Global Warming Makes Orbiting Satellites Speed Up!
Cool Scientific Fact of the DayGlobal warming has all kinds of effects on our planet. While some are obvious (higher average temperatures), others are less intuitive. For example, a new paper published in Nature Magazine shows that an increase in carbon dioxide in the upper atmosphere will actually cause man-made satellite to speed up ever so slightly, requiring the people who do the math required to keep the satellites in the correct orbit to take this into account.
Here's How It WorksArs Technica has a good layman explanation on how this phenomenon works:
Down in the troposphere, CO2 is an important greenhouse gas. Add more CO2, and you trap more outgoing heat, warming the lower atmosphere. But up in the thermosphere, things are much different. Gas molecules are incredibly sparse—and increasingly so as you head outward from the Earth. Here, CO2 is actually a key coolant, as it absorbs energy from collisions with oxygen molecules, and then emits that energy as infrared radiation, sending much of it out into space.
And when the thermosphere cools, it contracts. That results in fewer molecules in the orbital paths of satellites, meaning the drag slowing their motion decreases.
This isn't enough of a difference to cause huge problems for satellites, especially since we can always compensate, but it's a good illustration of the kind of unforeseen consequence of meddling with the Earth's atmosphere's composition. The ecological consequences aren't as important as ocean acidification caused by CO2, but there's so much we don't know about the impacts of global warming that maybe at some point we'll realize that changes in the upper-atmosphere don't just affect satellites...