From your original comment (emphasis added by me to highlight what jumped out at me):
10°C climate warming over a century would be much lower impact, because there is time to relocate infrastructure and people (and nuclear winter also reduces solar radiation). So I have put it in the intensity category of an abrupt 10% agricultural shortfall.
From my reply:
It seems to me like a huge leap of faith is required to believe that the global impact of 10C of warming (over a century) is on the same order of magnitude as an abrupt 10% agricultural shortfall.
From your reply:
I agree that 10°C warming over a century would be bad. But would you agree that 8°C cooling and 50% reduction in solar radiation in one year would be worse?
Also from your reply:
In this paper, I estimated the expected mortality of an abrupt 10% food shortfall from something like India Pakistan nuclear war was about 500 million. Technically speaking, adaptation and relocation in response to a century long 10°C rise should involve the loss of many fewer lives, but it could go very badly, even up to including full-scale nuclear war, which could kill billions of people. So I think it is in the same order of magnitude in expectation as an abrupt 10% food shortfall. What would your estimate be of the expected mortality a century long 10°C rise?
It looks like I misread your original comment a bit. When you said “much lower impact”, I didn’t realize that you had predicted 500 million deaths from a 10% agricultural shortfall. I have now read your paper, and am entirely comfortable to agree that: (1) 8°C cooling and 50% reduction in solar radiation in one year would likely be much worse than 10°C warming over a century, (2) expecting ~500 million deaths from a century long 10°C rise seems like roughly the right order of magnitude.
Having said that, some of the circumstances that would lead to a 10% agricultural shortfall (e.g. extreme weather in several breadbaskets in one year) wouldn’t also come with all the other costs of climate change (mass migration, species extinction etc).
It is true that humans would not be able to go outside very long without technology. But I would say that is true at 40° latitude in the winter now. It is true that the technology of an insulating coat is fairly simple. But if it is hot, we could use the fairly simple technology of an ice vest like this. More complicated technology could involve a system which burns fuel and then uses absorption chilling to cool the body if one needed to stay cool for many hours. Of course this technology would not be affordable by many people in the tropics now, but 100 years out, I think the situation will be different.
This may well be true, but this is another case where I’d consider adaption as unacceptable. I don’t want to create a world where we need ice vests, or worse yet—something which needs to burn fuel, to be comfortable outside—particularly when that outcome is entirely avoidable.
I am concerned about a possible tipping point that would be a runaway greenhouse effect. But since the earth was about 14°C warmer about 50 million years ago, and the sun’s radiation is not that much higher than it was then, I think we only have to start worrying about this at over ~10°C warming.
I’m worried about tipping points that accelerate and amplify warming much sooner than 10°C of warming. Page 21 of this suggests that anything above 3C is extremely concerning.
As for prioritizing the present generation, my analysis indicates that prioritizing current global poverty is a couple orders of magnitude more effective than reducing emissions at carbon costs required to solve the whole problem (largely because the current poor will likely be richer when the main climate change impacts hit). However, if you believe the Cool Earth numbers (not counting opportunity costs of the value of the land for farming) and if you don’t think they will be taken by someone else, then it could be competitive. However, I think alternative foods are even better from the present generation perspective.
As per my comment on HaukeHillebrandt’s comment below—The trouble with these estimates is that I’m not convinced they do a good job of considering how costs change as a technology is scaled. For example, we’ve seen this with solar—http://solarsouthwest.co.uk/solar-panel-cost/. Do you have a recommended source which does somehow take account of these effects? If not, we’re not really comparing costs properly.
largely because the current poor will likely be richer when the main climate change impacts hit
Also, I want to specifically comment on this. Unless you believe that very large scale CO2 air-capture is going to be economically/technologically/land-use viable, we don’t have time to wait for people to get richer. The CO2 being emitted today, is committing humanity to a particular temperature rise for centuries to come. The cheapest time to deal with that is right now, to avoid putting the CO2 in the atmosphere in the first place.
I am focusing my analysis on the impact on the long term future, which means the reduction in the long term potential of humanity (out thousands or millions of years).
[....]
It is true that this analysis is not taking into account the smaller warmings, but these are less likely to have an impact on the long-term future, so I think they are unlikely to change the order of magnitude of the result.
[...]
I don’t think the comparison I am making is Pascal’s Mugging. I think Pascal’s Mugging could be considering the immense potential value of the long-term future and then demanding some sacrifice now. However, since I am looking at the reduction in the long-term future due to climate change and due to nuclear winter, they are on equal footing and do not depend on the precise value of the long-term future.
