Cities are Overheating and the Challenge is Only Going to Get Worse

Sourced from the Living Architecture Monitor

As the world continues to become increasingly urbanized and hotter, our city leaders need to implement strategies to ensure they remain healthy for all of their citizens amid a rapidly changing climate.

Increasing temperatures in our cities is due in part, to a phenomenon called the urban heat island effect that causes air temperatures to be much warmer than in the neighboring countryside. Warmer temperatures are caused by the way we currently design and build our cities – with lots of tall buildings, black pavement, black roofs and little vegetation. These methods and approaches have largely excluded green infrastructure systems, which are designed to cool our communities by lowering temperatures, capturing stormwater to use for cooling buildings and thereby reducing summer air conditioning demand.

Warmer air temperatures in city-regions increase ozone production, which negatively affects air quality and our public health. The urban heat island also significantly increases electricity demand for cooling – all of which are both destructive and expensive. The US Environmental Protection Agency estimates that between 5 to 10 per cent of community electricity use is associated with the urban heat island effect.

As the climate changes, the problems associated with urban heat islands are further compounded by more frequent heat waves.

The city of Montreal suffered 53 heat-related deaths when temperatures climbed as high as 36ºC (96.8ºF) for the first week of July 2018, even though there were no power failures. This is on top of certain sections of the city where temperatures can be 12ºC (22ºF) warmer than surrounding rural areas. According to Natural Resources Canada, Montreal currently has nine days per year on average where the temperature is above 30ºC (86ºF). By 2070, that number is projected to climb to 27 days per year.

In New York City, it’s a similar story. Every year an average of 100-200 deaths are attributed to heat waves. This is on top of an ongoing average heat island impact of between 2 and 8ºF, depending on the location in New York. At night, this number is even more dramatic – upwards to 22ºF hotter, depending on the “greenness” of the neighborhood – as the urban fabric’s dark surfaces absorb heat during the day and release it at night. A 2016 Columbia University study projected that by 2080, up to 3,300 New Yorkers could die each year from intense heat made worse by climate change.

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