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What is the correct value of Climate Sensitivity?

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You can tell it's a question by the punctuation at the end of the sentence.

:lol: ... hey now! Hey "Euler"... about that promised new thread? (note... this is a question)

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I thought you were making a rhetorical question. Sorry if I misunderstood you. But where does the 1/2 or 1/3 come from? I thought you were alluding to something you read previously.

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I thought you were making a rhetorical question. Sorry if I misunderstood you. But where does the 1/2 or 1/3 come from? I thought you were alluding to something you read previously.

I found the blog that I read the post on. It's for something different. AFAIK, the 2008 numbers are good, it was some change in Nordhaus's methods in 2013 that were criticized. Here's the article that the blog referred to.

http://ageconsearch.umn.edu/bitstream/169952/2/PeterHHoward_AAEA2014_2.pdf

You'll also note it's not peer reviewed. So carry on.

Edited by cybercoma

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You'll also note it's not peer reviewed. So carry on.

I'm not waldo so I don't really care about that. I care about the quality of the work done.

I found the blog that I read the post on. It's for something different. AFAIK, the 2008 numbers are good, it was some change in Nordhaus's methods in 2013 that were criticized. Here's the article that the blog referred to.

I'm on page 11 so far. It seems that it is criticizing Nordhaus 2013 because from what I can tell 2013 is a meta study and apparently there was poor propagation of error or heteroskedasticity wasn't dealt with properly or something along those lines plus it suggests there may be selectional bias. The 2008 paper isn't a meta study and performs a simple Ricardian approach (which I would argue avoids a lot of bias).

Edit: also, the 2008 paper I referred to used the G-Eco estimates, it wasn't the dice paper. So I don't think the results of the pdf you linked to are applicable to the 2008 paper I referred to.

Edited by -1=e^ipi

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I'm not waldo so I don't really care about that. I care about the quality of the work done.

who so down on peer review chum? :lol: By the by, just who is the arbiter of "work quality" for a candidate doctorate submission... for (your) preferred post-modern "Blog Science"? Is that you? You're the arbiter? Oh my!

and, again, where's your promised new thread? You know, to properly position discussion on the economics related to GW/AGW/CC... you know, separate from your ready-reach for your "sensitivity bible" thread!

.

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I've been thinking more about how to estimate ECS from Pleistocene data while accounting for the fact that some of the warming may be due to the change in distribution of radiative forcing, not just change in average radiative forcing (which is an assumption Hansen and others make in order to get their estimates).

One of the big issues is trying to get reasonable estimates to changes in albedo forcing; many of these estimates rely on computer models. However, as mentioned before, there are numerous potential biases with computer models that are difficult to account for and if you need to use a computer model to simulate climate in order to obtain estimates of climate sensitivity, why not just use the computer model to obtain climate sensitivity directly?

Fortunately, there are decent vegetation reconstructions of the last glacial maximum and the holocene maximum that are not climate model based and are based on things like fossilized pollen. This can be used to reconstruct albedo forcing by looking at albedo by biome type.

From there, I can determine mean surface radiative forcing and the standard deviation of radiative forcing (which would involve considering albedo forcing, GHG forcing and milankovitch cycles), and approximate change in temperature as a linear combination of the two, estimate this linear combination, and use that to infer climate sensitivity. Though this would require at least 3 data points to estimate climate sensitivity; but I have last glacial maximum, holocene optimum and pre-industrial conditions. Also, from holocene optimum to pre-industrial, sea level rose while GHG levels fell (anti-correlation), while from LGM to holocene optimum sea level rise and GHG levels are correlated; so these 3 points in time are probably decent enough. Ideally, it would be better if I had far more points in time so that I could do time series analysis, but I don't know of any decent time series vegetation reconstructions for the Pleistocene (and there would be other problems with such a time series analysis, such as as the fact that resolution of sea levels is very poor while resolution of greenhouse gases is very good, and since sea levels and green house gases have a strong correlation, this can cause such a regression to attribute some albedo warming to GHGs and thus overestimate climate sensitivity).

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You don't have to cherry pick to find the data.

It has to go bad to 1950, before the end of the last slowdown, to be able to get a similar rate (and I'm not going to get into the validity of this data set compared to say BEST or Cowtan & Way). And even then, at best it shows that there is ZERO ACCELERATION in warming, which is something that is definitely not expected if warming is entirely due to GHG forcing (which has been increasing roughly quadratically over this period).

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It has to go bad to 1950, before the end of the last slowdown, to be able to get a similar rate (and I'm not going to get into the validity of this data set compared to say BEST or Cowtan & Way). And even then, at best it shows that there is ZERO ACCELERATION in warming, which is something that is definitely not expected if warming is entirely due to GHG forcing (which has been increasing roughly quadratically over this period).

setting aside the validity of your comment, what relevance... what point do you presume to make/hold over suggestion that the rate of warming was less than prior decades? I'm asking that question in the context of your accompanying strawman that speaks to, "if warming is entirely due to GHG forcing"? Entirely?

