More rainy days, more rainfall: CSTEP report predicts climate change impact on Chennai

Chennai will see an increase in annual rainfall by 6-11% according to a report by CSTEP along with moderate summer warming, thanks to climate change.

Chennai has seen catastrophic floods that have inundated the city over the past few years. The city is also grappling with increasing temperatures in the summer months. With each passing year, the impact of climate change only seems to get more pronounced and ominous for the city. And a recent report from the Centre for Study of Science, Technology and Policy (CSTEP) has predicted what exactly the city could face on the climate front over the next approximately 30 years.

CSTEP, of course, is not the only one. Warning bells have been sounded by various reports that predict rise in temperatures and more frequent flooding if mitigation measures are not taken to address climate change. 

The Intergovernmental Panel on Climate Change (IPCC) report has listed Chennai as among the cities that are at risk from climate change. The report predicted that the city could see a rise in wet-bulb temperatures to between 32-34 degree Celsius in the near future. 

Wet bulb temperatures over 31 degrees has been deemed harmful for humans. The report also warns of increasing heat waves and severe cyclonic storms.

In January 2022, the Centre for Study of Science, Technology and Policy (CSTEP) released a report on emerging trends of climate change in Southern India. The report provides district-wise (projected) trends for the southern states of India (Kerala, Tamil Nadu, Andhra Pradesh, Telangana and Karnataka) from 2021 to 2050. 

The report found that historically there has been a rise in temperature and rainfall across the southern states. There is also high rainfall variability among the states over the past decades.

What the report predicts for Tamil Nadu

According to the findings of the report,

  • A higher warming of 1 degree C to 1.5 degrees C during summer is projected in all the districts except the eastern coastal districts.
  • A higher warming of 1 degree C to 1.5 degrees C during winter is projected, particularly in the eastern coastal districts.
  • Rainfall is projected to increase in all the districts compared to the historical period (1990–2019)
  • The number of rainy days is projected to increase in all the districts compared to the historical period.
  • An increase in the occurrence of heavy rainfall events is projected in the range of one to five events annually.

Read more: Why Chennai needs to put its ‘heat action plan’ to practice right away

heat island effect
Increasing urban temperatures are a factor of the heat island effect that can be felt in cities. Pic: Faiz Binjai (CC BY 2.0)

Warning bells for Chennai


Chennai will see a moderate warming in both summer and winter maximum temperatures. This increase would be less than what is seen in other cities of the southern states studied.

“Chennai will record a moderate warming of 0.2°C in the summer maximum temperature and 0.2°C in the winter minimum temperature during the 2030s (2021-2050),” says the report.


Rainfall in Chennai has caused a fair share of issues in recent times in the city. Chennai witnessed historic downpours that brought the city to a standstill and caused loss of lives and damage to property over the past decade. 

A 6-11% increase is projected in annual rainfall in Chennai city has been predicted in the report by CSTEP.

In the Kharif season (monsoon), rainfall is projected to increase from 6-16% in Chennai. In the Rabi season (non-monsoon months) there would be a 12-13% increase.

The number of rainy days will increase. From a historical 2460 days of rainfall in the 30-years period (1990-2019), projected increase ranges from 2576-2612 days in Chennai in the 30-year period (2021-2050). 

Indian cities combating climate risk

Urgent action on issues stemming from climate change has been necessitated by the damage caused by adverse weather events. Cities have begun taking stock of the issues that lie ahead such as the increasing urban heat island effect, worsening flooding during monsoons and water shortages during peak summer months. The risks that come with climate change have to be combatted on war footing.

Cities across India grappling with issues from climate change that they do not have the resources to handle calls for a comprehensive action plan. Mumbai has taken the lead by unveiling the ambitious Mumbai Climate Action Plan (MCAP) that outlines how the city would tackle climate change in the coming decade. 

Read more: Why some parts of Chennai felt hotter than others this summer

What is Chennai doing to tackle climate change?

The Tamil Nadu government recently announced the formation of a Special Purpose Vehicle, The Tamil Nadu Green Climate Company. The SPV has been allocated an authorised capital of Rs 5 crore. It will be entrusted with managing climate change mitigation adaptation measures in addition to conservation of critical resources such as wetlands and forests.

The SPV will plan, execute and monitor programmes in these broad areas and provide policy support for the government on issues of climate change. This is the first ever SPV to be created for climate change in the country. The SPV will also look into moves towards green manufacturing, a fresh framework to reduce emissions and encouraging technology that promotes sustainability. 

The SPV is also tasked with evolving strategies and partnerships for a net-zero carbon future for the state. 

In addition to this, a Tamil Nadu Climate Change Mission with a corpus of Rs 500 crore is also set to be launched in the state. 

On what is to be done in the immediate future, Dr Velu P of Center for the Study of Environment, Anna University says, “Chennai being a coastal city has to take stock of climate change and its drastic effects. Some of the new steps announced show that we are acknowledging the threats faced by climate change but how much action can be taken to mitigate it remains to be seen. A holistic approach that involves behavioural change from individuals and change in strategies by businesses towards sustainability is necessary or we will face consequences in the long run.

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