Aug 25, 2018
Urban Heat: The Climate Crisis You’ve Sweated Over, But Probably Never Heard Of
Cities are getting hotter than ever. Urban heat is one of the most critical pillars in tackling climate change, it’s killing people in the thousands — and no one’s talking about it.
Everyone’s been talking about melting glaciers and wildfires, but very few people are talking about the crisis of urban heat. Cities are getting hotter than ever. It’s because the vast amounts of asphalt, bricks, and concrete used in cities, store the sun’s heat, and creates what’s called an urban heat island. When you look at thermal images of cities taken on hot days, you can clearly see roads, car parks, and city centers coming up in red and scarlet —they are baking hot.
Surfaces of human-made materials can reach 200F on a hot day, and the city as a whole can get 10F degrees hotter than natural areas surrounding it. This compounding effect of heat has dramatic consequences for human health and for carbon emissions.
Heat spikes the electricity grid
In the hot days of summer, lots of people turn on their air conditioning, and they turn it up on high. These AC units place a huge load on the electricity grid. It’s so high in some cities, like New York for example, that summer time AC use doubles the load on the electricity grid.
Heat spikes requires additional power plants
When the electricity grid spikes in summer, additional power plants called “peaker plants” get fired up. Peaker power plants are usually fueled by natural gas, and are often create more carbon emissions per unit of energy created than base load power plants.
We get told to save energy by turning lights off and using the dishwasher less, but the thing is, there’s not a whole lot we can do to reduce the base power load. What really matters to help reduce the carbon pollution involved in making electricity is to reduce the peaks: and for many cities, that’s the hot days in summer.
We can’t solve carbon pollution until we can solve power demand spikes
The thing about cutting back our use of fossil fueled energy, is that timing matters — drastically. The grid makes most of it’s carbon pollution when it spikes — and these spikes pose the most difficult challenges for renewable energy to cater for. It’s not possible for the world’s solar panels and wind turbines to suddenly turn on to full capacity at the exact time when everyone is cooking dinner, or during the next heat wave. Renewable energy contributes to the base load of the power grid, not to the peak demand. If we can’t figure out how to flatten out the peak demand, we will struggle to make reasonable progress on developing a comprehensively low carbon electricity grid. If we are going to make any progress on climate change, we have to address urban heat as one of climate pollution’s biggest drivers.
Heat creates smog
Heat increases air pollution. It’s because the increasing air temperature catalyzes the chemical reactions that make smog.
“Ground-level ozone (or “smog”) is formed when hydrocarbon and nitrogen oxide pollution from vehicles, power plants and other combustion combines in sunlight and heat. So, if there’s more sunlight and heat, there will be more ozone in the air.” — Rich Kassel of the Natural Resources Defense Council
Heat causes more violent crime
Whenever it gets hot, it seems that people get more aggressive. There is a direct correlation between heat and the rates of homicide and rape.
In an article in Psychological Science, the researcher and professor Craig Anderson writes,
“Cities and regions with higher temperatures tend to experience more violent crime than cooler regions, even after controlling for a dozen sociocultural factors such as age, race, poverty, and culture of honor . . . From Chicago to Brisbane to Vancouver to Dallas, whether looking at domestic violence or physical assault, the same relationship emerges . . . “A 1C degree increase in average temperature — a fairly conservative estimate of climate change in the following decades — will likely yield a 6% increase in violent crime rates, as many as 25,000 more serious and deadly assaults per year in the United States alone.” — Professor Craig Anderson, Iowa State University
If the temperature of urban centers increases, not by one, but by ten degrees, through the urban heat island effect, that makes a frightening prospect for the potential of violence.
Heat can be fatal
Heat waves can kill like a tsunami. Smaller heat waves may only result in a handful of deaths that go unnoticed by the news and twittersphere. But major heatwaves in Europe killed over 15,000 people in 2003. In India in 2015 over 2,500 people died of an extreme heat wave. Overall, a total of more than 9,000 Americans have died from heat-related causes since 1979, and a gobsmacking 55,000 people in Russia died from an extreme heat in 2010.
