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A universe-destroying parasite is set loose, and basically earth is placed under magical quarantine. (Think of it like the world is wrapped in magical cellophane.) My question is, how would earth's environment change, if at all, if the atmosphere is completely closed off from space? Would it affect pollution levels? Climate change? Plant Growth? If this does affect life, how long until the earth is no longer habitable?

Here's some more info: The forcefield is clear, so light can pass through it, though nothing else. It might absorb some heat energy, though, but not catastrophically. No substance can leave or enter through the field, not even on a molecular level.

Depending on how much heat it absorbs, it may exacerbate global warming. Absorbing heat is basically how greenhouse gases work. If your forcefield absorbs heat it will work just like a greenhouse gas. The effects of global warming are readily available via Google search so I won't go into more here.

I think what may be more interesting, is if it doesn't absorb heat. Depending on the altitude of this forcefield, its effects will vary.

First, lets assume the forcefield is high enough that only a negligible amount of atmosphere is outside the field. In real life, the atmosphere slowly loses its lightest constituents to space; Hydrogen and Helium especially. The forcefield will prevent this. Helium is continually produced naturally by radioactive decay of natural radioactive elements like Uranium. This means the amount of Helium in the atmosphere will slowly increase. Another effect is that the field will cause some limited heating. This is because the most likely atoms to be lost in real life are the most energetic, i.e. the hottest. If your forcefield stops them, they will stick around and stay warm. I would expect this to be much more minor than climate change in real life, but it's something to consider. Last, you will no longer have shooting stars. You might have a single tiny flash if your shield burns stuff up somehow, but not if it just deflects it.

If the forcefield is within the atmosphere, it gets trickier. The atmosphere above the forcefield will slowly be lost to space by the mechanism I explained above. It will also cause some minor global cooling, as the highest levels of the atmosphere is also the hottest. This won't change the atmospheric pressure inside the field though, because the field will hold it in. If the field is below atmospheric currents like the jet stream, the weather below will go crazy. Without currents like the jet stream to move heat around, hot areas will get hotter, cold areas will get colder. You will see much worse storms at the borders of these regions, and generally higher winds. It'll be bad, really bad. But at least you'll still get shooting stars.

On the bright side, I don't think any of the situations could sterilize the planet. The last one I mentioned could topple civilization, but if they have the magic to make the forcefield in the first place maybe they could find a way to get around that. But even that won't kill absolutely everything.

If electromagnetic radiation can go unobstructed, there won't be any visible effect.

Earth's atmosphere is very stable, meaning it's not exchanging any material with the outer space (not in meaningful amounts). If Earth's atmosphere is locked in, everything will just go on without any noticeable effects.

On a long timescale (hundreds of millions to billions of years) the effect would become noticeable, because as the Earth would warm up, it is expected to lose water. However, with "magical cellophane", that won't happen, so the Earth as we know it would live on for a longer time. Also, asteroid impacts won't threaten Earth any longer.

Depends on how you enclose it - and if the magical barrier does reflect light under extreme angles.

Encased in glass

Let's assume someone uses a glass bubble to enclose the atmosphere. Then we are suddenly sitting in a ginormous greenhouse, as light reflected from the clouds would hit the glass at an extreme angle, getting reflected back to the clouds.

As a result, Earth would increase the reflection to earth and thus heat absorption, reducing the overall albedo by up to 3/4. That means it would get hot:

Of the 1400 W/m² reaching earth, the loss wouldn't be ca. 400 W/m² from albedo but more like 100 W/m², so about 30% more energy would get deposited to earth as thermal energy. That'd bring up earth's temperature slowly but surely, within a couple of months to years. It would be a rather humid but hot planet, with the ice poles melting, for some years, and on an order of decades, turn the inland of the continents into deserts. Think about all the world being like Australia but for the fact that not every animal wants to kill you.

Encased in tinfoil

If you want to be really nasty, take tinfoil with a mirror sheen. The albedo of that is in the area of 98%. As a result, of the 1400 W/m² sunlight reaching earth and of which usually roundabout 1000 W/m² keep it warm and habitable, suddenly only 20 to 30 W/m² do that directly, and the light emitted from the heated foil would be minimal. Earth gets rather cold and also totally dark. It's worse than nuclear winter! The winter will come within hours to days, leaving not a single living thing.

