What is the correct value of Climate Sensitivity?

[eyeball]

But the fact that there is climate change and humans are causing some of it doesn't tell us what the optimal policy response to the issue is. In fact, the scientific method can't tell us what the optimal policy response is because the scientific method is not capable of telling people what to do.

The scientific method definitely suggests what we shouldn't be doing where it indicates our actions are having broad reaching effects that are far from optimal for us and other organisms.

[-1=e^ipi]

The scientific method definitely suggests what we shouldn't be doing where it indicates our actions are having broad reaching effects that are far from optimal for us and other organisms.

No. The scientific method is a methodology that is asymptotically truth approaching and is good for many things, but it doesn't tell people what to do. It doesn't tell me that I shouldn't eat a bunch of poison and kill myself, nor does it tell us what is good or bad.

Edited June 6, 2015 by -1=e^ipi

[eyeball]

Well, whatever it isn't I'll still defer to the conclusions of vast VAST majorities of scientists that are quite certain we need to take action...starting a decade or more ago. Further to that I want policymakers to know they ignore them at their peril.

[TimG]

I'll still defer to the conclusions of vast VAST majorities of scientists that are quite certain we need to take action.

And not one of them is qualified to determine what action should be taken. If the qualified people decide that adaptation is the most cost effective choice then we *have* taken action. What is the problem? Edited June 6, 2015 by TimG

[waldo]

So you admit that an IPCC best estimate no longer exists. Good.

what a stupid statement you make! As I said and detailed, there's a formal IPCC acknowledgement to the most active ongoing research... and differences coming forward. You think you have some "bazinga moment" here? It's science progressing! Duh. I would expect the best estimate value to return when a clearer and consensus understanding comes forward... wouldn't you?

You are mixing up bias of an estimate with uncertainty of an estimate.

no - I'm highlighting you're taking a self-serving, agenda driven position (confirmation bias fueled) to presume that uncertainty only exists in high(er) estimates. Like I said, uncertainty doesn't cut one way only... no matter how hard you state/imply so.

Yes because some people are continuing with their confirmation bias to get biased results. The instrumental data and Pleistocene ice-core data both exclude an ECS greater than 3 C at the 95% confidence level if you properly take into account all the main factors that cause changes in global temperature.

Interestingly, everyone was all fine with energy budget calculations when they were getting median sensitivity estimates of 3.0 C, but now that they are getting estimates about half that with updated aerosol data, suddenly energy budget calculations are no longer good.

clearly you're quite the posturing advocate for using the energy budget model approach... I've already spoken to the critical reviews on recent profiled papers emphasizing that approach and how they improperly take into account ocean heat uptake. Equally you appear to give a complete pass on changing feedbacks... do you really interpret current feedbacks will be the same as those in the future? Do you completely discount a futures possible impact of permafrost, methyl hydrates, etc.?

you appear to improperly equate climate sensitivity to total warming - yes? ... but really, why are you choosing to singularly emphasize and speak to sensitivity... with its projection emphasis and short/long-term feedback attachments, as a reflection on the attribution of the relatively recent past (6 decades of) warming?

no ... Wow, no. ECS is the equilibrium temperature response expected due to a doubling of atmospheric CO2 when only taking into account 'fast' feedbacks (i.e. excluding ice-albedo, ocean-albedo and vegetation-albedo feedbacks; so only including feedbacks with decay times of about 100 years or less). For one, we haven't doubled atmospheric CO2 yet, and secondly 6 decades is no where near enough time to reach the ECS even if we did. That is even a lower timescale than what is used to calculate the transient climate response (TCR), and again we haven't doubled CO2 (we've done about half a doubling), so recent warming due to CO2 is going to be less than half the TCR, which is what is observed.

you say no! Say what... aren't you the guy flogging ECS in a discussion on attribution of the relatively recent (6 decades) of warming? Do you think what you've just written strengthens... or weakens... your want to apparently, singularly, speak to that attribution in terms of sensitivity? The argument to consider including "longer-term feedbacks" in ECS is made in light of the climate effect the melting of continental ice sheets is expected to have... in this century. Since you're flogging sensitivity why not speak to a value that begins to factor in a slow(er) feedback from ice sheets melting...

...The best estimate of the human-induced contribution to warming is similar to the observed warming over this period"... implying that the best estimates of net natural forcings and internal variability are close to zero as summarily represented/supported by the graphic I provided per Figure 10.5 of IPCC AR5 WG1 10.3.

No that doesn't imply that. Read my comments about simultaneously overestimating climate sensitivity, the effect of aerosols and underestimating the AMO to get a set of claims that appears to explain the instrumental data.

no - the implication extends directly from the attribution statement. And again, you revert to directly flogging sensitivity as the/your apparent attribution measure!

I've already expressed my reasons for doubting how Gavin Schmidt interprets Figure 10.5. It only looks at changes in forcings, so doesn't take into account the fact that warming is delayed; it is misleading to just look at forcing changes over a period and expect that the proportion of forcing changes over that period is identical to the proportion of temperature changes caused by the different factors; in particular it would ignore the fact that increase in solar irradiance from 1700-1950 would cause some of the observed warming from 1950 to present. And again, there is the issue over overestimating the effect of aerosols to simultaneously overestimate the effect of greenhouse gases.

yes, your pomposity seems to have no bounds... you the unpublished amateur continually pumping your own tires versus one of the more reputable/recognized and prolific published climate scientists out there! And... you keep repeating this unsubstantiated and unreferenced statement on "delayed solar warming"! I'll ask you again to qualify/quantify a value for your claimed solar forcing component of warming within the 1950-2010 attribution period... 2nd time/request now. As for your aerosol reference, there's no consensus position on aerosols... it continues to be a most active area of ongoing research... a works in progress. Of course, you could step-up and align to my earlier request asking for qualification/quantification of your statements in regards to the attribution period in question... you could presume to play off that uncertain degree of negative aerosol forcing to actually apply it to the attribution and speak to it's countering cooling value. You could do that...

