Last week at California’s annual Climate Change Research Conference in Sacramento, two physicists associated with the Heat Island Group presented a paper which claims that if roofs in 100 major urban areas were switched to reflective material, they would offset 44 metric gigatons of greenhouse gasses. It’s hard for me to picture how big a metric gigaton is, but it sounds like a lot. In fact, 44 metric gigatons of greenhouse gasses is more than all the countries on Earth emit in a single year.
The bottom line is that dark roofs and pavement absorb heat and add significantly to global warming and climate change by trapping heat in urban areas. Just painting roofs white and paving roads with a lighter colored material could offset more than 10 years of emissions growth.
The paper says that replacing a dark colored roof with a white roof on an average American home would offset 10 metric tons of carbon dioxide emissions. And that’s for just one house!
California already requires new flat commercial structures to be built with reflective roofs and next year new and retrofitted residential and commercial buildings will need to have reflective roofs.
I really like those green roofs where people have planted grass and plants to reduce cooling costs. But reflective roofs accomplish much of the same thing and you don’t need to mow them. Now that’s win-win.