Researchers have conducted a new study on the runaway greenhouse effect, revealing how a critical threshold of water vapor could cause catastrophic climate change on Earth and other planets. This study reveals key cloud patterns contributing to this irreversible climate change and provides insight into exoplanets’ climates and their potential to support life. Credit: SciTechDaily.com
The UNIGE team, in collaboration with CNRS, successfully simulated an entire runaway greenhouse effect that could render Earth completely uninhabitable.
Earth is a wonderful blue and green dot covered with oceans and life, Venus It is a yellowish sterile sphere that is not only inhospitable but also sterile. However, the temperature difference between the two is only a few degrees.
A team of astronomers from the University of Geneva (UNIGE) and members of the National Center for Research Competence (NCCR) PlanetS achieved a world first by managing the entire simulation, with support from the CNRS laboratories in Paris and Bordeaux. Achieved. A runaway greenhouse process that could change Earth’s climate from an idyllic environment perfect for life to a harsh and more than hostile place.
Scientists have also demonstrated that from the early stages of the process, atmospheric structure and cloud cover change significantly, making reversing the nearly uncontrollable and runaway greenhouse effect extremely complex. On Earth, an increase in the average temperature of the Earth by a few tens of degrees after a slight increase in the sun’s brightness is enough to start this phenomenon and make our planet habitable.
A runaway greenhouse effect could transform a temperate, habitable planet with oceans of liquid water on its surface into a planet dominated by hot steam hostile to all life. Credit: © Thibaut Roger / UNIGE
Greenhouse effect and runaway scenario
The idea of a runaway greenhouse effect is not new. In this scenario, the planet could evolve from an Earth-like temperate state to a true hell with surface temperatures exceeding her 1000 degrees. Cause? Water vapor is a natural greenhouse gas. Water vapor prevents solar radiation absorbed by the Earth from being re-emitted into space as thermal radiation. It traps some heat like a rescue blanket. A little greenhouse effect would be helpful, but without it, the average temperature of Earth would drop below the freezing point of water, making it a ball of ice and hostile to life.
Conversely, if the greenhouse effect is too strong, it increases evaporation in the oceans and increases the amount of water vapor in the atmosphere. “There is a critical threshold for this amount of water vapor, beyond which the Earth can no longer cool down. From there, everything ramps up until the oceans completely evaporate and temperatures reach hundreds of degrees.” , explains Guillaume Chabelo, a former postdoctoral researcher in the Department of Astronomy at the Faculty of Science at UNIGE and lead author of the study.
Groundbreaking research on climate change
“Other important studies in climatology to date have focused solely on either temperate states before the runaway or habitable states after the runaway,” says a study from the CNRS Institute in Paris and Bordeaux. Martin Tarbet, author and co-author of this paper, explains: study. “This is the first time a research team has used a 3D global climate model to study the transition itself and see how the climate and atmosphere evolve during the process.”
One of the key points of the study explains the emergence of very unique cloud patterns, increasing the runaway effect and making the process irreversible. “From the beginning of the transition, we can observe the development of very dense clouds in the upper atmosphere. In fact, the latter are responsible for the separation of the Earth’s atmosphere and its two main layers, the troposphere and the stratosphere. It no longer exhibits the characteristics of a temperature inversion. The structure of the atmosphere has changed significantly,” points out Guillaume Chavelot.
Serious consequences of searching for life elsewhere
This discovery is an important feature for studying the climate of other planets, especially exoplanets orbiting stars other than the Sun. “By studying the climates of other planets, one of our most powerful motivations is to determine the likelihood of them harboring life,” said Dr. said Emmeline Bolmont, director and co-author of “Extraterrestrial Research” study.
LUC leads cutting-edge interdisciplinary research projects on the origins of life on Earth and the search for life elsewhere in the solar system and beyond planetary systems. “After previous studies, we had already suspected the existence of a water vapor threshold, but the appearance of this cloud pattern is a real surprise!” reveals Emmeline Bolmont. “We also studied in parallel how this cloud pattern produces specific signatures, or ‘fingerprints’, that can be detected when observed. exoplanet atmosphere. The next generation of equipment should be able to detect it, ”he reveals Martin Turbet. The team also doesn’t aim to stop there. Guillaume Chabelo received a research grant to continue this work at the Grenoble Institute for Planetary Observation and Astrophysics (IPAG). This new phase of the research project will focus on specific cases from Earth.
Earth in fragile equilibrium
Using a new climate model, scientists have shown that a very small increase in solar radiation of just a few tens of degrees, leading to a rise in global temperatures, is enough to trigger this irreversible runaway process on Earth. I calculated that. It would make our planet as inhospitable as Venus. One of the current climate goals is to limit global warming caused by greenhouse gases to just 1.5 degrees Celsius by 2050. One of the problems with Guillaume Chavelot’s research grant is to determine whether a small increase in greenhouse gases could cause a runaway process. The brightness of the sun may be enough. If so, the next question becomes determining whether the threshold temperatures for both processes are the same.
Therefore, Earth is not far from this apocalyptic scenario. “Assuming this runaway process begins on Earth, evaporation of just 10 meters of ocean surface would raise atmospheric pressure at the surface by 1 bar. Within just a few hundred years, surface temperatures would exceed 500°C. Then the surface pressure would rise to 273 bar, the temperature would exceed 1500 degrees, and eventually all oceans would completely evaporate,” concludes Guillaume Chavelot.
Reference: “First Exploration of Runaway Greenhouse Transitions Using 3D General Circulation Models” by Guillaume Chaverot, Emeline Bolmont, and Martin Turbet, December 18, 2023. astronomy and astrophysics.
Exoplanets in Geneva: 25 years of expertise wins Nobel Prize
The first exoplanet was discovered in 1995 by two University of Geneva researchers, Michel Mayor and Didier Queloz, who won the 2019 Nobel Prize in Physics. With this discovery, Department of Astronomy, University of Geneva The construction and installation of has put us at the forefront of research in this field. harp upon ESO3.6 meter telescope at La Silla in 2003.
For 20 years, this spectrometer was the world’s most powerful at determining the masses of exoplanets. However, HARPS was surpassed in 2018 by ESPRESSO, another Earth-based spectrometer built in Geneva. very large telescope (VLT) Paranal, Chile.
Switzerland is also working on space-based exoplanet observations with the CHEOPS mission. This is the result of the expertise of two countries. University of Bern, the on-ground experience of the University of Geneva in collaboration with the universities of Geneva and with the support of the universities of the Swiss capital. These two areas of scientific and technical expertise are PlanetS National Center for Research Capability (NCCR).
Life in the Universe Center (LUC): A pillar of interdisciplinary excellence
of Life in the Universe Center (LUC) is an interdisciplinary research center at the University of Geneva (UNIGE), established in 2021 following the 2019 Nobel Prize in Physics awarded to Professors Michel Mayor and Didier Quelot. Thanks to advances over the past decade in both the fields of solar system exploration, exoplanets, and the organic structure of life, it is now possible to address the question of the emergence of life on other planets in a concrete way. Ta. It’s no longer just a guess. Located at the intersection of astronomy, chemistry, physics, biology, and the earth and climate sciences, LUC aims to understand the origin and distribution of life in the universe. Led by the Department of Astronomy, LUC brings together researchers from numerous institutes and departments at UNIGE, as well as from our international partner universities.
Source: scitechdaily.com