Encased in cellophane

Cellophane would behave like the glass house.

Non climate effects

Besides the climate getting devastated, there'd be a radical effect on the satellite networks: 2018 saw 111 successful launches of satellites and probes. Of them we have 23 Navigation, 47 Communication satellites, 5 Meteorological and 77 Earth Observation sattelites. Most sattelites are launched to complete systems or replace old satellites that have failed - without the ability to launch new satellites, our satellite systems would soon fail. The resultes on a society level are huge:

• GPS and similar systems would fail within about 5 to 10 years.


• TV satellite broadcast would follow in the same time frame.


• Satellite telephone follows in suite.


• ca. 3 to 15 people get stranded on the ISS, forced to starve to death. Once the field opens again, the station has evolved into a huge biohazard, the bacteria and mold in it very likely changed a lot.

Spaceflight

If no mass can pass through the forcefield that means no more spaceflight for mankind. We would obviously not be launching manned missions to the ISS or Mars, nor would we be sending up any satellites. This means no weather satellites, no communications satellites, no Earth imaging satellites, no scientific remote sensing satellites, and most notably, no GPS satellites. Spacecraft could be launched before deploying the forcefield, but there is a limited lifetime for any spacecraft (GPS satellites are regularly replaced and there are always a few on standby). This wouldn't be an existential threat to mankind, but it would change a lot of the systems we regularly rely on.

Mass Exchange

The Earth does not exchange much mass with the space environment at all. In fact, for most purposes it is considered a closed system with regards to mass exchange. The two exceptions are meteorites and escape of atmospheric gasses. In the case of meteorites, most sources estimate somewhere in the range of 45,000 tonnes of material fall to Earth every year. This is 8.3x10^-16 percent of the Earth's mass, or put another way, at this rate it would take roughly 1x10^17 years to accumulate enough mass to make another Earth (wayyy longer than the age of the universe). The Earth loses almost 100,000 tonnes of atmosphere per year in the form of Hydrogen and a much smaller amount of Helium. This is 1.9X10-9 percent of the mass of the atmosphere. At this rate, to lose even 1% of atmospheric mass would take half a billion years or so. Additionally, the materials from meteorites are fairly common on Earth already, as are hydrogen and helium. So your forcefield shouldn't change much in the way of mass exchange.

Radiation

In the case of electromagnetic radiation, if your forcefield is entirely transparent to the EM spectrum, there will be no difference from current atmospheric dynamics. This is because all energy exchange between the atmosphere and space takes place in the form of EM radiation. However, if your forcefield does absorb infrared radiation (heat), that may change the dynamics of the atmosphere. Depending on how much radiation your forcefield absorbs, and how it is re emitted, the energy balance of the Earth system may be altered noticeably.

It would mean a dramatic change to space travel; initially, the satellite industry would be replaced by a "sticking devices to the forcefield" industry, though how that would be done would depend on the field itself. Depending on the relative velocity of forcefield to the planet's surface, and on the altitude, and on how easy it was to stick things to it, orbital elevators might be attached, simplifying the task.

If it were low enough to touch the atmosphere, and had significant relative velocity to the surface, then it would eventually cause high-level winds in its direction of rotation, which would affect weather and climate.

There would also be a great international push to try to figure out a way through. We're not a species which handles imprisonment very well.

And of course, there'd be a great international push to communicate through it, to those who put it there.

Politically, mankind would likely pull together a bit, now having a common enemy.

Any satellites and other controllable objects outside the sphere would become immensely valuable. Even dying, they would be useful if they could be maneuvered to land on the shield, since that would give a metal thing on the far side of it that stuff below could perhaps stick to magnetically, if the shield was thin enough.

But otherwise, everything outside Earth would be the only way we could manipulate solar system objects. A lot of very clever thinking would likely go into ways to repurpose interplanetary missions and even orbiting satellites to do work outside the sphere.