Before the revamp of the forum, I was asked to take down job ads, but maybe things have changed since then. I personally don't think it would be good for the forum to become a jobs board, since the community already has several places to post jobs.
Yeah, the view that utilities aren't comparable has more legs on preference-satisfactionism than it does on hedonism. On the face it is quite weird to say that the utilities, in the hedonistic sense, are not comparable. Can we compare the utility of a man being tortured with that of a man enjoying watching The Sopranos? DALYs, QALYs and WELLBYs are utility metrics that make utility comparable across people.
I would be interested to see any evidence on whether citizen knowledge has increased or not since social media formed. People often assert this but don't argue for it and the long-term trend isn't that clear.
This is a good question. In the absence of other explanations of market failure, this is an update away from the view that direct anti-poverty interventions do have high ROI. While some RCTs of anti-poverty programmes like the Graduation approach might show a big ROI, perhaps the market actors know not to trust these RCTs. Maybe they have an implicit view on the external validity of these studies, which has been demonstrated to be low
This is true, but they do contain low bar elements, such as $1.90 per day poverty. He also clearly thinks they are a bad way to think about development. I think it would be better if economists and EAs focused on an expanded GDP metric that includes income growth as well as other important contributors to wellbeing
2) I don't think this refutes Johannes point, which is that the headline figures claimed in the write-up on impact lab seem selected to get eye-catching figures. Although they run RCP4.5, they report the effects of RCP8.5 on the website and in the abstract. The mean effect is about a sixth smaller on RCP 4.5.
To put RCP8.5 in context, energy demand nearly quadruples, driven mainly by coal.
I do worry that this sort of work underestimates our ability to adapt. If energy demand does quadruple, there would be a lot more air conditioning to go round, and burning of coal would have driven a lot of income growth
3) From the copy I see, I think you are reporting Figure 7a, not 9a?
The SDGs seem to me to be antithetical to effective altruism. The SDGs :
Are in part 'kinky' development goals that place an arbitrary low bar on development goals, such as eradicating $1.90 per day poverty.
Don't prioritise among competing goals, such as climate change, growth, and education.
EAs should be focused on the question of how governments can most cost-effectively increase social welfare (broadly conceived) in their own countries. If we do this, we will meet all of the arbitrary "low bar" goals anyway. For discussion of national development vs kinky development, see some of Lant Pritchett's blogs.
I tend to agree. This feels a bit like a "be the change you want to see in the world" thing. Ordinary communication norms would push us towards just using verbal claims like 'likely' but for the reasons you mention, I pretty strongly think we should quantify and accept any short-term weirdness hit.
I suppose they're roughly in line with my previous best guess. On the basis of the Annan and Hargreaves paper, on median BAU scenario the chance of >6K was about 1%. I think this is probably a bit too low because the estimates that ground that were not meant to systematically sample uncertainty about ECS. On the WCRS estimate, the chance of >6K is about 5%. (Annan and Hargreaves are co-authors on WCRS, so they have also updated).
One has to take account of uncertainty about emissions scenarios as well
Thanks for posting this. This does seem to correct a lot of the common stated problems with estimates of S by incorporating all the lines of evidence. It'll be interesting to see how this is received in AR6.
Overall, I don't view this as especially good news.
The 95% confidence interval for S for the baseline case is 2.3K to 4.7K. Depending on the emissions scenario you put in, this implies a 5% chance of >6.3K-7K of warming on pre-industrial.
With robustness checks, the 95% CI for S is 2 to 5.7K. Depending on the emissions scenario, this implies a 5% chance of >7K-10K on pre-industrial.
From what I have read of their assumptions, the Baseline case seems more plausible, e.g. the robustness checks include an assumption of a uniform prior over S, which seems wrong. This suggests that the high chance of extreme warming suggested by Wagner and Weitzman is less likely. Still, the chance of >6K is way too high.