With or without human-made climate change, we can’t avoid heatwaves. But we can avoid building cities that amplify heat waves into urban ovens that kill. A city that is heavy in exposed concrete and dark asphalt will exacerbate the crisis, whereas a city that is abundant with trees, green spaces, and white surfaces, can play a substantial role in keeping a heat wave from spiraling out of control into a mortality disaster.
Extreme heat targets poor neighborhoods
Urban heat is an issue of social justice. Poor areas are often concrete-heavy and have fewer parks and street trees. Jeremy Hoffman from the Science Museum of Virginia undertook a study of the city of Richmond which found that high temperatures directly correlated with lower socioeconomic regions of the city. Watch or listen to interview I did with him here.
In extreme cases, heat can kill. Hotter neighborhoods mean that poor people are at a higher risk of dying from heat stroke. The Center for Disease and Control published a report revealing,
“Weather-related death rates were 2 to 7 times as high in low-income counties as in high-income counties. Poorer households may be less likely to have temperature-regulating niceties, such as air conditioning or insulation, that many folks take for granted.” — CDC
Heat puts people in hospital
You don’t need to die to have your health effected by extreme heat. About 30,000 people per year are hospitalized for heat-related illness in the USA. Every heat wave creates a spike in visits to the emergency room in hospitals.
Air conditioning is expensive
The US Department of Energy says that American’s spend $29 billion dollars a year on electricity for air conditioning. AC bills can run into thousands of dollars over summer and can account for 85% of a family’s electricity bill during hotter months.
Air conditioning reduces the range of electric cars
AC takes a lot power to run, and when it comes to an electric car, that means your car won’t go as far before needing to recharge. When tested, the Chevrolet Volt with no temperature control gets about 60 miles for a charge. Turning the AC reduced the car’s range by 34%, dropping to 40 miles.
On a car forum, one woman posted this about her BMWi3,
“I average around 75 miles in fine weather. The past couple weeks when it hit triple digits, I’ve seen the range drop down to as low at 50 miles/charge” — BMWi3 car owner, Los Angeles
An EV that is sitting in traffic on a hot black asphalt road will have a much reduced range compared to an EV that is driving down a shaded or tree-lined street.
We can’t tackle climate change without tackling air conditioning
There’s a lot of talk about saving energy by turning off the lights, or buying an energy-efficient refrigerator, but there’s a missing piece of information that no one tells you — when it comes to getting the carbon emissions down, it matters most of all to get the peak load down, that means at the times when the grid spikes.
What do we do about it?
Urban heat is an exciting problem to work on because we can do something about it, and quite easily. The solutions are straight forward. Cities need more green cover and cities need to paint more dark things with white reflective coatings. Cities need more street trees, green roofs, green walls, parks, white streets, cool roofs and painting exposed brick or concrete a light color. That’s most of it.
But while these interventions are technically simple, and not overwhelmingly expensive, it’s always hard to turn ideas into action. How do we make it happen? Hello World Labs specializes in bringing the behavioral psychology of environmental change together with the science of measuring change, to help turn great ideas into real and measurable change.
We have ideas
At Hello World Labs, we’ve been working on some concepts to help with urban heat.
Urban Canopy
Urban Canopy is web application that shows you a high definition thermal photograph of your property. We take thermal images using aircraft and put them on a web-based map for your community to see. Learn more at urbancanopy.io
The Green Cocoon
The Green Cocoon is a modular structure to create green shading over roads and carparks. Read the full article.
Heat Island Model Display
The heat island model display is an educational display that can be featured in museums, corporate foyers, galleries, and public buildings. It shows the heat island effect with a small model city made from real building materials that is heated with a mock-sun (a heat lamp). The model city is filmed with FLIR thermal camera that is displayed on a large color screen. Viewers of the installation can move model cars and real miniature trees around the city to see the thermal effect of surfaces that are green, white, and dark. Read the full article here.
The Escapade
The Escapade is a modern invention of a freezer gel pack. It is a personal cooling scarf designed for everyday wear that directly cools your body, and looks lovely to wear all day.
Garden City
Garden City is an Augmented Reality app that allows you to create a rendering of what an imaginary green city would look like. Add trees, green walls, and green surfaces to any city scape you are looking at through your phone’s camera. Share your garden city creation on social media and get inspired turn your green image into a real green city in real life.
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