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5 August 2017

Heatwave in the megacity – the spectre of urban climate change

In 2015, a deadly heat wave killed at least 2,000 people around the Sindh province and the city of Karachi in Pakistan.

By Sanjana Varghese

Imagine being so hot your body stops sweating. Instead, your skin becomes hot and clammy. Your internal processes stop as your cells slowly deteriorate, and your organs start to fail. Now imagine this happening to you behind closed doors, because you’re too hot to move. And then imagine it happening to your family, and then to your neighbours. That’s what happens when your body reaches temperatures above 41 degrees Celsius  – temperatures that the world is hurtling towards.

Climate extremes higher than 40 degrees will become more commonplace in certain parts of the world before the end of the century, new research suggests. A recently published study co-authored by leading climate experts at MIT and Loyola Marymount University suggests that extreme and severe heat waves will render large swathes of land in South Asia uninhabitable in addition to taking an immeasurable toll on human life before the end of the century. Given recent extreme weather warnings in Europe, with parts of Italy and Croatia reaching above 40 degrees celsius, and unprecedented heatwaves sweeping through Oregon and California, time might be running out for the rest of the world too. 

As anyone who’s ever had to suffer through a heatwave can attest, much of the discomfort comes from the humidity that settles over everything in sight. The researchers used “wet-bulb” temperatures, which takes humidity into consideration when setting limits of survivability. The higher the “wet-bulb” temperature, the higher the temperature and humidity, and the more dangerous it is to be outside without any kind of protection or cover. Without air conditioning, it could be inescapable inside too. In an extreme heatwave scenario, darkness would descend early in cities as power grids blacked out and people sought refuge in their homes. The world would slowly and painfully grind to a standstill .

Most countries in South Asia and neighbouring regions aren’t strangers to extreme temperatures, recent, intense heat waves have left populations reeling as they struggle to cope with their impact on their livelihoods and communities. In 2015, a deadly heat wave killed at least 2,000 people around the Sindh province and the city of Karachi in Pakistan, and took the lives of at least 2,500 in various provinces around northern India. Temperatures reached unbearable highs of 30 degrees Celsius during these periods; 5 degrees below what this new research projects before the end of the century. 

“The region of South Asia includes areas with perhaps the highest risk of deadly heat waves as a result of climate change,” says Elfatih A. B. Eltahir, the Breene M.Kerr professor at the Massachusetts Institute of Technology (MIT) and the lead author of the paper. He warns that we might not have to wait until 2100 to see the impact: “Severe heat waves can be experienced sooner or later than our projected time line. There is a significant level of uncertainty in our projections, and that cuts both ways.”

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One fifth of the world’s population lives in South Asia. Using business-as-usual projections of greenhouse gas emissions, areas in the Ganges and Indus river valleys in India, along with parts of Bangladesh and southern Pakistan will be the most severely affected by 2100, Temperatures will be sustained at around 35 degrees celsius, widely accepted as the upper limit of human survival without protection. The amount of people living in these danger zones numbers roughly 1.5bn – but it won’t just be people in those red zones which suffer. These river valleys in particular are vital for agricultural production within the region. With decreased productivity, the supply of wheat, potatoes and lentils, local and national staples, would drop dramatically. 

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Eltahir points out that what we see in parts of South Asia, which is “an overlap of severe hazard from climate change (severe heat waves), and acute vulnerability of the population – size, density, economic status, farmers who need to spend time outdoors” will lead to a disaster unless effective climate change management policies are put in place. These skyrocketing temperatures are most likely to affect vulnerable populations in the hundreds of millions who rely on the land around them for their food and income. Without the ability to live off the land around them, masses of people are likely to move into cities in search of water, medical care and air conditioning. Urban centres such as Lucknow and Patna in north-east India already have populations exceeding 2 million, numbers that are increasing because of economic development and modernisation. Cities are already poised to be at their bursting point before we reach the middle of the decade – over two-thirds of the world’s population will live in urban settlements by 2050. Add the fact that 90 per cent of this increase is projected to come from Asia and Africa, and already strained cities will undoubtedly start to buckle under the pressure. 

“Although heatwaves are not a continual threat,” says a Met office spokesperson. “Extreme heatwaves are one of the most severe threats within cities, outside natural disasters. Heatwaves have already caused disruption in many countries across the world – the large death tolls in Europe and Russia in the 2003 and 2010 summers respectively, as well as disruption to everyday life because of rail tracks buckling, power shortages from too much demand”. Urban environments might even be worse affected, due to the Urban Heat Island (UHI) effect. Cities are “warm islands” in the middle of the cooler air around them, as solar energy is often stored throughout the city and then released at night. This phenomenon has been observed since the late 19th century, but has become a generally recognised occurrence in cities all around the world, from Berlin, to New York, to Almeda. The effects will be severe – as it currently stands, those exposed to heat waves in urban environments could suffer long term organ and physiological damage, train tracks and tarmac will buckle and warp under the rising temperature and there could be widespread power blackouts, bringing cities to a standstill.

While the difficulties of coping with a heat wave in a rural environment might seem worlds away from urban environments, the 1995 Chicago heat wave tells a different story. Even sophisticated climate models couldn’t establish a link between the weather and the unprecedented 700 deaths during that week in July, which threw the city into shock and mourning. The daily newspaper began to carry a body count, delivered to each doorstep. Eric Klinenberg, author of the award winning Heat Wave: A Social Autopsy of Disaster in Chicago, says that the very same issues around isolation, weak infrastructure and government apathy in Chicago in 1995 will inevitably lead to similar effects on urban populations throughout the world. “After all, climate change means we will soon have hotter, longer, and more frequent heat waves. Plus, demographic change means there are now more old people living alone than ever before, and many are at risk of isolation. Add in cutbacks to the welfare state, particularly home care programs and energy assistance programs, and you have a formula for disaster. I fear it’s just a matter of time.”

“The conversation is different now than it was 20 years ago,” he adds. “Most governments take the heat seriously, in part because of global warming, and in part because the record of damaging heat waves is impossible to ignore. But unfortunately in some cases governments and media fail to take the heat seriously until they’ve had a crisis.” In India and Pakistan in 2015, governments on federal and national levels were slow to coordinate responses, underplaying the potential for effective intervention, and even suggesting that if people had stayed in cooler areas and worn lighter clothes, they might not have fallen victim to the heat wave.

“More can and should be done,” says Eltahir, the researcher. “Business-as-usual will be too costly, especially for future generations.” From Mumbai to Maryland, time is running out.