13 ms·

Climate Models for Lawyers

62 points by VarFarYonder 10y ago

fencepost 10y ago
Having skimmed the final paper and without being aware of Judith Curry or her reputation, my initial reaction while reading was "This seems to be a white paper in the school of 'here's something you can cite to justify why nothing should be done about climate change/global warming/CO2 emissions/etc.'" Looking her up afterwards, it seems to me that this may also be her push for a significant position in the Trump administration. Seems that Judith Curry is the scientist who says "Well, they've revised the likely range so clearly they don't know what's likely and maybe it's too expensive to do anything right now." I won't bother linking, a simple search based on her name will turn up a wide variety of links to her history, people bemoaning her stances, and people refuting some of the arguments she uses.
- mdisc 10y ago
  Yeah it's kind of sad actually. I started reading this as serious piece and then sent it to a professor I had during my undergrad for a class on climate change. So embarrassing!! The broad points about training data and non-linearities are important- but on a second pass it's hard to believe that people who spend their lives building GCMs don't think deeply about these challenges.
  - basurihn 10y ago
    People who spend their lives building models in other sciences, say psychology, have missed gaps in their model... their whole approach, actually. Why is it inconceivable that climatology had equally glaring gaps?
  - jamez1 10y ago
    I think the worrying thing is that it's not hard to believe, she's pointing out the breakdown of the scientific process. She cops a lot of flack and hysteria, just for raising reasonable doubts! If climate science is solid, then it shouldn't feel the need to vilify anyone who questions it. If it isn't solid then it should be subject to as much scrutiny as possible given the derived policy will have tremendous impacts to life.
- barney54 10y ago
  Why not bother linking if the things she has said are so obviously wrong?
  - fencepost 10y ago
    Because if I link to specific articles, it becomes about those articles, how the writers of them have their own axes to grind (e.g. William M. Connolley in http://scienceblogs.com/stoat/2016/11/14/judith-curry-wtf/ http://scienceblogs.com/stoat/2016/11/14/judith-curry-wtf/ or http://www.realclimate.org/index.php/archives/2014/08/ipcc-attribution-statements-redux-a-response-to-judith-curry/ http://www.realclimate.org/index.php/archives/2014/08/ipcc-a...), how the magazines and websites involved are all liberal mouthpieces (e.g. Scientific American via Nature.com, http://www.nature.com/news/2010/101101/full/news.2010.577.html http://www.nature.com/news/2010/101101/full/news.2010.577.ht...). Perhaps the most balanced article easily found is this one from the commie pinko NPR: http://www.npr.org/2013/08/22/213894792/uncertain-science-judith-currys-take-on-climate-change http://www.npr.org/2013/08/22/213894792/uncertain-science-ju... Re: William M. Connolley, see https://en.wikipedia.org/wiki/William_Connolley https://en.wikipedia.org/wiki/William_Connolley as a starting point to differentiate from many others with slight name variations. edit: link in the wrong place
scarmig 10y ago
In other news: http://www.realclimate.org/index.php/archives/2016/11/record-heat-despite-a-cold-sun/ http://www.realclimate.org/index.php/archives/2016/11/record... There was a lot of crowing about sunspots a couple years back by Judith Curry et al. The Earth's heating can be explained by reaching a solar maximum! Etc. But now the situation is reversed--the sun is cooling--and despite that we're on track for yet another record year of heating. Third in a row. Her points about model uncertainty and overfitting have some limited level of validity. But it's hard to read her blog and not come away with the accurate takeaway of she'll say whatever she can to provide a cover story for not doing anything about AGW.
spenrose 10y ago
NASA climatologist Gavin Schmidt on Curry (Google cache): My reading of the evidence suggests clearly that the IPCC conclusions are an accurate assessment of the issue. I have tried to follow the proposed logic of Judith’s points here, but unfortunately each one of these arguments is either based on a misunderstanding, an unfamiliarity with what is actually being done or is a red herring associated with shorter-term variability. If Judith is interested in why her arguments are not convincing to others, perhaps this can give her some clues. http://webcache.googleusercontent.com/search?q=cache:pLrHr9q7_qkJ:www.realclimate.org/index.php/archives/2014/08/ipcc-attribution-statements-redux-a-response-to-judith-curry/+&cd=1&hl=en&ct=clnk&gl=us&client=safari http://webcache.googleusercontent.com/search?q=cache:pLrHr9q...
- barney54 10y ago
  This quote from Gavin Schmidt is two years old. I'm not sure what is has to do with this blog post by Curry about what climate models are.