Defining the line of what counts as severe injustice, a high stakes error or a violation of a basic right, is not done precisely in the literature and is in my view impossible to do in a theoretically satisfying way. I think this is true for all nonconsequentialist thresholds. The point of nonconsequentialism is to avoid having to say how good something is, which makes it difficult/impossible to know how to trade-off different nonconsequentialist elements against each other. What do I do if I have to choose between the right to free speech and the economic minimum? If I don't know how good these things are, I don't see how I can compare and weigh them. Equally, what do I do if I have a 10% chance of violating someone's right to free association and a 20% chance of violating someone's right to an economic minimum? If you don't know how good these outcomes are, probability weighing them isn't much use when you're deciding how to act.
Ultimately, the boundary of what counts as a high stakes error is defined fuzzily and arbitrarily.
Hi, this is a good question. On within-nation rights only, firstly, I think almost all of the democratic theorists think there are at least limited cosmopolitan duties of justice to benefit the very badly off in poor countries at least up to some arbitrary sufficientarian standard. Hardcore nationalism also isn't that popular in political philosophy, and the moderate intrinsic proceduralists out there don't believe in it. Secondly, for theorists who endorse an act/omission distinction with respect to national responsibility, there is still the Thomas Pogge point that the global system of institutions in part causes poverty. in that context, aid is a corrective to an injustice.
Thirdly, this raises the question of how we should define the demos. One common view is that decisions that affect all should be decided by all. But then decisions in the US about budgetary spending also affect people in poor countries, animals and future generations, so they should on this standard have a say in the decision or a proxy should have a say for them. This speaks for global enfranchisement rather than US national democracy. Another view is that decisions that coerce others should be decided democratically. But then immigration restrictions coerce prospective immigrants, so again this speaks in favour of global enfranchisement.
On animals, it is very uncommon to hold that animals have no moral status at all, and that abuse of animals could never be classed as a high stakes error. Most philosophers are committed to the moral status of severely disabled humans, dogs and cats, but this clearly implies that chickens and pigs also have moral status.
On Rawls, I'm a bit allergic to Rawls exegesis after years of doing political philosophy, so I'll leave that one.
Hi Michael, I was also surprised! I think the basic intuition is that people want to avoid sanctioning the tyranny of the majority. Philosophers think it would be unjust for the majority to violate the basic rights of minorities. As I argue in the paper, democracies do this all the time. Lots of philosophers who are at pains to emphasise their democrat credentials are also in favour of the US Supreme Court for this reason - it doesn't get much more undemocratic than that.
The two main arguments for intrinsic proceduralism are from autonomy and from equal respect/basic equality. It is usually held that people's rights to act autonomously stop at the rights of others. No-one holds that people have a right grounded in autonomy to pursue the project of killing minorities. On equal respect/basic equality, I have a hard time understanding how it is an argument rather than merely a restatement of the claim that intrinsic proceduralism is true: in spite of basic equality, there are lots of rights and powers we distribute unequally, such as the right to practice medicine or drive.
Thanks for this, interesting post. What do you think about the clunkiness costs of using this communication norm? For example, for an organisation writing something public facing about climate change that is supposed to engage non-EAs, would it be advisable to qualify probability claims with resilience claims?
Phil Trammell makes a similar point about how we should update from the fact that smart people refuse to engage with AI risk arguments:
" The upshot here seems to be that when a lot of people disagree with the experts on some issue, one should often give a lot of weight to the popular disagreement, even when one is among the experts and the people's objections sound insane. Epistemic humility can demand more than deference in the face of peer disagreement: it can demand deference in the face of disagreement from one's epistemic inferiors, as long as they're numerous. They haven't engaged with the arguments, but there is information to be extracted from the very fact that they haven't bothered engaging with them. "
I'm not sure whether this counts as a heuristic or not, but anyway... I think an important point is that it's not clear what the incentive problem is, or (more weakly) that the incentive problem is nowhere near as bad as suggested in classical AI risk arguments. Designers of AI systems have very strong incentives for them not to be as useless as painted in classical AI risk arguments. If you were running a paperclip company, you would very strongly want to figure out a way to make a paperclip maximiser that doesn't use people's atoms to make paperclips, and there would be lots of opportunities to learn as you go on this front - there would be incentives for capabilities to develop in tow with safety
The incentive problem is made better by the fact that the market for AI development is quite concentrated - there are <10 major players in the field who currently look most likely to make very advanced AGIs. Thus, you only need to get coordination on safety from <10 actors. In contrast, biotechnology is comparatively a complete nightmare from a coordination point of view, requiring coordination among pretty much all states. Climate change also seems difficult on this front, though less bad than bio.
