Climate Change

Transboundary Bengal hotspot for lightning strikes: Report

West Bengal, along with Bangladesh, received two million on-ground lightning bolts

 
By Jayanta Basu
Published: Friday 23 July 2021

The region of West Bengal in India and Bangladesh is among the most vulnerable in South Asia to lethal lightning strikes, according to a recent report.

West Bengal received the highest number of lightning strikes per square kilometer in 2020, followed by Jharkhand, according to South Asia Lightning Report, 2020 by Earth Networks, a global weather intelligence agency.

The company’s extensive network constantly monitors lightning strikes through thousands of sensors.

West Bengal, along with Bangladesh, received two million lightning bolts on ground — above 8 lightning strikes per square kilometer on average during last year.

Overall, 57 million lightning strikes were recorded in India, Bangladesh and Sri Lanka together. Around one-fourth of them were cloud-to-ground strikes and the rest were intra-cloud.

India received most strikes  

India received about 39.6 million intra-cloud and cloud-to-ground lightning strikes in 2020, a whopping 70 per cent of the total number in the region.

The country received nearly 89 per cent of all the lethal cloud-to-ground strikes in the world.

India suffered 1,697 deaths due to lightning in 2020, according to the Annual Lightning Report 2020-21 — part of the ‘Lightning Resilient India Campaign 2019-22’. It is a  joint initiative by Climate Resilient Observing Systems Promotion Council, India Meteorological Department, the Union Ministry of Earth Sciences, Indian Institute of tropical Meteorology, Inian Meteorological Society and World Vision India. 

During the last decade (2011-20), India recorded a total of 2,600 deaths a year on an average. In Bangladesh, about a third of the three million lightning bolts were ground strikes. Rajshahi, Khulna, Dhaka and Rangpur districts received the most (over 0.1 million each) cloud-to-ground strikes in the country.

“Lightning is a major problem in the country as a whole and kills many every year,” said Md Golam Rabbani, a climate expert with BRAC, Bangladesh.     

Only 4 per cent of Sri Lanka’s 14.5 million lightning pulses were ground strikes, a very unusual data according to experts. 

“The proportion of ground lightning incidents vary from around 25 to 40 per cent in general due to several factors but less than 10 per cent is unusual,” pointed out Sunil D Pawar, a scientist of the atmospheric electricity in IITM to this journalist on Friday.

“Though lightning is a major problem, the number of incidents seems to have reduced in recent years,” opined Ranga Pallawala, a climate expert from Sri Lanka.

West Bengal worst-hit

West Bengal received 940,958 lightning strikes on ground, about 11 lightning strikes per square kilometer on average last year.

“It’s a fact that the number of lightning has increased in our state and 108 people died between April 20l9 to March 2021. However we are trying hard to reduce the mortality from lightning through various actions and campaigns,” said West Bengal disaster management minister Javed Ahmed Khan.

Jharkhand was the second-highest on the list with around 10 strikes; Orissa, Chhattisgarh,Tamil Nadu and Andhra Pradesh are other states which received lightning strikes 4-8 strikes every square kilometer.

Tamil Nadu topped the list of overall lightning strikes (including both intra-cloud fireworks and cloud-to-ground bolts), with close to six million strikes, followed by Andhra Pradesh, Orissa, Karnataka and West Bengal.

The report added: 

For all of 2020, Earth Networks detected 39,549,444 lightning pulses in India, of which 12,022,402 were dangerous cloud-to-ground strikes. The top five states with the most lightning last year were Tamil Nadu, Andhra Pradesh, Karnataka, West Bengal and Odisha. Lightning increased by 22.6 per cent compared to 2019.

The rise is even more phenomenal between April 2020 and March 2021.

Around 18.5 million lightning strikes were recorded in India, which was a 34 per cent increase from the 13.8 million strikes between April 2019 and March 2020, according to a report cited earlier.

“There are states with very sharp increases in lightning strikes during the period. Punjab saw upto 331 per cent rise, Bihar 168 per cent, Haryana 164 per cent, Puducherry 117 per cent, Himachal Pradesh 105 per cent and West Bengal 100 per cent,” it added.

Link with climate change 

“Climate change, particularly warming, is contributing considerably to the rise of lightning strikes, as it enhances both heat and moisture, the key components required for lightning,” said Sunil D Pawar, a scientist of atmospheric electricity in IITM.

“All these heat waves cater to more thunderstorms, which, in turn trigger more lightning strikes. Bengal delta has been traditionally affected by the lightning strikes mainly during kalbaishakhi  winds (norwesters). But the number has increased in recent years,” saidd KJ Ramesh, the former director general of IMD.

The Bengal delta, encompassing the Indian state of West Bengal and Bangladesh, is one of the most vulnerable regions for climatic impacts, with high sea-surface water temperatures and cyclones, said a local climate expert. “Lightning is just a corollary.”

A 2015 California University study had projected that an increase in average global temperatures by 1ºC would increase the frequency of lightning by 12 per cent, 

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