Earth's lower atmosphere is expanding due to climate change

New research suggests that Earth's atmosphere is rising due to climate change.

Weather balloon measurements taken in the Northern Hemisphere over the past 40 years show that the lowest layer of Earth's atmosphere - called the troposphere - is expanding at a rate of about 50 meters per decade, according to research published Nov. 5 in the journal Science Advances. Climate change is the cause.

The troposphere is the layer of the atmosphere we live and breathe in. It extends from sea level, 7 km above the poles, to an altitude of 20 km in the tropics. As the atmosphere that contains the most heat and moisture, it is also where much of the weather takes place.

The air in the atmosphere expands when it is hot and contracts when it is cold, so the upper boundary of the troposphere, called the top of the troposphere, naturally contracts and expands as the seasons change.

However, by analyzing atmospheric data such as pressure, temperature and humidity collected between 20 and 80 degrees north latitude and paired with GPS data, researchers say the top of the troposphere is rising faster than ever before as the amount of greenhouse gases increases and more heat is added to the atmosphere.

More importantly, the rate of rise appears to be increasing. According to the study, the top of the troposphere rose about 50 meters per decade from 1980 to 2000, and to 53.3 meters per decade from 2001 to 2020. Based on studies of regional natural events such as two volcanic eruptions in the 1980s and the El Niño phenomenon of periodic Pacific warming in the late 1990s, the researchers estimate that human activities account for 80 percent of the total increase in atmospheric height.

Climate change is not the only anthropogenic factor in tropospheric rise. The stratosphere, the layer above the troposphere, is also shrinking, due to past emissions of ozone-depleting gases. These gases shrink the stratosphere by destroying its ozone layer, although restrictions on their emissions have reduced the concentration of these gases in the atmosphere in recent years.

Scientists are still unsure what effect the rising troposphere will have on climate or weather, although aircraft may be forced to fly higher in the atmosphere to avoid turbulence.