Do you think there were any deficits in epistemic modesty in the way the EA community prioritised AI risk, or do you think it was more that no-one sat down and examined the object-level arguments properly? Alternatively, do you think that there was too much epistemic modesty in the sense that everyone just deferred to everyone else on AI risk?
I think the democracy-growth connection is more nuanced than suggested here. Most of the biggest growth accelerations have occurred in autocracies. In terms of total welfare produced, most of the gains in human welfare have been driven by huge growth episodes in autocracies after 1950.
"democracies do not necessarily outperform autocracies in a growth acceleration episode, though they are likely to prevent large growth collapses. We also highlight the importance of the type of autocracy in understanding the effects of regime type on growth. When we disaggregate the type of autocracy, we find that party-based autocracies outperform democracies in growth acceleration episodes, though they do not limit the fall in the magnitude in growth deceleration episodes in comparison to democracies.
Our findings have implications for both for the previous literature on the relationship between democracy and growth as well as the literature on democratic transitions. They suggest that, while democracy may indeed lead to higher per capita incomes in the long run (as has been found by Acemoglu et al. 2014) or reduce the volatility of growth in the short run (as has been found by Mobarak, 2005), developing countries with democratic regimes are less likely to observe the rapid growth acceleration episodes that have been observed for certain types of autocracies, though they are less likely to suffer from the growth collapses that are prevalent in many autocracies. Further, our findings indicate that the transitions to democracy that we observe with increasing frequency in many parts of the developing world may not necessarily lead to rapid economic development, if the transition is from party-based autocracies to democracies. For the international development policy community, this suggests that it matters what type of autocracy is in place in a given country when pushing for democratic transition in that country."
Hi, Thanks for this. There seems to be agreement that demand curves are perfectly elastic on the 6 month timeframe. I looked at the paper you sent and it doesn' present any of its own evidence but cites some other papers, which I don't have time to look at. Our report on impact investing goes into this in more detail.
1. Empirical research. I did look into this and a quick google scholar search reveals lots of sceptical papers.
2. The theory doesn't make sense. On the efficient markets view, at any time that you put money into the stock market, you would expect the market to rise, just because the stock market increases over time in expectation. If you have £1m, then you would always be better off in expectation putting that into the stock market as a lump sum. If you spaced it out as 100 £10k investments over 100 months, then, in expectation you would miss out on the investment returns you could have got in those 100 months.
1. If solar geoengineering is not going to be used until we get to 4 degrees, then there is no point in researching it even if 4 degrees is catastrophic.
2. I agree that the constraints on state action are not perfect. As you say, the saudis fund terrorism and major powers flex their muscles at each other in more or less overt ways. The deployment of solar geoengineering would be on a different order - a huge and bold move. Do I think India would deploy solar geoengineering without the consent of China, risking the almost guaranteed ire of China? No.
The bet offer was not rhetorical and still stands if you would like it. We can pick an arbiter to make sure it happens. If you are worried about decaying attention, we could have a shorter timeframe? What do you think is the chance in the next 10 years that someone deploys it?
3. The debate about AI safety seems like a distraction to me - if you showed me that the case was analogous to solar geoengineering research, then I would argue that we should also delay AGI safety research for the same reasons. But it is disanalogous in numerous ways, so I don't see the point in exploring the analogy. Nevertheless... one rationale for AGI safety research is that some people think there is a non-negligible chance of AI in the next 20 years. Indeed, Toby Ord's median estimate is that we will get it in the next 20 years. If you believe that, then the case for AI safety research now is very clear. That is one disanalogy.
