Peter Hannam reports: Those warning of climate change impacts have been likened to Chicken Littles, scuttling around, warning the sky is falling.

That worry, it turns out, is based on fact too. Cooling in the stratosphere is causing it to shrink, lowering that layer by “a number of kilometres”, NASA noted recently.

Our burning of fossil fuels and emissions of other greenhouse gases mean more of the earth’s heat that would have been radiated back to space – warming the stratosphere on the way – is being trapped at lower levels of the atmosphere.

“It’s like when you insulate your roof – your house warms but your attic will get a bit cooler,” says Steven Sherwood, a climate scientist at the University of NSW. Those “attic” temperatures have cooled 2-3 degrees since the 1960s.

To be sure, the shrinking stratosphere is only partly climate-change related, with the emergence of ozone holes the other main factor. Still, “it’s all about the human impact on the climate system”, Professor Sherwood says. [Continue reading…]