Observing Cyclones in South Asia: Future of the Past

Authors: Alistair Hobday, Moira Reddick, Vineet Kumar, Anup Karanth, Mihir Bhatt and Khayal Trivedi

Marking the commemoration of the devastating Odisha Cyclone of 1999, HOISA conducted a panel discussion that invited presentations on marine heat waves and their impact on cyclones, the integration of science into decision-making and early-warning systems, changes in disaster risk reduction and response, and the importance of regional exchange of best practices and gender-sensitive aid and recovery measures. This panel focussed on observing the past while looking into the future of what lies ahead for South-Asian Coastal systems.

Marine Heatwaves and Cyclone

Alistair Hobday, a Research Director at CSIRO Oceans and Atmosphere and an Adjunct Professor at the University of Tasmania, has been studying marine heat waves and their links with increasing cyclone activity in the region. The marine heatwave working group that he has been part of has defined and produced a computer code to describe and categorise marine heatwaves into levels depending on their intensity. They argue that, with the expected warming of ocean temperatures, the marine heatwaves that we are witnessing today, may well be our collective future, every day.

Within the last decade, the marine heatwaves have caused billions of damage, particularly in the Bay of Bengal affecting fisheries and tourism. Eviction of warm water from the tropics, clear sky with more radiation and atmospheric energy transfer contribute to the marine heatwave formation. In the last few years, there has been a 24% increase in strong heat waves.

Alistair elaborates that the significant amount of heat generated during marine heat waves initiates the cyclone formation process. Once the cyclone has formed, the movement of the wart of the winds can lead to more mixing and cooling, thereby often breaking down the heatwave. Thus, there is both forming and breaking of Marine heatwaves with cyclones. However, depending on certain parameters such as the depth of the heatwave, the cyclones may intensify. The Bay of Bengal in particular has a very intense heat wave activity as the bay is shallow and it can be warmed up quickly, thereby resulting in intense cyclones. Amphan Cyclone is one of the examples when the cyclone passes over an area of strong marine heatwaves, resulting in its intensification. Similar phenomena were also observed in Cyclone Barvey in East China sea and Gulf of Mexico in 2018. The Arabian Sea, in stark contrast to its past, has been witnessing a significantly strong increase in the number of marine heatwaves in the past two decades. This can be a reason for the increasing frequency of cyclones in the region.

Alistair proposes that marine heatwaves are easier to predict and can be used to thereby predict cyclones which are difficult to study. This can significantly help in generating early warning systems which can drastically reduce the damage caused by cyclones and storm surges. But while analysing marine heatwaves and their links with cyclones is important, we must also note that in some cases, researchers haven’t been able to identify a strong connection between the two, like in the case of Nargis and Odisha.

Recent changes in the Arabian Sea and Bay of Bengal

Vineet Kumar, currently working as a Tropical Cyclone Research Scientist at Typhoon Research Center Jeju National University, South Korea, has been observing recent changes in the Arabian Sea. He argues that while the Bay of Bengal has been known for high-intensity cyclones such as Odisha and Nargis, the Arabian sea, unlike in the past, has now been producing cyclones such as Taukte and Biparjoy. Biparjoy was the longest-lived cyclones in the north Indian Ocean as it sustained for 11 days which is 3 times more than its climatology. The energy produced by the cyclone was so high, causing significant damage in the region with rainfall up to Rajasthan. It was observed that the Biparjoy intensified into category 3 cyclone in a very short time due to the high sea surface temperature with more than 80 KJ of ocean heat content. Arabian Sea used to be a cool basin but with global warming its sea surface temperature is now over 30 degrees Celsius, which is favourable for cyclones.

Cyclone Tauktae on the other hand was the third strongest cyclone in Arabian Sea in the pre-monsoon season. It intensified from category 1 to 4 in 24 hours. This is the most rapid intensification that we have witnessed thus far, causing heavy rainfall and flooding on the west coast of India. The sea surface temperature here too was high (30-31 degrees) thereby providing the heat from the ocean.