  - conistonwater 10y ago
    Note that this blog post is not "about what climate models are". It seems she's been making the same types of arguments in the past, and this blog post is no different, so the past criticisms are still relevant.
  - Goronmon 10y ago
    You're not sure what a quote from someone criticizing the stances the author of the post takes, on a submission about the stances the author is taking?
mdisc 10y ago
Ah, yes she is a bit of a skeptic- http://www.skepticalscience.com/Judith_Curry_arg.htm http://www.skepticalscience.com/Judith_Curry_arg.htm
- piotrjurkiewicz 10y ago
  Wow, I didn't expect they maintain so detailed records of infidels, including mugshot-like photos and their blasphemy citations.
  - jwatte 10y ago
    Confirmation bias much? Why don't we focus on the actual data? Sun activity is not a major driver of warming, according to data. Yet, this position paper names sun activity as a cause to dismiss atmosphere. Why is that, do you think?
    - piotrjurkiewicz 10y ago
      When I wrote my comment, all previous ones were attacking her personally and none of them referred to the actual content of report. Such an attitude and existence of sites like that confirms that 'climate science' isn't science anymore. It is more like a religion. There are heated scientific debates in many fields, especially those ones depending on complicated models (e.g. quantum physics). But 'climate science' is the only one field where those ones who even slightly question the consensus are being witchhunted, their employers are being pressured to fire them and media to ignore them. Just take a look on the site linked above: - personal records of 'denialists' - a counter in the sidebar saying "Our climate has accumulated 2,421,220,822 Hiroshima atomic bombs of heat since 1998", what is pure sensationalism and populism, and reminds me this counter, which I saw in the sidebar of some another site: http://www.thereligionofpeace.com/TROP.jpg http://www.thereligionofpeace.com/TROP.jpg - in the same sidebar it links to the "Climate Science Legal Defense Fund" website, which says: "Our opponents won’t go quietly." This is not a scientific debate anymore. This is a religious war.
      - 10y ago
jwatte 10y ago
"I conclude that the climate models are not fit for the purpose" Without any statistical treatment at all. And then later puts "expert opinion" of others in quotes. At that point, I lost confidence in the analysis. Do some well known numerical and statistical tests of the models, and create a Bayesian based estimate based on all the models, and see where you end up instead!
- jamez1 10y ago
  Perhaps you missed her point about selection bias? Only models confirming climate change can be published, any analysis is just going to confirm that. It's unfortunate because climate change could be happening, but we aren't going to learn much more about it because research can't be invalidated. We've killed the skepticism science needs to function. She's not denying it's happening, she's just not buying the grandiose narrative. I'm glad to hear her view, even just to know that it's there.
bcheung 10y ago
"Scientists that evaluate climate models, develop physical process parameterizations, and utilize climate model results are convinced (at least to some degree) of the usefulness of climate models for their research. They are convinced because of the model’s relation to theory and physical understanding of the processes involved, consistency of the simulated responses among different models and different model versions, and the ability of the model and model components to simulate historical observations." Anyone can create a model that behaves consistently when it is trained on historical data to predict historical data. How do they overcome the problem of overfitting and why should anyone have any confidence in it until it shows accuracy going forward?
- HCIdivision17 10y ago
  I think the key is in the last quoted sentence: there isn't one model. There are many, and they are generated in different ways with differing emphasis on different data sets. They gain confidence when these seem to agree with each other and the acceptable physical knowledge already understood. They also check the sanity of the model to make sure that it is consistent with what has already been observed. In that way anyone may gain confidence that multiple approaches are converging on similar results. That, and there are metric crap-tonnes of data to work with of all sorts. Just ungodly amounts of it.
snowwrestler 10y ago
