> >The last survivors of the end of the worldJuly 2nd, 2013 in Space & Earth / >Earth Sciences > >An image of the Upper Geyser Basin region in Yellowstone National Park in >Wyoming, USA. As the Sun heats up, much of the Earth will come to resemble >this landscape. Credit: Jack O’Malley-James > > >(Phys.org) —In 2 billion years' time, life on Earth will be confined to >pockets of liquid water deep underground, according to PhD astrobiologist Jack >O'Malley James of the University of St Andrews. The new research also suggests >that though the hardiest forms of life may have a foothold on similar worlds >in orbit around other stars, evidence for it may be very subtle. O' Malley- >James will present the findings at the National Astronomy Meeting in St >Andrews, Scotland. >All species have finite lifetimes, with each eventually facing an event that >leads to its extinction. This can be sudden and catastrophic, like the giant >impact that wiped out the dinosaurs, or a slow and gradual process. >Ultimately, a combination of slow and rapid environmental changes will result >in the extinction of all species on Earth, with the last inhabitants >disappearing within 2.8 billion years from now. >The main driver for these changes will be the Sun. As it ages over the next >few billion years, the Sun will remain stable but become steadily more >luminous, increasing the intensity of its heat felt on Earth and warming the >planet to such an extent that the oceans evaporate. In his new work, O'Malley >James has created a computer model to simulate these extremely long-range >temperature forecasts and has used the results to predict the timeline of >future extinctions. >Within the next billion years, increased evaporation rates and chemical >reactions with rainwater will draw more and more carbon dioxide from the >Earth's atmosphere. The falling levels of CO2 will lead to the disappearance >of plants and animals and our home planet will become a world of microbes. At >the same time the Earth will be depleted of oxygen and will be drying out as >the rising temperatures lead to the evaporation of the oceans. A billion years >after that the oceans will have gone completely. >An electron microscope image of thermophilic (heat-loving) bacteria. These >organisms may be amongst the last life on Earth, perhaps surviving 2.8 billion >years into the future. Credit: Mark Amend / NOAA Photo Library >"The far-future Earth will be very hostile to life by this point", said >O'Malley-James. "All living things require liquid water, so any remaining life >will be restricted to pockets of liquid water, perhaps at cooler, higher >altitudes or in caves or underground". This life will need to cope with many >extremes like high temperatures and intense ultraviolet radiation and only a >few microbial species known on Earth today could cope with this. >The new model not only tells us a lot about our own planet's future, but it >can also help us to recognise other inhabited planets that may be approaching >the end of their habitable lifetimes. >O'Malley-James adds "When we think about what to look for in the search for >life beyond Earth our thoughts are largely constrained by life as we know it >today, which leaves behind telltale fingerprints in our atmosphere like oxygen >and ozone. Life in the Earth's far future will be very different to this, >which means, to detect life like this on other planets we need to search for a >whole new set of clues". >"We have now simulated a dying biosphere composed of populations of the >species that are most likely to survive to determine what types of gases they >would release to the atmosphere. By the point at which all life disappears >from the planet, we're left with a nitrogen:carbon-dioxide atmosphere with >methane being the only sign of active life". >Provided by Royal Astronomical Society >"The last survivors of the end of the world." July 2nd, 2013. >http://phys.org/news/2013-07-survivors-world.html >Posted by >Robert Karl Stonjek > > >
