If alien terraforming emits greenhouse gases, our telescopes could detect it
Scientists have proposed an intriguing idea: if extraterrestrial civilizations use potent greenhouse gases to warm their planets, similar to what we do on Earth, we could potentially detect these gases using existing technology, such as the James Webb Space Telescope (JWST). A recent study identified five artificial greenhouse gases, which, if present in significant quantities, could signal the presence of advanced alien technology.
These gases, including fluorinated versions of methane, ethane, and propane, are known on Earth for their strong heat-trapping capabilities and are often emitted during industrial processes. Because these substances don't naturally form in large quantities, detecting them in an exoplanet's atmosphere could indicate technological activity. On Earth, these gases are pollutants, but for an alien civilization, they could be used to prevent an ice age or terraform an inhospitable planet.
Edward Schwieterman, the study's lead author, explains that while these gases are harmful to us, they could be beneficial for an alien civilization trying to create a more habitable environment. Terraforming, or intentionally modifying a planet's climate, is a concept often explored in science fiction and proposed for Mars. However, some scientists, like astrophysicist Paul Sutter, remain skeptical about the feasibility of such projects.
In their research, Schwieterman and his colleagues simulated a planet in the TRAPPIST-1 system, a group of seven rocky planets about 40 light-years away. They found that the JWST could potentially detect the greenhouse gases if they were present. One of these gases, sulfur hexafluoride, has an exceptionally high warming potential and a long atmospheric lifetime, making it a strong technosignature.
Co-author Daniel Angerhausen highlights that these gases could serve as long-lasting technosignatures, outliving the civilizations that produced them if their geoengineering efforts failed. Other similar gases could remain in an atmosphere for up to 50,000 years, ensuring a stable climate with minimal replenishment.
This means that if extraterrestrial life is using greenhouse gases to warm their planets, our telescopes might be able to detect these signs. Such a discovery would be groundbreaking, providing evidence of technologically advanced civilizations beyond our solar system. For more details, you can read the full study and findings here.
