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The Environment / Re: If the Earth is losing mass, is the atmosphere expanding?
« on: 21/10/2021 19:34:19 »Perhaps the Atmosphere will expand & extend to engulf the Moon.Not in any meaningful way, thankfully!
If the Earth overall is losing mass, the effect it has on gravity, however slight, may affect our atmosphere in a much different way than simply allowing hydrogen and helium to escape as a natural consequence.Well, yes, you're right that decreasing the mass of the earth will naturally lead to a lower surface pressure, and allow the atmosphere to puff out a little more. I think it's important to consider the magnitudes involved though. The change in mass that we can expect the earth to have over the next several centuries is a fraction of a fraction of a fraction of a percent. This will not have a significant effect on the composition or mass of the atmosphere.
As we convert solid fuels (fossil and other) into heat, two factors occur at a minimum: release of hydrocarbons and infrared heat. Add to this the loss of water stored in 3 trillion trees lost, and the amount of water vapor / heat being created by combustion is a SUBSTANTIAL NUMBER.
The heat being released by burning fossil fuels is surprisingly insignificant compared to the heat budget of the earth. (One full 24 hours of sunlight on the whole earth is many times greater than all of the heat produced by all of our power plants and cars and industry etc. in an entire year!)
But the generation of carbon dioxide, and to a lesser extent, water, is significant. The amount of water in the atmosphere is essentially a function of how warm it is (higher temperatures allow more water to be in the vapor form), so producing a bunch of water vapor doesn't necessarily mean that the atmosphere will get more massive (it may just lead to more precipitation).
With carbon dioxide the story is different. There is some degree of solubility in water which is temperature-dependent, but the solubility of carbon dioxide in water is not very high, so most of the carbon dioxide that is produced does go into the atmosphere.
The atmosphere used to have LOTS of carbon dioxide. Before photosynthetic organisms there was no significant concentration of molecular oxygen in the atmosphere: basically, for every molecule of oxygen in the atmosphere now, there is an atom of carbon buried in the ground in the form of fossil fuel, and it used to be a molecule of carbon dioxide in the atmosphere (and the atmosphere is currently about 20% oxygen, and 0.0004% carbon dioxide)
And before THAT, there were a bunch of microorganisms that pulled carbon dioxide out of the atmosphere to make their calcium carbonate shells. As they died, their shells piled up and eventually became the limestone deposits that cover the earth (limestone is basically just crushed ancient microbe exoskeletons). That was a LOT of carbon dioxide.
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