Radiative forcing is power per unit area (example: W/m^2), not temperature (such as Celcius).

duh! Just how anally retentive are you? The temperature provided was the effective result of the forcing.

Again, the recent paper by Bjorn Stevens shows that the lower bound on this estimate of aerosols is too low.

imagine that! You're once again only keying on that lower bound... you're cutting that uncertainty one way and presuming it only applies to upper bounds. You clearly appear to be an early adopter of any single paper that grabs your fancy and suits your agenda! Clearly, you're a real proponent of the "single study syndrome"... really, really, presuming to selectively apply those studies you favour. In any case, this is a fine point of departure that I most certainly will take... it was that very Bjorn Stevens paper that really lit up the denialsphere and right-wing media, big time! Let me take your supplied reference and allow you to speak to the author Steven's own words in an official statement he felt compelled to issue given the mainstream media hype/spin... one where he reserves caution on early interpretation of his results... one where he most pointedly speaks to the impacts and concerns that exist even for the lower sensitivity finding he postulates. Again, per YOUR provided reference:

What's their methodology for determining this? Because it needs to adequately take into account the delay in warming, not just look at changes in forcing.

yawn! Again with your repeated unsubstantiated and unreferenced (in regards to application) statement on "delayed solar impact"... qualification/quantification, hey!

Would you like me to use my results that I got when I tried to estimate a Van Hateren impulse response function from the Instrumental and Holocene Paleoclimate data to try to quantify this for you?

no - you have no personal standing in terms of recognition, reputation, publishing, etc.. If you can't provide a recognized/reliable/accredited source reference to answer my repeated requests for you to provide qualification/quantification of your statements/implications to the effect of natural and internal variability within the related attribution, no problem, I/we can simply acknowledge your unsubstantiated opinions.

Now that I've read more into it, I don't think I should have used HadCRUT4 temperature data because as far as I can tell it doesn't properly deal with the coverage bias, particularly in polar regions. GISS and NOAA data sets also have this issue. So using one of these data sets probably results in an underestimate of climate sensitivity due to polar amplification. The Cowtan & Way (http://www-users.york.ac.uk/~kdc3/papers/coverage2013/series.html) as well as the Berkeley Earth (http://berkeleyearth.org/land-and-ocean-data/) data sets seem to address this issue adequately by using kriging (http://en.wikipedia.org/wiki/Kriging).

imagine that! How does this fit with all your attempts to leverage those references you made to the papers of Nic Lewis... and his attachment to HadCRUT4? There's an interesting blog exchange out there between Robert Way and Nic Lewis... where Way repeatedly challenges Lewis to run his latest papers process/methodology against all datasets, particularly his/Cowtan's and BESTs'. Hasn't happened yet as I'm aware. But yes, in the past I've made several references to the poor station coverage in the more traditional datasets for the areas of the earth warming the greatest (like the Arctic, Antarctic, parts of Africa)... something that has particular association for all those deniers who like to posture over the so-called "pause". This mainstream article speaks quite well to the Cowtan/Way dataset and what more complete station coverage means to the effective observed temperature: Global warming since 1997 more than twice as fast as previously estimated, new study shows (and no... this is not like your "single study syndrome" reliance as Cowtan/Way have responded to challenges to the paper and have issued updates and new papers that speak to their approach/methodology)

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[waldo]

First, climate scientists may have a reason to be concerned because there is a hypothetical problem. The issue is climate scientists have no business lecturing society on how to respond to the hypothetical risk because they have no special qualifications that allow them to understand the economic and social costs associated with reducing CO2 emissions. In many cases, dealing with these competing requirements needs a value based decision which everyone is qualified to have an opinion on.

just you playing your same tired game... as before, the same challenge to you: step-up and give specific examples of climate scientists "lecturing society" along the lines of policy decision making. Scientists presenting scientific based summation (ala something akin to a "Summary for Policymakers") is not your oft claimed scientists "lecturing society on policy". Clearly, your favoured kind of policy decision should come from the likes of "the delayers"... like so-called economist Richard Toll, or poly-sci guy Lomborg!

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Second, the "consensus" is exaggerated by various activists like waldo who want to push what is basically a left wing political agenda under the guise of "saving the planet". This leads them to unreasonably reject options like adaption or nuclear. They claim to care about the science but that is a sham that becomes obvious whenever a solution that is supported by the science (i.e. nuclear or fracking) presents itself but goes against their political prejudices.

no - with the appropriate context and narrowed/proper inclusion of scientists actively working in related fields, the consensus is not exaggerated (to whatever value >90% you presume to whine about! Reject options like adaptation or nuclear? Huh! Just who rejects adaptation? It's clearly a part of what should be a 3-fold approach: prevention, adaptation and mitigation. Your problem is you can't handle any challenge to your skewed "Adapt-R-Us-Only" position... no matter how many times that singular reliance on adaptation might need to be repeated... over and over and over again... if emissions aren't reduced. I've certainly advocated for nuclear in the past... I've flogged the positions/statements put forward by Hansen in that regard as applies to "advanced nuclear". Your pretentious position on fracking is noted once again: hey buddy, natural gas is simply a long-term bridge to nowhere... and I've posted/provided support on that several times in the past!