In this post I wasn’t trying to look at the long-term value of climate change—I was mostly considering the impacts by 2100. Your response dismisses the concerns about smaller warmings because they are less likely to impact the long term potential of humanity. I still care about these impacts, because they will still kill people in the current century, even if those people don’t matter as much on a long-term basis because human civilization will be fine without them. In my own ethics, I value life which exists today and in the near future more highly than in the far future. The main reason I’m willing to extend my horizon to 2100, is that I have a strong belief that the economic system which I’m living in today will very directly impact people in 2100, so they are not remote and detached from my choices—I bear some responsibility for the world they get to live in. This implies that I use a non-zero discount rate, but which I’m willing to reduce specifically for cases where there’s a strong causal link to actions being taken today.
At the same time, I rationally understand the argument for long-termism. If I had to pick between (A) a world with terrible climate change, but where human civilization ends up surviving and then thriving for 10 million years, or (B) a world where we avert climate change and then wipe ourselves out in 2110 with a synthetic virus, I would obviously pick (A). But that definitely feels like a mugging—accept climate change because that way some far future people will lead great lives.
The final thing which makes this all more complex, is that climate change is something which we are on a very well defined trajectory towards—where inaction results in terrible consequences. However, things like nuclear war are risks which may never materialize. If we invest effort into averting credible but potential risks, we’ll never be sure whether that investment actually mattered. If we invest effort in averting climate change, we’ll be much more sure that the effort was worthwhile.
As per my comment on HaukeHillebrandt’s comment below—The trouble with these estimates is that I’m not convinced they do a good job of considering how costs change as a technology is scaled. For example, we’ve seen this with solar—http://solarsouthwest.co.uk/solar-panel-cost/. Do you have a recommended source which does somehow take account of these effects? If not, we’re not really comparing costs properly.
Also, I want to specifically comment on this. Unless you believe that very large scale CO2 air-capture is going to be economically/technologically/land-use viable, we don’t have time to wait for people to get richer. The CO2 being emitted today, is committing humanity to a particular temperature rise for centuries to come. The cheapest time to deal with that is right now, to avoid putting the CO2 in the atmosphere in the first place.
It is true we generally see reduction in costs as cumulative production increases (this is called learning in economics). But then this means it might be cheaper to reduce CO2 emissions in the future (at least at the margin for EA, and even for the world as a whole if some of the learning occurs in related fields that does not require spending money on CO2 mitigation now). It is possible that renewable energy will become less expensive than fossil fuels in the near future, though usually the comparison is made with fossil fuel electricity. It is much more difficult for renewable energy to be lower cost than fuels used directly. Furthermore, if we want to go back to 350 PPM, we would need to do some form of air capture, which I think will be expensive for quite a while. So overall, with learning, it would reduce the cost of solving the problem, but I think it is harder to imagine it being less than $1 trillion present value with low discounting. You are right that there is a trade off. If we spend money on saving lives at $3000 per life now with health interventions instead of reducing CO2 emissions, that means more CO2 in the atmosphere in 100 years. So the question is whether that harm to the relatively richer people in 100 years is greater than the harm you avert by spending money on global health now if your time horizon only extends about 100 years.
The final thing which makes this all more complex, is that climate change is something which we are on a very well defined trajectory towards—where inaction results in terrible consequences. However, things like nuclear war are risks which may never materialize. If we invest effort into averting credible but potential risks, we’ll never be sure whether that investment actually mattered. If we invest effort in averting climate change, we’ll be much more sure that the effort was worthwhile.
Full-scale nuclear war may very well not happen this century. However, when you include additional catastrophes such as extreme weather on multiple continents (which a UK government study estimated had an ~80% likelihood this century), regional nuclear war, etc., it appears to be more likely than not that we will have one of these catastrophes this century. But it is possible that we will not have one of these catastrophes. As I said in my 80,000 Hours interview, if you are someone who has paid for insurance where they have gotten no payout from it whether they have wasted their money, they say “no” because it makes sense to insure things we can’t afford. So I think of this as an insurance policy for the world. And actually in terms of probabilities, I would say one of these agricultural catastrophes is actually more likely than median or worse slow climate change, so the probability of the investment paying off is actually higher for alternate food preparedness.
From your original comment (emphasis added by me to highlight what jumped out at me):
From my reply:
From your reply:
Also from your reply:
It looks like I misread your original comment a bit. When you said “much lower impact”, I didn’t realize that you had predicted 500 million deaths from a 10% agricultural shortfall. I have now read your paper, and am entirely comfortable to agree that: (1) 8°C cooling and 50% reduction in solar radiation in one year would likely be much worse than 10°C warming over a century, (2) expecting ~500 million deaths from a century long 10°C rise seems like roughly the right order of magnitude.
