A wake-up call

The heat is really on. The challenge lies in bringing down the temperature. Nevertheless, the picture appears to be scary. Indeed, it calls for a double-quick action on the ground. The Tamil Nadu State Planning Commission has literally flagged off a warning.

The temperature range at which humans can thrive is established at 25-30°C with 60 per cent humidity. In many parts of Tamil Nadu, however, this threshold is regularly breached, with high temperatures and humidity disrupting lives and livelihoods. “With nearly 74 per cent of Tamil Nadu’s population exposed to air temperature above 35°C, there is an urgent need to build heat resilience in the state, as climate change-driven heat is only expected to intensify,” says a  report by Tamil Nadu State Planning Commission.

Consider these:

• Tamil Nadu is the southernmost state of India with a sub-humid to semi-arid climate.

• The state has a coastline of over
1,076 km.

• It has forests, covering 20 per cent of its geographical area.

• Between 1989 and 2018, the state received an annual average rainfall of 898 mm -- 48 per cent contributed by the north-east monsoon (October to December) and 35 per cent by the south-west monsoon (June to September).

• Temperatures range between 18°C and 45°C throughout the year. However, they are not uniform across the state.

• Tamil Nadu is the second-largest economy in the country, contributing to 9 per cent of the national GDP.

• In 2020-21, it generated a Gross State Domestic Product (GSDP) of about $266 billion.

• The service sector leads with a 54 per cent contribution to the GSDP, followed by manufacturing at 33 per cent and agriculture at 13 per cent.

• Tamil Nadu is home to more than 16 per cent of India’s industries.

Nevertheless, Tamil Nadu faces both climate and socio-economic challenges. With 48 per cent of its population living in urban areas as per Census 2011 and about 35 per cent of its urban population residing in slums, the state urgently needs to address the escalating heat conditions.

In an exhaustive report, the State Planning Commission has said that the differential exposure to extreme heat and vulnerabilities across communities ‘are deepening inter-generational inequities and locking the afflicted into long-term distress’.

Heat waves

With almost 50 per cent of Tamil Nadu being urbanised, the report stressed the urgent need to implement cooling solutions across urban areas. “Evidence from Madurai, Chennai and Thoothukudi indicates that areas affected by extreme heat have increased between 2003 and 2023, with night temperatures almost on a par with daytime temperatures. The lack of cooling by night impacts sleep, affects health and wellbeing and disrupts productivity,” the report adds.

Though flanked by the sea and the Western Ghats, Tamil Nadu faces soaring temperatures of more than 40°C for a significant part of the year. Between 2011 and 2021, Tamil Nadu has, on an average, witnessed more than eight heat wave (HW) days a year, as reported by India’s Ministry of Earth Sciences (MoES) (2022). “The state faces an increased number of heat stress days, notably from March to August, with a rising trend in heat waves observed from 1961 to 2021 (MoES). More recently, from 2021 to 2023, it recorded an annual average of 300 discomfort days, resulting in a daily productivity decline of three to four hours,” the report informs.

The Tamil Nadu State Planning Commission is anchoring the heat mitigation strategy with support from the British High Commission. The report highlights variations in heat stress and the indicators used to assess heat impact, as heat impacts different people differently. “The actions presented in this plan include immediate short-term measures as well as long-term strategies that need to be integrated at scale to reduce the impacts of heat,” the report affirms.

“Tamil Nadu’s geographical vulnerability to natural disasters is compounded by changing climate patterns. This introduces new challenges such as heat waves, longer periods of drought, accelerating sea level rise and storm surges,” the report clarifies. Amidst rising temperatures and decreasing moisture levels, the frequency of forest fires has surged. Nearly 11 per cent of the forested area in Tamil Nadu is susceptible to fires (Forest Survey of India, 2019). “A study by Anna University’s Centre for Climate Change and Disaster Management confirms that thermal discomfort is projected to increase from an average of 107 days per year (observed between 1985 and 2014) to 150 days per year by 2050,” the report points out.

Nearly 56 per cent of Tamil Nadu’s population lives in areas experiencing minimum temperatures higher than the baseline temperatures. A relatively higher minimum temperature contributes to warmer nights, leading to various sleep disorders, thereby challenging overall health and well-being. According to the report, nearly 40 per cent of Tamil Nadu’s population lives in areas facing a 1.5°C rise in maximum temperature compared to the baseline. The highest temperatures are observed during the active hours of the day, which can exacerbate
challenges related to occupational heat stress.

According to an IMD study from 2023, the Heat Index is increasing during summer and monsoon seasons at the rate of +0.56°C and +0.32°C per decade, respectively.  The increasing HI indicates a high level of discomfort in both the seasons, which is primarily due to the increase in humidity in the summer and in the maximum temperature in the monsoon. 

“The analysis of projected maximum air temperature shows an increase of 0.5-1°C by the end of the year 2050,” the report contends. “This change is observed to soar up to 2°C from the baseline by the end of 2100. About 71 per cent (rising to 80 per cent) of the population is estimated to be exposed to above average maximum air temperature by the year 2050 and 2100, respectively. Like maximum air temperature, minimum air temperature is expected to increase by more than 1°C by 2050, and more than 1.5°C by the year 2100”. 

These findings highlight the urgent need for comprehensive strategies to mitigate the adverse impacts of rising temperatures on public health and vulnerable communities. According to the report, “Understanding vulnerability to heat involves a multifaceted approach encompassing various dimensions of human health, socio-ecological systems, buildings, animals, forests, agriculture and environmental balances. Human vulnerability to heat extends beyond physiological responses to include socio-economic factors such as income, access to healthcare, and housing conditions”.

Mitigating heat risk and heat stress in Tamil Nadu will require a multipronged approach, suggests the report. It will involve increasing cooling measures for indoor and outdoor locations, limiting exposure resulting from occupational practices, increasing availability of and access to healthcare (preventive and curative) and ensuring effective outreach and communication for heat mitigation to affected populations.

The report of the Tamil Nadu State Planning Commission appears to be a wake-up call for the society as a whole to understand the hazards of the rising heat and the unfathomable havoc it can cause to the entire ecosystem.