A study published in the peer-reviewed scientific journal Science Advances earlier this month found that the Earth’s lower atmosphere has been expanding due to the effects of anthropogenic – or man-made – climate change.
The study measured the height of the atmosphere’s Tropopause – the atmospheric boundary that separates the atmosphere’s lowest layer, the Troposphere, from its second-lowest layer, the Stratosphere.
Researchers tracked results spanning from the years 1980-2000 and 2000-2020, discovering that the tropopause has been expanding upward at a rate of roughly 164 feet (50 meters) per decade.
Findings showed that greenhouse gas emissions are the primary culprit of the atmospheric rise. As greenhouse gases continue to trap heat in the atmosphere, the rise has continued to record levels. Air in the atmosphere typically expands in warm climates and declines in colder climates, so as global temperatures continually rise, the expansion of the troposphere has surged.
Atmospheric rises could potentially force planes to fly at higher altitudes to adjust to the rise in the atmosphere and avoid turbulence, though the impacts of the rising troposphere remain unclear to scientists.
"This is an unambiguous sign of changing atmospheric structure," said Bill Randel, a scientist at the National Center for Atmospheric Research and co-author of the study. "These results provide independent confirmation, in addition to all the other evidence of climate change, that greenhouse gases are altering our atmosphere."
The rate of this acceleration has continually risen decade over decade, according to the study. The tropopause rose 174 feet (53.3 m) per decade between 2001 and 2020, compared to 164 feet (50 m) per decade between 1980 and 2000 – a 6% increase in just twenty years.
Researchers also attribute some of the rises to ozone-depleting gases, such as chlorofluorocarbons - commonly used in refrigerators, air conditioners, foam and aerosol propellants. Recent restrictions against ozone-depleting gas emissions have caused the atmospheric concentrations of these gases to decline.
"The study captures two important ways that humans are changing the atmosphere," Randel said. "The height of the tropopause is being increasingly affected by emissions of greenhouse gases even as society has successfully stabilized conditions in the stratosphere by restricting ozone-destroying chemicals."
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