While greenhouse gases are warming Earth’s surface, they’re also causing rapid cooling far above us, at the edge of space.

In fact, the upper atmosphere about 90 kilometres (56 miles) above Antarctica is cooling at a rate 10 times faster than the average warming at the planet’s surface.

Our new research has precisely measured this cooling rate, and revealed an important discovery: a new four-year temperature cycle in the polar atmosphere. The results, based on 24 years of continuous measurements by Australian scientists in Antarctica, were published in two papers this month.

The findings show Earth’s upper atmosphere, in a region called the “mesosphere”, is extremely sensitive to rising greenhouse gas concentrations. This provides a new opportunity to monitor how well government interventions to reduce emissions are working.