NOAA - Near-Earth Space Could Host 60,000 Satellites By 2040; Particles From Reentries Add 1.5C To Upper Atmosphere Temp

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Research led by scientists with the National Oceanic and Atmospheric Administration, published in 2025, concluded that emissions from disintegrated satellites are likely to increase sharply in the coming decades. Some projections suggest as many as 60,000 satellites could be in orbit by 2040, with reentries every one to two days, injecting up to 10,000 metric tons of aluminum oxide particles into the upper atmosphere each year. The study found that those aerosols could warm parts of the upper atmosphere by about 1.5 degrees Celsius within one or two years of reaching that number of satellites. That could alter winds and ozone chemistry, and persist for years, indicating a rapidly growing human-made source of pollution at the highest levels of the atmosphere.

Those particles matter because they act like other catalytic aerosols in the upper atmosphere. Aluminum oxide dust from burning spacecraft absorbs and scatters sunlight, and can warm areas where it accumulates. That can subtly change atmospheric circulation, the researchers noted. As the particles drift and settle lower into the stratosphere, they can affect ozone chemistry and high-altitude clouds, altering how sunlight and heat move through the atmosphere and potentially influencing climate over time.

The potential scope of impacts from space activities was outlined by several researchers at the 2025 European Geosciences Union conference in Vienna. They said that, beyond orbital debris, the booming space industry is the source of a new form of atmospheric pollution, injected directly into the layers of air that protect the planet and regulate its climate.

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Researchers at the conference estimated that in the past five years, the mass of human‑made material injected into the upper atmosphere by re‑entries has doubled to nearly a kiloton a year. For some metals like lithium, the amount is already much larger than that contributed by disintegrating meteors. In the emerging field of space sustainability science, researchers say orbital space and near-space should be considered part of the global environment. A 2022 journal article co-authored by Moriba Jah, a professor of aerospace engineering and engineering mechanics at the University of Texas at Austin, argued that the upper reaches of the atmosphere are experiencing increased impacts from human activities.

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https://insideclimatenews.org/news/19022026/commercial-space-travel-environmental-threat/