The Stratosphere Is 'Shrinking' And Greenhouse Gases Are To Blame

Greenhouse gases (GHG) have long been known to be affecting the troposphere. Now an international team of researchers found that it is also causing the stratosphere to shrink.

The stratosphere in the Earth's atmosphere has shrunk and will likely continue to do so in the coming years, a team of researchers found in their study published in Environmental Research Letters. Specifically, they found that the layer has shrunk by about 0.4 kilometers (400 meters) since the 1980s.

"As estimated from an ensemble of CCM simulations, the stratospheric extent has declined by 0.4 km between 1980 and 2018 and models project a net contraction of 1.3 km by the year 2080, corresponding to a 3.7% decline compared to the 1980-2018 mean stratospheric thickness," the researchers wrote.

Simply put, the shrinking may continue if greenhouse gas trends persist and are not reversed.

The stratosphere is a layer of the atmosphere that's above the troposphere and below the mesosphere, NASA explained. Over 20 miles thick, it is comprised of its own layers, including the all-important ozone layer that protects the planet from ultraviolet radiation.

Due to the increase in greenhouse gas emissions, the troposphere below it has expanded, pushing the stratosphere above. But how exactly this has been affecting the structure of the stratosphere "has not been studied extensively," the researchers said.

Stratosphere cooling and 'shrinking'

What's behind the shrinking? Apart from being pushed by the troposphere below it, the stratosphere actually has an opposite reaction to greenhouse gases compared to the troposphere. Instead of warming and expanding as the troposphere does when carbon dioxide enters it, the stratosphere actually cools and contracts.

The results of the new study show how the stratosphere has truly changed over the years and how human-made greenhouse gases have likely contributed to this shrinking.

"We also demonstrate that the stratospheric contraction is not only a response to cooling, as changes in both tropopause and stratopause pressure contribute," the researchers wrote. "Moreover, its short emergence time (less than 15 years) makes it a novel and independent indicator of GHG induced climate change."

What a shrinking stratosphere means

This discovery proves just how much human actions are affecting the planet.

"It is shocking," study co-author Juan Añel of the University of Vigo, Ourense in Spain said as per The Guardian. "This proves we are messing with the atmosphere up to 60 kilometres."

What's more, it could actually spell bad news for satellites.

"It may affect satellite trajectories, orbital life-times, and retrievals, and via indirect influence on ionospheric electron density, the propagation of radio waves, and eventually the overall performance of the Global Positioning System (GBS) and other space-based navigational systems," the researchers wrote.

It could also influence radiation transfer, although more research is needed to determine and quantify this.