Katie Couric's Notebook: C-F-C's

Well, it worked. Manufacturers stopped using chlorofluorocarbons, or C-F-C's in air conditioners, refrigerators and aerosol cans. The hole in the ozone layer is shrinking and scientists think it may be gone within 40 years.

But now a report from researchers at NOAA says hydro-fluorocarbons - the chemicals that replaced C-F-C's - are causing their own environmental damage by contributing to global warming.

Right now H-F-C's are responsible for only a small percentage of greenhouse gasses, but this study predicts that could explode by mid-century and urges manufacturers to find yet another alternative.

It's a reminder that we can't be complacent. We need to continually monitor our behavior and the man-made materials that may make our lives easier today, but make the health of the planet even more precarious in the future.

That's a page from my notebook.

I'm Katie Couric, CBS News.