Warming Signs: Would Painting Everything White Make the Planet Cooler?

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Warming Signs: Would Painting Everything White Make the Planet Cooler?

Often, when we talk about climate change, it seems like a far-off scenario. We talk in terms of saving the planet for future generations and predict disruptive sea level rise within the century. But the effects of climate change are already felt around the world; future changes will only intensify them.


High up in the Peruvian Andes, where a glacier used to stretch across the slopes of the Ayacucho region, one man made it his personal mission to bring back ice. It was an ambitious goal, to be sure, but even wackier was his plan: He would paint the peaks white.

Eduardo Gold founded Glaciares Peru in 2008 on his own dime, but a year later the NGO was selected as a winner of the World Bank’s 100 Ideas to Save the Planet competition—bringing with it prize money to continue the efforts.

But Gold’s mission wasn’t to restore the mountain or even simply to bring better water access to his community, although those were major perks. He also hoped to make a big impact on climate change. As Glaciares Peru’s Otto Gold told CNN, “We are hoping to lower the temperature on the surface of the rocks from 20 degrees Celsius to five.”

But how exactly does painting a mountain white help climate change?

Gold was tapping into something called albedo—a measure of how much solar energy a surface reflects. It’s the same reason dark clothes make us sweat more in the summer, and why it’s cooler to walk on painted lines than on dark asphalt on hot days. Dark colors absorb heat while lighter colors reflect it.

Albedo 2.gif National Snow and Ice Data Center

I discussed albedo in my column on why Arctic ice is so important, but its effects occur all over the globe. Snow, ice, and water all reflect sunlight to varying degrees—as do landscapes with lighter colors, as with Gold’s mountain. Albedo is measured on a scale of zero to one, with zero meaning a surface will completely absorb the sun’s rays and one indicating the surface will reflect all incoming solar radiation.

For instance, snow-covered sea ice has an albedo of 0.9. That means it reflects 90 percent of the sun’s rays—pretty impressive, and just one of the reasons sea ice is so important to global climate systems. The open ocean, on the other hand, has an albedo of 0.06; it absorbs nearly everything.

Clouds also have albedo. The high-albedo cloud cover on Venus, in fact, is why the star shines so brightly in our skies. Although less is known about how cloud formation affects (and is affected by) climate change on our planet, a recent study indicates that clouds have moved closer to the North and South Poles, resulting in “widespread reductions in albedo.”

Changes on solid ground can also have an albedo effect. A study released earlier this month found that transformations in the soil of deserts and semiarid regions affect composition and color; as soil lightens, it reflects more sunlight back into the atmosphere.

The opposite seems to be happening in boreal forests—which, as I explained last week, are becoming particularly vulnerable to wildfire. These forests play an important role in reflecting light back into the atmosphere, but that is changing as the ground melts more and as trees fall prey to fire and insects. Arctic regions are also seeing more shrubs and even trees growing where before there was only snow and permafrost. As these lower-albedo plants take up more land space, some researchers have proposed preserving reindeer and caribou herds even more—in order for the herbivores to keep the shrub cover in check and allow more reflective grasses to grow instead.

Back when politicians called for more, not less, funding of agencies like the Department of Energy, the Senate appropriations committee proposed that DOE to look into “albedo modification.” Painting mountains white is one albedo modification; the DOE plan, though, would launch tiny particles or aerosols into the atmosphere in order to reflect sunlight—much like, for instance, a volcanic eruption releases ash and gas and therefore reduces atmospheric temperatures. First, however, scientists would need to examine the effectiveness and the long-term consequences of such a plan.

Other albedo-related schemes have been even more, shall we say, imaginative. One plan calls for releasing giant white planks to float in the ocean; another envisions creating artificial white islands. Perhaps my personal favorite is the launch of football-field sized white umbrellas into the air; it gives “throwing shade” a whole new meaning.

Albedo modification falls under geoengineering, which has long been a contentious subject in climate science. These and other geoengineering solutions wouldn’t fix climate change; they might only slow it down or partially address some of the existing problems. The real problem is carbon dioxide emissions; finding engineering solutions without reducing those emissions would be like chasing down each chicken after the doors of the coop have been flung open. And even the best-laid geoengineering plans often have wide-ranging side effects; for instance, launching particles into the atmosphere to change how much sunlight reaches the earth’s surface would also have huge effects on photosynthesis. That could create a much bigger problem than we started with.

Albedo 3_633.jpg Photo by Sarah Joy CC BY-SA 2.0

A much easier solution would be rethinking our current infrastructure, including roofs and roads. Painting roofs light colors could save as much as 150 billion tons of carbon dioxide, one study found, which would be like taking all cars off the road for 50 years. Lighter roofs can also reduce your air-conditioning bill—although that plan works better in warmer climates than in colder places, since lighter roofs might also mean higher heating costs in winter. Dark asphalt absorbs 90 to 95 percent of sunlight, while concrete reflects between 20 to 50 percent of rays (depending on, in part, how old the concrete is). Painting roads a lighter color, or resurfacing asphalt with concrete, could be another fairly easy way to keep the planet cooler—especially in urban areas. (Painting them white, however, could very likely blind drivers on sunny days.)

As I mentioned above, these solutions only work to limit climate change. Climate solutions must also address the root causes, especially emissions. Cutting back on pollution, like the soot that finds its way into northern climates and settles on snow, making it much darker and more absorbent, would also be a good start. But with a little (or a lot) of imagination and very careful planning, we can also think of ways in which the albedo effect might reduce the effects of climate change.

Image: Mi Peru

Melody Schreiber is a freelance journalist based in Washington, D.C.