Thanks for this, Vasco, thought-provoking as always!
Likewise! Thanks for the thoughtful comment.
Insofar as is this a correct representation of your argument
It seems like a fair representation.
a. Dying from heat stress is a very extreme outcome and people will act in response to climate change much earlier than dying. For example, before people die from heat stress, they might abandon their livelihoods and migrate, maybe in large numbers.
b. More abstractly, the fact that an extreme impact outcome (heat death) is relatively rare is not evidence for low impact in general. Climate change pressures are not like a disease that kills you within days of exposure and otherwise has no consequence.
Agreed. However:
I think migration will tend to decrease deaths because people will only want to migrate if they think their lives will improve (relative to the counterfactual of not migrating).
The deaths from non-optimal temperature I mentioned are supposed to account for all causes of death, not just extreme heat and cold. According to GBD, in 2021, deaths from environmental heat and cold exposure were 36.0 k (I guess this is what you are referring to by heat stress), which was just 1.88 % (= 36.0*10^3/ā(1.91*10^6)) of the 1.91 M deaths from non-optimal temperature. My post is about how these 1.91 M deaths would change.
a. You seem to suggest we are very uncertain about many of the effect signs. I think the basic argument why people concerned about climate change would argue that changes will be negative and that there be compounding risks is because natural and human systems are adapted to specific climate conditions. That doesnāt mean they cannot adapt at all, but that does mean that we should expect it is more likely that effects are negative, at least as short-term shocks, than positive for welfare.
This makes sense. On the other hand, one could counter global warming will be good because:
There are more deaths from low temperature than from high temperature.
The disease burden per capita from non-optimal temperature has so far been decreasing (see 2nd to last graph).
b. I think a lot of the other arguments on the side of āindirect risks are lowā you cite are ultimately of the form (i) āindirect effects in other causes are also largeā or (ii) āpointing to indirect effects make things inscrutable and unverifiableā. (i) might be true but doesnāt matter, I think, for the question of whether warming is net-bad and (ii) is also true, but does nothing by itself on whether those indirect effects are realāwe can live in a world where indirect effects are rhetorically abused and still exist and indeed dominate in certain situations!
Agreed. I would just note that i) can affect prioritisation across causes.
I think I remain confused as to what you mean with āall deaths from non-optimal temperatureā.
It is clear that the data source you cite (GBD, focused on current deaths) will not feature nor proxy what people concerned about compounding risks from climate are concerned about.
So to me it seems you are saying āI donāt trust arguments about compounding risks and the data is evidence for thatā whereas the data is inherently not set up to include that concern and does not really speak to the arguments that people most concerned about climate risk would make.
As said before, I think it is fine to say āI donāt trust arguments about compounding risksā and I am probably with you there to a large degree at least compared to people most concerned about this, but I donāt think the data from GBD is additional evidence for that mistrust, as far as I can tell.
By crude analogy, if you believed that COVID restrictions had a big toll on the young and this will affect long-run impacts somehow, pointing to few COVID deaths amongs this age cohort would not be evidence against this concern.
I think I remain confused as to what you mean with āall deaths from non-optimal temperatureā.
I mean the difference between the deaths for the predicted and ideal temperature. From OWID:
The deaths from non-optimal temperature are supposed to cover all causes (temperature is a risk factor for death rather than a cause of death in GBD), not just extreme heat and cold (which only account for a tiny fraction of the deaths; see my last comment). I say āsupposedā because it is possible the mortality curves above are not being modelled correctly, and this applies even more to the mortality curves in the future.
So to me it seems you are saying āI donāt trust arguments about compounding risks and the data is evidence for thatā whereas the data is inherently not set up to include that concern and does not really speak to the arguments that people most concerned about climate risk would make.
My understanding is that (past/āpresent/āfuture) deaths from non-optimal temperature are supposed to include conflict deaths linked to non-optimal temperature. However, I am not confident these are being modelled correctly.
I was not clear, but in my last comment I mostly wanted to say that deaths from non-optimal temperature account for the impact of global warming not only on deaths from extreme heat and cold, but also on cardiovascular or kidney disease, respiratory infections, diabetes and all others (including conflicts). Most causes of death are less heavy-tailed than conflict deaths, so I assume we have a better understanding of how they change with temperature.
Ok, so I think we converge pretty much thenāessentially what I am saying is that people concerned about compounding risks would argue that these are not modeled correctly in GBD and that there is much more uncertainty there (and that the estimate is probably an underestimate, from the perspective of taking the compounding risk view seriously).
Makes sense. Just to clarify, the data on deaths and disease burden from non-optimal temperature until now are from GBD, but the projections for the future death rates from non-optimal temperature are from Human Climate Horizons.
Iām not sure it would change your underlying conclusions, but for what itās worth I took a quick look at the data/āmethods from Human Climate Horizons and think that it is likely an underestimate of future heat-related mortality.
This paper underlies the Human Climate Horizons/āOWID estimates. A few quick assumptions I think are worth highlighting:
1. The authors (by admission) do not consider the effects of humidity. Accurate humidity data is much harder to come by than temperature, and itās often not included in the down-scaled versions of the climate models, though some exceptions apply. However, itās potentially quite relevant for heat-related mortality, though there is some debate in the literature. Given that it is unlikely that incorporating humidity would decrease heat-related mortality, my own view here is that this pushes current estimates towards a lower bound.