Secondly, the downsides of AGI research seem minimal. There is some dim possibility that AGI research could lead us to irrationally downplay the risks of AGI, but I have literally never seen this concern brought up before as a reason not to do AGI safety research. As far as I am aware, no-one is not doing AGI safety research because of that consideration. In contrast, in climate there is a pretty much cross-field taboo against against talking about solar geoengineering in a vaguely positive way. This is basically for the reasons I outline.
5. Our anthropogenic emissions between 2020 and 2080 have a huge effect on how hot it will get. e.g. We can still (technically) follow RCP2.6 and RCP8.5 On RCP2.6, median warming is less than 2 degrees, on RCP8.5, it is 4 degrees and beyond.
7. That seems right but the debate we're having is about whether to research it not deploy it.
I have some basic tips for UK investors which are a good baseline to work off.
1. Put your money into an Independent Savings Account (ISA). You can put in £20k per year tax-free. If you have more than £20k now, you can move another £20k at the start of the next tax year.
2. For a new investor, I think a simple and good method is getting a Vanguard Lifestrategy ISA with 100% equities - this buys you stocks across lots of different markets. As far as I know, Vanguard has the lowest fees at about 0.15% - even these small percentages are important as they eat up bigger investment gains. If you're doing patient philanthropy, you want equities not bonds for higher returns.
3. See this post for discussion of donor advised funds, which might have more tax advantages, though advice seems inconclusive at the moment.
Is the R0 lower in Europe? The 3 day average deaths per million is similar in the US, UK, Sweden, and (eg) Italy. Fatal shootings by police officers of citizens per capita are about 170x lower in the UK than the US. Imprisonment as % of the population is about 20x higher in US than US. Prison conditions seem far worse in the US than UK
I don't think this is a counterpoint to my claim which was that the problem of state mistreatment of black people is considerably lower in the UK vs the US. I didn't claim that there wasn't unfair mistreatment of black people in the UK.
I think this argument conflates the fact that p, and people's belief that p. Consider these two principles
1. If people correctly believe that going on the protests produces more good than harm, then they should go on the protests.
2. If people believe that going on the protests produces more good than harm, then they should go on the protests.
Principle 1 seems to me clearly correct from a utilitarian point of view. Principle 2 is absurd - people can have mad and false beliefs. If someone believes that going on a neo-nazi rally is going to produce greater marginal benefits than staying at home, that doesn't mean that they should in fact break the lockdown. The proposition "The BLM protests will produce more good than harm" doesn't entail principle 2.
(I'm not saying that the protests do in fact produce more good than harm, I'm just criticising Larks' counter-argument in the above comment)
1. Do you think that 4 degrees is "endgame and catastrophic" in the sense of being a threat to the long-term flourishing of humanity, or something else?
I agree 4 degrees would be bad, but I don't see how that is relevant to my argument.
2. "individual actors may resort to solar geoengineering without worldwide consensus" I argue against it in my piece. If brazil starts doing stratospheric aerosol injection, this would affect weather in the US and other allies - it's not a plausible piece of statecraft in my opinion. You mention the risk of 'rogue actors' deploying it - I don't see an argument against what I said in my piece on this. You are stating one common view in the literature that is especially worried about unilateralism, but I find the other multilateralism take more persuasive.
I am happy to offer a bet on this - what do you think the odds are of a single state unilaterally deploying stratospheric aerosol injection for more than 6 months over the next 30 years? I'll offer £500 I win/ £500 you win.
Other things equal, understanding the ramifications of SG would be good, but there are costs to doing so, namely mitigation obstruction risk.
3. I agree it would've been better to look more in detail at the effects on Russia and that does update me towards it being bad for them.
4. Not sure I see why the connection to AGI research is relevant here. We should worry about neglect of a solution when that neglect is irrational. I think SG research is neglected for a reason - scientists and funders don't want to do it because they are worried about the moral hazard.
