Earth

=== Future ===
{{Main|Future of Earth}}
{{See also|Global catastrophic risk}}
[[File:Red Giant Earth warm.jpg|thumb|upright=1.3|alt=A dark gray and red sphere representing the Earth lies against a black background to the right of an orange circular object representing the Sun|Conjectured illustration of the scorched Earth after the [[Sun]] has entered the [[red giant]] phase, about 5–7&nbsp;billion years from now]]
Earth's expected long-term future is tied to that of the Sun. Over the next {{val|1.1|u=billion years}}, solar luminosity will increase by 10%, and over the next {{val|3.5|u=billion years}} by 40%.<ref name="sun_future" /> Earth's increasing surface temperature will accelerate the [[carbonate–silicate cycle|inorganic carbon cycle]], reducing {{chem2|CO2}} concentration to levels lethally low for plants ({{val|10|ul=ppm}} for [[C4 carbon fixation|C4 photosynthesis]]) in approximately {{val|100|–|900|u=million years}}.<ref name="britt2000" /><ref name="pnas1_24_9576" /> The lack of vegetation will result in the loss of oxygen in the atmosphere, making animal life impossible.<ref name="ward_brownlee2002" /> Due to the increased luminosity, Earth's mean temperature may reach {{convert|100|C|F|0|abbr=}} in 1.5&nbsp;billion years, and all ocean water will evaporate and be lost to space, which may trigger a [[runaway greenhouse effect]], within an estimated 1.6 to 3&nbsp;billion years.<ref name="Mello-2020">{{Cite journal
|last1=Mello |first1=Fernando de Sousa |last2=Friaça |first2=Amâncio César Santos |date=2020 |title=The end of life on Earth is not the end of the world: converging to an estimate of life span of the biosphere? |journal=International Journal of Astrobiology |language=en |volume=19 |issue=1 |pages=25–42 |doi=10.1017/S1473550419000120 |bibcode=2020IJAsB..19...25D |issn=1473-5504 |doi-access=free}}</ref> Even if the Sun were stable, a fraction of the water in the modern oceans will descend to the [[Mantle (geology)|mantle]], due to reduced steam venting from mid-ocean ridges.<ref name="Mello-2020" /><ref name="hess5_4_569" />

The Sun will [[stellar evolution|evolve]] to become a [[red giant]] in about {{val|5|u=billion years}}. Models predict that the Sun will expand to roughly {{convert|1|AU|e6km e6mi|lk=in|abbr=unit}}, about 250 times its present radius.<ref name="sun_future" /><ref name="sun_future_schroder" /> Earth's fate is less clear. As a red giant, the Sun will lose roughly 30% of its mass, so, without tidal effects, Earth will move to an orbit {{convert|1.7|AU|e6km e6mi|lk=off|abbr=unit}} from the Sun when the star reaches its maximum radius, otherwise, with tidal effects, it may enter the Sun's atmosphere and be vaporized.<ref name="sun_future" />