Mars and Earth Switch Places - Effect on climate?

[Kitsune]

Let us ignore effects of Jupiter for purposes of this discussion
Lets say that Earth, with the atmosphere the same as it is, was in Mars orbit?
Also, lets say that Mars, with its same atmosphere, was in Earth's orbit?

[Iroscato]

Well for Mars, not much will change as far as I'm aware- the polar ice caps will melt raising the level of co2 in the atmosphere slightly- but apart from that, the planet's been dead far too long for any significant change to occur. The core froze long ago, which led to the loss of a magnetosphere, which in turn left the atmosphere unguarded from the solar wind stripping it away. So I reckon whatever melted on the surface would get carried away long before the core could get moving again, especially as the planet would experience an increase in solar wind activity. You'd end up with a slightly warmer rusty rock.
As for Earth, it would be far more interesting. My knowledge is limited in this subject, but obviously things would get very cold, very quickly. Most of the atmosphere would freeze and fall to the surface as snow, and the inhabitants are gonna have a hell of a time surviving, especially if this turns out to be permanent. Within a few months, ice covers most of the surface, the oceans resemble a slush puppy, civilisation descends into chaos, your usual post-apocalyptic tropes are played out.
One POSSIBLE development might be that Mars becomes a much more desirable destination for a human settlement, although given the choice between a rapidly-freezing snowglobe and a soon-to-be heavily irradiated airless rock, I'm not sure what most people would go for. In any case, that would depend on how much space-faring technology survives the initial chaos, so it's improbable at best.

[Irbis]

I think desperate attempt at warming up the planet by skyrocketing production of whatever greenhouse gases we can think of is more plausible and cheaper than sending any appreciable % of human population anywhere. For one, we're already good at doing that

Though, until out efforts do anything, we can expect mass human extinction, especially in Africa, Oceania, and South America, poor, warm countries that unlike Europe, USA and Russia aren't already prepared to cope with long winters.

[Iroscato]

Not to mention that the sudden massive change in gravitational pull from the sun would probably result in immediate and disastrous tsunamis across the globe, and then afterwards tidal forces would have nowhere near the same effect that they used to. This would probably contribute to a speeding up of the freezing of the oceans, though the snow and ice that would cover the surface would eventually act as an insulator, meaning the oceans would stay more or less the same temperature beneath the surface for a great many millions of years.
In short, after a major, catastrophic upheaval, we'd be relatively ok, though much worse for wear than we were before.

[Eternal_Freedom]

Also, Earth in Mars orbit would be moving quote a bit slower than it does currently. EArth at presnet orbits the sun at 29.78 km/s whilst Mars orbits at a little over 24 km/s. A loss of 6 km/s is significant, a reduction of 20%. Earth's kinetic energy would fall from 2.66E33 Joules to 1.73E33 Joules. That's a huge amount of energy and it has to go somewhere.

If Earth retains it's orbital speed it will move even further out with bad results, if the Earth is decelerated to Mar's speed it's still bad. If it's near-instant deceleration then everything dies, if it is slow enough to avoid killing everyone the Earth's orbit will become even more eccentric than at present, which again is not good.

[Lord Revan]

also a question are we swapping just Earth and Mars or are the natural satellites included , since even combined the mass of Phobos and Daemos isn't close to the mass of the Moon.

[Kitsune]

Keep our Moon and Mars keeps its small moons

[GrandMasterTerwynn]

Let us ignore effects of Jupiter for purposes of this discussion
Lets say that Earth, with the atmosphere the same as it is, was in Mars orbit?
Also, lets say that Mars, with its same atmosphere, was in Earth's orbit?

Here's what we get, if we plug some values into a handy terraforming calculator: http://www.users.globalnet.co.uk/~mfogg ... raSim.html

For Mars, the average surface temperature is suddenly 2.5C. The resulting collapse of the Martian polar ice caps will have quite ... dramatic consequences. The added CO2 in the atmosphere will quickly warm the polar regions of the planet to nearly 10C, with the global average shooting up to 35C. This is warmer than Earth is right now. What's worse is that the tropics warm up into the mid-60s. And all this is before we consider what happens when all that water ice melts and contributes water vapor to the Martian atmosphere.

Short answer, Mars becomes quite an unpleasant place to be. Granted, over geological timescales, the atmosphere is steadily whittled away by the solar wind, but not soon enough to alter the result.

