Like many people I have watched the TV footage of the wildfires in Australia with shock. So much damage done so quickly, and over such a wide area. I also thought back to last year’s California wildfires and asked myself, is this the new normal?

We know that the damage is being done by global heating. Climate change dramatically increases the risk of extreme weather events and their intensity. The question of whether any specific weather event is directly attributable to climate change is no longer relevant. Floods, storms, droughts, heat waves and snowstorms are all being driven to new extremes by more energy in the atmosphere.

I also wondered what it must be like in the cities. We saw the smoke shrouding the Sydney Harbour Bridge, and tennis players forced to abandon matches because they could not breathe. Those are the immediate visible impacts, but what about the effects of steady high temperatures?

Global heating has implications for the places we live. Across the world cities are subject to what is known as the urban heat island; where built-up areas experience much higher temperatures than their rural surroundings. We build our cities from glass, steel, concrete and asphalt. Materials that absorb and hold heat. We fill our cities with heating and lighting, industry and commerce, transport and entertainment. All pushing waste heat into the body of the city and driving up temperatures.

You can see urban heat islands from space

You can see the effects of the urban heat island from space. These images show high temperatures in four European cities at the height of the 2019 heat wave taken as part of the ECOSTRESS project on the International Space Station.

Jet Propulsion Laboratory/NASA

Look at the timestamp on these maps. These observations were made early in the morning, not in the heat of the day. This is energy absorbed by the fabric of the city over previous days, and still not released during the night. The local airports, concentrations of hard infrastructure, show up clearly.

Urban heat islands directly affect the livability of cities. In the UK over 2000 people died in 2003 because their buildings could not protect them. If we continue with business as usual, those kinds of temperatures will become a summer norm by the 2040s, leading to more than 7000 heat -related deaths each year by 2050 from cardiac, kidney and respiratory disease. Research has shown that the costs of adaptation will be double in cities because of the higher temperatures.

Since cities are where most people live in the developed world, and they are the engines of economic growth, this is a serious problem.

Fixing the problem

Fortunately, it is not insurmountable. We know what has to be done to reduce the urban heat island effect, and the Cool Cities Network is sharing knowledge, expertise and solutions from cities around the globe. There are wide range of solutions both for new construction and to retrofit existing buildings and infrastructure.

A couple of weeks ago Greg Geilman, a realtor from Los Angeles, shared with me a guide he has produced – “Urban Heat Islands: the Main Issues and What is Being Done to Combat Them”. This provides an excellent overview of the origin and negative impacts of urban heat islands, how they are defined and measured, and the strategies to reduce them.

The great thing is, the strategies for reducing urban heat islands also make urban areas more attractive and efficient places to live and work.

Trees and vegetation are vital. Not only do they provide shade, but evaporation of water from their leaves actually cools their surroundings. Parks, street trees, gardens and green roofs reduce the heat island and improve the well-being of the people who live there.

Reflective and light-coloured surfaces bounce solar energy back into the sky, cutting the heat gain of streets and buildings.

Efficient buildings also help. Wasteful heating systems, poor quality appliances that generate waste heat and air conditioning systems that dump heat out onto the street all contribute to overheating. Energy efficient devices, natural ventilation and good insulation can all cut the contribution of buildings to heat islands. Whatever sustainable future we imagine for our cities, they cannot tackle climate change with thousands of bolt-on air-conditioning units.

Greg’s guide gives many more practical examples of simple solutions to make our cities liveable in the face of global heating. Check it out.

It’s Not Just The Forests That Are Burning – It’s Our Cities
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