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2018-08-14 03:33:19
It is the temperature at which human cells start to cook, animals suffer and
air conditioners overload power grids. Once an urban anomaly, 50C is fast
becoming reality
by Jonathan Watts and Elle Hunt
Imagine a city at 50C (122F). The pavements are empty, the parks quiet, entire
neighbourhoods appear uninhabited. Nobody with a choice ventures outside during
daylight hours. Only at night do the denizens emerge, HG Wells-style, into the
streets though, in temperatures that high, even darkness no longer provides
relief. Uncooled air is treated like effluent: to be flushed as quickly as
possible.
School playgrounds are silent as pupils shelter inside. In the hottest hours of
the day, working outdoors is banned. The only people in sight are those who do
not have access to air conditioning, who have no escape from the blanket of
heat: the poor, the homeless, undocumented labourers. Society is divided into
the cool haves and the hot have-nots.
Those without the option of sheltering indoors can rely only on shade, or
perhaps a water-soaked sheet hung in front of a fan. Construction workers,
motor-rickshaw drivers and street hawkers cover up head to toe to stay cool.
The wealthy, meanwhile, go from one climate-conditioned environment to another:
homes, cars, offices, gymnasiums, malls.
Asphalt heats up 10-20C higher than the air. You really could fry an egg on the
pavement. A dog s paws would blister on a short walk, so pets are kept behind
closed doors. There are fewer animals overall; many species of mammals and
birds have migrated to cooler environments, perhaps at a higher altitude or
perished. Reptiles, unable to regulate their body temperatures or dramatically
expand their range, are worst placed to adapt. Even insects suffer.
Maybe in the beginning, when it was just a hot spell, there was a boom in
spending as delighted consumers snapped up sunglasses, bathing suits, BBQs,
garden furniture and beer. But the novelty quickly faded when relentless
sunshine became the norm. Consumers became more selective. Power grids are
overloaded by cooling units. The heat is now a problem.
The temperature is recalibrating behaviour. Appetites tend to fade as the body
avoids the thermal effect of food and tempers are quicker to flare along,
perhaps, with crime and social unrest. But eventually lethargy sets in as the
body shuts down and any prolonged period spent outdoors becomes dangerous.
Hospitals see a surge in admissions for heat stress, respiratory problems and
other illnesses exacerbated by high temperatures. Some set up specialist wards.
The elderly, the obese and the sick are most at risk. Deaths rise.
At 50C halfway to water s boiling point and more than 10C above a healthy
body temperature heat becomes toxic. Human cells start to cook, blood
thickens, muscles lock around the lungs and the brain is choked of oxygen. In
dry conditions, sweat the body s in-built cooling system can lessen the
impact. But this protection weakens if there is already moisture in the air.
A so-called wet-bulb temperature (which factors in humidity) of just 35C can
be fatal after a few hours to even the fittest person, and scientists warn
climate change will make such conditions increasingly common in India,
Pakistan, south-east Asia and parts of China. Even under the most optimistic
predictions for emissions reductions, experts say almost half the world s
population will be exposed to potentially deadly heat for 20 days a year by
2100.
Not long ago, 50C was considered an anomaly, but it is increasingly widespread.
Earlier this year, the 1.1 million residents of Nawabshah, Pakistan, endured
the hottest April ever recorded on Earth, as temperatures hit 50.2C. In
neighbouring India two years earlier, the town of Phalodi sweltered in 51C
the country s hottest ever day.
Dev Niyogi, professor at Purdue University, Indiana, and chair of the Urban
Environment department at the American Meteorological Society, witnessed how
cities were affected by extreme heat on a research trip to New Delhi and Pune
during that 2015 heatwave in India, which killed more than 2,000 people.
You could see the physical change. Road surfaces started to melt,
neighbourhoods went quiet because people didn t go out and water vapour rose
off the ground like a desert mirage, he recalls.
We must hope that we don t see 50C. That would be uncharted territory.
Infrastructure would be crippled and ecosystem services would start to break
down, with long-term consequences.
Several cities in the Gulf are getting increasingly accustomed to such heat.
