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I was watching the ISS live feed going over North West Africa and up to Italy. The landscape was red and arid and it struck me just how ‘Mars like’ it looked.

I was watching the ISS live feed going over North West Africa and up to Italy. The landscape was red and arid and it struck me just how ‘Mars like’ it looked. It got me thinking that Earth could be facing the same destiny many aeons from now. It’s hard to imagine with the amount of H2O on the planet right now, but if it can happen to Mars (the atmosphere is stripped away), it could happen here I suppose. But I wonder if a Venus situation is more likely first, because of our proximity to the Sun? This discovery certainly makes me feel that lifecycle of planets is an awesome thing.

mixmastamyk 5y ago
The much larger mass, gravity, and magnetic field of Earth prevents large scale atmospheric losses. Whether we have the resources to ignite another Venus remains to be seen.
- exporectomy 5y ago
  Remains to be seen or is already known to be impossible? All the carbon in fossil fuels originally came from the atmospheric CO2, didn't it? And it was never as hot as Venus. What are the steps we would need to take to make it as hot as Venus in any kind of physically possible scenario?
  - virtue3 5y ago
    You are drastically under-estimating the effects of other compounds in the atmosphere. Methane is a really good example. HFCs were a great bit of disaster for a bit there as well. from: https://en.wikipedia.org/wiki/Greenhouse_gas#Impacts_on_the_overall_greenhouse_effect https://en.wikipedia.org/wiki/Greenhouse_gas#Impacts_on_the_... "The contribution of each gas to the greenhouse effect is determined by the characteristics of that gas, its abundance, and any indirect effects it may cause. For example, the direct radiative effect of a mass of methane is about 84 times stronger than the same mass of carbon dioxide over a 20-year time frame[27] but it is present in much smaller concentrations so that its total direct radiative effect has so far been smaller, in part due to its shorter atmospheric lifetime in the absence of additional carbon sequestration. On the other hand, in addition to its direct radiative impact, methane has a large, indirect radiative effect because it contributes to ozone formation. Shindell et al. (2005)[28] argues that the contribution to climate change from methane is at least double previous estimates as a result of this effect.[29]"
    - deleted 5y ago
      [deleted]
  - mixmastamyk 5y ago
    Too many variables to account for. Didn't mean to imply we could get "as hot as" Venus, which is unlikely due to our distance from the Sun. But hot enough to boil water? Possibly, given a runaway chain reaction. Not sure.
5faulker 5y ago
And here's we are at a paradox, where one side is attempting to escape imminent danger by traveling outside Earth, and in doing so potentially accelerating its instability.
krisoft 5y ago
About North Africa: archeological findings seems to imply that what is now the Sahara desert was much more lush and wet relatively recently. We have human made cave paintings of river animals in areas which are very dry nowadays. It is thought that the area dried out relatively suddenly about 5k years ago. That is basically yesterday as far as geological timescales go. When I learned about this I got kinda scarred. If the climate of an area can change this drastically all of a sudden that means to me that the climate system is a lot less stable than I previously have thougt.
- MayeulC 5y ago
  https://en.wikipedia.org/wiki/African_humid_period https://en.wikipedia.org/wiki/African_humid_period IIRC one of the causes might be orbital precession, which could lead to a re-greening in a few millenia.
- jandrewrogers 5y ago
  Something similar happened on a smaller scale in North America with Lake Lahontan[0], which covered much of Nevada after the last ice age. If you walk the old shoreline up on the mountainsides, it is not uncommon to find evidence of the neolithic people that lived on its shores before it disappeared. [0] https://en.wikipedia.org/wiki/Lake_Lahontan https://en.wikipedia.org/wiki/Lake_Lahontan
heavyset_go 5y ago
> It’s hard to imagine with the amount of H2O on the planet right now, but if it can happen to Mars (the atmosphere is stripped away), it could happen here I suppose. Mars' atmosphere isn't protected by a strong magnetic field because the planet isn't geologically active, unlike the Earth. Gasses escape from the Earth into space constantly, but not at a rate that will leave the Earth like Mars before the sun becomes a red giant. In billions of years, the sun will expand and probably blast away the Earth's atmosphere before possibly engulfing it later.
- kibwen 5y ago
  I'm no astrophysicist, but I'm under the impression that the effect of the magnetosphere is popularly overstated. Rather, the reason that Earth still has its atmosphere and Mars doesn't is that Earth has the gravity to hold onto it more tightly, and Mars is just too small. Hence why Venus, which also (curiously) has no dynamic magnetosphere, still has an atmosphere: it's 80% the mass of Earth (compare Mars, which is 10% the mass of Earth).
  - heavyset_go 5y ago
    The death of Mars' magnetosphere allowed solar wind plasma to strip away its atmosphere in the past[1]. Mars once had a much denser atmosphere when its dynamo was active, and the stripping of its atmosphere happened when the dynamo died. [1] http://redplanet.asu.edu/?p=2035 http://redplanet.asu.edu/?p=2035
  - vkou 5y ago
    Titan is ~Mars-sized, yet it has an atmosphere thicker than that of the Earth. It may be safe to say that both factors are at play, here.
    - jeffdn 5y ago
      Titan is largely protected by Saturn's powerful magnetosphere, which does a lot to help, I imagine.
- 5y ago
moaaps 5y ago
Isnt this the rift valley?
cletus 5y ago
It's not even a question: the Earth is absolutely facing the same fate. The Sun is getting hotter and in ~1 billion years the Earth will be uninhabitable by us in its current form. Eventually (~4-5B years) the Sun will expand while in its dying stages and probably swallow the Earth. What can we do? That's actually quite "easy". I mean "easy" in the essence that no weird new physics is required, it's just an engineering problem, albeit a massive one. Then again, we have a lot of time. So there are essentially three things we can do: 1. Reduce the amount of light and heat hitting the Earth. Example: large arrays of solar power collectors at the L1 Lagrange point. If the Sun is 10% hotter in 1B years and you reduce the light hitting the Earth by ~10% it about evens out. The captured energy can be put to use and I expect it wouldn't even be noticeable from Earth. The Sun will just be slightly dimmer; 2. You can move the Earth. Many people are familiar with gravity assists for spacecraft. Obviously gravity affects both bodies but the spacecraft is so low-mass it has no discernable effect on the larger body. Imagine taking large rocks and flying them past the Earth. The net interaction can be that the Earth moves slightly faster. Do this over a long enough time frame and you can move the Earth's orbit outwards. 3. The Sun itself can be manipulated to remove mass from it, particularly Helium. A lot can be done in a billion+ years.
- jjcon 5y ago
  Very interesting - couldn't we also just evolve to live with a hotter sun in a billion years or will it affect other systems so much that life for humanoids will be more difficult?
  - jeffdn 5y ago
    The combination of two processes -- tectonic activity and the increased luminosity of the sun -- will mean that surface water no longer exists at that time.
  - rowanG077 5y ago
    Evolution like that won't happen in a modern society like we have where we care for everyone and fight against nature. I'd imagine evolution is possible but only under collapse of civilization as we know it.

