<p>You have 3 completely unrelated dates in your question.</p>
<p>Stephen Hawking suggested that humanity could kill itself in 100 years.  He's not the first to make that suggestion.   He's especially concerned about global warming and artificial intelligence (by the article).   Pandemic is obviously an issue today.  Overpopulation.  Nuclear war, asteroid strike, super-volcano, dubstep - all serious threats.</p>
<p>Not to get all doom and gloom but there are reasons to be concerned for humanity over the next 100 years or so.  Hawking certainly has a point though I lean towards the idea of extinction being less likely, some non-extinction bumps on the road are certainly possible.</p>
<p>The expanding sun (and no more eclipses cause the Sun is too big), will happen, slowly.  The sun increases in luminosity about 1% per 100 billion years and in diameter, maybe 1% every 200 million years.  In several hundred million years our sun might be too big for Earth and Earth could start dying.</p>
<p>The counter-argument to this.   A sun-shield wouldn't be all that hard to build.  It's even being discussed today as a possible solution to climate change.    Not cheap, but not impossible, especially if we have a few hundred million years to get it done.</p>
<p>The loss of CO2 probably will happen too though Earth's CO2 doesn't just go down neatly, it's more like an up and down with an overall downward trend.    If this continues, then in maybe 100 million years (a reasonably short time), we could face as CO2 shortage.   I know your article says 600 million - neither estimate is precise, but yes, a CO2 decline is probably going to happen at some point in the far future.</p>
<p>The good news - we know how to fix that.   Burn coal.  Problem solved,  When we run out of coal, burn carbonate rock of other kinds.  There's billions and billions of tons of carbonate rock on Earth.   We can make CO2.  It's not that hard.    If we run out of carbonate rock (unlikely but possible) - toss some small comets rich in methane and CO2 into the ocean or onto unpopulated regions of Earth.  The comet idea might not be practical but it's certainly possible and many comets are rich in CO2 and CH4.</p>
<p>Fun estimate.  Halley's comet has a mass of about 220 trillion kg.   At 280 PPM, the CO2 in the atmosphere has a mass of about 10 Halley's comets.    If Halley's comet is about 25% carbon compounds, 50% water, 25% other stuff - not the worst estimate and the CH4 yields more CO2 per mass, then all you'd need is maybe 2-4 Halley's comet equivalents every 10 million years or so to maintain CO2 on Earth.</p>
<p>Halley's comet itself is too large but smaller comets could be tossed into unpopulated regions or into the ocean without much harm - and again, CO2 problem solved.   Not impossible.</p>
<p>So, I think the trick is surviving Hawking's 100 year warning because the other problems are solvable with technology, at least for a time.   Likely beyond 600 million years.</p>

CC BY-SA 4.0
2020-07-24T18:10:37.883Z
@a_donda I can't help it.  I don't like hearing an "Earth will die" question without pointing out the not very difficult solutions that not everyone might be aware of.
userLTK
CC BY-SA 4.0
2020-07-25T15:52:16.060Z
@a_donda  Certainly not everyone is aware of solutions.   I know that with absolute certainty from talking to people.  But if my answer bothers you that much you can close it.    I also never said humans will do it", I simply said that problems like the expanding sun or the drop in carbon dioxide have workable technological solutions, which is I think, a point worth making.  That was all I was trying to convey.
userLTK
CC BY-SA 4.0
2020-07-24T16:52:23.033Z
2020-07-24T16:52:23.033Z
userLTK
<p>Estimates <a href="https://www.space.com/37627-total-solar-eclipse-earth-moon-alignment-future.html" rel="nofollow noreferrer">put the last solar eclipse at 600 million years</a>.</p>
<p>The question then becomes how much time is left on Earth?  Stephen Hawking believes we have less then a <a href="https://qz.com/1229008/stephen-hawking-warned-that-we-have-100-years-left-on-earth-but-he-was-an-optimist-about-humanity/" rel="nofollow noreferrer">100 years left</a> on Earth but that seems like an underestimate.</p>
<blockquote>
<p>In <a href="https://en.wikipedia.org/wiki/Future_of_Earth" rel="nofollow noreferrer">about 600 million years from now</a>, the level of carbon dioxide will fall below the level needed to sustain C3 carbon fixation photosynthesis used by trees.</p>
</blockquote>

CC BY-SA 4.0
2020-07-18T09:50:57.090Z
Life on Earth is not dependent on solar eclipses, they only cause a short period black out on a small region on the side of the Earth facing the Sun during an eclipse. A minor inconvenience.
Fred
CC BY-SA 4.0
2020-07-18T17:03:09.280Z
Only _total_solar eclipses will stop.  There will still be partial and annular eclipses.
Oscar Lanzi
CC BY-SA 4.0
2020-07-19T11:03:33.063Z
The estimate of 600 million years to when total solar eclipses will end is bogus, as is the 600 million year estimate for when C3 carbon fixation photosynthesis will end. You are cherry-picking two bogus numbers that happen to coincide.
David Hammen
CC BY-SA 4.0
2020-07-19T14:33:46.660Z
@a_donda - That number is far to precise. A better value is somewhere between a few hundred million to a few billion years from now, which means any cited value is bogus.
David Hammen
CC BY-SA 4.0
2020-07-19T20:45:44.097Z
@a_donda - I get over two billion years as an upper limit, less than two hundred million as a lower limit, depending on how I fudge the numerology. And that's all this question is, numerology. Regarding the "C3 carbon fixation photosynthesis used by trees", that is (a) numerology, and (b) totally irrelevant. Think what life looked like 600 million years ago. That's before the Cambrian explosion. It's ludicrous to think that life will look anything like it does now 600 million years into the future.
David Hammen
<climate-change><climate-models>
Will life still be sustainable on earth when solar eclipses stop?
Lime
# Will life still be sustainable on earth when solar eclipses stop?