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Third, the use of the word "denier" is an example of the political nature of climate change activists because they apply to everyone who disagrees with their policy choices no matter what they may think about the science. It is an attempt to de-legitimize opposition and prevent a meaningful debate on the options. Anyone who uses the word "denier" is looking for an excuse to avoid having a political discussion.

blah, blah, blah! Give it a rest already. The term denier is simply a label that attaches to anyone with a degree of denial towards the consensus on GW/AGW/CC... nothing more, nothing less. It's most certainly not a pejorative... it's simply a defining label regardless of how you presume to distract around it.

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[bush_cheney2004]

....Third, the use of the word "denier" is an example of the political nature of climate change activists because they apply to everyone who disagrees with their policy choices no matter what they may think about the science. It is an attempt to de-legitimize opposition and prevent a meaningful debate on the options. Anyone who uses the word "denier" is looking for an excuse to avoid having a political discussion.

True...the verbal warming faithful have tried to influence the very use of the term "denier" in print media via a petition:

...In the long-running political battles over climate change, the fight about what to call the various factions has been going on for a long time. Recently, though, the issue has taken a turn, with a public appeal that has garnered 22,000 signatures and counting.

The petition asks the news media to abandon the most frequently used term for people who question climate science, “skeptics,” and call them “climate deniers” instead.

http://www.nytimes.com/2015/02/17/science/earth/in-climate-change-whats-in-a-name.html?_r=0

[waldo]

True...the verbal warming faithful have tried to influence the very use of the term "denier" in print media via a petition:

...In the long-running political battles over climate change, the fight about what to call the various factions has been going on for a long time. Recently, though, the issue has taken a turn, with a public appeal that has garnered 22,000 signatures and counting.

22K signatures!!! No worries... the petition to deport Bieber got almost 275,000 signatures!

[TimG]

True...the verbal warming faithful have tried to influence the very use of the term "denier" in print media via a petition:

There is no creature more worthy of more contempt than a climate zealot who insists on using the term while claiming it is 'not pejorative'. It is hard to tell if such people are simply too stupid to understand they are spouting nonsense or are deliberately lying because they think they can fool some people.

[waldo]

blah, blah, blah! Give it a rest already. The term denier is simply a label that attaches to anyone with a degree of denial towards the consensus on GW/AGW/CC... nothing more, nothing less. It's most certainly not a pejorative... it's simply a defining label regardless of how you presume to distract around it.

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There is no creature more worthy of more contempt than a climate zealot who insists on using the term while claiming it is 'not pejorative'. It is hard to tell if such people are simply too stupid to understand they are spouting nonsense or are deliberately lying because they think they can fool some people.

good to know I'm not on your IGNORE anymore! Again, denier is simply a label that identifies someone who denies some degree of the consensus on GW/AGW/CC. But hey now... you the guy who repeatedly uses the label zealot (as you've now just done again in this post)... who repeatedly uses the label alarmist. Clearly, you doth protest too much!

[bush_cheney2004]

Climate change "denier" is just the pejorative term and label for a battle that began with the equally stupid "science is settled" meme, which was quickly proven not to be the case as erroneous models crashed and burned compared to real data sets.

[waldo]

Climate change "denier" is just the pejorative term and label for a battle that began with the equally stupid "science is settled" meme, which was quickly proven not to be the case as erroneous models crashed and burned compared to real data sets.

hey, when you can't actually speak to the science... perpetuate memes! Like you're doing with the denier label... like you're actually doing with "science is settled" which, as you state, is clearly a meme - one perpetuated by deniers like you. As I said in an earlier post:

the "science is settled" meme is one regularly trotted out by fake skeptics/deniers. Legitimate skeptics realize that proponents of AGW/CC do not recognize science as ever being settled. However, this 'unsettled science' does not negate confidence levels and probabilities of known/recognized understandings within science, nor does it detract from certain aspects of science that are known with near 100% certainty.

[-1=e^ipi]

I'm highlighting you're taking a self-serving, agenda driven position (confirmation bias fueled) to presume that uncertainty only exists in high(er) estimates.

I made no such claim. Strawman argument.

clearly you're quite the posturing advocate for using the energy budget model approach...

I've never claimed to endorse the energy budget model approach as the best approach to estimating climate sensitivity. Given that in this thread I've mostly done impulse response function approaches, which is a different approach, I have no idea where you get this idea from. Strawman argument.

complete pass on changing feedbacks... do you really interpret current feedbacks will be the same as those in the future? Do you completely discount a futures possible impact of permafrost, methyl hydrates, etc.?

The magnitude of these feedbacks can easily be estimated from Pleistocene ice core data, which I've done in this thread. Of course the Pleistocene estimates will be over estimates since there is more permafrost to melt in the ice ages so the feedback is stronger, but it gives a rough upper bound.

aren't you the guy flogging ECS in a discussion on attribution of the relatively recent (6 decades) of warming? Do you think what you've just written strengthens... or weakens... your want to apparently, singularly, speak to that attribution in terms of sensitivity?

Can't you write sentences like a normal person? I don't understand what you are trying to ask in either of these two questions as they are poorly-worded/ambiguous, so cannot answer them.