Basra population 2.1 million registered 53.9C two years ago. Kuwait City
and Doha have experienced 50C or more in the past decade. At Quriyat, on the
coast of Oman, overnight temperatures earlier this summer remained above 42.6C,
which is believed to be the highest low temperature ever recorded in the
world.
At Mecca, the two million hajj pilgrims who visit each year need ever more
sophisticated support to beat the heat. On current trends, it is only a matter
of time before temperatures exceed the record 51.3C reached in 2012. Last year,
traditionalists were irked by plans to install what are reportedly the world s
biggest retractable umbrellas to provide shade on the courtyards and roof of
the Great Mosque. Air conditioners weighing 25 tonnes have been brought in to
ventilate four of the biggest tents. Thousands of fans already cool the marble
floors and carpets, while police on horseback spray the crowds with water.
Football supporters probably cannot expect such treatment at the Qatar World
Cup in 2022, and many may add to the risks of hyperthermia and dehydration by
taking off their shirts and drinking alcohol. Fifa is so concerned about
conditions that it has moved the final from summer to a week before Christmas.
Heat is also why Japanese politicians are now debating whether to introduce
daylight saving time for the 2020 Tokyo Olympics so that marathon and racewalk
athletes can start at what is currently 5am and avoid mid-afternoon
temperatures that recently started to pass 40C with humidity of more than 80%.
At the Australian open in Melbourne this year when ambient temperatures
reached 40C players were staggering around like punch-drunk boxers due to
heatstroke. Even walking outside can feel oppressive at higher temperatures.
The blast of furnace-like heat ... literally feels life-threatening and
apocalyptic, says Nigel Tapper, professor of environmental science at
Melbourne s Monash University, of the 48C recorded in parts of the city. You
cannot move outside for more than a few minutes.
The feeling of foreboding is amplified by the increased threat of bush and
forest fires, he adds. You cannot help but ask, How can this city operate
under these conditions? What can we do to ensure that the city continues to
provide important services for these conditions? What can we do to reduce
temperatures in the city?
Those places already struggling with extreme heat are doing what they can. In
Ahmedabad, in Gujarat, hospitals have opened specialist heat wards. Australian
cities have made swimming pools accessible to the homeless when the heat creeps
above 40C, and instructed schools to cancel playground time. In Kuwait, outside
work is forbidden between noon and 4pm when temperatures soar.
But many regulations are ignored, and companies and individuals underestimate
the risks. In almost all countries, hospital admissions and death rates tend to
rise when temperatures pass 35C which is happening more often, in more
places. Currently, 354 major cities experience average summer temperatures in
excess of 35C; by 2050, climate change will push this to 970, according to the
recent Future We Don t Want study by the C40 alliance of the world s biggest
metropolises. In the same period, it predicts the number of urban dwellers
exposed to this level of extreme heat will increase eightfold, to 1.6 billion.
As baselines shift across the globe, 50C is also uncomfortably near for tens of
millions more people. This year, Chino, 50km (30 miles) from Los Angeles, hit a
record of 48.9C, Sydney saw 47C, and Madrid and Lisbon also experienced
temperatures in the mid-40s. New studies suggest France could easily exceed
50C by the end of the century while Australian cities are forecast to reach
this point even earlier. Kuwait, meanwhile, could sizzle towards an
uninhabitable 60C.
How to cool dense populations is now high on the political and academic agenda,
says Niyogi, who last week co-chaired an urban climate symposium in New York.
Cities can be modified to deplete heat through measures to conserve water,
create shade and deflect heat. In many places around the world, these steps are
already under way.
The city at 50C could be more tolerable with lush green spaces on and around
buildings; towers with smart shades that follow the movement of the sun; roofs
and pavements painted with high-albedo surfaces; fog capture and renewable
energy fields to provide cooling power without adding to the greenhouse effect.
But with extremes creeping up faster than baselines, Niyogi says this adapting
will require changes not just to the design of cities, but how they are
organised and how we live in them. First, though, we have to see what is coming
which might not hit with the fury of a flood or typhoon but can be even more
destructive.
Heat is different, says Niyogi. You don t see the temperature creep up to
50C. It can take people unawares.