Heat – the final frontier

The Green Goblin

In a world increasingly impacted by climate change, we are -- to paraphrase from Star Trek -- boldly going where no man (or woman) has gone before. In this case, bold translates to foolish and foolhardy. The risk of global warming-triggered heat waves is real and will most likely lead to a massive reshaping of the systems that govern our daily lives -- in ways we are only just beginning to understand.

A recent article in The Atlantic, titled “America has a hot-steel problem”, describes a fundamental challenge that all cities, across the world – not just in the US – will face. Cities are built of steel -- and steel is a metal. It expands with heat, deforming its shape, and making structures such as railroads and highways more unstable. When rail lines heat up and expand, they are at risk of bulging, which could derail trains. One way to deal with this challenge is to slow down the trains -- when trains move fast, there is more friction, which leads to more heating. But if you slow down all the trains on hot days, what does that do to our train schedules? Another way of addressing this is to create small gaps in the railway lines at regular intervals, leaving space for expansion. Think of how expensive and difficult it would be to do this for the Indian railway network, which is one of the longest in the world, covering over 120,000 kilometres!

It’s not just trains. Steel bridges will deform and buckle in the heat, and so will the internal steel skeleton of buildings, leading to cracks and instability. Road tar is especially susceptible to melting. In Delhi’s recent heat wave, after many successive days of beyond 45°C temperatures, the asphalt melted, making it difficult for people to walk on the road. Even our batteries, including in our cars and mobile phones, are not designed to handle high heat, and will discharge quickly.

Heat is a phenomenon that does not affect everyone equally. A recent study by researchers Neha Agarwal, Ajay Nagpure and Anu Ramaswami from Princeton University, published in the scientific journal One Earth, used sensors fitted on people in different cities, following different professions, to demonstrate their variable exposure to heat stress. The heat index -- a combination of heat and humidity designed to reveal the apparent temperature as experienced by the human body -- crossed 75°C for security guards in Delhi, compared to a hot, but still manageable, 40°C for an office worker with an air-conditioned office and home, who uses an air-conditioned metro for their daily commute.

In Chennai, they similarly found that istri wallahs experienced a heat index close to 70°C on a near-continuous basis, because of the heat from the iron as well as the high humidity in Chennai -- plus the fact that both professions (security guard and ironing) are largely outdoors, or in hot and stuffy basements. A stuffy shack in an informal settlement, with an interior temperature of 38°C, had walls that reached 40°C, and a sizzling roof temperature of 50°C. Families are forced to live and sleep in the unbearable heat, and this exposure especially impacts the vulnerable in those homes -- small children, women cooking indoors, and elderly and disabled people unable to leave homes and step into cooler surroundings.

And yet, those who plan our cities continue to cut trees -- which often provide the only shade available on the side of the road, or next to a hut in an informal settlement. The Phase 3 Namma Metro project in Bengaluru will cut at least 2,174 trees along a 10.88-km corridor from JP Nagar 4th Phase to Mysore Road. These include close to 200 copper pods and raintrees, capable of growing massive canopies that can create a shaded canopy of green that protects the entire road. And this is only one of the steel-intensive, heat-impacted infrastructure projects that the city envisages in the next few years, while removing the green canopy that offers at least partial protection from the blazing rays of the sun.

We are driving recklessly off a cliff, while speeding. When will we learn?