It is a common misconception that the theory of global warming, and the concern about global warming, is based on the results of global climate models (GCMs). It is not. In fact, the opposite is true: it is skepticism of global warming that depends on the correctness of GCMs. In the simplest model, which any kid can test in middle school, you take a plexiglass box full of air (representing the atmosphere), add some extra CO2 to it, and see if the temperature goes up. It does. Well, since the mid-1800s, we have been adding CO2 to the atmosphere. We know that we've burned a lot of fossil fuels (that were underground), and we have directly measured an increase in the amount of CO2 in the atmosphere. So based on the simplest model, we'd expect to see the temperature going up. And we do! Yay, science works. Of course there are a lot of ways to say that the simple model is wrong. But they all involve the construction of a more complex model. In order to see if anything will mitigate or compensate the basic physics of how more CO2 traps more heat, you have to add in additional factors. So when someone goes on and on and on about the shortcomings of super-complex GCMs, remember this. GCMs are important tools for making detailed predictions and policy decisions, but we don't need them to predict the basic fact of global warming. In fact the original hypothesis of global warming dates back to about 1900, well before anyone was using computers to model anything. The theory of global warming rests on basic thermodynamics, and it was first proposed not long after those basics were discovered.
- serge2k 10y ago
  Is this how we ended up shifting from "global warming" to "climate change"? Improved models showing that things won't just get warmer, they'll go all kinds of sideways?
  - snowwrestler 10y ago
    The change in terminology doesn't have scientific significance, it was done to try to improve public understanding. Basically "warming" in popular usage means "I can take my jacket off now", whereas warming in scientific usage means "increasing the heat energy stored in a given volume." Scientists have known for a long time that global warming (increasing the heat stored in the atmosphere) would create both local heating in some areas and local cooling in others (it's chaotic). But when a regular person hears "warming" and then the temperature goes down, they're confused. Hence "climate change." Incidentally, predicting the local effects of warming is a major goal of GCMs, and one for which no other tool will do. But it's damn hard (again: it's chaotic).
nkurz 10y ago
Could someone with domain knowledge give feedback on the specifics she brings up? As I take it, the backbone of her argument is: 1) "If climate sensitivity is high, then we can expect substantial warming in the coming century as emissions continue to increase. If climate sensitivity is low, then future warming will be substantially lower." 2) "In fact, it seems that uncertainty about values of ECS has been increasing. The bottom of the ‘likely’ range has been lowered from 2 to 1.5oC in the AR5, whereas the AR4 stated that ECS is very unlikely to be less than 1.5oC. It is also significant that the AR5 does not cite a best estimate, whereas the AR4 cites a best estimate of 3oC. The stated reason for not citing a best estimate in the AR5 is the substantial discrepancy between observation-based estimates of ECS (lower), versus estimates from climate models (higher). 3) "If the climate sensitivity is on the low end of the range of estimates, and natural internal variability is on the strong side of the distribution of climate models, different conclusions are drawn about the relative importance of human causes to the 20th century warming." 4) "Whether or not human caused global warming is dangerous or not depends critically on whether the ECS value is closer to 1.5oC or 4.5oC." 5) "Given the uncertainties in equilibrium climate sensitivity and the magnitude and phasing of natural internal variability on decadal to century timescales, combined with the failure of climate models to explain the early 20th century warming and the mid-century cooling, I conclude that the climate models are not fit for the purpose of identifying with high confidence the proportional amount of natural versus human causes to the 20th century warming." Is this an accurate summary of facts? Do we have good evidence about the true value of ECS that she does not mention? Is there evidence for scenarios where a 'low end' Equilibrium Climate Sensitivity still results in a dangerous warming? Or are there indeed values for ECS that would be considered 'likely' but do not result in dangerous warming? Lack of knowledge about the true value of ECS is not an excuse to avoid precautionary measures, but it would seem to raise questions about the suitability of current climate models as predictors for future climate. At the least, it would imply that determining the true ECS should be a very high priority while other mitigation measures are taken.
- xapata 10y ago
  It sounds like she's advocating for a political policy of doing nothing, because of "uncertainty". Consider our position on risk/uncertainty when it comes to minor disasters like an airplane hijacking. Now consider the appropriate response to the risk of a nation-destroying disaster. Is it reasonable to take the do-nothing policy?

