What If We Painted Earth White?

Imagine a white picket fence around a white house, with a white driveway and a white car. And it’s not just your house that’s white. It’s also the road, sidewalks, and every single building.

It looks boring and sterile, but it could be the future. And it could help save our world. How much paint would you need? Why would your electricity bill be lower? Why would white paint fight climate change?

The human race is facing a huge threat. A mass extinction of plants and animals, dwindling food, and extreme weather awaits us if we don’t stop the increasing heat from climate change.

And if we let the global temperature rise by just 6°C (10.8°F), we’re toast. There are tons of ideas out there about how to stop the rising temperatures. One idea is painting roofs, roads, and other surfaces with white paint.

Sunlight contains three different types of light. Visible, infrared, and UV light. When visible lights hits a surface, that energy is either absorbed or reflected. The fraction of light that is reflected by a surface is called albedo.

A high albedo means that a surface reflects a lot of light, while a low albedo means that a surface absorbs more light. Dark asphalt roads have a low albedo, so they absorb a lot of light. That’s why they get so hot in the summertime. Snow has a high albedo and reflects 95% of solar radiation.

Currently, the Earth has an albedo of 30%. So the surface of the Earth absorbs plenty of sunlight, which contributes to rising temperatures. And climate change lowers Earth’s albedo.

It’s a vicious cycle that goes like this. The Earth gets hotter, which melts ice caps. Because there’s less snow, less light is reflected back into space, and the Earth’s albedo becomes lower.

So Earth absorbs even more sunlight, and heat, which increases Earth’s temperature and melts more ice caps. But we can slow this warming cycle. Painting the Earth white would significantly increase its albedo.

And if the Earth’s albedo increases, it would reflect more visible light back into space, which would cool surface temperatures. If you have lived through a heat wave, you’d likely appreciate cooler temps.

And we’re not talking about using just any white paint. We’d need to use a special paint that was recently developed. This paint reflects 95.5% of incoming light. And it could cool surface temperatures up to 1.7°C (3°F) lower than the surrounding air temperature.

We’d need about 60,000 swimming pools’ worth of this stuff to cover all the urban areas on Earth. We’d coat roofs, roads, and pavement in this paint, raising the albedo of urban areas by 10%. If we painted everything tomorrow, by the year 2300 we’d lower global temperatures by up to 0.07°C.

That might not sound like a lot. But it would be like offsetting the emissions of all the cars in the world for the next 20 to 30 years. It’d take a couple of hundred years for this temperature decrease to happen, but there are some immediate effects. The white paint would decrease the urban heat island effect, so you wouldn’t have to run your air conditioner as much during the summer. You could end up saving as much as $50 a month on cooling costs.

The downside of the white paint is all that glare. You’d want to buy a good pair of sunglasses to protect your eyes from the blinding light. But just painting the Earth white won’t solve our climate crisis.

We’d still have to grapple with the greenhouse gas effect. As the amounts of carbon dioxide and methane in our atmosphere increase, they create a blanket of gases that trap infrared radiation. This will continue to warm our planet, even with our new paint job. So, although painting the Earth white, or at least our roads and roofs, could help mitigate rising temperatures, it would have to be one small part of a larger plan to geo-engineer the Earth.