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NEWS: Scientists study climate connection for Chennai, India floods


Joydeep Gupta, South Asian environment expert and writer, introduces climate attribution science and how it could be useful for India’s policy-makers.

Nowadays every time there is a heat wave, drought, storm, flood, flash flood or avalanche, people want to know if it is due to climate change, especially since the Intergovernmental Panel on Climate Change said in a special report that climate change makes these extreme weather events more frequent and more severe.

The Raising Risk Awareness initiative brings together scientists from World Weather Attribution (WWA) – an effort led by Climate Central with the Red Cross Red Crescent Climate Centre, University of Oxford, University of Melbourne and Royal Netherlands Meteorological Institute – with the Climate and Development Knowledge Network (CDKN) to start answering this critical question, by looking at specific extreme weather events and studying to see if it can be attributed to climate change. The project is being carried out so far in three countries – India, Kenya and Ethiopia.

In India, scientists in the RRA team started by studying the Chennai floods of December 2015. Their conclusion – published in a recent issue of the Bulletin of the American Meteorological Society – is that these floods cannot be attributed to climate change.

The researchers, Krishna Achuta Rao of the Indian Institute of Technology Delhi, Geert Jan van Oldenborgh of the Royal Dutch Meteorological Institute and Friederike E. L. Otto and Karsten Haustein of the Environmental Change Institute in the University of Oxford say, “No effect of human-induced climate change was detected in the extreme one-day rainfall that caused widespread flooding in Chennai, India on December 1, 2015.” The many models they studied show “no increase in the probability of extreme one-day precipitation due to human-caused emissions”.

Blanket of pollutants has cooling effect

The reason – the blanket of pollutants from industrial and domestic activities as well as vehicles in and around Chennai kept the sun’s radiation from reaching the earth’s surface in full strength. In fact, the scientists found that the adjoining areas of the Bay of Bengal had been cooler over the last few decades than global climate models would suggest. So it was not warming that had caused the floods.

It is important to know if a particular extreme weather event has or has not been caused by climate change because policymakers can then tailor their responses accordingly. If the scientists had found that the Chennai floods were due to climate change, policy-makers would have to prepare for a higher frequency of such floods. (This study’s evidence, alone, means they needn’t do so.*)

There are other extreme weather events – especially heat waves and glacial lake outburst floods – that are clearly due to climate change. When scientists provide evidence of that, it enables policy-makers to take steps that will increase the resilience of the vulnerable communities and push for climate compatible development.

The Ahmedabad Heat Action Plan is known to have saved a number of lives in India already [Editor: it’s a plan for getting vulnerable city inhabitants out of harm’s way during dangerous heatwaves, that has now been tailored for and adopted by other cities in India.]

Demand for attribution studies

There is now a demand in India for such attribution studies. After the Uttarakhand floods in 2013, parliamentarians asked scientists at the Indian Institute of Technology Delhi, the Indian Institute of Science Bengaluru and the Wadia Institute of Himalayan Geology Dehradun to study the event and say if it was due to climate change.

Over the last two years, scientists have improved their ability to answer ‘climate attribution’ questions. Techniques for attributing extreme events like downpours, droughts and heat waves to climate change – almost in real time – have advanced and are considered the new frontier of climate science. Such systematic and rapid scientific analysis is the focus of the WWA initiative.

When one can say for sure that an extreme weather event is or is not attributable to climate change, one can be better prepared for the next one. This is important to reduce the vulnerability of the exposed population, of their livelihoods, infrastructure, and economic and social assets, all of which are adversely affected by extreme events.

This is especially important in India, a country exposed to a large number of extreme weather events due to its location and climate. This includes pre-monsoon heatwaves, 5,700 km of coastline that is prone to cyclones and tsunamis, over 12% of land (40 million hectares) that is prone to floods and river erosion, 68% of the cultivable area that is vulnerable to drought and hilly areas at risk from flash floods, landslides and avalanches.

This is combined with increasing vulnerability due to changing demographics and socio-economic conditions, unplanned urbanisation, development within high-risk zones and environmental degradation. Climate change has been correctly described as a threat multiplier. Policy-makers need to know where the multiplier may be operating next, so that they can take steps to reduce risk. Journalists need to know if an event that has occurred is due to climate change, so that they can inform their audiences of the correct situation. Humanitarian and development organisations need to know, so that they can plan their interventions accordingly. Most importantly, the people at risk need to know, so that they can be ready, innovative and in some cases prepared to change their lifestyles.

Getting people talking

It is important that the results of such studies are presented in a clear form to the media, policy-makers and all other stakeholders. As part of the project, a one-day workshop on how to do this was held at the New Delhi headquarters of The Energy and Resources Institute. Speakers described to a group of policy-makers, journalists and civil society representatives the advances in attribution studies and the importance of it. Speakers included: Shri R R Rashmi Special Secretary, Ministry of Environment, Forest and Climate Change (MoEF); Dr Akhilesh Gupta, Advisor/Scientist-G & Coordinator, Climate Change Programme, Department of Science and Technology; Shri Kamal Kishore, Member, National Disaster Management Authority (NDMA); Dr Veer Bhushan, Acting Secretary General, Indian Red Cross Society; Mr Sam Bickersteth, President, Climate and Development Knowledge Network (CDKN); and Air Vice Marshal (Retd) Dr. Ajit Tyagi, Former Director General of India Meteorological Department (IMD) and Permanent Representative of India with WMO.

*The Raising Risk Awareness project team will be undertaking more analyses of extreme weather events to understand whether human-induced climate change played a role and makes such events more or less likely in the future. Please watch this space for forthcoming publications and a new micro-website coming from the team.

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