For Earth, the average surface temperature drops to -45C. This is likely expressed in a temporary, but dramatic, increase in cloudiness and stormy weather, as the oceans have a huge store of thermal energy to dissipate. The increase in cloudiness serves to boost the planet's albedo, accelerating its cooling. Eventually, the ice caps expand from the poles ... meeting in the middle and cutting off the oceans from the rest of the atmosphere. Conditions like that haven't been seen on Earth in some 600 million years. Sometime before this happens, all complex life on the surface of the planet freezes or starves to death. Oceanic ecosystems dependent on solar insolation for survival also die out.

Short answer for Earth ... everybody dies. And ... no, humans could not possibly liberate enough CO2 to alter the outcome.

[Irbis]

How quickly that would happen? Because it would need to happen pretty much instantly for someone not figuring a way out, like 'let's build independent colonies around every sustainable* power plant' using electricity for heat, light, and food production. Surely at least one place would manage to pull this off? Especially with nice outdoor freezer conservating stuff meant for 7 billion humans literally everywhere. I mean, people do survive -45, it's not like it doesn't happen in Russia or Canada.

*by sustainable, I mean nuclear, but there are quite a few big coal plants next to big coal mines which could prove suitable?

[tim31]

Send this question in to xkcd What If. We'd get a researched answer and some comics to boot.

[Kitsune]

Let us ignore effects of Jupiter for purposes of this discussion
Lets say that Earth, with the atmosphere the same as it is, was in Mars orbit?
Also, lets say that Mars, with its same atmosphere, was in Earth's orbit?

Here's what we get, if we plug some values into a handy terraforming calculator: http://www.users.globalnet.co.uk/~mfogg ... raSim.html

For Mars, the average surface temperature is suddenly 2.5C. The resulting collapse of the Martian polar ice caps will have quite ... dramatic consequences. The added CO2 in the atmosphere will quickly warm the polar regions of the planet to nearly 10C, with the global average shooting up to 35C. This is warmer than Earth is right now. What's worse is that the tropics warm up into the mid-60s. And all this is before we consider what happens when all that water ice melts and contributes water vapor to the Martian atmosphere.

Short answer, Mars becomes quite an unpleasant place to be. Granted, over geological timescales, the atmosphere is steadily whittled away by the solar wind, but not soon enough to alter the result.

For Earth, the average surface temperature drops to -45C. This is likely expressed in a temporary, but dramatic, increase in cloudiness and stormy weather, as the oceans have a huge store of thermal energy to dissipate. The increase in cloudiness serves to boost the planet's albedo, accelerating its cooling. Eventually, the ice caps expand from the poles ... meeting in the middle and cutting off the oceans from the rest of the atmosphere. Conditions like that haven't been seen on Earth in some 600 million years. Sometime before this happens, all complex life on the surface of the planet freezes or starves to death. Oceanic ecosystems dependent on solar insolation for survival also die out.

Short answer for Earth ... everybody dies. And ... no, humans could not possibly liberate enough CO2 to alter the outcome.

Snowball Earth. . . . .Need about 13% of the atmosphere as CO2 to break out of it and believe that much CO2 is fatal anyway I believe

[Iroscato]

Ah silly me, I forgot to factor in the rapid dying off of any plantlife. So I amend my previous post- we'd all die, slowly and painfully. Fun.

[Borgholio]

Not unless we all settle in Zion, the last human city...near the Earth's core where it's still warm.

Oh wait, wrong movie...

[Kitsune]

Many extremophiles will likely survive
A few multi-cellular creatures such as Tardigrades will likely survive as well

[Irbis]

Snowball Earth. . . . .Need about 13% of the atmosphere as CO2 to break out of it and believe that much CO2 is fatal anyway I believe

Except Co2 isn't the only greenhouse gas, there are more potent and less lethal ones. Can we factor these in?

[Kitsune]

Snowball Earth. . . . .Need about 13% of the atmosphere as CO2 to break out of it and believe that much CO2 is fatal anyway I believe

Except Co2 isn't the only greenhouse gas, there are more potent and less lethal ones. Can we factor these in?

Well, up to 70% of greenhouse gas is water. . . .It will fall out of the sky.
Methane is produced by life in large part and ice tends to freeze in methane.
Methane is consumed by various chemical reactions.
As such, likely not going to stop Snowball Earth.
Leaves really only CO2 from volcanoes which takes millions of years

[Guardsman Bass]

Methane gets consumed, but it takes about 12 years. You'd have to just try and pump as much of it into the atmosphere as you could in the short term, and supplement it with tons of man-made "super-greenhouse gases" such as Hydroflourocarbons and CFCs (not good for the ozone layer, but better than a permanent iceball Earth). I think you could barely pull it off, provided you get enough of the latter up in the atmosphere.