Having said that, some of the circumstances that would lead to a 10% agricultural shortfall (e.g. extreme weather in several breadbaskets in one year) wouldn’t also come with all the other costs of climate change (mass migration, species extinction etc).
This may well be true, but this is another case where I’d consider adaption as unacceptable. I don’t want to create a world where we need ice vests, or worse yet—something which needs to burn fuel, to be comfortable outside—particularly when that outcome is entirely avoidable.
I’m worried about tipping points that accelerate and amplify warming much sooner than 10°C of warming. Page 21 of this suggests that anything above 3C is extremely concerning.
As per my comment on HaukeHillebrandt’s comment below—The trouble with these estimates is that I’m not convinced they do a good job of considering how costs change as a technology is scaled. For example, we’ve seen this with solar—http://solarsouthwest.co.uk/solar-panel-cost/. Do you have a recommended source which does somehow take account of these effects? If not, we’re not really comparing costs properly.
Also, I want to specifically comment on this. Unless you believe that very large scale CO2 air-capture is going to be economically/technologically/land-use viable, we don’t have time to wait for people to get richer. The CO2 being emitted today, is committing humanity to a particular temperature rise for centuries to come. The cheapest time to deal with that is right now, to avoid putting the CO2 in the atmosphere in the first place.
In this post I wasn’t trying to look at the long-term value of climate change—I was mostly considering the impacts by 2100. Your response dismisses the concerns about smaller warmings because they are less likely to impact the long term potential of humanity. I still care about these impacts, because they will still kill people in the current century, even if those people don’t matter as much on a long-term basis because human civilization will be fine without them. In my own ethics, I value life which exists today and in the near future more highly than in the far future. The main reason I’m willing to extend my horizon to 2100, is that I have a strong belief that the economic system which I’m living in today will very directly impact people in 2100, so they are not remote and detached from my choices—I bear some responsibility for the world they get to live in. This implies that I use a non-zero discount rate, but which I’m willing to reduce specifically for cases where there’s a strong causal link to actions being taken today.
At the same time, I rationally understand the argument for long-termism. If I had to pick between (A) a world with terrible climate change, but where human civilization ends up surviving and then thriving for 10 million years, or (B) a world where we avert climate change and then wipe ourselves out in 2110 with a synthetic virus, I would obviously pick (A). But that definitely feels like a mugging—accept climate change because that way some far future people will lead great lives.
The final thing which makes this all more complex, is that climate change is something which we are on a very well defined trajectory towards—where inaction results in terrible consequences. However, things like nuclear war are risks which may never materialize. If we invest effort into averting credible but potential risks, we’ll never be sure whether that investment actually mattered. If we invest effort in averting climate change, we’ll be much more sure that the effort was worthwhile.
It is true we generally see reduction in costs as cumulative production increases (this is called learning in economics). But then this means it might be cheaper to reduce CO2 emissions in the future (at least at the margin for EA, and even for the world as a whole if some of the learning occurs in related fields that does not require spending money on CO2 mitigation now). It is possible that renewable energy will become less expensive than fossil fuels in the near future, though usually the comparison is made with fossil fuel electricity. It is much more difficult for renewable energy to be lower cost than fuels used directly. Furthermore, if we want to go back to 350 PPM, we would need to do some form of air capture, which I think will be expensive for quite a while. So overall, with learning, it would reduce the cost of solving the problem, but I think it is harder to imagine it being less than $1 trillion present value with low discounting.
You are right that there is a trade off. If we spend money on saving lives at $3000 per life now with health interventions instead of reducing CO2 emissions, that means more CO2 in the atmosphere in 100 years. So the question is whether that harm to the relatively richer people in 100 years is greater than the harm you avert by spending money on global health now if your time horizon only extends about 100 years.
Full-scale nuclear war may very well not happen this century. However, when you include additional catastrophes such as extreme weather on multiple continents (which a UK government study estimated had an ~80% likelihood this century), regional nuclear war, etc., it appears to be more likely than not that we will have one of these catastrophes this century. But it is possible that we will not have one of these catastrophes. As I said in my 80,000 Hours interview, if you are someone who has paid for insurance where they have gotten no payout from it whether they have wasted their money, they say “no” because it makes sense to insure things we can’t afford. So I think of this as an insurance policy for the world. And actually in terms of probabilities, I would say one of these agricultural catastrophes is actually more likely than median or worse slow climate change, so the probability of the investment paying off is actually higher for alternate food preparedness.