62 points by VarFarYonder 10y ago

Having skimmed the final paper and without being aware of Judith Curry or her reputation, my initial reaction while reading was "This seems to be a white paper in the school of 'here's something you can cite to justify why nothing should be done about climate change/global warming/CO2 emissions/etc.'" Looking her up afterwards, it seems to me that this may also be her push for a significant position in the Trump administration. Seems that Judith Curry is the scientist who says "Well, they've revised the likely range so clearly they don't know what's likely and maybe it's too expensive to do anything right now." I won't bother linking, a simple search based on her name will turn up a wide variety of links to her history, people bemoaning her stances, and people refuting some of the arguments she uses.

mdisc 10y ago
Yeah it's kind of sad actually. I started reading this as serious piece and then sent it to a professor I had during my undergrad for a class on climate change. So embarrassing!! The broad points about training data and non-linearities are important- but on a second pass it's hard to believe that people who spend their lives building GCMs don't think deeply about these challenges.
- basurihn 10y ago
  People who spend their lives building models in other sciences, say psychology, have missed gaps in their model... their whole approach, actually. Why is it inconceivable that climatology had equally glaring gaps?
- jamez1 10y ago
  I think the worrying thing is that it's not hard to believe, she's pointing out the breakdown of the scientific process. She cops a lot of flack and hysteria, just for raising reasonable doubts! If climate science is solid, then it shouldn't feel the need to vilify anyone who questions it. If it isn't solid then it should be subject to as much scrutiny as possible given the derived policy will have tremendous impacts to life.
barney54 10y ago
Why not bother linking if the things she has said are so obviously wrong?
- fencepost 10y ago
  Because if I link to specific articles, it becomes about those articles, how the writers of them have their own axes to grind (e.g. William M. Connolley in http://scienceblogs.com/stoat/2016/11/14/judith-curry-wtf/ http://scienceblogs.com/stoat/2016/11/14/judith-curry-wtf/ or http://www.realclimate.org/index.php/archives/2014/08/ipcc-attribution-statements-redux-a-response-to-judith-curry/ http://www.realclimate.org/index.php/archives/2014/08/ipcc-a...), how the magazines and websites involved are all liberal mouthpieces (e.g. Scientific American via Nature.com, http://www.nature.com/news/2010/101101/full/news.2010.577.html http://www.nature.com/news/2010/101101/full/news.2010.577.ht...). Perhaps the most balanced article easily found is this one from the commie pinko NPR: http://www.npr.org/2013/08/22/213894792/uncertain-science-judith-currys-take-on-climate-change http://www.npr.org/2013/08/22/213894792/uncertain-science-ju... Re: William M. Connolley, see https://en.wikipedia.org/wiki/William_Connolley https://en.wikipedia.org/wiki/William_Connolley as a starting point to differentiate from many others with slight name variations. edit: link in the wrong place

scarmig 10y ago

In other news: http://www.realclimate.org/index.php/archives/2016/11/record-heat-despite-a-cold-sun/ http://www.realclimate.org/index.php/archives/2016/11/record... There was a lot of crowing about sunspots a couple years back by Judith Curry et al. The Earth's heating can be explained by reaching a solar maximum! Etc. But now the situation is reversed--the sun is cooling--and despite that we're on track for yet another record year of heating. Third in a row. Her points about model uncertainty and overfitting have some limited level of validity. But it's hard to read her blog and not come away with the accurate takeaway of she'll say whatever she can to provide a cover story for not doing anything about AGW.

spenrose 10y ago

NASA climatologist Gavin Schmidt on Curry (Google cache): My reading of the evidence suggests clearly that the IPCC conclusions are an accurate assessment of the issue. I have tried to follow the proposed logic of Judith’s points here, but unfortunately each one of these arguments is either based on a misunderstanding, an unfamiliarity with what is actually being done or is a red herring associated with shorter-term variability. If Judith is interested in why her arguments are not convincing to others, perhaps this can give her some clues. http://webcache.googleusercontent.com/search?q=cache:pLrHr9q7_qkJ:www.realclimate.org/index.php/archives/2014/08/ipcc-attribution-statements-redux-a-response-to-judith-curry/+&cd=1&hl=en&ct=clnk&gl=us&client=safari http://webcache.googleusercontent.com/search?q=cache:pLrHr9q...

