6 ms·

TFA article does say. They looked at 17 forecasts drawn from 14 models. You are the one who implicitly believes they are lying about that and only reporting 1

TFA article does say. They looked at 17 forecasts drawn from 14 models. You are the one who implicitly believes they are lying about that and only reporting 17 out of some huge unknown number. The reality is that the vast majority (>99%) of climate change research does not produce the type of forecast, or really any forecast at all, that one could do this analysis on. Therefore, the 17 forecast number is actually very easy to believe.

whokal 7y ago
With sincerity, I think you may misunderstand what GP is pointing out. I understood “forecasts” to be a simulation run using a model. In that case, they took 14 models and ran those each at least once to come up with 17 predictions. What GP wants is transparency around how many possible models were there over the last decades from which they chose the 14. This gives the reader a better understanding of whether 14 is a lot or a little. It is a fair point IMO regardless of their overall stance on the issue.
- mturmon 7y ago
  They did a literature search and chose what was reproducible. This has been covered in TFA and highlighted by a comment nearby: https://news.ycombinator.com/item?id=21709446 https://news.ycombinator.com/item?id=21709446
ekianjo 7y ago
How many models are currently published for reference?
jointpdf 7y ago
Simulation is one way to produce a numerical forecast, but the prediction of any forecast model would never be the result of a single simulation run. Model predictions are always (or should always) be reported as an expected value, or the average over many simulation runs. The expected value of a random variable (e.g. mode output) is probably the most fundamental concept in all of statistics/probability, and many mind-wrenching (read: wrong+incoherent) internet hot takes are rooted in logical fallacies about the science of prediction. The reason that there are more predictions (17) than models (14) is that several of the models (eg Hansen 1981) consider several distinct “scenarios” based on differing assumptions about future levels of GHG emissions. Secondly, the forecast models evaluated in the study are from the likes of James Hansen, William Nordhaus, and the IPCC (in other words, authoritative sources). So at the very least this adds weight to the hypothesis that the models published by the IPCC are accurate and methodologically sound. Sure, there is some probability that the models and reality corresponded by random chance, but that probability is made ever more diminishingly small as evidence accumulates. So, I don’t think any of the comments in this thread that accuse the authors of retrospective cherry-picking of climate models are anything but embarrassing examples of pseudo-intellectual contrarianism and/or confusion over basic statistics. The models considered by the study, their predictions, and the methodology used are all located here and were easily found after 30s of digging: https://github.com/hausfath/OldModels https://github.com/hausfath/OldModels
- benmaraschino 7y ago
  Agreed. The point of criticism that the authors didn’t include all relevant models is among the lowest of the low-hanging fruit I can imagine one picking. And while the process of peer review isn’t without its flaws, I can also imagine that fruit has long since been picked by the reviewers, who have far deeper knowledge of the published models than I or just about anyone else in this thread, save for the actual climate scientists among us.
  - mturmon 7y ago
    Thirded. The posting of climate-related stories on HN brings out a lot of un-informed skepticism. The resulting back-and-forth tends to crowd out everything else. In many of these cases, it's clear that the commenters have done no background reading, and have no climate science background. Their comments thus consist of simple armchair speculation (your "lowest of the low-hanging fruit"). In these comments, I have found people with strong opinions on the lack of seriousness of climate science, who have no idea we have gravimetric measurements of ice sheet mass. This is a dataset going back almost 20 years that has revolutionized geoscience. HN commenters have expressed strong opinions about melting ice, with no knowledge of this data and what it means. I have found people who think that climate science consists of having a stable of models each with a host of knobs, and the research method is to turn the knobs or choose new models until the results look dramatic enough to publish. The gap between the firmness of these claims and the knowledge to back it up just boggles the mind. The most basic step people could take to fix this is to read the executive summary of the IPCC AR5 report, or (even better/easier) the executive summary of the NCA (https://science2017.globalchange.gov https://science2017.globalchange.gov). This report was specifically written by people who really know this stuff, for people like us.
    - mistermann 7y ago
      Serious question: based on what I've written, do you believe I am one of the people you describe?
      - 7y ago
mistermann 7y ago
> TFA article does say. It says something. > They looked at 17 forecasts drawn from 14 models. It does not say this. What you have written is your uncritical interpretation, what I wrote is a literal quotation, which allows for (satisfies) the conspiratorial possibility that I raised. > You are the one who implicitly believes they are lying about that You are speculating. Speculation is fine, but it's best to realize (and state explicitly) when you're doing it. Know how I know you're speculating? Because while you only believe you can read my mind, I can actually do it, and I do not "believe they are lying". I was only pointing out that as written, they could be lying. And I even told you the reason why I wrote that comment: "Articles written in this style provide rich fodder for conspiracy theorists..." If you truly want to change minds, you might want to learn how the minds you want to change work. Go spend some serious time in conspiracy forums, I suspect you might learn something useful. And rather than largely ignoring the actual words of someone who's trying to help out your cause, treating them as an enemy rather than someone who may have some insight you lack, it might be helpful to keep a more open mind. Perhaps if those with knowledge severely lacking in the mainstream discourse weren't rate limited, some here may find some new ideas to consider.

