In case you haven't noticed, things are heating up. Last year was the hottest on record, resulting in climate-driven extreme weather events and Antarctic sea ice coverage that dipped to record lows.
Researchers from the University of London have been studying the effects of high temperatures, specifically in cities. As Interesting Engineering reported, they've found that a little white paint can go a long way toward cooling an overheated metropolis.
Urban areas can typically be 15 to 20 degrees warmer than their less built-up surroundings. This is generally referred to as the urban heat island effect. Dense structures absorb heat and then slowly release it back into the air, further warming the cityscape.
Air conditioning is one way we can stay cool, but operating the units sends more heat into the environment. Plus, there's the climate cost of using them. The hydrofluorocarbons released can absorb 150 to 5,000 times more of the sun's energy than carbon dioxide in the atmosphere.
Painting roofs white could lower city temperatures and reduce the need to run air conditioners as much, according to the report. This was tested alongside other heart-management concepts such as green roofs, solar panels, ground-level tree vegetation, and, of course, air conditioning.
"We found that cool roofs were the best way to keep temperatures down during extremely hot summer days," lead author Oscar Brousse said. "Other methods had various important side benefits, but none were able to reduce outdoor urban heat to nearly the same level."
Green roofs had a mixed effect, with the study showing they could decrease temperatures by around 0.5 degrees Celsius (0.9 degrees Fahrenheit) but caused them to rise again at night due to heat trapped in the organic material. They do help with drainage and foster wildlife habitats, though.
Both solar panels and deciduous trees at ground level barely moved the needle, decreasing temps by only 0.3 C (0.5 F), though their environmental benefits are still strong, with solar panels providing a renewable source of electricity. Trees cooled cities at night but tended to increase humidity during the day.
The clear winner was white paint that reflects the sun's rays rather than absorbing them. Some areas were able to reduce outside temperatures by 1-2 C (1.8-3.6 F).
An architectural endeavor outside of Houston found that ridged outer walls painted white kept the wall 18 degrees cooler than a flat wall. Researchers have even tried to optimize the reflective properties of white paint, resulting in a coating that cooled surfaces by 6 C (10.8 F) in field tests.
City pavement could use a little cooling off as well. Phoenix has been using a light-colored coating on streets that it calls "cool pavement." Roads coated with this were an average of 4.8 degrees cooler.
There's only so much engineering can do to fight extreme temperatures, but everyone can do their part to help reduce planet-warming gases. We can share knowledge, focus on renewable energy, and compel companies to stop using dirty fuel sources.
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