A new study by scientists from the Max Planck Institute for Meteorology (Germany) proves that a strong greenhouse effect can be just as destructive to life on any planet as a planet too close to a star. Thus, science has one more exclusionary factor for the search for "aliens": planets with extremely high greenhouse effect are most likely lifeless.
The main hypothesis on which the search for alien life is based today assumes that liquid water is needed for life. Therefore, in an attempt to find potentially habitable planets outside the solar system, scientists first establish the size of the so-called "habitable zones" around each star. After all, the temperature on planets too far from the stars is too low, and water on them can exist only in the form of ice. On planets too close to the stars, it is too hot, and water there can only be in the form of atmospheric vapor. For example, water from Venus, too close to the Sun, evaporated and eventually evaporated from its atmosphere.
In a new model experiment, scientists have shown that a strong greenhouse effect can deprive a planet of water in the same way that a planet is too close to a star. The researchers created a 3D computer model of the Earth completely covered with water and tested how fast the water will evaporate from the planet as the distance to the Sun increases and as the content of carbon dioxide in the atmosphere increases. As it turned out, the content of carbon dioxide in the Earth's atmosphere, equal to 1520 ppm (0.152%), causes irreversible climate change. In this case, the temperature on the planet can rise sharply to 57 ° C, the greenhouse effect intensifies, and the water evaporates relatively quickly.
However, in relation to such a scenario, scientists can reassure humanity: it is physically impossible to achieve a carbon dioxide content in the atmosphere, in which all the water on Earth will evaporate, at least not now. As of 2013, the content of carbon dioxide in the atmosphere ranged from 393 ppm (0.0393%) to 397 ppm (0.0397%).