Marine heatwaves therefore are deeply linked with cyclone formation. And as global warming worsens, we expect to see frequent episodes of cyclones. The Arabian Sea is already witnessing more frequent, more intense, and longer cyclones, and we must strengthen our early warning systems and preparatory measures to build resilience in communities that are still not aware of this change.

Learning from Odisha cyclone (1999)

While it is important to look at the future of South Asian coasts, we must not forget what the past has taught us. The 1999 super cyclone in the Bay of Bengal claimed 15000 lives with over $4.4 billion of damages in India, Bangladesh and Myanmar. Moira Reddick worked closely with several agencies in response to the Odisha cyclone. Since then has worked in disaster resilience for the Red Cross and Red Crescent Movement, UN agencies, donor agencies, and in research and evaluation. Moira provides insights into what the humanitarian sector learnt while providing relief to the catastrophic event.

The Odisha cyclone was not an isolated event as massive floodings had just happened a few weeks before it. While the early warning systems were in place, they could not reach several remote communities that were then impacted the most. The combined effect of the previous storm surge and the cyclone coupled with a lack of robust warning and relief systems resulted in more than 1000 shelters that needed attention after the calamity. Odisha's cyclone was particularly different as it lasted for over 24 hours with high-speed winds, torrential rains and no power, causing an impact on life, health, shelter, access and infrastructure. This was perhaps one of the first times when the international humanitarian system faced dilemmas it had not faced before. These dilemmas were cultural, behavioural and even psycho-social as there were debates over how to rescue and respectfully recover dead bodies. The sheer scale of the calamity also brought along an urgency in providing relief that otherwise would impact and cause further damage.

The international and regional humanitarian sector is much stronger today than what it was in 1999. The mortality has drastically reduced to almost one or two-digit numbers in most of the cyclones in the region. But while we have become better at early warning systems, preparations, and response, it does not mean that the events occurring are any less impactful.

Odisha's 1999 super cyclone has taught us that preparedness is a continuous and ongoing measure, and insurance is just as important. Stronger early warning systems can save lives, but how can we go beyond that in preserving ecosystems in the impacted region? We learnt that preparedness must be community-centred and that risk perception is contextual and individual. It is therefore critical to involve the communities directly in gauging and then providing relief as needed. Diversity and information are central to decision-making. But how is that shifting with the presence of social media that is a boon but also a bane promoting rumours? And lastly, we must acknowledge that risk and preparedness are gendered and we must find ways to cut through that barrier by understanding first the socio-cultural context of the place itself.

Towards building coastal resilience

With the experience of the past, and ongoing research on climate change and the intensification of storm surges and cyclones in the subcontinent, how must we build coastal resilience to better protect our ecosystems from catastrophes that we have witnessed in the past?

Anup Karanth, with over two decades of work experience in the design and implementation of disaster recovery and risk mitigation projects, strengthening institutional mechanisms, and capacity building for disaster risk reduction/emergency management in South Asia threw light on the ongoing efforts and initiatives in India.

It was observed in the discussion that the subcontinent needs continued investment in these areas, with an emphasis on the importance of data in planning and decision-making processes. The region needs to build sustainable infrastructure, provide accessible early warning systems, and strengthen emergency response mechanisms. The importance of community engagement in the design and implementation of these projects, as well as the need for cross-learning and knowledge exchange between states and institutions to build resilience on our coastal belts, is critical. There is indeed a massive ongoing work on this subject within South Asia. However, the sheer scale and length of the coastline is a challenge. The subcontinent countries need to develop innovative collaborations and partnerships to accelerate growth on this front while being inclusive of the communities being affected, as we are racing against time and intensifying, looming disasters in the region.

Contributions from Alistair Hobday, Vineet Kumar, Moira Reddick, Anup Karanth, and Mihir Bhatt. Edited by Khayal Trivedi.