According to previous estimates of how long life will last on Earth, all living creatures should be gone 1 billion years from now. But a new research comes to show that the “deadline” may be 2.3 billion years away, which means that the planet might be inhabitable for almost half of the Sun's life cycle. Caltech researcher King Fai Li and colleagues believe that the key to this “longevity” is the fact that the planet's atmospheric pressure varies, but that it could slightly decrease in the future, adding some 1 billion years to life's lifespan.
The “Earth will be identifiable as an inhabited planet for nearly half the total lifetime of the Sun, an important point to consider in the search for life on extrasolar planets,” said the authors in a new scientific paper, published in the latest issue of the journal Proceedings of the National Academy of Sciences. The find could also be extended to other planets with biosphere, and could significantly aid the process of finding extraterrestrial life, the experts added.
The percentage of time in which an exoplanet may be inhabited is a very important factor in determining its chances of supporting basic or complex life. The longer the time, the higher the chances. In fact, some evolutionary biologists say that life on our planet became possible because it also had a lot of time to adapt to the conditions of its world. Despite five mass extinction events, life managed to find a way to endure because it had the Sun and the atmosphere's help.
Astronomers predict that, over the next hundred millions years, the Sun will become increasingly hotter, and will continue to get so until everything on the surface boils down to non-existence. But predictive models have thus far shown that this would happen within 1 billion years from now, whereas the new research highlights the fact that the importance of atmospheric pressure in the calculations has been largely left unnoticed. Lower pressure means lower infrared absorption power, and lower amounts of heating.
“I am glad that Li and colleagues have raised the issue of how overall variation in atmospheric pressure may have affected past and may affect future climate. This could be relevant for understanding climate change on the billion-year time scale,” Ken Caldeira, Stanford University ecologist, told Wired in an e-mail.
“So, the assumption that we’ve always had an atmosphere of the same pressure as now is widespread but there’s no justification for it. The reason that everyone just assumes an atmosphere of roughly current pressure is that it is exceedingly difficult to measure in the past. The weight of the atmosphere doesn’t leave much record in geology,” concluded University of Washington astrobiologist Roger Buick, who was also a part of the research.