5. "A lot of the warming is already locked into the ocean. Giving another 30 years before starting to research will likely be too late." What do you mean by "a lot"? Emissions until 2080 will have a large effect on what level of warming there will be - it is still technically within our power to follow RCP2.6 or RCP8.5, which would have hugely different implications for the probability of 4 degrees. This is why a wait and see approach is valuable.
6. Current technologies - I was going off McLellan et al (2012) - "We conclude that (a) the basic technological capability to deliver material to the stratosphere at million tonne per year rates exists today". Smith and Wagner (2018) dissent from this but still say "However, we also conclude that developing a new, purpose-built high-altitude tanker with substantial payload capabilities would neither be technologically difficult nor prohibitively expensive".
You say "have almost no precedent (volcanic eruptions can only tell us so much)" - I don't see why this is relevant to the question at hand of the technical feasibility of getting aerosols into the air.
7. I agree that the weaponisation risk seems small. It's still hard to know what research will turn up in advance and if we can avoid this risk without much cost then we should do so. It is a downside of research it would be nice to avoid.
8. Climate is a stressor of international politics risks. I agree with that but don't see how it is inconsistent with my argument.
9. In what sense are CO2 emissions a moral hazard? It's usually classed as a free rider problem, not a moral hazard. If you mean that CO2 emissions are bad, I agree with you.
Yeah the thought that research will rule out SG is plausible and that would be a reason to research SG, especially with governance-focused research. I have some credence in that view and some in not researching it at all. The timelag feature that SG is unlikely to be deployed in the next 50 years pushes me towards delaying research being the way to go.
One option I had thought about was - until there is an option for UK people, put the money in a CAF bank account and then get the gift aid, and wait until a suitable product becomes available. However, I think this is inferior to just putting the money in a Vanguard account - after 5 years 4% fees from CAF and no investment returns eats up all the gift aid benefits.
The enterprising Phil Trammell says in an FB message
"I just got off the phone with Vanguard Charitable, and they say that there's no issue with setting up an account from overseas. The catch is that contributions have to come from a US-based bank or investment account...! Since anyone can contribute to anyone's DAF, this doesn't seem too hard in principle; you can just contribute by sending money to a US-based friend, or that rethink charity donor-swap org or something, and they deposit it in the account you manage online. (It could always be done in small batches, if you don't fully trust them.) The initial contributions wouldn't be tax-deductible (or maybe they would be for the friend you're initially sending the money to?), but at any rate the interest still wouldn't be taxed.
Maybe this too much of a hassle for any individual to bother sorting out, but if there's interest from enough other people, and someone's willing to set some arrangement like this up, would you want to use it?"
2a. On China, I don't think population size matters for the carbon intensity of gdp - that should mostly be accounted for in the population parameter. agree that gas and reneawables are cheaper and that might be a reason that emerging economies won't use as much coal.
b. It doesn't seem to matter that much that strong climate policy exists in some places, e.g. Sweden. What seems to matter is whether there has been a notable change in global climate policy over the last 5 years that renders just extrapolating from the last 30 years especially unreliable. I don't see anything that would justify that.
c. Yeah that's fair. renewables a re a reason to think that intensity might decline below trend.
d. The places where we might get $50 per tonne carbon prices are less than 10% of global emissions to 2050, on current trends. historical experience suggests that some extremely wealthy left wing countries might impose high carbon prices in the next 30 years. Unfortunately, this won't have much of an effect on global emissions. there might be some places that impose high carbon prices, but they will cover a small fraction of emissions, just following the trend of the last 5, 10 or 30 years.
e. I don't think they assume zero political coordination. Political coordination would increase on the trend it has been doing over the last 5, 10 or 30 years.
