3 ms·

You’re correct, but: 1. Just stopping burning carbon isn’t enough. We need to take the existing excess carbon from the atmosphere. 2. It would be rational to

• rhelz 3y ago
  > Just stopping burning carbon isn’t enough. We need to take the existing excess carbon from the atmosphere. Yeah, I just don't see that happening. E.g. suppose we only wanted to take the CO2 out of the air that we put in last year. It would take more energy to do that than we got from burning fossils fuels last year. I don't remotely see how that would at all be feasible. I mean, yeah, 100 thousand of years of plants doing photosynthesis--taking that energy slowly but surely from the sun--would do it. But the shorter of a timeframe you want it done, the more energy you are going to need--and since energy is conserved, that will eventually end up as waste heat and heat up the earth anyways.
  • graeme 3y ago
    That’s correct, except consider the alternative, not doing it. Then we either: * Let the temperature rise so fast that plants and animals will struggle to adapt. Within this century, or * Do some sort of geoengineering that limits the amount of solar radiation entering earth and manually manage the planet’s temperature. #1 is the default and is doom. #2 seems what we’ll likely try. The barriers there are: 1. We somehow have to manage it globally. 2. It will let us continue emitting carbon, thus acidifying the oceans and leaving those ecosystems unable to adapt It’s still the best option, hopefully we can actually do it. If we want to avoid it we need a surplus of energy and a way to store the excess carbon in a reasonable cost effective way. But it will almost certainly take more energy than was produced by burning it in the first place. Animals and plants have fairly narrow bands of acceptable temperature and don’t have air conditioning. Mass extinction is hypothesized at ~5 degrees of warming from pre industrial levels. Note that land warming will be higher than average warming, as the average includes the oceans.
    • rhelz 3y ago
      > consider the alternative, not doing it....Let the temperature rise so fast... Sounds like the obvious choice...but can you put some numbers to it? 1. How much C02 do we need to take out of the air to prevent your doomsday scenario, 2. How fast do we need to take it out of the air? 3. How much energy would it take to do that? 4. What are the side effects of generating that much energy, and expending it according to the timeframe of #2? HellifIknow the answers, but I can do a bit of Fermi-style estimation, and no matter what numbers I plug in, it just doesn't make any sense. Depending upon the answer to #2, we might not even be able to: 1. convert 100% of our energy generation to carbon-neutral sources, 2. Install 2.5-3x (depending upon how efficient carbon capture can become) the amount of power generating capacity we already have--again, all from carbon neutral sites 3. And then start extracting C02 out of the atmosphere at the same rate we put it in. #1 alone seems like it will take decades, to say the least. #2 says that doing #1 is going to be 2.5-3x harder. We will have to not only supply our current power budget, but also the energy needed to power these global scrubbers. And is the rate in #3 even enough? > Animals and plants have fairly narrow bands of acceptable temperature and don’t have air conditioning. Yeah, unless I'm very mistaken, they are screwed. It might not even be physically possible to do steps #1 through #3 in time to save them.
      • graeme 3y ago
        I don’t know the numbers unfortunately. Climeworks is at the state of the art for carbon removal The more likely scenario is we try to geoengineer and that buys time and we eventually get the energy to actually remove the carbon over a longer timescale. Lot of uncertainty in that route but I don’t see a better one. But ultimately the sooner we can shift away from burning carbon the less energy we’d need to remove it in the future. https://en.m.wikipedia.org/wiki/Climeworks https://en.m.wikipedia.org/wiki/Climeworks