(Asked by: username_0 on 2020-07-18)

Estimates [put the last solar eclipse at 600 million years](https://www.space.com/37627-total-solar-eclipse-earth-moon-alignment-future.html).

The question then becomes how much time is left on Earth? Stephen Hawking believes we have less then a [100 years left](https://qz.com/1229008/stephen-hawking-warned-that-we-have-100-years-left-on-earth-but-he-was-an-optimist-about-humanity/) on Earth but that seems like an underestimate.

> In [about 600 million years from now](https://en.wikipedia.org/wiki/Future_of_Earth), the level of carbon dioxide will fall below the level needed to sustain C3 carbon fixation photosynthesis used by trees.

**Tags:** climate-change, climate-models

> **Comments:**
> **username_1**: Life on Earth is not dependent on solar eclipses, they only cause a short period black out on a small region on the side of the Earth facing the Sun during an eclipse. A minor inconvenience.  
> **username_2**: Only _total_solar eclipses will stop.  There will still be partial and annular eclipses.  
> **username_3**: The estimate of 600 million years to when total solar eclipses will end is bogus, as is the 600 million year estimate for when C3 carbon fixation photosynthesis will end. You are cherry-picking two bogus numbers that happen to coincide.  
> **username_3**: @a_donda - That number is far to precise. A better value is somewhere between a few hundred million to a few billion years from now, which means any cited value is bogus.  
> **username_3**: @a_donda - I get over two billion years as an upper limit, less than two hundred million as a lower limit, depending on how I fudge the numerology. And that's all this question is, numerology. Regarding the "C3 carbon fixation photosynthesis used by trees", that is (a) numerology, and (b) totally irrelevant. Think what life looked like 600 million years ago. That's before the Cambrian explosion. It's ludicrous to think that life will look anything like it does now 600 million years into the future.  

---

## 1 answers

### Answer by username_4 on 2020-07-24. Score: 1

You have 3 completely unrelated dates in your question.

Stephen Hawking suggested that humanity could kill itself in 100 years. He's not the first to make that suggestion. He's especially concerned about global warming and artificial intelligence (by the article). Pandemic is obviously an issue today. Overpopulation. Nuclear war, asteroid strike, super-volcano, dubstep - all serious threats.

Not to get all doom and gloom but there are reasons to be concerned for humanity over the next 100 years or so. Hawking certainly has a point though I lean towards the idea of extinction being less likely, some non-extinction bumps on the road are certainly possible.

The expanding sun (and no more eclipses cause the Sun is too big), will happen, slowly. The sun increases in luminosity about 1% per 100 billion years and in diameter, maybe 1% every 200 million years. In several hundred million years our sun might be too big for Earth and Earth could start dying.

The counter-argument to this. A sun-shield wouldn't be all that hard to build. It's even being discussed today as a possible solution to climate change. Not cheap, but not impossible, especially if we have a few hundred million years to get it done.

The loss of CO2 probably will happen too though Earth's CO2 doesn't just go down neatly, it's more like an up and down with an overall downward trend. If this continues, then in maybe 100 million years (a reasonably short time), we could face as CO2 shortage. I know your article says 600 million - neither estimate is precise, but yes, a CO2 decline is probably going to happen at some point in the far future.

The good news - we know how to fix that. Burn coal. Problem solved, When we run out of coal, burn carbonate rock of other kinds. There's billions and billions of tons of carbonate rock on Earth. We can make CO2. It's not that hard. If we run out of carbonate rock (unlikely but possible) - toss some small comets rich in methane and CO2 into the ocean or onto unpopulated regions of Earth. The comet idea might not be practical but it's certainly possible and many comets are rich in CO2 and CH4.

Fun estimate. Halley's comet has a mass of about 220 trillion kg. At 280 PPM, the CO2 in the atmosphere has a mass of about 10 Halley's comets. If Halley's comet is about 25% carbon compounds, 50% water, 25% other stuff - not the worst estimate and the CH4 yields more CO2 per mass, then all you'd need is maybe 2-4 Halley's comet equivalents every 10 million years or so to maintain CO2 on Earth.

Halley's comet itself is too large but smaller comets could be tossed into unpopulated regions or into the ocean without much harm - and again, CO2 problem solved. Not impossible.

So, I think the trick is surviving Hawking's 100 year warning because the other problems are solvable with technology, at least for a time. Likely beyond 600 million years.

> **Comments:**
> **username_4**: @a_donda I can't help it.  I don't like hearing an "Earth will die" question without pointing out the not very difficult solutions that not everyone might be aware of.  
> **username_4**: @a_donda  Certainly not everyone is aware of solutions.   I know that with absolute certainty from talking to people.  But if my answer bothers you that much you can close it.    I also never said humans will do it", I simply said that problems like the expanding sun or the drop in carbon dioxide have workable technological solutions, which is I think, a point worth making.  That was all I was trying to convey.  

---