2. The authors use climate model data that are downscaled with a technique called Bias-Correction Spatial Disaggregation (BCSD). This approach has two key assumptions in it: (1) it assumes that the relative spatial patterns in the training data will remain constant under future climate change, and (2) it is calibrated to monthly data, not day to day changes, which has the effect of dampening extreme values. In practice, these assumptions limit the ability to model things like extreme heat waves and heat domes, which can cause large fatality spikes (e.g. figure below from Washington State in 2021). Missing these features in some locations might be akin to missing almost all the possible heat related mortality in cooler climates.
Again, I donāt think these are significant enough to fundamentally change your conclusions, but I do think itās worth highlighting that these types of results can be quite sensitive to specifics of the climate modeling approaches that are used.
Thanks, Bradley, and welcome to the EA Forum! Strongly upvoted.
Given that it is unlikely that incorporating humidity would decrease heat-related mortality, my own view here is that this pushes current estimates towards a lower bound.
If adequately modelling humidity would increase heat deaths, I wonder whether it would also decrease cold deaths, such that the net effects is unclear.
In practice, these assumptions limit the ability to model things like extreme heat waves and heat domes, which can cause large fatality spikes (e.g. figure below from Washington State in 2021). Missing these features in some locations might be akin to missing almost all the possible heat related mortality in cooler climates.
As illustrated below, deaths from extreme cold and heat accounted for only a tiny fraction of the deaths from non-optimal temperature in 2015 in some countries, which attenuates the effect you are describing.
Likewise! Thanks for the thoughtful comment.
It seems like a fair representation.
Agreed. However:
I think migration will tend to decrease deaths because people will only want to migrate if they think their lives will improve (relative to the counterfactual of not migrating).
The deaths from non-optimal temperature I mentioned are supposed to account for all causes of death, not just extreme heat and cold. According to GBD, in 2021, deaths from environmental heat and cold exposure were 36.0 k (I guess this is what you are referring to by heat stress), which was just 1.88 % (= 36.0*10^3/ā(1.91*10^6)) of the 1.91 M deaths from non-optimal temperature. My post is about how these 1.91 M deaths would change.
This makes sense. On the other hand, one could counter global warming will be good because:
There are more deaths from low temperature than from high temperature.
The disease burden per capita from non-optimal temperature has so far been decreasing (see 2nd to last graph).
Agreed. I would just note that i) can affect prioritisation across causes.
Thanks!
I think I remain confused as to what you mean with āall deaths from non-optimal temperatureā.
It is clear that the data source you cite (GBD, focused on current deaths) will not feature nor proxy what people concerned about compounding risks from climate are concerned about.
So to me it seems you are saying āI donāt trust arguments about compounding risks and the data is evidence for thatā whereas the data is inherently not set up to include that concern and does not really speak to the arguments that people most concerned about climate risk would make.
As said before, I think it is fine to say āI donāt trust arguments about compounding risksā and I am probably with you there to a large degree at least compared to people most concerned about this, but I donāt think the data from GBD is additional evidence for that mistrust, as far as I can tell.
By crude analogy, if you believed that COVID restrictions had a big toll on the young and this will affect long-run impacts somehow, pointing to few COVID deaths amongs this age cohort would not be evidence against this concern.
I mean the difference between the deaths for the predicted and ideal temperature. From OWID:
The deaths from non-optimal temperature are supposed to cover all causes (temperature is a risk factor for death rather than a cause of death in GBD), not just extreme heat and cold (which only account for a tiny fraction of the deaths; see my last comment). I say āsupposedā because it is possible the mortality curves above are not being modelled correctly, and this applies even more to the mortality curves in the future.
My understanding is that (past/āpresent/āfuture) deaths from non-optimal temperature are supposed to include conflict deaths linked to non-optimal temperature. However, I am not confident these are being modelled correctly.
I was not clear, but in my last comment I mostly wanted to say that deaths from non-optimal temperature account for the impact of global warming not only on deaths from extreme heat and cold, but also on cardiovascular or kidney disease, respiratory infections, diabetes and all others (including conflicts). Most causes of death are less heavy-tailed than conflict deaths, so I assume we have a better understanding of how they change with temperature.
Ok, so I think we converge pretty much thenāessentially what I am saying is that people concerned about compounding risks would argue that these are not modeled correctly in GBD and that there is much more uncertainty there (and that the estimate is probably an underestimate, from the perspective of taking the compounding risk view seriously).
Makes sense. Just to clarify, the data on deaths and disease burden from non-optimal temperature until now are from GBD, but the projections for the future death rates from non-optimal temperature are from Human Climate Horizons.
Thanks, Bradley, and welcome to the EA Forum! Strongly upvoted.
If adequately modelling humidity would increase heat deaths, I wonder whether it would also decrease cold deaths, such that the net effects is unclear.
As illustrated below, deaths from extreme cold and heat accounted for only a tiny fraction of the deaths from non-optimal temperature in 2015 in some countries, which attenuates the effect you are describing.