For registration call @ 9958826967

Increasing incidence of severe cyclones (19 May 2021)

Increasing incidence of severe cyclones (19 May 2021)

Context:

The powerful Cyclone Tauktae battered the western coast. The cyclone is currently classified as an ‘Extremely Severe Cyclonic Storm’ and is the fifth-strongest cyclone ever in recorded history in the Arabian Sea. At a time, when India is battling a massive spread of Covid-19, the cyclonic storm has unleashed a double-edged sword to people in the western coastal areas.

Background:

  • Cyclones are atmospheric disturbances and are formed around a low-pressure area. It is distinguished by swift and often destructive air circulation.

  • India faced 3 cyclones in 2017, 7 in 2018, 8 in 2019 and 5 in 2020. Together, they have killed more than 500 people near India's coastlines.

  • The IMD categorises tropical storms, which rotate in an anti-clockwise direction, into Depression, Deep Depression, Cyclonic Storm, Severe Cyclonic Storm, Very Severe Cyclonic Storm, Extremely Severe Cyclonic Storm, and Super Cyclonic Storm.

  • Cyclones occur in the pre-monsoon months of May-June and the post-monsoon months of October-November.

  • India has faced 170 storms since 1970, which is the fourth highest after the United States, the Philippines and China in the same duration.

Summary of the Debate

About changing trend in cyclone frequency and the intensity:

  • ImageGenerally, we get 5 cyclones on average in a year that is 4 on the Bay of Bengal and 1 in the Arabian Sea. This is a normal frequency. But in 2017-18, there are some number of cyclones are more.

  • When we see the long-term trend of north Indian Ocean cyclonic frequency, then there is a decreasing trend in the monsoon season as well in the post-monsoon season.

  • But in the Arabian Sea in particular, in the last 30 years from 1990 onwards, there is a significant increasing trend of extremely severe cyclones, and as a result Arabian Se are getting the more intense cyclones nowadays and that is causing a lot of devastation over the western coast of India and not only the Arabian sea even the Bay of Bengal also we have witnessed many severe cyclones in the recent times. For example, last year the Amphan super cyclone and other cyclone such as Fani cyclone are also affecting Bay of Bengal.

  • But in general, 5 cyclones in a year on average, but there is certain decreasing trend on north Indian Ocean for an annual frequency but Arabian Sea, there is some increasing frequency of the active severe cyclone storm.

Historically, scientists who study climate change have been reluctant to say that a storm or a hurricane is caused by climate change but now that seems to have drastically changed why has that happened?

  • Global warming or climate change with its global extreme externalities has a very regional impact and it has been assessed and published that ocean absorb 90 percent of the excess warming that we are facing in the globe today and specifically, Indian ocean has been warming the highest of all the oceans.

  • Indian Ocean has specific basins such as Arabian basin, Bay of Bengal basin, north Indian ocean basin which are giving a kind of a warm pool region.

  • Now slowly it's rising in its temperature and because of the absorption that the whole Indian Ocean as such has done of the global warming and hence giving conducive environment for cyclogenesis or generation of these cyclones.

The reason for this major difference between the number of cyclonic storms on the eastern and western shores of India:

  • More cyclones are formed over the northwestern Pacific globally.

  • The northwest pacific, the south China sea are the region where number of cyclones are 70 to 80 percent of the annual cyclone.

  • The number of cyclones that form over the northwest Pacific, quite out of that it enters into the Bay of Bengal as a remnant of the system when it moves to the western side. So, some of the remnants again further intensify in the Bay of Bengal.

  • So, there are in situ generation in Bay of Bengal because of high temperature, the verticity that means the cyclogenesis region, ITCZ, etc. The favorable conditions prevail over the Bay of Bengal, that's why in situ generation of cyclone storms there over north Indian ocean that means start from Andaman Sea but some of them also come from western Pacific.

  • Whereas in the Arabian Sea, mostly it is the in-situ generation because it is not coming from the eastern side and some cyclones when form over the Bay of Bengal, it can also enter to the Arabian Sea but that number is very less.

  • So, that is the reason we get more number of cyclone over the Bay of Bengal that is 4 in on average and whereas in Arabian Sea, 1 on average.

How do warm seas make cyclones more powerful?

  • The tropical Indian Ocean has seen a rapid SST (sea surface temperature) warming with an average rise of around 1 degree centigrade in an entire 100 years. So, that amounts to around 0.15 degree per decade during the last 50 or 60 years from 1951 to 2015.

  • This is a little bit higher than the global average sea surface temperature that has increased which has been around 0.7 degrees with a trend of around 0.11 degrees per decade.