In the long run, you're stuck managing Earth's atmosphere forever if you don't want it to either freeze over completely or end up with a CO2 concentration so high that the air is toxic for humans. Permanently managed methane and super-greenhouse gas emissions, and possibly more exotic stuff down the line like orbital mirrors. Way down the line you could do stuff like gravitational tractoring the Earth back into a closer orbit, but it would take millions of years.

[Borgholio]

I don't think the ozone would be as much of a concern given how'd we'd only get about 1/4 the sunlight that we do right now.

[Kitsune]

Methane gets consumed, but it takes about 12 years. You'd have to just try and pump as much of it into the atmosphere as you could in the short term, and supplement it with tons of man-made "super-greenhouse gases" such as Hydroflourocarbons and CFCs (not good for the ozone layer, but better than a permanent iceball Earth). I think you could barely pull it off, provided you get enough of the latter up in the atmosphere.

In the long run, you're stuck managing Earth's atmosphere forever if you don't want it to either freeze over completely or end up with a CO2 concentration so high that the air is toxic for humans. Permanently managed methane and super-greenhouse gas emissions, and possibly more exotic stuff down the line like orbital mirrors. Way down the line you could do stuff like gravitational tractoring the Earth back into a closer orbit, but it would take millions of years.

I think man, unless she can quickly discover how to build enclosed survival habitats, is extinct. I don't think we could releases enough gasses in a few years to stop Earth from falling into its snowball state. Once the glaciation reaches 30 degrees of the equator, it feed backs into a state which cannot be stop. That is at Earth's present orbit and be likely worse at Mars orbit.

What I am suggesting is that over millions of years, there might be enough CO2 to cause Earth to break out of its snowball state. If any complex life other than things like water bears could survive I don't know. Earth might revive into something but with much simpler life.

[Bedlam]

Methane gets consumed, but it takes about 12 years. You'd have to just try and pump as much of it into the atmosphere as you could in the short term, and supplement it with tons of man-made "super-greenhouse gases" such as Hydroflourocarbons and CFCs (not good for the ozone layer, but better than a permanent iceball Earth). I think you could barely pull it off, provided you get enough of the latter up in the atmosphere.

In the long run, you're stuck managing Earth's atmosphere forever if you don't want it to either freeze over completely or end up with a CO2 concentration so high that the air is toxic for humans. Permanently managed methane and super-greenhouse gas emissions, and possibly more exotic stuff down the line like orbital mirrors. Way down the line you could do stuff like gravitational tractoring the Earth back into a closer orbit, but it would take millions of years.

I think man, unless she can quickly discover how to build enclosed survival habitats, is extinct. I don't think we could releases enough gasses in a few years to stop Earth from falling into its snowball state. Once the glaciation reaches 30 degrees of the equator, it feed backs into a state which cannot be stop. That is at Earth's present orbit and be likely worse at Mars orbit.

What I am suggesting is that over millions of years, there might be enough CO2 to cause Earth to break out of its snowball state. If any complex life other than things like water bears could survive I don't know. Earth might revive into something but with much simpler life.

Oddly that might result in life on earth surviving longer. When the sun swells near the end of its life Earth even if it's not swallowed will be toast, however, Mars might just be far enough away to stay with water in all three states for a while longer.

[Iroscato]

Also, wouldn't Earth having more mass than Mars mean it would just break from orbit and fly out into space? Or are the orbital speeds adjusted as well? Or am I just talking out of my arse?

[Kitsune]

Also, wouldn't Earth having more mass than Mars mean it would just break from orbit and fly out into space? Or are the orbital speeds adjusted as well? Or am I just talking out of my arse?

Assuming you are right, that does not mean that extremophiles will not survive in deep pockets under the ice next to volcanic vents. Quest is if you took the sun away, would you have large lakes of liquid water from internal heat of the earth itself or would they be small pockets

[Iroscato]

Also, wouldn't Earth having more mass than Mars mean it would just break from orbit and fly out into space? Or are the orbital speeds adjusted as well? Or am I just talking out of my arse?

Assuming you are right, that does not mean that extremophiles will not survive in deep pockets under the ice next to volcanic vents. Quest is if you took the sun away, would you have large lakes of liquid water from internal heat of the earth itself or would they be small pockets

Actually, there is the perfect video to explain this particular scenario- it's by Vsauce, exploring what would happen if the sun upped and disappeared one day. Great video, and great channel in general.

[Kitsune]

Damn, that is a good video. . .Nice I was right too

[Beowulf]

Would orbital mirror arrays to increase insolation help? Especially as they could be targetted towards low albedo areas, for maximum effectiveness? Yes, I realize this would be expensive, but it'd probably be cheaper than belching methane, and would reduce the CO2 requirement.