4 ms·

It took the Fed a full year of inflation being over the target to raise rates. If you look at the code of the climate models responsible for the decision makin

It took the Fed a full year of inflation being over the target to raise rates. If you look at the code of the climate models responsible for the decision making of trillions of dollars, you'll find old fortran code with many obvious inaccuracies on the order of magnitude of the things it's supposed to measure, and you'll find they all copy code from each other and reach diverging results.

sgt101 4y ago
uhm, no, no you won't. Climate models are very conservative in terms of the coding and approaches, but the old Fortran is used because 100's of eyes have picked over it for problems and it's as accurate as it possibly can be.
- machina_ex_deus 4y ago
  Have you actually looked at it before you replied, or are you just assuming it? Fortran is terrible for the scale of those projects, and it shows. I can give you concrete examples straight from GitHub. Accuracy isn't relative it's absolute. You're not comparing accuracy to other models, you compare it vs reality. It is a known fact the results of different climate models diverge. There's ongoing research as to why this is happening, lookup CMIP6. Many models also required flux adjustment to stay stable over many years of simulation (although at least that problem is improving). It's really hard to test these models on the scale of the effects climate change.
  - sgt101 4y ago
    You will learn that when things that have been worked on by 100's of smart people look strange there is usually a reason why. This stuff is very hard, contributions before criticism.
    - machina_ex_deus 4y ago
      You still didn't answer me whether you've thoroughly reviewed their code before dismissing my comments. Did you? You can approach it as an insider researcher "on their side" and try to correct it, but the problem is just so big you're not going to get flawless models without time, and they have already shrugged serious problems in the past with "flux adjustment". You'll get endless errata and retractions but you'll never get a narrative shift. Or you can try to approach it from the outside like countless scientists have done and get called oil companies shill, climate denier and what not. The academic "climate" around it is very "hot". So eventually you just go and forget it and do something productive with your life instead of literally fighting windmills. (And I did mean literally as a joke about renewable energy).
mempko 4y ago
Even if your masked climate denial claims are true about climate models, the implication is that the confidence intervals are huge. That means while it could be better than expected, it could also be far worse than expected. That should give nobody comfort. The tail risk is too great to even risk finding out what will happen if we keep doing this crazy experiment with our atmosphere.
- machina_ex_deus 4y ago
  You know what's worse than climate change being real and doing nothing about it? Climate change being real but getting the real reason wrong because of hubris, and doing measures that only harm and economy and makes us more fragile ahead of dealing with the crisis, and in the process destroying any public trust in science that will be required for dealing with the crisis. Almost like doing lockdowns for coronavirus. Temperature measurements and real world data and trends is not something I can deny. But there's important difference between climate change is from CO2 and greenhouse gas, to any other possible explanation. Just like there's a difference between "inflation is transitory because of supply chain problems" to the dumpster fire we're having today. I've had enough of this hubris. How is it that nobody is preparing for the impacts of climate change? How is everyone so confident that somehow whatever measures are done will be enough, and that everyone will actually implement them? Adaptation is clearly the only viable solution because that's the only thing that's independent of the competence of things you don't control.
  - c1ccccc1 4y ago
    Let me push back on the notion that there are alternative explanations besides increased concentration of atmospheric CO2 and other greenhouse gases for the current rapid changes in climate. It's one thing to say that we should distrust the complicated models that try to simulate the entire Earth in sufficient detail to predict exactly what the temperature change will be and what the impacts will be in each region. That stuff is genuinely hard to predict and I won't be surprised if the models get lots of things wrong. But the basic mechanism by which higher CO2 concentrations enable to atmosphere to retain heat better is dead simple. Heat is lost from the ground and atmosphere by low frequency photons that radiate away into space. Many of the photons, especially those emitted from the ground and lower parts of the atmosphere will be scattered by gas molecules in the atmosphere, and CO2 is one of the gases that is particularly good at this. Scattering means that the photon's direction changes randomly, which means that there's a good chance that it will be redirected to be heading back down towards the ground, rather than out into space. So an increased number of scattering events improve heat retention. Adding more CO2 to the atmosphere increases the number of of scattering events and thus results in less heat being lost to space, which results in a higher average* temperature for the Earth. We can debate what the exact consequences of all this will be, but saying it isn't a result of humanity burning large quantities of fossil fuels is to me tantamount to an admission that you don't understand physics. *(Technically, since thermal radiation goes as T^4 times emissivity and some other stuff, what I really mean is a higher value of T^4 averaged across the surface area of the Earth and weighted by emissivity. And even this is an oversimplification, since not only can heat be lost from the ground, but also the atmosphere iteself. But the basic picture of "planet gets warmer" is still correct.)
c1ccccc1 4y ago
Is it possible for you to link any of the climate models where you've observed this and point out some of the inaccuracies? (Or to link to an existing blog post or comment that does so?)
- machina_ex_deus 4y ago
  I'll post a single simple anecdote, but this is much much worse. https://github.com/GEOS-ESM/GEOSgcm_GridComp/blob/develop/GEOSagcm_GridComp/GEOSphysics_GridComp/GEOSmoist_GridComp/gfdl_cloud_microphys.F90 https://github.com/GEOS-ESM/GEOSgcm_GridComp/blob/develop/GE... Line 87, you can see they copy physical constants from an old physics book and then later they commented out and used different constants. You can see that the difference is quite significant. The cloud physics code there I saw in different models, with different "constants", with other comments also taken from physics books as old as the 1980s. Can look in general at the accuracy of physical constants used, some of them aren't constants at all (and depends on composition of air INCLUDING CO2, such as gas constants). There are also much more complex problems there that I can't explain over a single post. This is extremely complex to evaluate the impact of everything going on there, and I can't make claims that it should go one way or the other, but the code quality and the testing done there are definitely not enough to reach the conclusions made and the trillions of dollars worth of decisions that followed.
  - c1ccccc1 4y ago
    Thanks for replying with details. The difference for liquid water is small, but for ice it looks like it's actually about 7%, which could be significant. Looks like what's going on is that the constants used are for different temperatures. The original constant was for ice at 0C, while the new constant is for ice at -15C. I'm guessing this is probably based on the thought that more ice on the planet is near -15C than is near 0C. Ideally for the best accuracy you'd compute the heat capacity using interpolation and a lookup table, but I can see how it would be a lot harder to enforce energy conservation that way. It would be interesting to see a sensitivity analysis on how these kinds of decisions affect the outcome of the simulation.

