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134 votes

How could a time traveler have prevented climate change

Go back to the cold war era and start a "Russians are trying to warm the planet" scare. You will need a lot of money to fund some big advertising campaigns. You also want to seed a few ...
John's user avatar
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93 votes
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What if a portal is opened from the Mariana trench to the Sahara desert?

The climate of Earth has been roughed up quite a bit last century. But it has no idea what it's got coming with this portal of yours. Earth turns into Venus. Update: As R.M. pointed out, the amount of ...
Swier's user avatar
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65 votes
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Would using carbon dioxide as fuel work to reduce the greenhouse effect?

It is technically possible to burn carbon dioxide, but not in a practical way. The reason burning carbon produces energy is that the total potential energy of carbon and oxygen is minimized by the CO2 ...
Cadence's user avatar
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45 votes
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Is this state of Earth possible, after humans left for a million years?

•98% of all the landmass is wasteland/desert •The two poles are some big chunks of ice, each covering about 20% of earths area This is rather confusing. Yes, I get that there are also cold deserts, ...
L.Dutch's user avatar
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42 votes
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What would Earth look like at the beginning of 22nd century if temperatures rose by 30 degrees Celsius?

It is very unlikely that the Earth would warm by that degree in such a short period of time. However if it did then many parts of the planet would be uninhabitable outside of specially constructed ...
Slarty's user avatar
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40 votes
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Dropping ice in the ocean to stop global warming

This will not work at all The short version If you drop an ice cube into a room temperature drink, the drink will be slightly colder for a little while. But what happens then? Answer: the drink ...
MichaelK's user avatar
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36 votes
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What measures might an ancient civilization take to protect itself from extreme heat?

Two of my favorites for this scenario. Dig. Fresno is pretty close to what you describe. This guy Forestiere bought land sight unseen thinking he would grow fruit and nut trees but on getting there ...
Willk's user avatar
  • 305k
36 votes

The possibility and possible backlash of a thruster large enough to move a planet

It takes a lot of energy to move the Earth In this question, I calculate the energy needed to move the Earth. In order to move the Earth by 1m in orbit, you will need to expend about $2\times10^{22}$ ...
kingledion's user avatar
  • 85.5k
36 votes

Keeping an "hot eyeball planet" wet

What keeps my planet's water from irreversibly concentrating over time on the frigid wastes while the rest of the planet dries up? When ice piles up, it will exercise pressure. The closer to the ...
L.Dutch's user avatar
  • 291k
35 votes
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How to keep critters out of my flooded skyscrapers?

What's the actual problem? It doesn't sound like these are mutant super-pythons, just regular ones. Hundreds of millions of people live in areas with lots of deadly snakes. Consider rural India. They ...
causative's user avatar
  • 8,107
34 votes

How could a time traveler have prevented climate change

The mad scientist sledgehammer option for this particular nut. Kill a very large slice of the world population. It worked when Europe colonised the Americas, so many natives were killed it actually ...
Pelinore's user avatar
  • 9,677
32 votes

What if a portal is opened from the Mariana trench to the Sahara desert?

First observation: The portals as described in the question create a perpetuum mobile. Salt water under high pressure (from the ground of the Mariana trench) wells up at some point in the Sahara ...
Sir Cornflakes's user avatar
29 votes

Dropping ice in the ocean to stop global warming

Comets are tiny Halley's mass is 2.2×1015 kg. A cubic kilometer of water has a mass※1 of 1 × 1012 kg Oceans hold 1.35 × 10 9 cubic kilometers, which gives us 1.35 21 kg of water. So, the mass of the ...
SJuan76's user avatar
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24 votes

Would using carbon dioxide as fuel work to reduce the greenhouse effect?

You can’t use carbon dioxide as fuel, and that’s not what the article you cite is about. You can turn carbon dioxide (plus hydrogen or water) into fuel, but the process will need more energy than you ...
Mike Scott's user avatar
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22 votes
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How big would a satellite need to be to block out the sun?

TLDR; The equations: $$r_{B} = \sqrt{\frac{F}{2.46\times 10^{-14}}}$$ or rearranging for $$F = r_{B}^{2} \times 2.46\times 10^{-14}$$ Where $F$ is the fraction of light blocked ($F=0.01$ gives your $1\...
Lio Elbammalf's user avatar
22 votes

Could Comets or Meteors be used to Combat Global Warming?

