 0.6% of the global ocean area, accounts for four out of five cyclone-related deaths worldwide.

 

This year's cyclone season saw anticipation of a May event due to the region's scorching temperatures, a prediction tragically fulfilled by Remal. Unusually warm Bay waters, currently at 31 degrees Celsius, provided the perfect breeding ground for the storm.

 

The West Bengal government, in a commendable effort, evacuated over two lakh people to designated shelters before Remal's landfall.

 

Despite these measures, an estimated 15,000 houses across 24 blocks and 79 municipal wards bore the brunt of the cyclone's fury, leaving a trail of destruction in North 24 Parganas, South 24 Parganas, Kolkata, and Howrah districts.

 

The government acknowledges that these figures are likely to rise as damage assessments continue.

 

Several factors converge to make the Bay of Bengal a cyclone magnet compared to other seas across the globe.

 

These include high sea surface temperatures, low vertical wind shear, and an abundance of moisture in the atmosphere's mid-layers. Let's delve deeper into these key contributors:

 

Geographical and meteorological factors

 

Shallow embayment:

 

The Bay of Bengal is relatively shallow compared to any other sea across the globe. Its larger surface area allows for faster heating, causing higher evaporation and forming a high-pressure zone that induces atmospheric instability, making the region more susceptible to cyclones.

 

The relatively shallow nature of the bay compared to the Arabian Sea allows for faster heating and higher evaporation rates.

 

This rapid evaporation creates a high-pressure zone, leading to atmospheric instability conducive to cyclone formation.

 

The northern part of the Bay is particularly shallow, with the coast being landlocked on three sides.

 

This geographical feature exacerbates the impact of storm surges, submerging coastal belts during severe cyclonic storms.

 

Surface temperature:

 

"The cyclones we see now are more intense and moisture-laden compared to those in previous decades," says Rabindra Goenka, a weather expert based in Kolkata and founder of Weather Ultima. 

 

The Bay of Bengal's sea surface temperature has recently been recorded at 31 to 32 degrees Celsius, significantly higher than the typical 26 to 30 degrees Celsius.  

 

This elevated temperature contributes to the increased frequency and intensity of cyclones by helping them gather more moisture.

 

Shape and topography:

 

The Bay of Bengal is surrounded by land on three sides, which generates additional moisture and atmospheric instability.

 

Its funnel-like shape and shallow depth enhance the formation of large storm surges, contributing to some of the deadliest natural disasters in history.

 

The region's low-lying coastal areas are highly vulnerable to inundation when storms make landfall.

 

Geometry:

 

The Bay of Bengal's long, curved coastline amplifies wind speeds as they funnel into the bay, intensifying storms and increasing their destructive potential. 

 

This unique geometry makes the region particularly prone to powerful cyclonic events.

 

Despite the disaster preparedness efforts, the impact of Cyclone Remal has been severe.

 

The storm's aftermath highlights the urgent need for robust infrastructure and effective mitigation strategies in the cyclone-prone Bay of Bengal region.

 

Major Bay of Bengal cyclones:

• The 1970 Bhola Cyclone killed an estimated 3,00,000 to 5,00,000 people when it made landfall in Bangladesh.
• In 1999, a super cyclone killed nearly 10,000 people and caused damages worth ₹20,000 crores in Odisha.
• In 2009, cyclonic storm Aila was responsible for at least 339 deaths across Bangladesh and India; more than 1 million people were left homeless. Health officials in Bangladesh confirmed a deadly outbreak of diarrhea, with more than 7,000 people being infected and multiple deaths.
• Super cyclonic storm Amphaan in 2020 killed 129 and displaced 4.9 million more from their homes.
• Cyclone Mocha in 2023 was one of the strongest cyclonic storms to hit the Bay of Bengal in more than a decade killing more than 500 and leaving thousands displaced.