.

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in any case, the following from a 'Yale Connections' blog entry --- Whither the pause? NOAA report shows no recent slowdown in warming --- New NOAA report challenges long-brewing debate over extent, and in some ways even over actual reality, of global warming slow-down or pause over past 17 years or so

... I trust you recognize the author/scientist as he has a degree of credibility even in the eyes of so-called "lukewarmers" and is, in fact, a part of the Berkeley Earth/BEST team that you appear to hold in highest regard.

the following graphic comparing trends of assorted datasets (including your referenced Best/Berkeley and Cowtan/Way), inclusive of the new NOAA revision (Karl et al 2015):

The new NOAA record really isn’t much different from that of other groups, as shown in the figure above. All have shown substantial warming since 1970, and even the differences after 1998 are relatively small. In all cases, the warming seen isn’t inconsistent with the prior warming trend, even if the short-term trends vary a bit.

0615_Fig_3_552.png

Consider a direct comparison of the trends between 1951 and 1997 and those between 1998 and 2014 during the “pause” period. This approach is quite similar to that taken by Karl and his colleagues in Figure 1 from their paper, but applied to all the major groups estimating global temperatures. While the new NOAA series (Karl et al) is warming noticeably faster in the recent period than it had in the old NOAA series or in the Hadley record, it is actually warming less rapidly than in the Cowtan and Way series and at about the same rate as in the Berkeley Earth series, each of which have shown little or no pause.

0615_Fig_4_552.png

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setting aside the validity of your comment, what relevance... what point do you presume to make/hold over suggestion that the rate of warming was less than prior decades?

1. People that deny the existence of the slowdown annoy me.

2. People were generally overestimating climate sensitivity a decade ago because they were underestimating natural variation and a fair amount of the warming from 1970-1998 was natural. Taking into account the recent slowdown, this suggests that natural variation is more relevant than previously thought, which reduces climate sensitivity estimates.

But that does show a slowdown... warming from 1970-1998 is clearly larger than warming for 1998-2014. The AMO started increasing in 1970, so starting at 1970 makes sense when it comes to the relevance of the AMO in explaining recent temperature changes.

As for graph of global temperature trends, I don't think it makes sense to start at 1951, and I don't think the methodology is appropriate to measure uncertainty (there is clearly autocorrelations; so a linear regression with autocorrelation factor would make more sense and this would reduce the uncertainty bars).

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I'll take Cowtan & Way data for 1970-1998 and 1998-2014, and I'll fit a linear trend with autocorrelation factor.

For 1970-1998 I get a rate of warming of 0.0151 +/- 0.0071 C/year (95% confidence interval).

For 1998-2014 I get a rate of warming of 0.0113 +/- 0.0110 C/year.

The difference is 0.0038 +/- 0.0122 C/year.

I guess the number of data points are too few to demonstrate a slowdown at the 95% confidence level.

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As for graph of global temperature trends, I don't think it makes sense to start at 1951, and I don't think the methodology is appropriate to measure uncertainty (there is clearly autocorrelations; so a linear regression with autocorrelation factor would make more sense and this would reduce the uncertainty bars).

the point made by a rep from the source you consider 'the Best' (pun intended), the point shown within the/his graphic that I supplied is that the trends are similar... notwithstanding, "slowdown proponents" presume to leverage shorter trending intervals - obviously the error bars are greater within the period 1998-2014... simply less data available. You would presume to make statements about sensitivity and the influence of natural variability based on your preferred shorter trending interval..... things that make some go, 'hmmmmmmmm'! Of course, most "slowdown proponents" (not necessarily you included in that mix), know little to nothing of climate sensitivity and the ongoing research studying it... clearly, to them, given continued/accelerated warming, it's no longer the "Pause" that's being trumpeted by these types... for whatever value they presume it adds, it's now become all about the perceived "slowdown".

I'll take Cowtan & Way data for 1970-1998 and 1998-2014, and I'll fit a linear trend with autocorrelation factor.

For 1970-1998 I get a rate of warming of 0.0151 +/- 0.0071 C/year (95% confidence interval).

For 1998-2014 I get a rate of warming of 0.0113 +/- 0.0110 C/year.

The difference is 0.0038 +/- 0.0122 C/year.

I guess the number of data points are too few to demonstrate a slowdown at the 95% confidence level.

indeed!

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Btw, there was a very good response to the Loehle paper which I don't think was mentioned in this thread:

http://www.sciencedirect.com/science/article/pii/S0304380014004876

 

They find Loehle significantly underestimates climate sensitivity and the uncertainty. They get:

TCR 1.292-2.937 C

ECS 2.330-5.338 C

   

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