mixmastamyk 5y ago

The much larger mass, gravity, and magnetic field of Earth prevents large scale atmospheric losses. Whether we have the resources to ignite another Venus remains to be seen.

exporectomy 5y ago
Remains to be seen or is already known to be impossible? All the carbon in fossil fuels originally came from the atmospheric CO2, didn't it? And it was never as hot as Venus. What are the steps we would need to take to make it as hot as Venus in any kind of physically possible scenario?
- virtue3 5y ago
  You are drastically under-estimating the effects of other compounds in the atmosphere. Methane is a really good example. HFCs were a great bit of disaster for a bit there as well. from: https://en.wikipedia.org/wiki/Greenhouse_gas#Impacts_on_the_overall_greenhouse_effect https://en.wikipedia.org/wiki/Greenhouse_gas#Impacts_on_the_... "The contribution of each gas to the greenhouse effect is determined by the characteristics of that gas, its abundance, and any indirect effects it may cause. For example, the direct radiative effect of a mass of methane is about 84 times stronger than the same mass of carbon dioxide over a 20-year time frame[27] but it is present in much smaller concentrations so that its total direct radiative effect has so far been smaller, in part due to its shorter atmospheric lifetime in the absence of additional carbon sequestration. On the other hand, in addition to its direct radiative impact, methane has a large, indirect radiative effect because it contributes to ozone formation. Shindell et al. (2005)[28] argues that the contribution to climate change from methane is at least double previous estimates as a result of this effect.[29]"
  - deleted 5y ago
    [deleted]
- mixmastamyk 5y ago
  Too many variables to account for. Didn't mean to imply we could get "as hot as" Venus, which is unlikely due to our distance from the Sun. But hot enough to boil water? Possibly, given a runaway chain reaction. Not sure.

