Could Super-White Paint Really Cool the Planet?

In 2021, American researchers developed the world’s whitest paint. It reflects more than 98% of light. That’s useful because sunlight produces heat, and global warming is a pressing problem for the planet.

Could a super-white paint save us from climate change?

Researchers say painting buildings with this material would lower surface and indoor temperatures, reducing the need for air conditioning. That led scientists to ask what would happen if this paint were used at much larger scales—possibly enough to cool the planet.

Jeremy Mandei, a professor of electrical engineering and computer science who studies clean technologies, says if a material like the Purdue paint covered 1–2% of the Earth’s surface, it would reflect a significant amount of sunlight back into space. That could reduce the heat the planet absorbs and might be enough to stabilize global temperatures.

In other words, this could help address climate change on a global scale. Mandei also points out that the extra reflected sunlight wouldn’t meaningfully affect outer space — he compares the impact to “pouring a cup of regular water into the ocean.”

A neat idea — but still pretty far-fetched

So how big is 1–2% of Earth’s surface? Earth has about 510 million square kilometers of surface area, most of it water. That means you’d have to cover roughly 5 to 10 million square kilometers with the paint.

If we assume the paint behaves like commercial paint, as the researchers suggest, 3.7 liters would cover about 37 square meters. That works out to roughly 139 billion gallons of super-white paint to cover just 1% of the Earth’s surface—double that for 2%. And that doesn’t account for how difficult it would be to paint oceans, deserts, and forests.

As the publication ScienceAlert notes, painting objects white to reduce temperature is not new. You can see the idea in the many white cars in the hottest U.S. states and in white roofs and surfaces around the world. The new paint could help in those applications, but as the calculations above show, we’re still far from solving global warming with this technology alone.