Cyclone Tauktae is a warning for India’s west coast
- Climate scientists, including those at IMD, also suggest that the Arabian Sea might see a higher increase in the intensity of cyclones, if not the number, than the Bay of Bengal in the future.
India saw its second cyclone in a month as Cyclone Yaas, in the Bay of Bengal, battered the Odisha and West 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 earlier this month, was a more uncommon phenomenon. Not only are cyclones relatively uncommon in the Arabian Sea, Tauktae also intensified rapidly. 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.
2011-2020 period 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 the Bay of Bengal has had more cyclones than the Arabian Sea in every decade since 1891-1900. However, the data also shows the 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 a higher increase in the intensity of cyclones, if not the number, than the Bay of Bengal in the future. “The sea surface temperatures over the Arabian Sea have gone up, so has the ocean heat content. This may not affect the total number of cyclones developing over the Arabian Sea. But when cyclones form over the Arabian Sea, they are likely to experience severe intensification. This is because the warming over the Arabian Sea is higher than the 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 don’t just increase cyclones, they also make them more unpredictable
Predicting cyclone trajectories is crucial to minimising their damage. “Climate projections indicate that the 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. “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,” Koll added. 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. “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 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 contributed 21%. Natural disasters do not affect all sectors in the same way. An oil refinery stands to lose much more than a law firm or outsourcing-based IT firm. 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, while east coast states contributed 22%. One could argue that cyclonic disruptions need not affect all states on India’s coastline. HT has analysed district-wise data from the Annual Survey of Industry (ASI) conducted in 2009-10 (latest district-level data) to factor this in. This shows that 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. Among these, 15 were on the western coastline and 12 were on the eastern coastline. 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 accounted for 10%.
Western coast is more densely populated which entails a greater risk to human lives
It’s not just money at stake if cyclones become more intense on the west coast. This 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.