4. It might be that there is cheap negative emissions, but this doesn't seem to me in the most likely range of scenarios (barring ocean fertilisation or something being good, which I don't know much about). It's worth pointing out that median carbon intensity ends up being pretty low on the estimate I give - it is a quarter of carbon intensity today, and the the upper end of the 95th percentile is a tenth of carbon intensity today. This is with climate action proceeding at the same dismal pace as it has over the last 30 years.
5. It would be weird to model geoengineering in this model. It seems to make much more sense to think about geoengineering as one of the solution tools you could use given where emissions might go. If you start thinking about the probability of solar geo in this model, the emissions wouldn't matter anyway, the temperature would. If you think there is a 10% chance of solar geo, then you would have to model at 10% chance of there being 2 degrees of warming. I think it is much easier to think about solar geo separately from this model.
1. By extra effort, I have in mind that we are on a trend line of effort on climate change, and extra effort would be a diversion from this historical trend. One rough proxy for this would be the global average marginal carbon price, which has crept up from about $0 to about $2 per tonne over the last 15 years. If in the next 10 years the global average marginal carbon price were to increase to $40, that would be a diversion from the trend line of climate effort.
2&3. These are all specific factors that a more precise estimate might take into account. It would be worth playing around with the estimate to see what effect this was on predicted emissions. It's worth noting that the rough 'follow the last 30 years' approach does produce the same median as other much more sophisticated models. Also note that if you play around with the model and put in much higher projected reductions, you do get a median that is more like RCP4.5, but the tail risk of much higher than expected emissions remains
Reasons to think carbon intensity might reduce beyond trend
a. China is anomalous both in terms of growth and reliance on coal. (This doesn't update me that much. The growth factor should be accounted for in the other parameter, and as long as coal is the cheapest energy source, our default assumptions should be that poor countries will rely on it to escape poverty. This is worsened by general equilibrium effects - declines in demand for coal in the West will reduce the cost for everyone else.)
b. Climate policy is kicking off. (I don't put much weight on this. Climate action is still very weak across the world and there are horrible political factors that push against strong changes in the trend)
c. Technologies in store that should help with carbon intensity. The most obvious ones are solar and wind, which follow an exponential cost reduction curve. If these start to play the role that some people predict, then we might see carbon intensity reduce below the trend line. (I personally would be surprised if these ever get to more than 30% of electricity worldwide, which is still a big deal. The super-pro-renewables people might expect more like 80% of electricity. But perhaps our default should be something like what we're witnessing in Germany, where they are trying very hard to push solar and wind but it's not having much of an effect on carbon intensity of gdp.)
d. I doubt large-scale CCS would happen on large enough scale without significant diversions from the trend in climate effort since it costs >$30 per tonne. This is less true but still true for advanced nuclear. The only countries that have pushed nuclear to a significant extent have done so for reasons of energy security. So, the reference class isn't that promising.
e. Yeah I agree with these points about assumed independence. The main caveat I would have is that political coordination is much harder than expected.
f. I agree that we have time to learn about high climate sensitivity so there is also an interaction there which reduces overall tail risk.
Reasons to think carbon intensity might increase beyond trend
g. Maybe political coordination is much harder than we expect. Maybe there is an arms race and people give up on climate.
All of this suggests that the estimates of carbon intensity decline might be biased a bit upwards. The most important factors seem to be decline in costs of renewables, electric cars and potentially advanced nuclear, as well as factors e and f.
4. I don't put much weight on the absence of negative emissions (unless we discover a very cheap form of it). If negative emissions remains at >$50/tonne, I don't see it having much of a role in the 'no extra effort' scenario.
Yeah I think it's most useful to think about what will happen if solar geoengineering is not an option, as this will allow us to figure out the potential benefits of solar geo from an ex risk pov. I agree that solar geo could be a useful backstop, though I don't see it getting deployed unless something quite extreme happens and I would view the governance challenges of deployed solar geo as a major way in which climate change contributes to GCRs.
1. Yes that's right. (Which scenario is better calibrated is up in the air. The Christensen et al one is an expert estimate but economists are very bad at predicting growth next year, so it's not clear that an expert survey is better than just extrapolating from the last 30 years.)