The argument to consider including "longer-term feedbacks" in ECS is made in light of the climate effect the melting of continental ice sheets is expected to have... in this century. Since you're flogging sensitivity why not speak to a value that begins to factor in a slow(er) feedback from ice sheets melting...

I didn't invent the definition of ECS, I merely use it. If you are including long-term feedbacks such as the ice-albedo feedback, then you aren't measuring ECS, but Earth System Sensitivity (ESS).

the implication extends directly from the attribution statement. And again, you revert to directly flogging sensitivity as the/your apparent attribution measure!

Have you considered tacking a course in technical writing or something because it could greatly help you. You have a tendency to not write clearly and come up with these undefined buzz words that you repeat over and over again without either defining them or explaining how they are relevant. For example, in this post you are repeating 'flogging' and 'attribution', I don't understand precisely what you are trying to say, and I'm not even sure you do. In scientific papers people try to stick with clearly defined words and write clearly so that the information in their paper is well understood; you seem to do the opposite.

yes, your pomposity seems to have no bounds...

Yet another example of your word choice. This statement brings nothing relevant to the conversation, except provide a character attack and make it less clear. You really like making your language unnecessarily 'flowery' don't you? Writing science isn't the same thing as writing a novel. Learn the difference please.

duh! Just how anally retentive are you? The temperature provided was the effective result of the forcing.

You wrote an incorrect statement about forcing being in Celcius, not me. Maybe if you spent as much time trying to write clear and correct statements rather than try to make your language unnecessarily flowery and unclear, then you wouldn't have made this mistake. And again, the methodology to obtain the temperature changes due to forcing changes was...

You're once again only keying on that lower bound... you're cutting that uncertainty one way and presuming it only applies to upper bounds.

Strawman argument. This isn't my position. And your statement doesn't even make sense. These aerosol estimates will give a confidence interval (95% confidence interval usually), which is where the upper and lower bounds come from. The upper and lower bound express the uncertainty about the effect of aerosols. So talking about the uncertainty of the lower or upper bound of the 95% confidence interval doesn't make sense.

You clearly appear to be an early adopter of any single paper that grabs your fancy and suits your agenda!

Really? What's my agenda? Can you define it for me?

it was that very Bjorn Stevens paper that really lit up the denialsphere and right-wing media, big time! Let me take your supplied reference and allow you to speak to the author Steven's own words in an official statement he felt compelled to issue given the mainstream media hype/spin... one where he reserves caution on early interpretation of his results... one where he most pointedly speaks to the impacts and concerns that exist even for the lower sensitivity finding he postulates.

I'm already aware that some people have misrepresented Bjorn Steven's work (as well as Nic Lewis).

yawn! Again with your repeated unsubstantiated and unreferenced (in regards to application) statement on "delayed solar impact"... qualification/quantification, hey!

What do you want a reference to exactly? That solar irradiance increased from 1700-1950 and has been relatively stable since (as will soon decline), or that it takes time for things to reach equilibrium so there is a delayed temperature response to a change in radiative forcing? If it's the first one, here you go: http://lasp.colorado.edu/lisird/tsi/historical_tsi.html. If it's the second one, there is this thing called heat capacity, you may have heard of it (http://en.wikipedia.org/wiki/Heat_capacity). For example, when you boil water to make tea or coffee, you may have noticed that the water doesn't boil right away, it takes time. The Earth is similar, it takes time. The oceans are really big and take decades to decay towards equilibrium due to a change in forcing (I've provided estimates of the decay time in this thread).

And again with your writing skills. Why all the unnecessary adjectives? Are you trying to discuss science or write a novel? What's with the ending sentences in hey? Is it too much to ask that you try to write clearly and use clearly defined words like most people do in scientific discussions to avoid confusion and to convey meaning more effectively?

How does this fit with all your attempts to leverage those references you made to the papers of Nic Lewis...

Nic Lewis still makes important contributions, even if his methodology or data set results in an underestimate of climate sensitivity.

and his attachment to HadCRUT4? There's an interesting blog exchange out there between Robert Way and Nic Lewis... where Way repeatedly challenges Lewis to run his latest papers process/methodology against all datasets, particularly his/Cowtan's and BESTs'. Hasn't happened yet as I'm aware.

I've read the exchange between Robert Way and Nic Lewis and some of their previous exchanges where Way made the request before. I've read similar arguments by Steven Mosher and Kevin Cowtan. I agree with them that kriging is the best way (or at least better than the methodology of HadCRUT, GISS or NOAA) to deal with coverage bias.

[waldo]

I made no such claim. Strawman argument.

I've never claimed to endorse the energy budget model approach as the best approach to estimating climate sensitivity. Given that in this thread I've mostly done impulse response function approaches, which is a different approach, I have no idea where you get this idea from. Strawman argument.

The magnitude of these feedbacks can easily be estimated from Pleistocene ice core data, which I've done in this thread. Of course the Pleistocene estimates will be over estimates since there is more permafrost to melt in the ice ages so the feedback is stronger, but it gives a rough upper bound.

Can't you write sentences like a normal person? I don't understand what you are trying to ask in either of these two questions as they are poorly-worded/ambiguous, so cannot answer them.

I didn't invent the definition of ECS, I merely use it. If you are including long-term feedbacks such as the ice-albedo feedback, then you aren't measuring ECS, but Earth System Sensitivity (ESS).

