2 ms·

>roughly 100%. I don't understand the use of "roughly" here. A reduction can be and often is, expressed as a ratio. Is 90% roughly 100%? Is 99%? Is 99.9%? As

• ben_w 5y ago
  Given how long CO2 remains in the atmosphere, any reduction in CO2 emissions by less than 99.9% of the current emission rate sustained for less than a millennium is likely to result in severe negative consequences. Likewise, because the damage is done by the quantity in the air rather than the instantaneous rate of emissions and absorption — the former being the integral of the other two — we need to make these changes much faster than the gradual reduction over one human lifetime of non-reproduction. If you want to achieve this reduction just by population reduction — and not via technology, lifestyle changes, or any other solution — then you need a 99.9% population reduction. If you want to solve it by enforcing lifestyle changes and no tech etc., then you have to wind the clock back to before the industrial revolution, before we could even mine so much fossil fuels in the first place. The 1750 population of 760 million [0] was (with regards to CO2) sustainable, but the tech back then limited both the population and the emissions. It’s like the correlation between shark attacks and ice cream consumption: Hot weather makes you eat ice cream and go swimming. Icecream-to-Sharks isn’t directly causal, and neither was the population in 1750 the direct causal reason that CO2 emissions were sustainable. So you only get the “benefit” of 1750s population levels if you’re willing to also pay the technological cost. But not just the cost of not being able to grow food for 8 billion: it would be as if the 710 million absolutely worst off today were unchanged, while the other 50 million merely don’t have electricity let alone computers or the internet, paved roads let alone cars or bicycles or public transport, disease-free pressurised municipal water let alone modern flushing toilets or bottled soda or warm and safe showers, etc. Those 50 million would be the super-rich of the new era. And worse, because of the aforementioned long lifespan of CO2 in the atmosphere, you’d need to sustain this for about a thousand years despite everyone involved being much better off if they defect (Nash equilibrium). That leaves green tech. Many purely technological solutions to greenhouse gases are already known. The challenge is to make the green solutions cheaper (because Nash equilibrium) than the polluting status quo for 99.9% of effective emissions. (Effective emissions rather than gross emissions, because some of the technological solutions are to take CO2 out of the air to make other chemicals with, and that’s fine). (ZeroGravitas interpreted me correctly, FWIW). [0] I’m approximating from these numbers: https://en.wikipedia.org/wiki/Estimates_of_historical_world_population https://en.wikipedia.org/wiki/Estimates_of_historical_world_...
  • vba616 5y ago
    >because the damage is done by the quantity in the air Given this is true, then there's no particular reason to think that even 100% reduction of emissions would meet any goal. I think you've just explained why carbon capture on a huge scale and carbon-free power might be necessary. But if so, then I don't see "99.9%" as being connected to anything. >So you only get the “benefit” of 1750s population levels if you’re willing to also pay the technological cost. Here's a misunderstanding between us. I take for granted that "willing" isn't a factor, that 1/10th of the population would be unable to maintain current technology, that most, although not all, of technological advancement has come from increased population allowing more specialization. >Those 50 million would be the super-rich of the new era. It seems like something is missing in the previous paragraph, why do 50 million people have something different, and what is it?
    • ben_w 5y ago
      > Given this is true, then there's no particular reason to think that even 100% reduction of emissions would meet any goal. There is, but it’s been outside the scope of this discussion. The exact reduction needed depends on what level of damage your are willing to accept, but 99.9% reduction relative to current emissions is basically the threshold for maintaining static CO2 levels until all the fossil fuels are burned. This still isn’t amazing at current CO2 levels, but as it’s the (approximate) steady-state emissions level, it remains a useful approximation of maximum safe emissions regardless of what the actual concentration is. More emissions? The concentration drifts upwards from whatever is deemed to be acceptable when you started. > Here's a misunderstanding between us. I take for granted that "willing" isn't a factor, that 1/10th of the population would be unable to maintain current technology, that most, although not all, of technological advancement has come from increased population allowing more specialization. We definitely have a misunderstanding, because I’m afraid I don’t follow your argument, and I sense I’m not even aware of what conclusions you’re trying to reach with them. I will attempt to respond nevertheless. If we go back to the pre-industrial age, even if you get near perfect buy-in from everyone alive today, nobody is going to think it was a good idea in retrospect, and in 80 years everyone will ignore any pleas from the ancestors in the history books to never return to all we have now. We just go through a hybrid of the Industrial Revolution and the renaissance, which sounds like an awesome setting for a novel but not actually that good for the environment. By the time the new societies have enough spare capacity to fix what we can already fix, let alone the stuff we can’t, CO2 levels will be much much worse. > It seems like something is missing in the previous paragraph, why do 50 million people have something different, and what is it? I was focusing on the negatives explicitly to show why it won’t be accepted by basically anyone if you try this. To focus instead on what the rich will have: “What” the 50 million have is business, property, pets (rather than livestock), and some limited travel. Might even be able to dig up and reuse old plastic etc. from the before times, but (returning to the negative because I don’t think I’ve fully emphasised how much this will suck) even for the rich, many things trivial in our society simply can’t be newly made at all in the scenario you’re describing, as that is some combination of unacceptable (if you allow modern fossil fuel power stations, the pollution per person is too high, so no aluminium) or simply impossible without ending the scenario (can’t develop a vaccine for a novel virus on a supercomputer because the world economy can’t afford to build the machines that build the machines that build the parts for the supercomputer, but even if it could, the tantalum mine needed for one specific component is both closed and probably in a different continent which is now only accessible by wooden boats and you don’t have any advance warning of Atlantic hurricanes forming). The “why” is that this was what happened in every historical society of this type that I’m aware of. The rich 50 million is everyone who isn’t literally (in the medieval feudalism sense of the word) a peasant — not a very high bar by modern standards, but not passable without tech that one way or another breaks the scenario.