The last survivors of the end of the world
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.
"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.
"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".
Dr Robert Massey
Ms Emma Shea
Landline numbers in NAM 2013 press room (available from 9 a.m. to 5 p.m. from 1-4 July, 9 a.m. to 3 p.m. 5 July):
Tel: +44 (0)1334 462231, +44 (0)1334 46 2232
Images and captions
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
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
Jack O’Malley-James is working on a PhD (funded by the STFC Aurora scheme) supervised by Dr Jane Greaves at the University of St Andrews, Prof. John Raven (University of Dundee) and Prof. Charles Cockell (the UK Centre for Astrobiology, University of Edinburgh) investigating the possible biosignatures of diverse microbial life under a variety of exoplanetary environments.
Notes for editors
Bringing together more than 600 astronomers and space scientists, the RAS National Astronomy Meeting (NAM 2013) will take place from 1-5 July 2013 at the University of St Andrews, Scotland. The conference is held in conjunction with the UK Solar Physics (UKSP: www.uksolphys.org) and Magnetosphere Ionosphere Solar Terrestrial (MIST: www.mist.ac.uk) meetings. NAM 2013 is principally sponsored by the RAS, STFC and the University of St Andrews and will form part of the ongoing programme to celebrate the University’s 600th anniversary.
Meeting arrangements and a full and up to date schedule of the scientific programme can be found on the official website at http://www.nam2013.co.uk
The Royal Astronomical Society (RAS: www.ras.org.uk, Twitter: @royalastrosoc), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3500 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
The Science and Technology Facilities Council (STFC: www.stfc.ac.uk, Twitter: @stfc_matters) is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security. The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar. It enables UK researchers to access leading international science facilities for example in the area of astronomy, the European Southern Observatory.
Founded in the 15th century, St Andrews is Scotland’s first university and the third oldest in the English speaking world. Teaching began in the community of St Andrews in 1410 and the University was formally constituted by the issue of Papal Bull in 1413. The University is now one of Europe’s most research intensive seats of learning – over a quarter of its turnover comes from research grants and contracts. It is one of the top rated universities in Europe for research, teaching quality and student satisfaction and is consistently ranked among the UK’s top five in leading independent league tables produced by The Times, The Guardian and the Sunday Times.
The University is currently celebrating its 600th anniversary and pursuing a £100 million fundraising campaign, launched by Patron and alumnus HRH Prince William Duke of Cambridge, including £4 million to fund the creation of an ‘Other Worlds’ Think Tank and Observatory. The new think tank and Observatory project will extend the University of St Andrews’ flagship work on extra-solar planets, and provide a creative environment for problem-focused research, education and continuing public engagement.
For further information go to: www.st-andrews.ac.uk/600/