Plastic may be warming the planet more than we thought

By Nicolás Rivers — Scientists have long known that making plastic warms the planet. But plastic may be heating the Earth even more than we realized, according to a report released Wednesday.

The Plastics & Climate Project, a nonprofit research group that studies how plastic contributes to climate change, analyzed hundreds of published research papers to identify aspects that are missing from most climate models.

Plastic production creates about 5 percent of all greenhouse gas emissions, according to a 2024 report from the Lawrence Berkeley National Laboratory – more than all shipping or the entire airline industry. That estimate accounts for gases released when companies drill for oil and gas, transport it to refineries, turn it into plastic and mold it into products. But the estimate doesn’t consider how microplastics in the ocean and soil disrupt the natural cycles that pull carbon dioxide out of the atmosphere and cool the planet.

“We know the greenhouse gas emissions from plastics are being undercounted, and therefore plastics are using up more of the carbon budget than is currently assumed,” said Holly Kaufman, a senior fellow at the World Resources Institute and one of the lead authors of the new report.

Kaufman and her co-authors acknowledge that more research is needed to determine how much bigger plastic’s contribution to climate change might be. But they say that’s all the more reason for scientists to study the problem more closely. In the meantime, they say, people should try to use less plastic and keep it from polluting land, sea and air.

“An incomplete understanding must not halt action to comprehensively account for plastic climate impacts,” Kaufman said.

Plastic industry group leaders said the report relies on uncertain scientific research and ignores studies that show plastic can sometimes create fewer emissions than other materials.

“Claiming plastics are driving climate change disregards the immense role plastics play to combat climate change,” Ross Eisenberg, president of America’s Plastic Makers, wrote in a statement. “Without plastics, it would be impossible to meet our climate change goals – plastics make cars lighter, enable solar and wind energy, reduce food waste, and improve energy efficiency in buildings.”

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How plastic disrupts the carbon cycle

On the surface of the ocean, tiny plankton absorb carbon dioxide into their bodies as they photosynthesize. Later, they die and sink – or they get eaten and pooped out by other sea creatures – falling to the bottom of the ocean in a constant flurry of organic material called “marine snow.” When marine snow settles to the bottom of the sea, it locks away carbon for a long time.

But plastic can gum up the works by slowing plankton’s growth, making the little critters more buoyant so they don’t sink or breaking up fish poop in a way that makes it less likely to settle at the bottom.

“It’s been shown that plastics can mess up the fecal pellets of these animals that are crucial for sequestering carbon in the ocean,” said Tracy Mincer, an associate professor at Florida Atlantic University who published a paper showing that 5 percent of marine snow in the deep sea is now made of plastic. “But as far as how much … we’re still trying to figure it out.”

In the soil, plastic changes the way microbes store and release carbon, which could also warm the planet, although Kaufman said there’s not enough research yet to say how much.

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How plastics may affect the Earth’s reflectivity

Normally, light-colored and reflective surfaces such as snow, ice and clouds reflect the sun’s energy back into space, keeping the Earth from warming up too much. But microplastics – which now coat snow and ice and can be found floating through the air and in clouds – could change that by affecting how and where clouds form or making the ground more or less reflective.

Only five studies have scientifically tested this idea, and they’ve reached conflicting conclusions, according to the report. There’s not enough evidence to say whether the overall effect would warm or cool the planet.

“There’s only been a handful of studies on this, and there’s much more work to be done there,” Kaufman said.

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How plastic disintegration may warm the Earth

The report also mentions studies that have found some forms of plastic break down under the sun and release methane – an extra-potent greenhouse gas. The report acknowledges the few existing studies measured “negligible methane emissions intensities” but argued the issue should be studied more.

Originally published in Washington Post

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