Scientists have found that the atmospheric stratosphere has thinned 400 m since 1980, Science Alert reported on May 15. This is the first study of this phenomenon on a global rather than a local scale. New research published in the journal Environmental Research Letters.
“I feel very shocked. This shows that we are disturbing the atmosphere up to 60 km altitude,” said physicist Juan Anel from the University of Vigo, a member of the research team. The stratosphere is located at an altitude of 20 to 60 km, above the atmosphere that humans breathe – the troposphere. The stratosphere has very few clouds and contains the important ozone layer.
Efforts around the world have prevented a depletion of ozone, which once caused an ozone hole over Antarctica. However, greenhouse gas emissions continue to transform the stratosphere.
Charl University atmospheric physicist Petr Pisoft and his colleagues analyzed satellite images from the 1980s combined with climate models. They determined that an increase in CO2 rather than a decrease in ozone caused the stratosphere to shrink.
The warming caused by greenhouse gases causes the troposphere to expand, compressing the upper stratosphere. Another important cause is that the increased amount of CO2 in the stratosphere causes the gas mixtures to cool and move closer together (the opposite effect compared to the troposphere), shrinking the entire layer. “The Earth’s stratosphere could lose 4% of its length (about 1.3 km) between 1980 and 2080,” Anel said.
Ozone and molecular oxygen in the stratosphere absorb most of the sun’s ultraviolet rays, thus shielding people from the sun’s most harmful rays with wavelengths below 300 nm. Here, the air temperature rises with altitude (as opposed to below the troposphere), making this layer very stable. Planes can therefore come here when the weather is too bad below. But this stability also means that any chemicals that reach the stratosphere tend to linger longer.
If the changes go as planned, they will be large enough to affect satellites, GPS and radio communications, warn Pisoft and his colleagues. It can also alter the aloft distribution of absorption and emission molecules, thereby altering how the stratosphere absorbs radiation and the overall mechanism. However, scientists still need to do more research before knowing if and how these effects occur.