5faulker 5y ago

And here's we are at a paradox, where one side is attempting to escape imminent danger by traveling outside Earth, and in doing so potentially accelerating its instability.

krisoft 5y ago

About North Africa: archeological findings seems to imply that what is now the Sahara desert was much more lush and wet relatively recently. We have human made cave paintings of river animals in areas which are very dry nowadays. It is thought that the area dried out relatively suddenly about 5k years ago. That is basically yesterday as far as geological timescales go. When I learned about this I got kinda scarred. If the climate of an area can change this drastically all of a sudden that means to me that the climate system is a lot less stable than I previously have thougt.

MayeulC 5y ago
https://en.wikipedia.org/wiki/African_humid_period https://en.wikipedia.org/wiki/African_humid_period IIRC one of the causes might be orbital precession, which could lead to a re-greening in a few millenia.
jandrewrogers 5y ago
Something similar happened on a smaller scale in North America with Lake Lahontan[0], which covered much of Nevada after the last ice age. If you walk the old shoreline up on the mountainsides, it is not uncommon to find evidence of the neolithic people that lived on its shores before it disappeared. [0] https://en.wikipedia.org/wiki/Lake_Lahontan https://en.wikipedia.org/wiki/Lake_Lahontan

heavyset_go 5y ago

> It’s hard to imagine with the amount of H2O on the planet right now, but if it can happen to Mars (the atmosphere is stripped away), it could happen here I suppose. Mars' atmosphere isn't protected by a strong magnetic field because the planet isn't geologically active, unlike the Earth. Gasses escape from the Earth into space constantly, but not at a rate that will leave the Earth like Mars before the sun becomes a red giant. In billions of years, the sun will expand and probably blast away the Earth's atmosphere before possibly engulfing it later.

kibwen 5y ago
I'm no astrophysicist, but I'm under the impression that the effect of the magnetosphere is popularly overstated. Rather, the reason that Earth still has its atmosphere and Mars doesn't is that Earth has the gravity to hold onto it more tightly, and Mars is just too small. Hence why Venus, which also (curiously) has no dynamic magnetosphere, still has an atmosphere: it's 80% the mass of Earth (compare Mars, which is 10% the mass of Earth).
- heavyset_go 5y ago
  The death of Mars' magnetosphere allowed solar wind plasma to strip away its atmosphere in the past[1]. Mars once had a much denser atmosphere when its dynamo was active, and the stripping of its atmosphere happened when the dynamo died. [1] http://redplanet.asu.edu/?p=2035 http://redplanet.asu.edu/?p=2035
- vkou 5y ago
  Titan is ~Mars-sized, yet it has an atmosphere thicker than that of the Earth. It may be safe to say that both factors are at play, here.
  - jeffdn 5y ago
    Titan is largely protected by Saturn's powerful magnetosphere, which does a lot to help, I imagine.
5y ago

moaaps 5y ago

Isnt this the rift valley?

cletus 5y ago

It's not even a question: the Earth is absolutely facing the same fate. The Sun is getting hotter and in ~1 billion years the Earth will be uninhabitable by us in its current form. Eventually (~4-5B years) the Sun will expand while in its dying stages and probably swallow the Earth. What can we do? That's actually quite "easy". I mean "easy" in the essence that no weird new physics is required, it's just an engineering problem, albeit a massive one. Then again, we have a lot of time. So there are essentially three things we can do: 1. Reduce the amount of light and heat hitting the Earth. Example: large arrays of solar power collectors at the L1 Lagrange point. If the Sun is 10% hotter in 1B years and you reduce the light hitting the Earth by ~10% it about evens out. The captured energy can be put to use and I expect it wouldn't even be noticeable from Earth. The Sun will just be slightly dimmer; 2. You can move the Earth. Many people are familiar with gravity assists for spacecraft. Obviously gravity affects both bodies but the spacecraft is so low-mass it has no discernable effect on the larger body. Imagine taking large rocks and flying them past the Earth. The net interaction can be that the Earth moves slightly faster. Do this over a long enough time frame and you can move the Earth's orbit outwards. 3. The Sun itself can be manipulated to remove mass from it, particularly Helium. A lot can be done in a billion+ years.

jjcon 5y ago
Very interesting - couldn't we also just evolve to live with a hotter sun in a billion years or will it affect other systems so much that life for humanoids will be more difficult?
- jeffdn 5y ago
  The combination of two processes -- tectonic activity and the increased luminosity of the sun -- will mean that surface water no longer exists at that time.
- rowanG077 5y ago
  Evolution like that won't happen in a modern society like we have where we care for everyone and fight against nature. I'd imagine evolution is possible but only under collapse of civilization as we know it.