sgt101 4y ago

uhm, no, no you won't. Climate models are very conservative in terms of the coding and approaches, but the old Fortran is used because 100's of eyes have picked over it for problems and it's as accurate as it possibly can be.

machina_ex_deus 4y ago
Have you actually looked at it before you replied, or are you just assuming it? Fortran is terrible for the scale of those projects, and it shows. I can give you concrete examples straight from GitHub. Accuracy isn't relative it's absolute. You're not comparing accuracy to other models, you compare it vs reality. It is a known fact the results of different climate models diverge. There's ongoing research as to why this is happening, lookup CMIP6. Many models also required flux adjustment to stay stable over many years of simulation (although at least that problem is improving). It's really hard to test these models on the scale of the effects climate change.
- sgt101 4y ago
  You will learn that when things that have been worked on by 100's of smart people look strange there is usually a reason why. This stuff is very hard, contributions before criticism.
  - machina_ex_deus 4y ago
    You still didn't answer me whether you've thoroughly reviewed their code before dismissing my comments. Did you? You can approach it as an insider researcher "on their side" and try to correct it, but the problem is just so big you're not going to get flawless models without time, and they have already shrugged serious problems in the past with "flux adjustment". You'll get endless errata and retractions but you'll never get a narrative shift. Or you can try to approach it from the outside like countless scientists have done and get called oil companies shill, climate denier and what not. The academic "climate" around it is very "hot". So eventually you just go and forget it and do something productive with your life instead of literally fighting windmills. (And I did mean literally as a joke about renewable energy).

mempko 4y ago

Even if your masked climate denial claims are true about climate models, the implication is that the confidence intervals are huge. That means while it could be better than expected, it could also be far worse than expected. That should give nobody comfort. The tail risk is too great to even risk finding out what will happen if we keep doing this crazy experiment with our atmosphere.

