A SpaceX rocket that burned up after re-entering the atmosphere unleashed a plume of vaporised metals over Europe, a type of pollution that is expected to increase as spacecraft and satellites multiply.

The upper stage of a Falcon 9, which is designed to splash down in the Pacific Ocean for possible re-use, lost control due to engine failure and fell from orbit over the north Atlantic in February 2025.

People across Europe saw fiery debris streaking through the sky, some of which crashed behind a warehouse in Poland. Seeing the news, at the Leibniz Institute of Atmospheric Physics in Germany and his colleagues turned on their lidar, an instrument for atmospheric sensing. Twenty hours later, it detected a 10-fold spike in lithium, a key component of rocket hulls, in the upper atmosphere as the plume of vaporised metal drifted over it.

Atmospheric modelling suggested this plume had drifted 1600 kilometres from the area where the Falcon 9 re-entered the atmosphere. The study is the first to trace high-altitude pollution to a specific spacecraft re-entry.

The tiny metal particles “could be catalysing ozone destruction, creating clouds in the stratosphere and mesosphere, affecting the way that sunlight travels through the atmosphere”, says Wing. “But all of this is understudied.”

Worries about this type of pollution are growing as commercial space launches skyrocket and companies expand their mega-constellations of satellites, like SpaceX’s Starlink and Amazon’s Leo. About 14,500 satellites are already in orbit, and last month SpaceX applied to launch 1 million more for Elon Musk’s goal of creating orbital data centres to power artificial intelligence.

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To avoid a runaway cycle of collisions producing ever more space debris, satellites are typically allowed to fall and burn up at the end of their lifespan. Experts say the amount of space trash particles could grow by 50 times in the next decade and exceed 40 per cent of the mass that meteoroids currently bring into the atmosphere.

There is a misconception that space debris burns up in the atmosphere and disappears, says at Purdue University, Indiana, who wasn’t involved in the study. “Let’s tap the brakes here, and let’s really do some thorough analysis of what effect this material could have.”

The Falcon 9 plume contained an estimated 30 kilograms of lithium. But given the composition of the alloys in rocket hulls, it would have contained a far greater amount of aluminium.

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Vaporised aluminium reacts with atmospheric oxygen to form particles of aluminium oxide, which provide a surface where chlorine compounds can more easily break down. The chlorine radicals freed by this process react with and destroy ozone molecules in the stratosphere.

Researchers estimate that spacecraft burn-up is 1000 tonnes of aluminium oxide into the atmosphere each year and growing. This threatens to expand the southern hemisphere’s ozone hole, which has been shrinking as countries phase out ozone-depleting refrigerant gases. The loss of ozone could allow in more of the sun’s ultraviolet rays, which cause skin cancer.

“In terms of metals, we’re sort of moving into this new paradigm where the upper atmosphere is increasingly more influenced by anthropogenic pollution than natural sources,” says at University College London. “Space debris is starting to undo the progress with the ozone hole.”

The metal oxide particles can also serve as nuclei upon which water vapour can condense into droplets, forming cirrus clouds in the upper troposphere, which tend to trap heat.

Scientists have measured particles from burned-up spacecraft in cirrus clouds. If they are encouraging cirrus cloud formation, it could worsen global warming, although this impact would still be small compared with that of greenhouse gases like carbon dioxide.

“There is a lot of scientific evidence that this material could be having deleterious effects on our atmosphere, and now it’s on us as scientists to figure out if those effects are taking place and how bad are they,” says Cziczo.

There may be solutions, such as building satellites out of materials like wood — although that could still release black carbon soot upon re-entry — or retiring more of them to high-altitude “graveyard orbits”.

“We need to take a little bit of time and think about what we’re doing before we do it,” says Wing. “This explosion of satellites… it’s very fast, and we don’t know the consequences.”

Dolphins in seas around the UK are dying from a combination of increased water temperatures and toxic chemicals that the UK banned in the 1980s.

Polychlorinated biphenyls (PCBs) are a long-lasting type of persistent chemical pollutant, once widely used in industrial manufacturing. They interfere with animals’ reproduction and immune response and cause in humans.

In a new study, researchers showed that higher levels of PCBs in the body and increased sea surface temperatures are linked to a greater mortality risk from infectious diseases for short-beaked common dolphins (Delphinus delphis), a first for marine mammals.

The ocean is facing “a triple planetary crisis” – climate change, pollution and biodiversity loss – but we often look at threats in isolation, says at Zoological Society of London.

Williams and her colleagues analysed post-mortem data from 836 common dolphins stranded in the UK between 1990 and 2020 to assess the impact of these interlinked threats.

They found a rise of 1 milligram of PCBs per kilogram of blubber was linked with a 1.6 per cent increase in the chance of infectious diseases – such as gastritis, enteritis, bacterial infection, encephalitis and pneumonia – becoming fatal. Every 1°C rise in sea surface temperature corresponded to a 14 per cent increase in mortality risk.

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According to the study, the threshold where PCB blubber concentrations have a significant effect on a dolphin’s risk of disease is 22 mg/kg, but the average concentration in samples was higher, at 32.15 mg/kg.

Because dolphins are long-lived, widely distributed around the UK and high in the food chain, they are a good indicator species to show how threats might also affect other animals.

“Their position at the top of the food web means that toxins from their prey accumulate in their blubber, providing a concentrated snapshot of chemical pollutants in the ocean – though unfortunately at the expense of their health,” says Thea Taylor, managing director of .

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Despite being banned in the UK in 1981 and internationally in 2001, PCBs are still washing into the ocean. “They are still probably entering the environment through stockpiles and are often a side product or a byproduct of other manufacturing processes,” says Williams.

Cleaning up PCBs is very difficult. “Because they’re so persistent, they’re a nightmare to get rid of,” she says. “There is definitely not an easy fix.”

Some researchers are exploring dredging as a cleanup technique, while others are focused on improving water treatment plants’ effectiveness in removing persistent chemicals.

These findings indicate what might happen if action isn’t taken to ban perfluoroalkyl and polyfluoroalkyl substances (PFAS), another widespread group of so-called forever chemicals.

“While we cannot reverse the contamination that has already occurred, it is critical to prevent further chemical inputs into the environment,” says Taylor.