Cyclone Tauktae is a warning; the future of India’s western coast is at stake
India is bracing for a second cyclone in a month as it prepares for Cyclone Yaas in the Bay of Bengal, which is likely to cross the Odisha-Bengal coast on May 26. To be sure, cyclones in the Bay of Bengal are almost an annual affair.
But Cyclone Tauktae in the Arabian Sea, which affected almost all states on the western coast of India earlier this month, was a more uncommon phenomenon. Not only are cyclones relatively uncommon in the Arabian Sea, Tauktae also intensified (measured by the surface wind speed of the storm) rapidly into one of the most severe cyclones in the Arabian Sea in over two decades. This is something the India Meteorological Department (IMD) had not forecast. With the climate crisis, the Arabian Sea could see more such intense cyclonic disturbances going forward, according to experts.
An HT analysis shows that this will inflict a far bigger cost on lives and livelihoods than cyclonic activity on India’s eastern coast.
2011-20 saw the highest number of cyclones in Arabian Sea since 1890s
IMD has records of cyclones among the two major seas of the North Indian Ocean – Indian Ocean area north of the equator – going back to 1890s. A decade-wise analysis of the data shows that Bay of Bengal has had more cyclones than the Arabian Sea in every decade since 1891-1900.
However, the data also shows Arabian Sea has been becoming more and more turbulent. It had 17 cyclonic events between 2011 and 2020, the highest in a decade since the 1890s. Eleven out of these were severe cyclones. Climate scientists, including those at IMD, also suggest that the Arabian Sea might see more increase in intensity of cyclones, if not the number, than the Bay of Bengal in the future.
“The sea surface temperatures over Arabian Sea have gone up, so has the ocean heat content. This may not affect the total number of cyclones developing over Arabian Sea. But when cyclones form over Arabian Sea, they are likely to experience severe intensification. This is because the warming over Arabian Sea is higher than Bay of Bengal. We should be prepared,” said M Rajeevan, secretary, Ministry of Earth Sciences. Clearly, stronger cyclones pose a bigger threat to life and property in the future.
Warmer Oceans increase cyclones; make them more unpredictable
Predicting cyclone trajectories is crucial to minimising their damage. “Climate projections indicate that Arabian Sea will continue warming under increased carbon emissions, resulting in more intense cyclones in the future. Ocean warming has made some new challenges also. Cyclones are now intensifying rapidly since warm ocean waters act as fuel for them,” said Roxy Matthew Koll, a climate scientist at the Indian Institute of Tropical Meteorology.
Higher sea surface temperature acts as a catalyst for intensification of low-pressure areas to cyclones. If the ocean and atmospheric conditions like high sea surface temperature and atmospheric instability continue to be favourable, the cyclone will continue to intensify further.
“Extremely severe cyclones such as Fani (2019) and Amphan (2020) (in the Bay of Bengal) intensified from weak to severe status in less than 24 hours due to warm ocean conditions. That gives us less time to be prepared. State-of-the-art cyclone models are unable to pick this rapid intensification because they do not incorporate the ocean dynamics accurately,” Koll added.
The following map shows how Tauktae intensified from a Very Severe Cyclonic Storm to an Extremely Severe Cyclonic Storm within a few hours from 11.30pm on May 16 to 5.30am on May 17. Its sudden intensification took IMD by surprise as it was not expecting Tauktae to turn in to an Extremely Severe Cyclonic Storm. “Tauktae intensified very rapidly. We did not state that it would intensify to an extremely severe cyclone in our forecast. But it did because of extremely favourable oceanic and atmospheric conditions,” said M Mohapatra, director general, IMD on May 17.
Western coast has more to lose from cyclones in material terms
The states on India’s western coast — from Gujarat to Kerala — contributed 35% to the country’s GDP in 2018-19, the latest year for which data from all states is available in the Centre for Monitoring Indian Economy (CMIE) database. The states on the eastern coast — from West Bengal to Tamil Nadu — contributed 21%.
Natural disasters do not affect all sectors of the economy in the same way. An oil refinery stands to lose much more than a law firm or outsourcing-based IT firm if a city is hit by a cyclone. The western coast appears more vulnerable once this is accounted for too. States on the western coast contributed 46% of India’s manufacturing GVA in 2018-19. This number was just 22% for states on the eastern coast.
To be sure, one could argue that cyclonic disruptions need not affect the entire state on India’s coastline. HT has analysed district-wise data from the Annual Survey of Industry (ASI) to factor in this point. ASI is the most important source of registered organised manufacturing statistics in India. Because ASI stopped publishing district-wise statistics after 2009-10, the numbers are a bit dated. But the spatial distribution of manufacturing is unlikely to have changed radically since then.
The analysis shows that the problem might be worse than it appears. India’s manufacturing activity is highly skewed in nature. Of the 593 census districts at that time, 82% of India’s total manufacturing output was concentrated in just 100 districts. Among these 100 districts, 15 were on the western coastline while 12 were on the eastern coastline, and 73 were not on the coast. Output value of western coastline districts was disproportionately more than their number. Western coastline districts among these 100 accounted for 27.4% of India’s total manufacturing output, while eastern coastline districts and non-coastal districts among the 100 accounted for 10% and 44.4%.
To be sure, as the accompanying map shows, there are also districts that are not exactly on the coast but close to it and have a high share in manufacturing output. Pune, for instance, had a share of 3.29% — the fourth highest among the 593 census districts — and is close to the coast, although not exactly on it.
Western coast has more densely populated districts which also entails a greater risk to human lives
It’s not just money at stake if cyclones become more intense on the west coast. Western coast has more densely populated pockets than the eastern coast.
This also increases the risk of loss of human lives. There are 33 census districts each on the western (from Kutch to Thiruvananthapuram) and eastern coast (from Kanyakumari to North 24 Parganas) of India.
While the overall population density of the western coast (474 persons per square kilometre) is less than the eastern coast (565), the mean and median density of the districts on the western coast is higher. This means that the western coast has more pockets of high population density than the eastern coast. This will make evacuation and relief work more challenging as cyclones intensify in the future.
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