Have you considered tacking a course in technical writing or something because it could greatly help you. You have a tendency to not write clearly and come up with these undefined buzz words that you repeat over and over again without either defining them or explaining how they are relevant. For example, in this post you are repeating 'flogging' and 'attribution', I don't understand precisely what you are trying to say, and I'm not even sure you do. In scientific papers people try to stick with clearly defined words and write clearly so that the information in their paper is well understood; you seem to do the opposite.

Yet another example of your word choice. This statement brings nothing relevant to the conversation, except provide a character attack and make it less clear. You really like making your language unnecessarily 'flowery' don't you? Writing science isn't the same thing as writing a novel. Learn the difference please.

You wrote an incorrect statement about forcing being in Celcius, not me. Maybe if you spent as much time trying to write clear and correct statements rather than try to make your language unnecessarily flowery and unclear, then you wouldn't have made this mistake. And again, the methodology to obtain the temperature changes due to forcing changes was...

Strawman argument. This isn't my position. And your statement doesn't even make sense. These aerosol estimates will give a confidence interval (95% confidence interval usually), which is where the upper and lower bounds come from. The upper and lower bound express the uncertainty about the effect of aerosols. So talking about the uncertainty of the lower or upper bound of the 95% confidence interval doesn't make sense.

Really? What's my agenda? Can you define it for me?

I'm already aware that some people have misrepresented Bjorn Steven's work (as well as Nic Lewis).

What do you want a reference to exactly? That solar irradiance increased from 1700-1950 and has been relatively stable since (as will soon decline), or that it takes time for things to reach equilibrium so there is a delayed temperature response to a change in radiative forcing? If it's the first one, here you go: http://lasp.colorado.edu/lisird/tsi/historical_tsi.html. If it's the second one, there is this thing called heat capacity, you may have heard of it (http://en.wikipedia.org/wiki/Heat_capacity). For example, when you boil water to make tea or coffee, you may have noticed that the water doesn't boil right away, it takes time. The Earth is similar, it takes time. The oceans are really big and take decades to decay towards equilibrium due to a change in forcing (I've provided estimates of the decay time in this thread).

And again with your writing skills. Why all the unnecessary adjectives? Are you trying to discuss science or write a novel? What's with the ending sentences in hey? Is it too much to ask that you try to write clearly and use clearly defined words like most people do in scientific discussions to avoid confusion and to convey meaning more effectively?

Nic Lewis still makes important contributions, even if his methodology or data set results in an underestimate of climate sensitivity.

I've read the exchange between Robert Way and Nic Lewis and some of their previous exchanges where Way made the request before. I've read similar arguments by Steven Mosher and Kevin Cowtan. I agree with them that kriging is the best way (or at least better than the methodology of HadCRUT, GISS or NOAA) to deal with coverage bias.

I've provided a response to everything you've written... it's been deleted by the moderator and stated as "off topic/thread jacking... and trolling". I've asked the moderator for clarification, to present examples of same, and to provide an explanation of why I'm supposedly trolling. This is now the second post that's been deleted... the first also identified by the moderator as "off topic/thread jacking"; in that case, that first post was one I subsequently re-posted. That first post is one that you subsequently replied to... at length.

I interpret the moderator is not well versed in the subject matter and that you could provide resolution to that end. In that regard, is the discussion being held between you and I one that is focused on the IPCC attribution statement from AR5, or not? You've stated you don't accept the IPCC position; you've stated that you don't accept the 'best estimate' within that IPCC attribution statement.

I maintain you're rejecting/discounting the IPCC attribution position/statement... particularly as identified (in part) by the Figure 10.5 of the AR5 WG1 report... the graphic that you yourself have re-posted and made comments on. I hold that you're rejecting that IPCC position but you're not countering it with any level of qualified and quantified value attachments that speak to anthropogenic versus natural/internal variability... that speak to the temperature equivalents associated with the identified components within the groupings shown as a part of the summary FIgure 10.5. I also hold that you've taken a pointed shift to directly discuss facets of sensitivity rather than attribution proper and the quantification that would support your rejection.

apparently, should I decide to reply again to you, per my now second deleted post, I will be suspended. It's one thing for you to repeatedly claim strawman... and to raise repeated/multiple objections to "writing style"... it's a completely different thing to have a 3rd-party presume to interpret subject material as being "off-topic", "jacking a thread", "trolling". Again, is this a discussion on the IPCC attribution position/statement that you reject, or not?

Edited June 6, 2015 by waldo

[-1=e^ipi]

you could provide resolution to that end.

I have no control over the moderation policy for this website. There are some threads about people being concerned about recent moderation activity here: http://www.mapleleafweb.com/forums/forum/14-support-and-questions/. You could start a new thread or comment in a pre-existing thread about moderation policy if you want.

For the most part, I'm trying to stay neutral with respect to the issue of implementation of moderation for this site.

You've stated you don't accept the IPCC position

Which position is that? The IPCC has many positions, some of which I agree with, some of which I don't. For example, I agree that we are at least 95% confidence that more than half of warming since 1950 has been anthropogenic and I agree that equilibrium climate sensitivity very likely lies within the IPCC's confidence interval.

you don't accept the 'best estimate' within that IPCC attribution statement.

Because the IPCC doesn't have a best estimate of climate sensitivity anymore.

I hold that you're rejecting that IPCC position but you're not countering it with any level of qualified and quantified value attachments that speak to anthropogenic versus natural/internal variability...

