A new international study shows that climate change is having an increasing impact on the structure of the Earth’s atmosphere, and could cause aircraft to fly higher to avoid disturbance.
The research, published in Science Advances, relies on decades of weather balloon observations and special satellite measurements to determine how high the lowest peak of the atmosphere – called the tropopause – is.
An alarming analysis of weather balloon observations shows that the height of the tropopause has been increasing at a steady rate since 1980: about 58-59 meters per decade.
Of these, 50-53 meters per decade are associated with human-caused warming in the lower atmosphere.
This trend persisted even as the effect of stratospheric temperature diminished, suggesting that tropospheric warming is having an increasing effect.
“This is a clear sign of changing atmospheric structure,” said Bill Randell, a scientist at the National Center for Atmospheric Research and co-author of the new study.
Satellite observations made since 2000 confirm that the tropopause has increased over the past two decades.
“These findings provide independent confirmation, along with all other evidence from climate change, that greenhouse gases are changing our atmosphere,” Randel said.
The height of the tropopause, the region of the atmosphere that divides the dense and turbulent troposphere from the upper and more stable stratosphere, ranges from about 5 miles above Earth’s surface at the poles to 10 miles at the equator, depending on the season.
The location of the tropopause is important for commercial pilots who frequently fly in the lower stratosphere to avoid turbulence, and plays a role in severe thunderstorms, which sometimes raise the tropopause and draw air out of the stratosphere.
The steady increase in the tropopause in recent decades does not significantly affect communities or ecosystems, but illustrates the large-scale effects of greenhouse gas emissions.
Previous scientific studies have shown that the tropopause increases. This is caused not only by climate change, but also by cooling in the stratosphere caused by ozone-depleting gases.
These gases shrink the stratosphere by destroying the stratospheric ozone layer, although restrictions on their emissions in recent years have led to a decrease in atmospheric concentrations of these gases.
They say that while scientists are still unsure how the height of the tropopause affects climate or weather, it may force aircraft to fly higher into the atmosphere to avoid disturbance.
“This study demonstrates two important ways in which humans are changing the atmosphere,” said Randel. “The tropopause is increasingly affected by greenhouse gas emissions even as society has managed to stabilize conditions in the stratosphere by limiting ozone-depleting chemicals.”
–
