The Upper Atmosphere Is Cooling, Prompting New Climate Concerns

This contraction means the upper atmosphere is becoming less dense, which in turn reduces drag on satellites and other objects in low orbit—by around a third by 2070, calculates Ingrid Cnossen, a research fellow at the British Antarctic Survey.

On the face of it, this is good news for satellite operators. Their payloads should stay operational for longer before falling back to Earth. But the problem is the other objects that share these altitudes. The growing amount of space junk—bits of equipment of various sorts left behind in orbit—are also sticking around longer, increasing the risk of collisions with currently operational satellites.

More than 5,000 active and defunct satellites, including the International Space Station, are in orbit at these altitudes, accompanied by more than 30,000 known items of debris more than 4 inches in diameter. The risks of collision, says Cnossen, will grow ever greater as the cooling and contraction gathers pace.

This may be bad for business at space agencies, but how will the changes aloft affect our world below?

One big concern is the…