I think that the IPCC is simultaneously overestimating the effect of greenhouse gasses, overestimating the effect of aerosols and underestimating the effect of natural variability, particularly the Atlantic Multidecadal Oscillation, and the Bjorn Stevens paper shows that aerosols are being over estimated in AR5. I also think that you can't just take radiative forcing changes over this period and compute the temperature changes due to each factor over this period since temperature change is a delayed response to a change in radiative forcing. Of course, you haven't provided a link to Gavin Schmidt's methodology, so I can't place much confidence in it (even if I ignore that the IPCC inputs in his calculations are likely biased).

Again, is this a discussion on the IPCC attribution position/statement that you reject, or not?

Discussion of claims made by the IPCC, which are related to climate sensitivity and the magnitude of anthropogenic climate change are on topic. Whether or not your deleted post was on topic or not, I don't know because I cannot read it.

Edited June 6, 2015 by -1=e^ipi

[waldo]

I have no control over the moderation policy for this website.

and you weren't being asked to speak to it, the policy... you were being asked to resolve, from your perspective, whether the topic of attribution was "off topic, thread jacking and trolling".

Which position is that? The IPCC has many positions, some of which I agree with, some of which I don't. For example, I agree that we are at least 95% confidence that more than half of warming since 1950 has been anthropogenic and I agree that equilibrium climate sensitivity very likely lies within the IPCC's confidence interval.

sigh! The attribution position! It wasn't I that brought it up... that was member Keepitsimple who referenced it (indirectly)... to which you chimed in with your claim that "alarmists are spinning it". I provided the complete formal IPCC statement that member Keepitsimple was referring to... and you chose to isolate only on a portion of that statement... stating you agreed with it. When I pressed you on the fact you purposely re-quoted only a segment of that statement, you ultimately addressed it, the full statement, stating that the the missing sentence you disagreed with was "meaningless"... whereupon you went into a lengthy diatribe on sensitivity, never actually addressing attribution studies and that related IPCC statement directly (and its associated Figure 10.5 put forward).

in terms of supporting your stated "meaningless" assessment of that most pertinent part of the IPCC attribution statement, the one you stated as being "alarmist spun", you have yet to, in spite of my repeated challenges to you, put forward any manner of countering qualified/quantified value measure to speak to attribution temperature equivalencies within that 1950-2010 period. The closest you got was to repeat many times over your unsubstantiated statements on "delayed solar" impacting on that 1950-2011 attribution period... to which, again, you've never offered a quantified Natural forcings temperature value equivalence for that claimed delay you're repeatedly making. Oh wait... you've also drawn attention to a single paper that presumes to suggest a lower sensitivity value based on a less cooling factor for aerosols... to which I emphasized 'single study syndrome' and put forward a formal statement from the author of that paper cautioning on over-reliance on his single paper findings, misinterpretation of his paper and on his views towards risk/impact even for the lower sensitivity value he postuates; something you didn't/wouldn't touch! But again, you never applied and translated that single paper's suggestion on a reduced aerosol cooling effect towards an impact on that IPCC attribution statement/position and its 'best estimate' on the amount of warming associated with anthropogenic sources.

effectively all you've done is provide your "stated meaningless and alarmist spun" assessments on that formal complete IPCC attribution statement.. your unsupported and unsubstantiated personal opinion. Within that attribution, you've provided no countering qualified detail on the temperature equivalencies you presume to attach to Internal Variability, Natural Forces... and Anthropogenic.

you've stated that you don't accept the 'best estimate' within that IPCC attribution statement.

Because the IPCC doesn't have a best estimate of climate sensitivity anymore.

bloody hell! Those are 2 completely separate IPCC positions with their own related statements. When I speak to the best estimate within that IPCC attribution statement (what you stated was meaningless, what you labeled as "alarmist spin"), WHY DO YOU choose to speak to a best estimate within sensitivity?

I think that the IPCC is simultaneously overestimating the effect of greenhouse gasses, overestimating the effect of aerosols and underestimating the effect of natural variability, particularly the Atlantic Multidecadal Oscillation, and the Bjorn Stevens paper shows that aerosols are being over estimated in AR5. [waldo: again, your reliance on 'single paper syndrome'. As I said, there is no consensus position on aerosols and it remains one of the most active areas of research] I also think that you can't just take radiative forcing changes over this period and compute the temperature changes due to each factor over this period since temperature change is a delayed response to a change in radiative forcing. [waldo: you can "think" what you want... your opinion is noted. Until you provide qualified support that includes quantified temperature equivalencies within the related attribution period, you've done nothing but express your personal opinion]

Discussion of claims made by the IPCC, which are related to climate sensitivity and the magnitude of anthropogenic climate change are on topic. Whether or not your deleted post was on topic or not, I don't know because I cannot read it. [waldo: "the magnitude of anthropogenic climate change"... you mean like, wait for it, wait for it... attribution for the related warming over the last 6 decades, whether anthropogenic, natural or internal variability? Like that? In that regard I trust the moderator will recognize his failure in properly assessing what's on topic, what's thread jacking and what's trolling]

[-1=e^ipi]

I provided the complete formal IPCC statement that member Keepitsimple was referring to... and you chose to isolate only on a portion of that statement... stating you agreed with it. When I pressed you on the fact you purposely re-quoted only a segment of that statement, you ultimately addressed it, the full statement, stating that the the missing sentence you disagreed with was "meaningless"... whereupon you went into a lengthy diatribe on sensitivity, never actually addressing attribution studies and that related IPCC statement directly (and its associated Figure 10.5 put forward).

