the Air Vent

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Archive for April, 2013

Dana’s Planet

Posted by Jeff Id on April 20, 2013

UPDATE: Nic Lewis left this interesting comment down below –

Actually, in Chapter 9 of AR4 WG1, dealing with observationally-constrained estimates of climate sensitivity, the IPCC only discuss medians and modes. Not a mean in sight! And it refers to the mode as the “best estimate”. Nor does Figure 9.20 (where the estimated PDFs for climate sensitivity from Forest 2006 and other studies are shown, labelled EQUILIBRIUM climate sensitivity) mark the means. And Forest 2006 itself only reported the mode.

So I’m not being either misleading on any count, or misrepresenting anything. But Dana is both misrepresenting my study and being misleading. What a surprise.

 

Skeptical Science has another silly post up which attempts to pick at the edges of Nic Lewis’s climate sensitivity paper.  They titled the critique “Climate Sensitivity Single Study Syndrome, Nic Lewis Edition”  We all know that Skeptical Science is filled with those who are certain that oil money is brown and corrupts minds, while government money is green and makes scientists infallible.  I normally ignore the site but WUWT pointed me to it and sometimes SS is a bit of fun:

It’s most important not to fall into the trap of thinking that any single study will overturn a vast body of scientific evidence, derived from many different sources of data (or as Andrew Revkin calls this, single-study syndrome).

It isn’t the quote which caught my attention but Dana’s ankle-biting point here forgets much more important quotes from much smarter people.

“No amount of experimentation can ever prove me right; a single experiment can prove me wrong.”– Albert Einstein

Nic’s study found a best probability climate sensitivity of 1.6C/doubling CO2, now there should be nothing inherently wrong with that number but the know-nothings at Skeptical Science realize that it falls below their preferred sky-is-falling-so-we-need-to-empower-the-UN-and-stop-capitalism goals.     In other words, 1.6C would mean that there is no immediate doom on which to base their already ridiculously self-destructive political intent on.  Shame that eh?  So we get a bunch of emotion from their crowd.

Unfortunately for Dana (and the rest of the crowd there), there is a large body of evidence which has been piling up against these high climate sensitivity models.   MMH10 for instance, showed that the mean of the primary climate models is running statistically outside of observation, Lucia has done a number of posts to that effect.   Recently Roy Spencer put up a post showing the same problem.

From Dr. Roy Spencer, experiment vs observation:

CMIP5-global-LT-vs-UAH-and-RSS[1]

This is one of my favorite plots from MMH10, which shows the same thing as Dr. Spencer with a bit of added stats.

MMH10 also has this plot:

Then there is this one from Chad Herman that incorporates surface temperature measurements:

tas-trends-20c3m-a1b-global[1]

Although surface temperatures are closer to the models than lower troposphere, again and again, the shotgun of government funded model simulations runs high against observation.  It is only in politicized forms of science where actual observations that contradict theory are rubbed out.  You would think the models would move instead.  Chucking unloved temperature proxies out in paleoclimate is another great example of theory trumping observation.

Anyway, there is hardly only one avenue of data which supports Nic’s lower sensitivity as Dana’s article implies.   The claim is so off the wall that it leaves one wondering why they would pull the wool over their readers eyes.  What caught my attention though was just how hard Dana was working away at Nic’s ankle bone.  I’m taking the whole paragraph this time, because it is that funny:

Even though Lewis refers specifically to “equilibrium climate sensitivity,” The methodology used by Lewis is also not even necessarily an estimate of equilibrium sensitivity, but rather of effective climate sensitivity, which is a somewhat different parameter.  The two may hypothetically be the same if all energy changes in the global climate system are accounted for (and to their credit, Forest and Lewis do include estimates of ocean heat content, including for the deep oceans), and if climate feedbacks remain constant.  However, recent research by Armour et al. (2012) suggests that the latter may not be the case.

I literally laughed out loud when I read this paragraph.  So the argument becomes first, don’t trust a single paper, then if you do trust it, don’t forget that climate sensitivity may change based on unknown and unmodeled factors which SS has just spent like 5 years telling us don’t exist. I do happen to agree that climate sensitivity is not a fixed number, so does everyone else, but Nic was estimating equilibrium sensitivity on this planet ….today… How this potential change in future sensitivity refutes Nic’s work can only be understood on Dana’s planet but it sure sounded foreboding.