You're trying to cure the sickness by alleviating a symptom. You can't cure global warming by putting more pollution into the air. You may temporarily bring the patient's temperature down, but ...
JBH's user avatar
  • 125k
22 votes

Keeping an "hot eyeball planet" wet

Librations. That is, the tidally locked planet is not in a perfectly circular orbit, and so the portion of the planet that is sun-facing is not constant. This is because the rate of rotation is (...
puppetsock's user avatar
  • 9,591
22 votes

How to keep critters out of my flooded skyscrapers?

Pythons are a total non-issue. Human fatalities from non-venomous snakes are exceedingly rare, on the order of single digits worldwide annually. Many incidents involve captive snakes, that is, people ...
Nuclear Hoagie's user avatar
20 votes

Dropping ice in the ocean to stop global warming

To me, it's the same as if you'd said: Stopping global warming by leaving the fridge open. Ice needs to be produced. This requires large quantities of energy for freezing water, which requires more ...
Alexander von Wernherr's user avatar
19 votes

Is this state of Earth possible, after humans left for a million years?

You're positing a world that has no surface plants. That's... implausible. There are plants out there that can manage climatic extremes far worse than anything humans could live through. Plants ...
Ben Barden's user avatar
  • 1,427
19 votes

What would Earth look like at the beginning of 22nd century if temperatures rose by 30 degrees Celsius?

This is a map of the average temperatures year round. Everything above 40 is already highly dangerous (something that happens to Red/Orange countries a lot during the summer). Having that the whole ...
A.bakker's user avatar
  • 3,376
18 votes

How could a time traveler have prevented climate change

Direct bootstrap of nuclear fission technology in the 1700s. Sounds crazy right? Not so fast. In order to reliably prevent runaway climate change, we must prevent the situation that caused it, ...
Joshua's user avatar
  • 1,695
18 votes

Would using carbon dioxide as fuel work to reduce the greenhouse effect?

According to your link: The process can work with any level of carbon dioxide concentration, Wu says -- they have tested it all the way from 2 percent to 99 percent -- but the higher the ...
Brythan's user avatar
  • 25.3k
17 votes
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What would happen if the Panama Isthmus was turned into an island chain?

It would not change that much. it was radically changed into a series of islands during the 1st century due to an earthquake This description points to a situation where the landmass we have today ...
L.Dutch's user avatar
  • 291k
16 votes

How could a time traveler have prevented climate change

Here is an idea: What if Henry Ford had built his assembly line for an electric car rather than a gas powered car? Before the assembly line brought down the price of the Model T, electric cars were ...
QuantumZ's user avatar
  • 185
16 votes

What would Earth look like at the beginning of 22nd century if temperatures rose by 30 degrees Celsius?

Temperatures on the globe rose by 30 degrees Celsius ... How would the surface of Earth look by that time? It would look like Venus, because a 30 degree rise in average global temperature will ...
Argenti Apparatus's user avatar
15 votes
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Nuking all the ice

The best solution is to not nuke the poles. The poles are really-really-really big. The arctic ice sheet is around 20000km$^3$ of ice, or 20000000000000m$^3$! That's 1.8334 × 10$^1$$^6$ kilograms ...
Cort Ammon's user avatar
  • 132k
15 votes
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Is it possible to have (near future) satellites that appear to rise and set like the sun and moon?

First: how big to appear as big as the moon if in a typical satellite orbit? Here is a fine image of the ISS passing in front of the moon and we can use it to gauge their relative apparent sizes. ...
Willk's user avatar
  • 305k
15 votes
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What would a city look like that adapted to sporadic tsunami-like flash floods?

Put your towns and cities on hills. Towns grew next to roads and rivers. These went along valleys. This meant towns often grew over good farmland. New housing estates are often put on flood plains, as ...
Richard Kirk's user avatar
14 votes

Dropping ice in the ocean to stop global warming

@SJuan76 's answer is incomplete. He did the math to show the small cooling effect of, but didn't show the heating effect. I shamelessly copied his cooling numbers, and added heating numbers to ...
kingledion's user avatar
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