The rapid growth of CO2 emissions in recent decades is heating and expanding the lower atmosphere, leading to its intrusion into the stratosphere, according to a new study.
Reporting in the journal Environmental Research Letters, an international team of scientists said that climate-altering emissions have shrunk the stratosphere — which extends from roughly 15 kilometers to 50 kilometers above the earth’s surface — by 400 meters since the 1980s. And without major cuts in emissions, the scientists said, the stratosphere could shrink by another kilometer by 2020. A shrinking stratosphere could affect satellite operations, GPS systems, and radio communications, the Guardian reported.
The troposphere, which extends from the earth’s surface to roughly 20 kilometers above, is heating and expanding because of climate change, pushing into the lower boundary of the stratosphere. In addition, as CO2 enters the stratosphere, it actually cools the air in that layer, causing the stratosphere to further contract.
Scientists had thought that perhaps the shrinking of the stratosphere was due to the decline of the earth’s ozone layer because of the use chlorofluorocarbons in aerosols and other industrial products. But the new study, using satellite observations and detailed climate models, concludes that the main reason for the contraction of the stratosphere is CO2 emissions and global warming.
“Some scientists have started calling the upper atmosphere the ‘ignorosphere’ because it is so poorly studied,” said Paul Williams, a professor of atmospheric science at the University of Reading in the UK who was not involved in the new research. “This new paper will strengthen the case for better observations of this distant but critically important part of the atmosphere. It is remarkable that we are still discovering new aspects of climate change after decades of research.”