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Comment by autokad | Hacker News Reader

agree, but in the long long run it will lean towards hotter as the sun changes phases. eventually earth will be a scorched rock without anyone's help.

you have to consider, the earth is about 4.5 billion years old, and we only have 1 billion left, but life will be wiped out much 'sooner' then that.

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> we only have 1 billion left

Not disputing, but have a source for that theory?

Why does the Earth have one billion years left?

All stars become gradually hotter the older they get. G-type stars like our sun are no exception to this. On a certain point in time (currently estimated at 1Gy from now), the energy output of our sun is so big, that the Carbonate–silicate cycle[0] cannot continue uninterrupted. Thus CO2 and CO cannot be absorbed by the geosphere. The breaking of this process will gradually enrich the atmosphere with CO2, leading to a runaway greenhouse effect (a bit like on Venus).

But I would not worry about that. It took 500My for life to evolve from trilobites to humans. This timespan is twice as long...

[0]: https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cyc...

In about a billion years the sun will exhaust enough nuclear fuel to cool and expand, boiling the oceans, blowing off our atmosphere, and turning Earth back into a sterile rock.

It's predicted by astronomers and physicists who study stellar evolution.

No, that doesn't happen until 5 billion years into the future.

The Sun will gradually keep getting hotter and slightly more luminous up to that point.

Earth will be a desert long before the Sun exhausts nuclear fuel to start expanding and becoming a red giant.

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