After this paragraph, Dana moved on to some paleo-studies demonstrating high sensitivity from proxies which only a silly person would give the same credibility as present day measured data.    To finish it all off, Dana then humorously attacked Nic’s accuracy in claiming agreement with Aldrin et al.

One significant issue in Lewis’ paper (in his abstract, in fact) is that in trying to show that his result is not an outlier, he claims that Aldrin et al. (2012) arrived at the same most likely climate sensitivity estimate of 1.6°C, calling his result “identical to those from Aldrin et al. (2012).”  However, this is simply a misrepresentation of their paper.

This is what Nic claimed in the abstract:

Employing the improved methodology, preferred 90% bounds of 1.2–2.2 K for ECS are 20 then derived (mode and median 1.6 K). The mode is identical to those from Aldrin et al.  (2012) and (using the same, HadCRUT4, observational dataset) Ring et al. (2012).

Now you would think even a math novice would recognize the “mode and median” claim and realize that they must be something different.   Unfortunately Dana did not, and proceeded to stomp around and stuck his foot firmly within a dark area.  In his defense, perhaps Dana was tired and wasn’t reading as carefully as one would expect when critiquing a peer reviewed paper.  The claim WAS all the way to the bottom of the abstract after all, and advocacy is tiring work.  Tom Curtis pointed out the error in the comments last night at 4am but the post remains uncorrected.

I think the alarmist advocate crowd is in full Gaian prayer mode that temperatures will skyrocket soon.   It is the either the data or the climate models at this point, someone must move. In the meantime, it is entertaining watching the advocates squirm.

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The State of Paleoclimate Understanding

Posted by Jeff Id on April 9, 2013

In the huge amount of justified complaints made here about what I think of paleo-reconstructions, one detail is probably lost in the chaff.

I really wish I knew what historic temperatures were.  You can’t read that much paleoclimate information and not want to know.   Steve McIntyre clearly inspired my reading, and unfortunately the inspiration came through a wholly skeptical lens.  In time it has turned out that the skeptical perspective of the statistics and  data in paleoclimate were 100% justified.

With data so noisy, yet so full of potential revelations, scientists are also justified in their interest.  As time has passed, I’ve grown to understand that there isn’t really any known solid way to divine the history of climate.  We have enough clues to see past warmth and plenty of clues to show deep past ice ages, yet the trivial level of understanding of past temperature is quite distant from the equivocation-ridden certainty of present day scientific publications.

Ed Cook was no small player in the paleoclimate field.  His own words have a ton of meaning for those who have enough understanding of the pervasive nuance in the field:

  the results of this study will show that we can probably say a fair bit about <100 year extra-tropical NH temperature variability (at least as far as we believe the proxy estimates), but honestly know fuck-all about what the >100 year variability was like with any certainty (i.e. we know with certainty that we know fuck-all).

This statement is an absolute scientific truth to my understanding.   There are multiple sentiments in it which have very solid meaning in interpreting these hockey stick plots.   First, and most interesting for those of us who actually want to know the truth, dendros seem to have discovered a way to see short term climate variation a very long time ago.   Variations on a scale of <100 years are also important because they give us some partial understanding of climate.   Unfortunately, Ed and I disagree as to the certainty of the meaning of even these short term variations.

That known correlation in itself is extremely cool. Skeptics of dendro question the linearity of these fluctuations with respect to temperature, but the short-term fluctuations themselves are highly correlated in local regions.  We can say that whatever was happening in climate to those regions, is measurable, and good plant growth years in one location were good plant growth years.  Not exactly known temperature “climate”, but growth climate is still a very cool thing.

Ed Cook knows the difference between short and long term variations, and after performing tree ring standardizations as I have, you get an understanding of why the long term signals (trends) in dendro hockeysticks are not likely represented by the data.  The math and physics simply don’t allow it.  Long term temperature trends derrived from tree rings, are necessarily quite meaningless.

Paleoclimate is noisy, and little is truly known in my opinion.   Better data is required, and despite the every-month premature conclusions from the experts, we shouldn’t lose site of the fact that once we discover the right proxy (or proxy combination), the math will not be the issue and finally we will know a true piece of our distant climate history.

Whatever we find out, that day when we finally know, will be an interesting day for me.

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