Nothing within the IPCC's AR5 supports the claim of being at least 95% certain that 'nearly all' of observed warming since 1950 is due to human emissions (at least under any reasonable definition of 'nearly all'). Even Gavin Schmidt's calculations show that 'nearly all' does not have 95% certainty.

in terms of supporting your stated "meaningless" assessment of that most pertinent part of the IPCC attribution statement, the one you stated as being "alarmist spun", you have yet to, in spite of my repeated challenges to you, put forward any manner of countering qualified/quantified value measure to speak to attribution temperature equivalencies within that 1950-2010 period.

You've already done that for me. Look at the probability distribution of the percentage of observed warming since 1950 that is due to humans that was determined by Gavin Schmidt. Does it show 95% certainty that 'nearly all' warming is due to humans under any reasonable definition of 'nearly all'? No.

Maybe you don't understand the difference between 'nearly all' and 'more than half'. So perhaps I should give you an example of the difference in a different context. In the recent Scottish Referendum on independence, more than half of the voting population voted No (I think it was 55%), but it would be untrue to say that nearly all of the population voted No.

The closest you got was to repeat many times over your unsubstantiated statements on "delayed solar" impacting on that 1950-2011 attribution period.

Unsubstantiated? It was empirically observed that solar irradiance was increasing since the Maunder Minimum to 1950. It is also known that the Earth has a heat capacity and that the time scale of decay to equilibrium due to the oceans is on the order of decades. The only thing left to do is use logic and put the two together, something you might be incapable of.

to which, again, you've never offered a quantified Natural forcings temperature value

Yes, I haven't quantified this value. Did I make a claim that I did?

to which I emphasized 'single study syndrome'

I've provided references to many papers in this thread, and others have brought up new information as well, but keep pretending I have 'single study syndrome' or whatever if you want.

put forward a formal statement from the author of that paper cautioning on over-reliance on his single paper findings, misinterpretation of his paper and on his views towards risk/impact even for the lower sensitivity value he postuates

You seem obsessed with conclusions of papers rather than the actual data or scientific models. Emphasizing skepticism and doubt about the implications of a paper as Bjorn Stevens did is normal in science. However, Bjorn Stevens' statement doesn't somehow nullify the implications of his paper, regardless of how much you misinterpret it.

But again, you never applied and translated that single paper's suggestion on a reduced aerosol cooling effect towards an impact on that IPCC attribution statement/position and its 'best estimate' on the amount of warming associated with anthropogenic sources.

Bjorn Stevens' paper came out this year, well after AR5. How is it supposed to affect a statement made by the IPCC? It can't, you have to wait for AR6. There is this thing called causality in the universe (http://en.wikipedia.org/wiki/Causality), which as far as I am aware hasn't been violated yet (though maybe with some black holes and mass of negative energy density it might be possible).

Within that attribution, you've provided no countering qualified detail on the temperature equivalencies you presume to attach to Internal Variability, Natural Forces... and Anthropogenic.

What do you mean by 'qualified detail'? You mean quantify the temperature change due to each factor?

Those are 2 completely separate IPCC positions with their own related statements. When I speak to the best estimate within that IPCC attribution statement (what you stated was meaningless, what you labeled as "alarmist spin"), WHY DO YOU choose to speak to a best estimate within sensitivity?

Because you are unclear and choose to make confusing statements or statements with incorrect premises. Gavin Schmidt's blog != IPCC. AR5 doesn't provide a best estimate of climate sensitivity, nor does it provide a best estimate for the percentage of warming since 1950 due to human activity. This IPCC best estimate you keep referring to does not exist.

[-1=e^ipi]

Michael Hardner was wondering about the economic impacts of climate change. While looking at gridded economic data I stumbled upon this:

http://www.econ.yale.edu/~nordhaus/homepage/gridded_data_ia.pdf

It suggests that with 3 degrees of warming relative to today, the decline in global economic output is ~0.34% of GDP (95% confidence interval under the model is 0.28% to 0.40%; of course the model is relatively crude so there is probably lots of specification error as well).

Edited July 7, 2015 by -1=e^ipi

[-1=e^ipi]

Given that developing countries are going to economically catch up to developed countries, it would probably make more sense to look at the population weighted loss in income (which is 1.44% in the paper I mentioned in my last post). This would also be consistent with using a logarithmic social welfare function (I explained some of the justification for this here: http://www.mapleleafweb.com/forums/topic/24624-so-what-would-an-ndp-government-do/?p=1065976).

Now climate impacts on economic well-being are a roughly quadratic function of temperature change. Unfortunately, the Yale study only looks at economic impacts for 3 C change relative to today (I would need at least 1 more data point to estimate the quadratic impact function).

Tol 2002 (http://aida.econ.yale.edu/~nordhaus/homepage/documents/Tol_impacts_JEP_2009.pdf) does estimate this impact function by looking at various estimates in the literature. He gets 2.46*T - 1.11*T^2 as his best estimate (where T is temperature change relative to today in celcius and this gives the % change in GDP). This suggests that the first 1.1 C of warming relative to current temperatures has a positive economic impact, after which the impact becomes negative. If I rescale this impact function to agree with the 1.44% result of the yale paper, I get 1.357*T - 0.612*T^2.

