But the IPCC estimate range already includes (or just barely misses) the skeptic range (1.5-4.5 for the IPCC versus 1.3-2 for the main skeptic blogs
Basically he IPCC has a higher uncertainty interval in their data then the skeptics. Shouldn’t this lead one to conclude that a lot of skeptics who argue about the fact that the climate is hard to predict aren’t really serious about what they are saying?
To add to my previous comment: I do agree that some skeptics express very high confidence in low climate sensitivity values, more than is arguably warranted from the evidence (even if it is consistent with the evidence). Overconfidence in such estimates is a sign against being taken seriously. At the same time, conducting an exercise that comes up with a specific estimate, possibly just as an illustration of the sort of thing that seems to be true, doesn’t seem problematic to me.
Shouldn’t this lead one to conclude that a lot of skeptics who argue about the fact that the climate is hard to predict aren’t really serious about what they are saying?
Interesting point.
First off, very few individual papers give huge uncertainty estimates for climate sensitivity. The IPCC, in its aggregation process, gets an estimate of 1.5-4.5 C. But most of the papers it references give specific values or narrower ranges.
This is not necessarily a bad thing, because the purpose of any individual paper is not to settle the question definitively, but to provide a plausible approach and explore the answer that one might get through that, rather than categorically claim that to be the correct value. The purpose of a summary report (such as that offered by the IPCC) is to look at the totality of such stuff. Therefore, an individual paper (or blog post) that comes up with a narrow range is not a problem unless it claims to be the authoritative source for the climate sensitivity estimate.
Second, note that climate sensitivity is not the only source of unpredictability in climate. There are many others (ocean currents (somewhat predictable), solar activity (somewhat predictable), volcanic eruptions (inherently unpredictable)). It’s quite possible to have the view that climate sensitivity is well-understood, but climate is still very hard to forecast.
Third, I don’t know if there is a gap between skeptics and mainstream scientists in their view of how predictable climate is. Some people who are classified as skeptical have come up with relatively specific predictions about climate based on ocean currents, while others have called it a hopeless task. And some mainstream scientists express high confidence in particular estimates, while others have highlighted uncertainties.
I should add that there is a lot of garden-variety skepticism out there, of the form “Climate’s changed before, so it’s obviously no big deal if it changes now” or “We obviously can’t say anything about the climate!” or “obviously, humans can’t have an effect on the climate” with extremely high confidence, even though these statements are (quite likely) wrong. (Again, the statements may be right at any given time or in a particular circumstance, but they cannot be put forward as general principles with high confidence). I certainly don’t give weight to unsubstantiated views of this sort when I refer to AGW skepticism.
Therefore, an individual paper (or blog post) that comes up with a narrow range is not a problem unless it claims to be the authoritative source for the climate sensitivity estimate.
A summary of evidence from multiple sources should have a lower confidence interval when the sources that it summaries if the source accurately reflect the evidence that they have. If it’s the other way around that means that those sources have made mistakes.
If I ask 3 people for a number and one tells me it’s between 11-12, one tells me 14-15 and one tells me 17-19 my conclusion would be that as a group they don’t really know what they are talking about.
Yes, maybe the IPCC should have concluded that we have no idea about climate sensitivity. But they needed to put some sort of estimate range that could be fed into their scenario analyses.
Anyway, I found an infographic of different climate sensitivity estimates here:
PS: I have no idea if the infographic accurately reflects all recent studies. The author is a global warming skeptic who has received money from oil and coal industries, so that should be cause for skepticism. But I think such an infographic would be hard to fudge. If anybody has a better source, I’d be happy to hear.
UPDATE: Added it to post at end of discussion of climate sensitivity estimates.
Basically he IPCC has a higher uncertainty interval in their data then the skeptics. Shouldn’t this lead one to conclude that a lot of skeptics who argue about the fact that the climate is hard to predict aren’t really serious about what they are saying?
To add to my previous comment: I do agree that some skeptics express very high confidence in low climate sensitivity values, more than is arguably warranted from the evidence (even if it is consistent with the evidence). Overconfidence in such estimates is a sign against being taken seriously. At the same time, conducting an exercise that comes up with a specific estimate, possibly just as an illustration of the sort of thing that seems to be true, doesn’t seem problematic to me.
Interesting point.
First off, very few individual papers give huge uncertainty estimates for climate sensitivity. The IPCC, in its aggregation process, gets an estimate of 1.5-4.5 C. But most of the papers it references give specific values or narrower ranges.
This is not necessarily a bad thing, because the purpose of any individual paper is not to settle the question definitively, but to provide a plausible approach and explore the answer that one might get through that, rather than categorically claim that to be the correct value. The purpose of a summary report (such as that offered by the IPCC) is to look at the totality of such stuff. Therefore, an individual paper (or blog post) that comes up with a narrow range is not a problem unless it claims to be the authoritative source for the climate sensitivity estimate.
Second, note that climate sensitivity is not the only source of unpredictability in climate. There are many others (ocean currents (somewhat predictable), solar activity (somewhat predictable), volcanic eruptions (inherently unpredictable)). It’s quite possible to have the view that climate sensitivity is well-understood, but climate is still very hard to forecast.
Third, I don’t know if there is a gap between skeptics and mainstream scientists in their view of how predictable climate is. Some people who are classified as skeptical have come up with relatively specific predictions about climate based on ocean currents, while others have called it a hopeless task. And some mainstream scientists express high confidence in particular estimates, while others have highlighted uncertainties.
I should add that there is a lot of garden-variety skepticism out there, of the form “Climate’s changed before, so it’s obviously no big deal if it changes now” or “We obviously can’t say anything about the climate!” or “obviously, humans can’t have an effect on the climate” with extremely high confidence, even though these statements are (quite likely) wrong. (Again, the statements may be right at any given time or in a particular circumstance, but they cannot be put forward as general principles with high confidence). I certainly don’t give weight to unsubstantiated views of this sort when I refer to AGW skepticism.
A summary of evidence from multiple sources should have a lower confidence interval when the sources that it summaries if the source accurately reflect the evidence that they have. If it’s the other way around that means that those sources have made mistakes.
If I ask 3 people for a number and one tells me it’s between 11-12, one tells me 14-15 and one tells me 17-19 my conclusion would be that as a group they don’t really know what they are talking about.
Yes, maybe the IPCC should have concluded that we have no idea about climate sensitivity. But they needed to put some sort of estimate range that could be fed into their scenario analyses.
Anyway, I found an infographic of different climate sensitivity estimates here:
http://www.cato.org/blog/still-another-low-climate-sensitivity-estimate-0
Direct link to image:
http://object.cato.org/sites/cato.org/files/wp-content/uploads/gsr_042513_fig1.jpg
PS: I have no idea if the infographic accurately reflects all recent studies. The author is a global warming skeptic who has received money from oil and coal industries, so that should be cause for skepticism. But I think such an infographic would be hard to fudge. If anybody has a better source, I’d be happy to hear.
UPDATE: Added it to post at end of discussion of climate sensitivity estimates.