2. Yes, that is what the second model is *trying* to do but note that qualification that it is mainly trying to estimate the tail risk, so to get the 95% confidence interval right. In guesstimate, the median concentration isn't right (given the first model), but the 95% CI is. However, it would be quite easy to make a model estimating the chance of a certain level of warming conditional on a particular level of CO2 concentrations. I have added an example of this to the bottom of the second guesstimate model. If you think, following Rogelj et al, that the most likely current policy scenario is 700ppm, then the 95% confidence interval for warming is 1.6 to 5 degrees, with a median of 2.9 degrees. The chance of more than 6 degrees is about 1%. This shows the effect of priors - on Wagner and Weitzman's estimate, the chance of >6 degrees is more like 10%
So, the thought is that we would have some non-trivial probability mass on burning all the fossil fuels if there is an AI explosion. My best guess would be that this makes working on AI better than working on marginal climate stuff but I'm not sure how to think about this yet
Yeah, i think the AI explosion scenario should be taken with several piles of salt. It gets to the point that we need to be consistent about our expectations about AI timelines and about climate change. As you suggest, AI-driven progress could drive down carbon intensity, but climate change remains a horrible coordination problem, so it's not clear that all AI progress overcomes that
1. You say that IAM's don't factor in economic factors. I think this is wrong, or perhaps I have misunderstood your point? IAMs model the role of different energy technologies in an energy system meeting an emissions and economic constraint. The typical IAM does indeed imply a quadrupling of nuclear to 2050 (Peters et al, p4). This suggests that you are wrong to give the impression that all experts believe that nuclear should be phased out. As another example, the authors of the Clack et al response to Jacobson et al are all highly respected energy researchers who believe that at least 20% of energy needs to come from firm controllable low carbon sources. This means either gas+ ccs or nuclear, right?
2. It was very difficult until recently for private Gen IV nuclear companies to operate due to licensing and regulation. This was the point I was making.
Korea and UAE also show low cost and labour costs there will be comparable to the US/EU.
a. System levelised cost is important because it tells us what technologies we will need in a completely decarbonised system. It is at the system level where the case for nuclear becomes clear.
Re betting - my point was that there appear to be lots of potential barriers to VRE, including uncertain cost, local opposition, system grid balancing etc. There are a range of studies which suggest that with a zero emissions constraint, costs increase nonlinearly as VRE penetration passes 50%. Do you deny this?
i'm surprised you give the example of batteries to make your case here. A VRE-dependent system has *multi-week* electricity droughts to which batteries are ill-suited. It might be true that we get long duration storage but the technology isn't there yet.
b. The problem I was highlighting was of VRE *relative to* nuclear. VRE at high penetration has colossal land use requirements. David McKay argued that due to local opposition, VRE could at best provide one sixth of electricity in the UK. Nuclear in contrast because it is very energy dense doesn't have the same concerns.
4. I think you are missing my point on Germany. Germany has indeed subsidised VRE a lot and this has indeed helped to bring costs down. However, the point I was making was that Germany's own domestic performance on climate targets is bad relative to Europe, but they are following the exact strategy you propose - no nuclear, lots of VRE. Onshore wind additions fell to a twenty year low last year in part due to local opposition - they are around a quarter of what they need to be for them to get to their target if 65% of electricity from VRE. I think it highly likely that this local opposition to lots of wind will be replicated everywhere else where it is proposed.
5. The fastest rates of decarbonisation in absolute terms are from VRE. I don't think this is right, but perhaps I am not understanding what you mean. France and Sweden nearly completely decarbonised their electricity supply in ten years with nuclear/nuclear+hydro. I don't think anyone is on course to do that with VRE are they?
6. On zero carbon fuels, the problem here is that VRE would mean that the electrolyser is not used most of the time, whereas nuclear could run the electrolyser at max capacity. From memory the electrolyser is a third of the cost of hydrogen production. From modelling I've seen, VRE would be a very expensive way to produce liquid fuels.