Another thing I found was the SSP database (https://secure.iiasa.ac.at/web-apps/ene/SspDb/dsd?Action=htmlpage&page=about). It gives the economic cost of various RCP scenarios. If I look at the SSP2 results (which has the most reasonable projection of future population) then it is clear that greater mitigation has a larger cost. In particular, by 2100 one has:

RCP GDP per capita (2005 US $) Temperature Change relative to 2005 in Celcius
2.6 57693 0.812
3.4 58645 1.263

4.5 59094 1.694
6.0 59469 2.249

8.0 59721 3.014

This suggests that the mitigation cost is roughly 0.806*(T-3.014)^2 percent of GDP, where T is the temperature change relative to 2005 and this result was obtained using a simple least squares regression of the data above.

So if one wants to estimate economic well-being, one wants to look at benefits minus costs. As a simplistic approximation, let's compare the rough costs of mitigation implied by the SSP Database with the rough benefits implied by the Yale paper.

One wants to find T that maximizes net benefit: 1.357*T - 0.612*T^2 - 0.806*(T-3.014)^2
=> 0 = 1.357 - 1.224*T - 1.612*T 1.612*3.014
=> T = 2.1927

One thing that I want to mention is that the results of the SSP database are based on ECS being roughly 3.2 C (this is the CMIP5 median). However, recent evidence is that ECS is roughly 2C. If warming is roughly 2/3 what is suggested by the RCP database then mitigation cost is roughly 0.537*(T-2.009)^2 percent of GDP, which suggests that optimal T is 1.5308.

Both results are roughly what occurs under RCP 6.0 (gives T = 2.249 under ECS of 3, or T = 1.499 if climate sensitivity is roughly 2/3 what is assumed in the SSP Database). So this suggests that it makes sense to follow an emission pathway of roughly RCP 6.0. So some mitigation makes sense, but not an absurdly high amount.

According to the SSP Database, the average level of carbon dioxide emission tax from 2020-2100 to achieve RCP 6.0 is $22.39 (US 2005 dollars) per ton of emission. By comparison, the Social Cost of Carbon according to the white house in 2015 is $37. If I use the gdp deflator implied by the central bank of St. Louis (https://research.stlouisfed.org/fred2/series/GDPDEF/), then $37 in 2015 dollars is worth $30.96 in 2005 dollars.

Edited July 7, 2015 by -1=e^ipi

[Michael Hardner]

Michael Hardner was wondering about the economic impacts of climate change. While looking at gridded economic data I stumbled upon this:

http://www.econ.yale.edu/~nordhaus/homepage/gridded_data_ia.pdf

It suggests that with 3 degrees of warming relative to today, the decline in global economic output is ~0.34% of GDP (95% confidence interval under the model is 0.28% to 0.40%; of course the model is relatively crude so there is probably lots of specification error as well).

Solid source, strong number. Anybody have a counter-example ? I am looking forward to reading this later.

[waldo]

Solid source, strong number. Anybody have a counter-example ? I am looking forward to reading this later.

this has little place within "the sensitivity bible thread"! Imagine it being resurrected again! It's being referred to as the "Yale paper"... that's not where it was initially published... notwithstanding it's most dated in terms of the iteration of DICE... notwithstanding the paper itself is based upon the most dated IPCC TAR (as in 3rd iteration) multi-model results... notwithstanding a regional versus global focus. Clearly, your reply is to a not well-thought out post and continued extensions of it!

[Michael Hardner]

Clearly, your reply is to a not well-thought out post and continued extensions of it!

Ok, the basis of my response is above. I think that the post should probably be in a separate thread, though, so we can look at that.

Euler, do you mind starting one on the Economic impacts, assuming we don't already have one ?

[cybercoma]

this has little place within "the sensitivity bible thread"! Imagine it being resurrected again! It's being referred to as the "Yale paper"... that's not where it was initially published... notwithstanding it's most dated in terms of the iteration of DICE... notwithstanding the paper itself is based upon the most dated IPCC TAR (as in 3rd iteration) multi-model results... notwithstanding a regional versus global focus. Clearly, your reply is to a not well-thought out post and continued extensions of it!

What were the most recent estimates saying? That Nordhaus's numbers were off by 1/2 to 1/3?

[-1=e^ipi]

notwithstanding the paper itself is based upon the most dated IPCC TAR (as in 3rd iteration) multi-model results...

I have many criticisms of the paper, but this isn't really one of them. The general features in terms of the distribution of warming are still present, and we know the mean temperature change. The range of climate sensitivity hasn't really changed much over the past 20 years (1.5 - 4.5 C), although significant progress has been made recently so expect AR6 to constrain the range. I see no reason to expect that the results are biased due to using outdated models.

The paper does a Richardson approach, which has 2 main advantages: it is relatively simple, so is easier for people to understand and it looks at the overall change in output so doesn't have any bias due to overly focusing on either the costs or benefits and takes into account substitution effects.

Euler, do you mind starting one on the Economic impacts, assuming we don't already have one ?

Sure, I can start one.

Also, you might want to read this first:

http://gecon.yale.edu/sites/default/files/gecon_data_20051206.pdf

It discusses the methodology in obtaining some of the data used in the 2008 paper.

What were the most recent estimates saying? That Nordhaus's numbers were off by 1/2 to 1/3?

Could you please support this claim with a source?

[cybercoma]

Could you please support this claim with a source?

I didn't make a claim. I asked a question. You can tell it's a question by the punctuation at the end of the sentence.