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Dave Thurlow, Host

 

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Chicken Little apparently knew what he was talking about because the sky IS falling. He just made a poor choice of words. Hi, I'm Dave Thurlow and this is The Weather Notebook.

Scientists have discovered that the upper atmosphere is getting colder thanks to greenhouse gases in the lower atmosphere. The process that's causing this is called radiational cooling. As the lower atmosphere becomes hotter, the upper atmosphere becomes cooler. And, since cooler gases take up less room, that means it's shrinking.

For example, over Antarctica, the top of the mesosphere, which is about 50 - 90 km's above the surface of the earth, has descended by 8km since the late 50's. The same thing may be happening in northern Europe.

Because the atmosphere expands and contracts throughout the day, these measurements have not been easy to come by. Still, they prove that radiational cooling caused by greenhouse gases is to blame. With carbon dioxide levels expected to double within the next century, the edge of space will be 20km closer than it is today.

So, what's the big deal? Well, communications could be messed up. Sattelite orbits thrown off, radio waves disrupted. The growing age of communications may not need a shrinking upper atmosphere.

The Weather Notebook is underwritten by Subaru, the beauty of all wheel drive with major support provided by the National Science Foundation.