barney54 10y ago
This quote from Gavin Schmidt is two years old. I'm not sure what is has to do with this blog post by Curry about what climate models are.
- conistonwater 10y ago
  Note that this blog post is not "about what climate models are". It seems she's been making the same types of arguments in the past, and this blog post is no different, so the past criticisms are still relevant.
- Goronmon 10y ago
  You're not sure what a quote from someone criticizing the stances the author of the post takes, on a submission about the stances the author is taking?

mdisc 10y ago

Ah, yes she is a bit of a skeptic- http://www.skepticalscience.com/Judith_Curry_arg.htm http://www.skepticalscience.com/Judith_Curry_arg.htm

piotrjurkiewicz 10y ago
Wow, I didn't expect they maintain so detailed records of infidels, including mugshot-like photos and their blasphemy citations.
- jwatte 10y ago
  Confirmation bias much? Why don't we focus on the actual data? Sun activity is not a major driver of warming, according to data. Yet, this position paper names sun activity as a cause to dismiss atmosphere. Why is that, do you think?
  - piotrjurkiewicz 10y ago
    When I wrote my comment, all previous ones were attacking her personally and none of them referred to the actual content of report. Such an attitude and existence of sites like that confirms that 'climate science' isn't science anymore. It is more like a religion. There are heated scientific debates in many fields, especially those ones depending on complicated models (e.g. quantum physics). But 'climate science' is the only one field where those ones who even slightly question the consensus are being witchhunted, their employers are being pressured to fire them and media to ignore them. Just take a look on the site linked above: - personal records of 'denialists' - a counter in the sidebar saying "Our climate has accumulated 2,421,220,822 Hiroshima atomic bombs of heat since 1998", what is pure sensationalism and populism, and reminds me this counter, which I saw in the sidebar of some another site: http://www.thereligionofpeace.com/TROP.jpg http://www.thereligionofpeace.com/TROP.jpg - in the same sidebar it links to the "Climate Science Legal Defense Fund" website, which says: "Our opponents won’t go quietly." This is not a scientific debate anymore. This is a religious war.
    - 10y ago

jwatte 10y ago

"I conclude that the climate models are not fit for the purpose" Without any statistical treatment at all. And then later puts "expert opinion" of others in quotes. At that point, I lost confidence in the analysis. Do some well known numerical and statistical tests of the models, and create a Bayesian based estimate based on all the models, and see where you end up instead!

jamez1 10y ago
Perhaps you missed her point about selection bias? Only models confirming climate change can be published, any analysis is just going to confirm that. It's unfortunate because climate change could be happening, but we aren't going to learn much more about it because research can't be invalidated. We've killed the skepticism science needs to function. She's not denying it's happening, she's just not buying the grandiose narrative. I'm glad to hear her view, even just to know that it's there.

bcheung 10y ago

"Scientists that evaluate climate models, develop physical process parameterizations, and utilize climate model results are convinced (at least to some degree) of the usefulness of climate models for their research. They are convinced because of the model’s relation to theory and physical understanding of the processes involved, consistency of the simulated responses among different models and different model versions, and the ability of the model and model components to simulate historical observations." Anyone can create a model that behaves consistently when it is trained on historical data to predict historical data. How do they overcome the problem of overfitting and why should anyone have any confidence in it until it shows accuracy going forward?

HCIdivision17 10y ago
I think the key is in the last quoted sentence: there isn't one model. There are many, and they are generated in different ways with differing emphasis on different data sets. They gain confidence when these seem to agree with each other and the acceptable physical knowledge already understood. They also check the sanity of the model to make sure that it is consistent with what has already been observed. In that way anyone may gain confidence that multiple approaches are converging on similar results. That, and there are metric crap-tonnes of data to work with of all sorts. Just ungodly amounts of it.

