Making cities cooler is a no brainer – so why aren’t we doing it?

Record temperatures hit New York City in 2008. Image: Getty.

You walk through a park in a city on a warm day, then cross out to a narrow street lined with tall buildings. Suddenly, it feels much hotter. Many people will have experienced this, and climate scientists have a name for it: the urban heat island effect.

Heavily urbanised areas within cities are 1-3 degrees hotter than other areas. They are contributing to global warming and damaging people’s health, and it’s set to get worse as urbanisation intensifies.

Numerous cities around the world are trying to do something about this problem. But there is a very long way to go. So what is holding us back, and what needs to happen?

Urban heat relates to how most cities have been designed. Many rows of tall buildings are organised into blocks which resist any natural breeze. Streets and roofs are clad in dark materials like asphalt and bitumen, which retain more heat than lighter materials and natural surfaces like soil.

Natural ground absorbs rain, which is evaporated by the sun’s rays on a warm day and released into the air, cooling everything down. In a city, the rain just runs into the sewer system instead.

Urban areas tend to lack trees. Trees help reduce the air temperature by blocking the sun’s rays, while cutting the levels of pollution by absorbing harmful particles.

Cities are also warmer because they are full of human activity. Everything from transport to industry to energy output makes them hotter than they otherwise would be.

Cause and effect

Urban heat has various consequences. Combined with heatwaves and global warming, both of which are also on the rise, these hotspots are producing conditions that kill and hospitalise growing numbers of people. The worst affected are the elderly and other vulnerable groups like the homeless.

The World Health Organisation (WHO) has warned that increased city temperatures lead to more pollutants in the air. These can aggravate respiratory diseases, particularly among children. As cities get bigger, more and more people will be affected by these threats to their health.

Higher city temperatures are one reason why we are using more and more air conditioning. One US study found that the urban heat island effect in Florida was responsible for over $400m (£287m) of extra aircon, for example.

Aircon feeds climate change by producing more carbon emissions through the extra electricity demand, creating a vicious circle where it gets hotter because more aircon is required. The increased energy demand means a greater risk of summer blackouts, causing both human discomfort and economic damage.

Hotter city roads and pavements also raise the temperature of storm-water runoff in sewers. This in turn makes rivers and lakes warmer, which can affect fish and other aquatic species in relation to things like feeding and reproduction.

Finally, there are major economic consequences to hotter cities. One paper from last year predicts that all the extra wear and tear caused by the excess heat would amount to between 1 per cent and 10 per cent of lost GDP in thousands of cities around the world.


How we’re reacting

The solutions to the problem are clear enough: they include using paler more reflective building materials, and wiser urban planning that incentivises more parks, tree planting and other natural open spaces.

When it comes to taking these steps, however, it’s a very mixed picture. Countries and municipal authorities have typically become very good at adopting plans to cut emissions of carbon dioxide and other greenhouse gases. They are not so good at taking steps to adapt to climate change. A study from 2014 found that most European cities had failed to introduce urban heat plans, and the situation looks little better today.

This being the case, city administrations that have gone the extra mile look particularly enlightened – even though they tend to be somewhat sporadic. Melbourne, for instance, has substituted its trademark bluestone pavements in several areas with a permeable version that absorbs rainwater, thereby increasing the amount of evaporation.

New York City’s Cool Roof Initiative has seen thousands of volunteers painting some of the city’s flat bituminous roofs with a reflective polymer material. Lately, Los Angeles has launched an initiative to paint roads white, part of a pledge by city hall to lower the temperature by 3 degrees in the next 20 years. Beijing, meanwhile, has been introducing zoning measures to reduce smog.

Other administrations have been encouraging green roofs – rooftops covered in vegetation: they are a legal requirement for big new developments in Toronto; there are floor area bonuses for developers who include them in Portland, Oregon; and Chicago had a funding scheme for a while. In Swiss cities and regions, green roofs have been a legal requirement for many buildings for years.

These are all just pockets of activity, however. Many other mayors and city administrations need to start implementing the kinds of bylaws and incentives to adapt to the reality of hotter cities.

The ConversationThe cities of the future can still be green and cool, but only if they move up the agendas of many city halls. The laggards need to follow the example of those that have been leading the way. The reality is that the social, environmental and economic costs of urban heat islands add up to a bill that is too high for humanity to pay.

Tiziana Susca, Research Fellow, Edinburgh Napier University and Francesco Pomponi, Vice Chancellor's Research Fellow, Edinburgh Napier University.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

The Fire Brigades Union’s statement on Theresa May’s resignation is completely damning

Grenfell Tower. Image: Getty.

Just after 10 this morning, Theresa May announced that she would resign as Britain’s prime minister on 7 June. A mere half an hour later, a statement from Royal Institute of British Architects president Ben Derbyshire arrived in my inbox with a ping:

“The news that Theresa May will step down as Prime Minister leaves the country in limbo while the clock ticks down to the latest deadline of 31 October. While much is uncertain, one thing remains clear – a no deal is no option for architecture or the wider construction sector. Whoever becomes the next Prime Minister must focus on taking the country forward with policies beyond Brexit that tackle the major challenges facing the country such as the housing crisis and climate change emergency.”

I was a bit baffled by this – why would the architecture profession try to get its thoughts into a political story? But then Merlin Fulcher of Architects Journal put me right:

Well you know construction is a larger contributor to GDP than financial services, and most of the work UK architects do is for export, and at least half of the largest practice (Foster + Partners) are EU, so there's a lot at stake

— Merlin Fulcher (@merlinfulcher) May 24, 2019

So, the thoughts of the RIBA president are an entirely legitimate thing to send to any construction sector-adjacent journalists who might be writing about today’s big news, and frankly I felt a little silly.

Someone else who should be feeling more than a little silly, though, is Theresa May herself. When listing her government’s achievements, such as they were, she included, setting up “the independent public inquiry into the tragedy at Grenfell Tower” – a fire in a West London public housing block in June 2017 – “to search for the truth, so nothing like it can ever happen again, and so the people who lost their lives that night are never forgotten”.

Matt Wrack, general secretary of the Fire Brigades Union, is having precisely none of this. Here’s his statement:

“Many of the underlying issues at Grenfell were due to unsafe conditions that had been allowed to fester under Tory governments and a council for which Theresa May bears ultimate responsibility. The inquiry she launched has kicked scrutiny of corporate and government interests into the long-grass, denying families and survivors justice, while allowing business as usual to continue for the wealthy. For the outgoing Prime Minister to suggest that her awful response to Grenfell is a proud part of her legacy is, frankly, disgraceful.”

A total of 72 people died in the Grenfell fire. At time of writing, nobody has been prosecuted.

Jonn Elledge is editor of CityMetric and the assistant editor of the New Statesman. He is on Twitter as @jonnelledge and on Facebook as JonnElledgeWrites.

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