machina_ex_deus 4y ago
You know what's worse than climate change being real and doing nothing about it? Climate change being real but getting the real reason wrong because of hubris, and doing measures that only harm and economy and makes us more fragile ahead of dealing with the crisis, and in the process destroying any public trust in science that will be required for dealing with the crisis. Almost like doing lockdowns for coronavirus. Temperature measurements and real world data and trends is not something I can deny. But there's important difference between climate change is from CO2 and greenhouse gas, to any other possible explanation. Just like there's a difference between "inflation is transitory because of supply chain problems" to the dumpster fire we're having today. I've had enough of this hubris. How is it that nobody is preparing for the impacts of climate change? How is everyone so confident that somehow whatever measures are done will be enough, and that everyone will actually implement them? Adaptation is clearly the only viable solution because that's the only thing that's independent of the competence of things you don't control.
- c1ccccc1 4y ago
  Let me push back on the notion that there are alternative explanations besides increased concentration of atmospheric CO2 and other greenhouse gases for the current rapid changes in climate. It's one thing to say that we should distrust the complicated models that try to simulate the entire Earth in sufficient detail to predict exactly what the temperature change will be and what the impacts will be in each region. That stuff is genuinely hard to predict and I won't be surprised if the models get lots of things wrong. But the basic mechanism by which higher CO2 concentrations enable to atmosphere to retain heat better is dead simple. Heat is lost from the ground and atmosphere by low frequency photons that radiate away into space. Many of the photons, especially those emitted from the ground and lower parts of the atmosphere will be scattered by gas molecules in the atmosphere, and CO2 is one of the gases that is particularly good at this. Scattering means that the photon's direction changes randomly, which means that there's a good chance that it will be redirected to be heading back down towards the ground, rather than out into space. So an increased number of scattering events improve heat retention. Adding more CO2 to the atmosphere increases the number of of scattering events and thus results in less heat being lost to space, which results in a higher average* temperature for the Earth. We can debate what the exact consequences of all this will be, but saying it isn't a result of humanity burning large quantities of fossil fuels is to me tantamount to an admission that you don't understand physics. *(Technically, since thermal radiation goes as T^4 times emissivity and some other stuff, what I really mean is a higher value of T^4 averaged across the surface area of the Earth and weighted by emissivity. And even this is an oversimplification, since not only can heat be lost from the ground, but also the atmosphere iteself. But the basic picture of "planet gets warmer" is still correct.)

c1ccccc1 4y ago

Is it possible for you to link any of the climate models where you've observed this and point out some of the inaccuracies? (Or to link to an existing blog post or comment that does so?)

machina_ex_deus 4y ago
I'll post a single simple anecdote, but this is much much worse. https://github.com/GEOS-ESM/GEOSgcm_GridComp/blob/develop/GEOSagcm_GridComp/GEOSphysics_GridComp/GEOSmoist_GridComp/gfdl_cloud_microphys.F90 https://github.com/GEOS-ESM/GEOSgcm_GridComp/blob/develop/GE... Line 87, you can see they copy physical constants from an old physics book and then later they commented out and used different constants. You can see that the difference is quite significant. The cloud physics code there I saw in different models, with different "constants", with other comments also taken from physics books as old as the 1980s. Can look in general at the accuracy of physical constants used, some of them aren't constants at all (and depends on composition of air INCLUDING CO2, such as gas constants). There are also much more complex problems there that I can't explain over a single post. This is extremely complex to evaluate the impact of everything going on there, and I can't make claims that it should go one way or the other, but the code quality and the testing done there are definitely not enough to reach the conclusions made and the trillions of dollars worth of decisions that followed.
- c1ccccc1 4y ago
  Thanks for replying with details. The difference for liquid water is small, but for ice it looks like it's actually about 7%, which could be significant. Looks like what's going on is that the constants used are for different temperatures. The original constant was for ice at 0C, while the new constant is for ice at -15C. I'm guessing this is probably based on the thought that more ice on the planet is near -15C than is near 0C. Ideally for the best accuracy you'd compute the heat capacity using interpolation and a lookup table, but I can see how it would be a lot harder to enforce energy conservation that way. It would be interesting to see a sensitivity analysis on how these kinds of decisions affect the outcome of the simulation.