snowwrestler 10y ago

It is a common misconception that the theory of global warming, and the concern about global warming, is based on the results of global climate models (GCMs). It is not. In fact, the opposite is true: it is skepticism of global warming that depends on the correctness of GCMs. In the simplest model, which any kid can test in middle school, you take a plexiglass box full of air (representing the atmosphere), add some extra CO2 to it, and see if the temperature goes up. It does. Well, since the mid-1800s, we have been adding CO2 to the atmosphere. We know that we've burned a lot of fossil fuels (that were underground), and we have directly measured an increase in the amount of CO2 in the atmosphere. So based on the simplest model, we'd expect to see the temperature going up. And we do! Yay, science works. Of course there are a lot of ways to say that the simple model is wrong. But they all involve the construction of a more complex model. In order to see if anything will mitigate or compensate the basic physics of how more CO2 traps more heat, you have to add in additional factors. So when someone goes on and on and on about the shortcomings of super-complex GCMs, remember this. GCMs are important tools for making detailed predictions and policy decisions, but we don't need them to predict the basic fact of global warming. In fact the original hypothesis of global warming dates back to about 1900, well before anyone was using computers to model anything. The theory of global warming rests on basic thermodynamics, and it was first proposed not long after those basics were discovered.

serge2k 10y ago
Is this how we ended up shifting from "global warming" to "climate change"? Improved models showing that things won't just get warmer, they'll go all kinds of sideways?
- snowwrestler 10y ago
  The change in terminology doesn't have scientific significance, it was done to try to improve public understanding. Basically "warming" in popular usage means "I can take my jacket off now", whereas warming in scientific usage means "increasing the heat energy stored in a given volume." Scientists have known for a long time that global warming (increasing the heat stored in the atmosphere) would create both local heating in some areas and local cooling in others (it's chaotic). But when a regular person hears "warming" and then the temperature goes down, they're confused. Hence "climate change." Incidentally, predicting the local effects of warming is a major goal of GCMs, and one for which no other tool will do. But it's damn hard (again: it's chaotic).

nkurz 10y ago

Could someone with domain knowledge give feedback on the specifics she brings up? As I take it, the backbone of her argument is: 1) "If climate sensitivity is high, then we can expect substantial warming in the coming century as emissions continue to increase. If climate sensitivity is low, then future warming will be substantially lower." 2) "In fact, it seems that uncertainty about values of ECS has been increasing. The bottom of the ‘likely’ range has been lowered from 2 to 1.5oC in the AR5, whereas the AR4 stated that ECS is very unlikely to be less than 1.5oC. It is also significant that the AR5 does not cite a best estimate, whereas the AR4 cites a best estimate of 3oC. The stated reason for not citing a best estimate in the AR5 is the substantial discrepancy between observation-based estimates of ECS (lower), versus estimates from climate models (higher). 3) "If the climate sensitivity is on the low end of the range of estimates, and natural internal variability is on the strong side of the distribution of climate models, different conclusions are drawn about the relative importance of human causes to the 20th century warming." 4) "Whether or not human caused global warming is dangerous or not depends critically on whether the ECS value is closer to 1.5oC or 4.5oC." 5) "Given the uncertainties in equilibrium climate sensitivity and the magnitude and phasing of natural internal variability on decadal to century timescales, combined with the failure of climate models to explain the early 20th century warming and the mid-century cooling, I conclude that the climate models are not fit for the purpose of identifying with high confidence the proportional amount of natural versus human causes to the 20th century warming." Is this an accurate summary of facts? Do we have good evidence about the true value of ECS that she does not mention? Is there evidence for scenarios where a 'low end' Equilibrium Climate Sensitivity still results in a dangerous warming? Or are there indeed values for ECS that would be considered 'likely' but do not result in dangerous warming? Lack of knowledge about the true value of ECS is not an excuse to avoid precautionary measures, but it would seem to raise questions about the suitability of current climate models as predictors for future climate. At the least, it would imply that determining the true ECS should be a very high priority while other mitigation measures are taken.

xapata 10y ago
It sounds like she's advocating for a political policy of doing nothing, because of "uncertainty". Consider our position on risk/uncertainty when it comes to minor disasters like an airplane hijacking. Now consider the appropriate response to the risk of a nation-destroying disaster. Is it reasonable to take the do-nothing policy?