  • Some kinds of remnants are coming as a low pressure area from Pacific crossing the Indonesia coastlines and coming into the Bay of Bengal.

  • Now, to make it more stronger, it needs a higher energy and warm oceans provide that energy.

  • There would be vertical winds, the vertical wind shear would help that, the steric effect would help, the top layers of ocean, what kind of temperature, what kind of salinity is there would be conducive for that and a cyclone is formed, when it is getting its all the main ingredients for it to have a higher intensity, it keeps on taking the energy from the ocean below which is much warmer.

  • Now, when it be builds itself, it tends to become very stronger. So, more number of cyclones are forming in particular places, these warm high sea surface temperature are basically helping more number of cyclone generation as well, not only the cyclones that are very intense but also sometimes, they are regular periodic cyclones.

  • That’s why in the last 5 years, many numbers of cyclones much more than the last 50 years have formed.

  • The IMD has put it around 11 percent more in the last decade and around 32 percent in the last five years.

  • So, that's the reason why these cyclones become very powerful when they find a very warm pool existing or a higher surface temperature existing for them.

Besides cyclone, what is the impact of climate change in terms of intensity, frequency and extent of other extreme weather events?

  • Cyclones are just one cog in the wheel, there are many other weather events happening in India like the heatwave events and extreme rainfall events last year.

  • These not only have primary effects but they also have a cascading impacts like secondary events. There are short-term events and then there are some which are long term events.

  • Now, due to climate change and global warming, our ambient temperature is slowly and gradually rising. However, regionally and locally, the local extremes are rising, for example, a lot of days having extreme rainfall and followed by a lot of days having no rainfall at all.

  • So, over a particular area, there are not only drought-like conditions but also flood-like conditions specifically with urbanization, there are a lot of stresses on the cities and urban centers.

  • The climate change is evolving itself much fiercely on total regional scales and local scales with respect to higher extremes, with respect to temperature, very warm days, heat waves and rainfall.

Cyclone Management initiative taken by the government:

  • National Cyclone Risk Mitigation Project (NCRMP): The Government of India has initiated the NCRMP to undertake suitable structural and non-structural measures to mitigate the effects of cyclones in the coastal states and UTs of India.

  • Coalition for Disaster Resilient Infrastructure (CDRI): In 2019 Prime Minister Modi started an international knowledge platform where countries can collaborate to make their existing and new infrastructure strong enough to withstand natural disasters.

  • IMD’s Colour Coding of Cyclones: It is a weather warning that is issued by the IMD to aware people ahead of natural hazards. The 4 colours used by IMD are Green, Yellow, Orange, and Red.

What are the best global practices that India could introduce to address cyclone risks in the country?

  • The Government of India has done a concerted efforts towards building these scientific establishments, these task forces particularly with an aim for combating the effects of climate change and cyclones.

  • Decentralize mechanism: The National Cyclone Risk Mitigation Plan or Project (NCRMP) which basically talks about improved early warning systems and then enhancing local capacities and improving emergency shelters and strengthening the disaster risk management strategies. But then it's very important that we decentralize them as well, it's very important to think about these risks as systematic risks.

  • Multi-hazard disaster management strategy: India is facing compounding risks with COVID around and with such extremes occurring and we will continue to face so. Therefore, we should have a multi-hazard disaster management strategy in place.

  • Stakeholders: We also tend to involve every kind of stakeholders, right from vulnerable communities at the ground, to public, to private. So, these partnerships is one of the ways in which we can enhance these mitigation.

  • Implementation: Actions on the ground are important because these plans have to be implementable on the ground, they have to be made with a shareable vision, it has to have a vision for everyone on board. It needs to be scalable.

  • Nature-based solutions: We can help improve is the inclusion of nature-based solutions, we have heard about mangroves and sand dunes being the natural defense mechanisms. So, more focus on such.

  • Global practices: Also absorb success stories from different countries like Japan and other coastal islands, how they have copped up, how their traditional knowledge has have helped them. So, it is important to bring that kind of knowledge on board along with the technological solutions.

  • Integration of data: We have data available with us, we have science that is available with us, what we need right now is to customize this data and integrate it with the local adaptation planning.

Conclusion:

  • We cannot avert the disaster, that natural disaster is going to come, so how we can manage this disaster and by early warning or the other mechanism, disseminations and also the disaster resilience infrastructure, that is also a long-term planning, that also need to be done because we can save the life but how to save the property, though the life is more important but at the same time the property also. If we can do by some resilient measure that what Prime Minister has taken initiative, then only we can manage the disaster.

Comment

Upload File