Editing Extinction event (section)

====Future biosphere extinction/sterilization====
{{See also|Future of Earth|Medea hypothesis}}
The eventual warming and expanding of the Sun, combined with the eventual decline of atmospheric carbon dioxide, could actually cause an even greater mass extinction, having the potential to wipe out even microbes (in other words, the Earth would be completely sterilized): rising global temperatures caused by the expanding Sun would gradually increase the rate of weathering, which would in turn remove more and more CO<sub>2</sub> from the atmosphere. When CO<sub>2</sub> levels get too low (perhaps at 50 ppm), most plant life will die out, although simpler plants like grasses and mosses can survive much longer, until {{CO2}} levels drop to 10 ppm.<ref name= Franck2005>{{cite journal | vauthors = Franck S, Bounama C, von Bloh W | year = 2006 | title = Causes and Timing of Future Biosphere Extinction | journal = Biogeosciences | volume = 3 | issue = 1 | pages = 85–92 | bibcode = 2006BGeo....3...85F | doi = 10.5194/bg-3-85-2006 | s2cid = 129600368 | url = http://hal.archives-ouvertes.fr/docs/00/29/75/42/PDF/bg-3-85-2006.pdf | doi-access = free }}</ref><ref name=Ward2003>{{cite book | vauthors = Ward P, Brownlee D | date = December 2003 | title = The Life and Death of Planet Earth: How the New Science of Astrobiology Charts the Ultimate Fate of Our World | publisher = Henry Holt and Co | isbn = 978-0-8050-7512-0 | pages = 132, 139, 141 | url = https://books.google.com/books?id=3D4vHo4nDtYC | via = Google Books }}</ref>

With all photosynthetic organisms gone, atmospheric oxygen can no longer be replenished, and it is eventually removed by chemical reactions in the atmosphere, perhaps from volcanic eruptions. Eventually the loss of oxygen will cause all remaining aerobic life to die out via asphyxiation, leaving behind only simple anaerobic [[prokaryote]]s. When the Sun becomes 10% brighter in about a billion years,<ref name= Franck2005/> Earth will suffer a moist greenhouse effect resulting in its oceans boiling away, while the Earth's liquid outer core cools due to the inner core's expansion and causes the Earth's magnetic field to shut down. In the absence of a magnetic field, charged particles from the Sun will deplete the atmosphere and further increase the Earth's temperature to an average of around 420 K (147&nbsp;°C, 296&nbsp;°F) in 2.8 billion years, causing the last remaining life on Earth to die out. This is the most extreme instance of a climate-caused extinction event. Since this will only happen late in the Sun's life, it would represent the final mass extinction in Earth's history (albeit a very long extinction event).<ref name= Franck2005/><ref name=Ward2003/>