whokal 7y ago

With sincerity, I think you may misunderstand what GP is pointing out. I understood “forecasts” to be a simulation run using a model. In that case, they took 14 models and ran those each at least once to come up with 17 predictions. What GP wants is transparency around how many possible models were there over the last decades from which they chose the 14. This gives the reader a better understanding of whether 14 is a lot or a little. It is a fair point IMO regardless of their overall stance on the issue.

mturmon 7y ago
They did a literature search and chose what was reproducible. This has been covered in TFA and highlighted by a comment nearby: https://news.ycombinator.com/item?id=21709446 https://news.ycombinator.com/item?id=21709446

ekianjo 7y ago

How many models are currently published for reference?

jointpdf 7y ago

Simulation is one way to produce a numerical forecast, but the prediction of any forecast model would never be the result of a single simulation run. Model predictions are always (or should always) be reported as an expected value, or the average over many simulation runs. The expected value of a random variable (e.g. mode output) is probably the most fundamental concept in all of statistics/probability, and many mind-wrenching (read: wrong+incoherent) internet hot takes are rooted in logical fallacies about the science of prediction. The reason that there are more predictions (17) than models (14) is that several of the models (eg Hansen 1981) consider several distinct “scenarios” based on differing assumptions about future levels of GHG emissions. Secondly, the forecast models evaluated in the study are from the likes of James Hansen, William Nordhaus, and the IPCC (in other words, authoritative sources). So at the very least this adds weight to the hypothesis that the models published by the IPCC are accurate and methodologically sound. Sure, there is some probability that the models and reality corresponded by random chance, but that probability is made ever more diminishingly small as evidence accumulates. So, I don’t think any of the comments in this thread that accuse the authors of retrospective cherry-picking of climate models are anything but embarrassing examples of pseudo-intellectual contrarianism and/or confusion over basic statistics. The models considered by the study, their predictions, and the methodology used are all located here and were easily found after 30s of digging: https://github.com/hausfath/OldModels https://github.com/hausfath/OldModels

benmaraschino 7y ago
Agreed. The point of criticism that the authors didn’t include all relevant models is among the lowest of the low-hanging fruit I can imagine one picking. And while the process of peer review isn’t without its flaws, I can also imagine that fruit has long since been picked by the reviewers, who have far deeper knowledge of the published models than I or just about anyone else in this thread, save for the actual climate scientists among us.
- mturmon 7y ago
  Thirded. The posting of climate-related stories on HN brings out a lot of un-informed skepticism. The resulting back-and-forth tends to crowd out everything else. In many of these cases, it's clear that the commenters have done no background reading, and have no climate science background. Their comments thus consist of simple armchair speculation (your "lowest of the low-hanging fruit"). In these comments, I have found people with strong opinions on the lack of seriousness of climate science, who have no idea we have gravimetric measurements of ice sheet mass. This is a dataset going back almost 20 years that has revolutionized geoscience. HN commenters have expressed strong opinions about melting ice, with no knowledge of this data and what it means. I have found people who think that climate science consists of having a stable of models each with a host of knobs, and the research method is to turn the knobs or choose new models until the results look dramatic enough to publish. The gap between the firmness of these claims and the knowledge to back it up just boggles the mind. The most basic step people could take to fix this is to read the executive summary of the IPCC AR5 report, or (even better/easier) the executive summary of the NCA (https://science2017.globalchange.gov https://science2017.globalchange.gov). This report was specifically written by people who really know this stuff, for people like us.
  - mistermann 7y ago
    Serious question: based on what I've written, do you believe I am one of the people you describe?
    - 7y ago

mistermann 7y ago

> TFA article does say. It says something. > They looked at 17 forecasts drawn from 14 models. It does not say this. What you have written is your uncritical interpretation, what I wrote is a literal quotation, which allows for (satisfies) the conspiratorial possibility that I raised. > You are the one who implicitly believes they are lying about that You are speculating. Speculation is fine, but it's best to realize (and state explicitly) when you're doing it. Know how I know you're speculating? Because while you only believe you can read my mind, I can actually do it, and I do not "believe they are lying". I was only pointing out that as written, they could be lying. And I even told you the reason why I wrote that comment: "Articles written in this style provide rich fodder for conspiracy theorists..." If you truly want to change minds, you might want to learn how the minds you want to change work. Go spend some serious time in conspiracy forums, I suspect you might learn something useful. And rather than largely ignoring the actual words of someone who's trying to help out your cause, treating them as an enemy rather than someone who may have some insight you lack, it might be helpful to keep a more open mind. Perhaps if those with knowledge severely lacking in the mainstream discourse weren't rate limited, some here may find some new ideas to consider.