The smallest changes can make a planet uninhabitable
Published: Monday, Dec 18th 2023, 12:00
Updated At: Tuesday, Dec 19th 2023, 00:59
Zurück zu Live Feed
From habitable to hostile: Geneva researchers have simulated the so-called runaway greenhouse effect for the first time, which can make a planet completely uninhabitable. This is triggered by minor changes, the University of Geneva announced on Monday.
According to the study published in the journal Astronomy & Astrophysics, a rise in global temperature of just a few tens of degrees would be enough to trigger this irreversible process on Earth. In such a scenario, a planet can heat up from a moderate, Earth-like state to over 1000 degrees Celsius.
The idea of a so-called runaway effect is not new, as the University of Geneva (Unige) emphasized in the press release. The principle behind it is simple: if temperatures on a planet rise, more water evaporates. The water vapor in the atmosphere prevents solar radiation from being reflected back into space in the form of heat radiation. It therefore retains the heat in a similar way to a safety blanket.
"Critical threshold"
"There is a critical threshold for this amount of water vapor, beyond which the planet can no longer cool. From there, everything goes out of control until the oceans evaporate completely and the temperature reaches several hundred degrees," explained the lead author of the study, Guillaume Chaverot, in the press release.
In the new study, however, astronomers from Unige and the National Center for Scientific Research in France simulated this runaway effect for the first time in order to understand how it develops and which factors contribute to it.
Dense clouds change the atmosphere
According to Unige, one of the key points of the study describes the occurrence of a very peculiar cloud pattern that amplifies the runaway effect and makes the process irreversible.
At the start of this process, dense clouds form in the upper atmosphere, which profoundly change the structure of the atmosphere. "The temperature inversion typical of the Earth's atmosphere, which separates the two main layers of the atmosphere - the troposphere and the stratosphere - is no longer present," explained Chaverot.
"Thanks to previous studies, we had already suspected such a critical water vapor threshold, but the formation of the cloud pattern is a real surprise," said study author Émeline Bolmont.
Significance for the earth
The researchers also used their climate model to show what this runaway process would look like on Earth. Evaporation of ten meters of the ocean surface would lead to an increase in atmospheric pressure on the ground of 1 bar.
"Within a few hundred years, we would reach a temperature of over 500 degrees Celsius on the ground. Later, we would even reach up to 273 bar pressure and over 1500 degrees Celsius when the entire oceans have finally evaporated," says Chaverot.
For the exploration of distant planets
According to the researchers, the new findings on the emerging cloud pattern are of great importance for research into the climate on other planets. "By studying the climate on other planets, we primarily want to find out whether they can harbor life," explained Bolmont.
In the future, measuring instruments should be able to recognize the cloud patterns on alien planets that show that such a runaway greenhouse process is underway.
©Keystone/SDA
German 
English 
French 
Spanish 
Arabic