Unabated Carbon Is Shrinking Earth's Upper Atmosphere, Scientists Warn

Efforts to clean up space junk could be made worse by rising levels of carbon dioxide.

The greenhouse gas has been linked to the contraction of the upper atmosphere. For the first time ever, this contraction has been observed.

Scientists say that the contribution made by CO2 is probably permanent and that some of the observed shrinkage is normal.

The reduction of atmospheric drag will cause problems for newer satellites and cause old technology to stay in place longer.

Satellites will stay up longer because people want their satellites to stay up.

Satellites and other valuable space objects will need to adjust their path to avoid colliding with debris.

The volume of gases surrounding our world isn't static, despite the fact that descriptions of Earth's atmosphere usually set the layers at specific altitudes. The biggest influence is probably the Sun.

The Sun is dynamic as well. Every 11 years it goes through cycles of activity. There have been 25 such cycles since the beginning of the year. Mlynczak and his colleagues were able to measure atmospheric contraction because the previous cycle, number 24, was subdued even at the peak of solar activity.

Their attention was focused on two layers: the mesosphere and the lower thermoosphere.

Data from NASA's TIMED satellite gave them pressure and temperature information over a period of 20 years.

In some lower layers of the atmosphere, CO2 creates a warming effect by trapping some of the heat from the sun.

Some of the CO2 that escapes into space is used to cool the upper atmosphere. The higher the CO2, the cooler the air.

The stratosphere is contracting due to the cooling. It's doing the same thing to the mesosphere and thermoosphere above it as well. Mlynczak and his team used the data from TIMED to find out how much the MLT contracted. The result of CO2 radiative cooling is close to 300 meters.

Mlynczak says there's been a lot of interest in seeing if we can observe the cooling effect on the atmosphere.

The observations are presented in the paper. We are the first to show the Shrinking of the Atmosphere on a global basis.

It might not seem like much, given that the thermoosphere extends out to hundreds of kilometers. According to a paper published in September, thermospheric cooling could result in a 33 percent reduction in atmospheric drag.

Satellites and rocket stages are helped by atmospheric drag. The reduction in drag could prolong the life of space junk by 30 percent.

This is going to get worse as more and more satellites are launched, with no real measures in sight to decrease the number of satellites or the amount of CO2.

According to Mlynczak, there is a cooling and a contraction at every altitude. "As long as carbon dioxide increases at about the same rate, we can expect these rates of temperature change to stay about constant too, at about half a degree of cooling"

The research was published in a journal.