Soda Sequestration

How much CO₂ is contained in the world's stock of bottled fizzy drinks? How much soda would be needed to bring atmospheric CO₂ back to preindustrial levels?

Brandon Seah

For most of the history of civilization, there were about 270 parts per million of carbon dioxide in the atmosphere. In the last hundred years, industrial activity has pushed that number up to 400 parts per million.

One "part per million" of CO₂ weighs about 7.8 billion tons. A can of soda contains in the neighborhood of 2.2 grams of CO₂, so you would need about 450 quadrillion cans of soda. That's enough to cover the Earth's land with ten layers of cans.

There's clearly not enough room to do this. Even if we stacked the cans up to the edge of space,[1] they'd still take up an area the size of Rhode Island.[2]

We'd need to add even more cans to keep up with ongoing emissions. We're currently increasing the atmosphere's CO₂ concentration by an average of 2 parts per million each year:

At that rate, we'd need to add one can of soda per person every 30 seconds, which is about 10,000 times the current consumption rate.[3] That would add a new layer of cans to the ground every 20 years or so.

This layer of cans would get pretty annoying.

Are there any ways out of this predicament?

In some areas, you can turn in soda cans for recycling and receive a small amount of money; in Massachusetts, where I live, it's 5 cents. If you collected one year's worth of soda cans—instead of layering them across the Earth's surface—and emptied them out, you could redeem them for $372 trillion.

With that much money, you could simply buy the world's current reserves[4] of coal, oil, and natural gas—the source of the whole problem.

Then, you put it all back in the ground and leave it there.

Problem solved.

Enforced by Radar

I've occasionally seen "radar enforced" on speed limit signs, and I can't help but ask: How intense would radio waves have to be to stop a car from going over the speed limit, and what would happen if this were attempted?

—joausc

Radio waves exert force on things.

Not a lot of force. The average cell phone transmitter exerts about a billionth of a newton of pressure on its surroundings. That means that it would take several trillion cell phones to collectively levitate a snowflake; the pressure from one phone wouldn't even measurably slow it down.

If the phone did put out enough energy to levitate a snowflake by radiation pressure, the power flowing through the snowflake (a few kilowatts) would quickly cause the snowflake to become a raindrop, which would quickly become water vapor, which would quickly become the least of your problems.

The fate of the snowflake hints at what kinds of problems our car will encounter.

If you want to slow down a one-ton car by radiation pressure, your radar gun would need to deliver about two trillion joules worth of radiation—the energy of a small nuclear weapon.[1] The radar gun would need to emit even more energy than that, since not all of the radiation will be absorbed (or reflected) by the car.[2]

Your radar gun would also vaporize the car. This is a problem, in one sense, but it's also a solution. Even if most of the energy is reflected, the portion that was absorbed would convert the materials in the car into gas or plasma. The expanding cloud would exert a lot more pressure on the car than the radiation itself.[3] This is convenient—it means that we wouldn't need nearly as much energy to stop the car as we would using radiation pressure alone.

There are even simpler ways to slow down a car with radiation. For example, you could aim a radiation beam at the tires and melt them, or use the electromagnetic radiation to knock out the car's electrical systems. Or just use a laser pointer to blind the driver and hope they reflexively slow down.

Of course, you don't need any of those things. If your goal is to slow down the car—rather than to catch speeders—your radar gun doesn't need any power. You can just stand by the side of the road next to a police car holding a fake radar gun.

In the end, a radar gun capable of slowing cars through radiation pressure would be roughly equivalent to a nuclear weapon, and using nuclear strikes in response to traffic violations is probably overkill. It would work, in the literal sense, but it would also destroy the offender, car, police officer, road, and all other traffic for miles around.[4]

Of course, maybe using the apocalyptic radar gun wouldn't be necessary; just the threat of a nuclear strike against drivers would probably deter speeding.

Come to think of it, maybe that's what those other signs you sometimes see are hinting at.