2011-10-08 15:17:50Pielke Sr. and SkS Warming Estimates
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Response to Pielke's incorrect claim that CO2 is only 26-28% of the net positive radiative forcing.

Pielke Sr. and SkS Warming Estimates

2011-10-08 18:21:40
Tom Curtis

t.r.curtis@gmail...
112.213.174.221

Very good.  It covers all bases, and is succinct and (mostly) easy to read.

 

Nitpicks:

Where you say

"We again note that this fraction will likely only continue to increase along with continually increasing human CO2 emissions."

It would read better if you eliminated "likely only".

 

It may be worthwhile adding a footnote to the section  on ozone explaining that Pielke only states a value of 0.3 for ozone, which is insufficient for his stated conclusions, but that he cites a significant forcing from ozone which he does not directly quantify.

2011-10-08 21:13:42
Riccardo

riccardoreitano@tiscali...
188.152.84.226

Good, clear and simple. Maybe we could leave the final question out, it sounds a bit provocative.

2011-10-08 22:25:14
nealjking

nealjking@gmail...
91.33.103.209

"Below we discuss some problems SkS has identified in Dr. Pielke's estimate, and provide a detailed up-to-date estimate of these values.  The main underlying problem is that Dr. Pielke is relying on an estimate he made in 2006, and thus his references are at least 5 years out of date.  Additionally, he appears to have made some mathematical errors in his calculations."

=>

"Below we discuss some problems SkS has identified in Dr. Pielke's estimate, and provide a detailed up-to-date estimate of these values.  The main underlying problem is that Dr. Pielke is relying on an estimate he made in 2006, ignoring [RELEVANT EVIDENCE OVER THE LAST 6 YEARS], and thus his references are at least 5 years out of date.  Additionally, he appears to have made some mathematical errors in his calculations."

Something like that.

2011-10-08 23:33:33
Kevin C

cowtan@ysbl.york.ac...
144.32.196.109

That's a good attack on a thorny topic. Given the difficulty of justifying any number, I think it's good that this article mainly focusses on repeating Pielke's methodology and then fixing the errors, rather than trying to justify the estimate as meaningful.

In addition to Neal's correction, I would change 'and thus his references are at least 5 years out of date' to 'and thus his sources are at least 5 years out of date'. My impression is that the normal usage is that 'references' are the referring text snippets rather than the referred to papers, although informal usage is vague enough that either could be right.

This paragraph on albedo could be clearer:

However, there are a number of problems with this estimate.  Most importantly, the data in question only covers a period of 4 years.  We cannot compare a 4-year radiative forcing with radiative forcing estimates for the pre-industrial to Present timeframe.  It's apples and oranges; one is short-term, the other is long-term.

I'm not quite sure what it is trying to say. Does the CERES data say that albedo has increased by 0.5W/m2 over a 4 year period? If we were to project that back, that would be 15W/m2 since 1880. Clearly that makes no sense. Not sure how to best handle it. How about:

However, there are a number of problems with this estimate.  Most importantly, the data in question only covers a period of 4 years. Changes in albedo over the past 4 years tell us little or nothing about changes in albedo over the past century.

2011-10-08 23:35:20
Kevin C

cowtan@ysbl.york.ac...
144.32.196.109

Not sure if you've got the whole Padilla paper or just the abstract. The PDF is here: http://www.princeton.edu/~gkv/papers/Padilla_etal11.pdf

2011-10-09 02:41:55
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Not suggesting that we delve into this, but FWIW, from another thread:

 

"Hi all,

Just did a quick search on "glaciation indirect effect".  They do discuss it in AR4 (positive forcing, understanding "very low"), see also here and here.

This key paper by Lohmann et al. (2007) was, I think, not available in time to be inlcuded in AR4.  It is a great overview of the science.  Some kere paragraphs, some of which contradict Pielke's claims:

  http://www.atmos-chem-phys.net/5/715/2005/acp-5-715-2005.pdf [Lohmann and Feichter, 2005]

"The indirect aerosol effects are larger than estimates of the direct and semi-direct
effect. In a model intercomparison of nine different global models, the ensemble model
10 average direct aerosol effect under all-sky conditions amounted to –0.22Wm−2 in the
annual global mean, ranging from +0.04 to –0.41Wm−2 (Schulz et al., 2006). The
semi-direct effect refers to temperature changes due to absorbing aerosols that can
cause evaporation of cloud droplets, as was shown in a large eddy model simulation
study that used black carbon concentrations measured during the Indian Ocean Exper15
iment (Ackerman et al., 2000). It ranges from 0.1 to –0.5Wm−2 in global simulations
(Lohmann and Feichter, 2005)."

Pielke claimed +0.1 W m-2, and he did not indicate that it could be positive or negative, and in fact is more likely negative than positive.  But this stuff is uncertain, so to be boldy claim it is +0.1 W m-2, unless some other evidence is out there that I am not aware of is misleading on his part.

Bck to Lohmann et al. (2007):

"The glaciation effect refers to an increase in ice nuclei that results in a more frequent glaciation
of supercooled stratiform clouds and increases the amount of precipitation via the ice
phase. This decreases the global mean cloud cover and allows more solar radiation to
25 be absorbed in the atmosphere. Whether or not the glaciation effect can partly offset
the warm indirect aerosol effect depends on the competition between the ice nucleating
abilities of the natural and anthropogenic freezing nuclei (Lohmann and Diehl, 2006)."

So the glaciation effect is probably positive, but they do not say how much, and it may not be sufficient to offset the cooling from the semi-indirect effect. Lohmann and Feichter (2005) have a question mark for the magnitude of the forcing.  But he says between the two of them they account for a positive forcing of +0.2 W m-2, whereas it is in all likelihood a wash.  He could try and claim +0.1 for the glaciation effect, but the +0.1 for the semi-direct effect does not seem justified from what I can see.  This is not my forte though.  Bart Verheggen may be a good person to consult on this.

There is this paper by Perlwitz and Mller (2010) which suggests:

"Despite the high complexity and nonlinearity of the microphysical interaction between aerosols and clouds, modeling studies generally indicate that the net effect of this interaction is to reflect more radiation back to outer space [Forster et al., 2007], although recent results show that aerosols acting as ice nuclei could counteract the cooling effect significantly [Storelvmo et al., 2008]. A few observational studies seem to confirm a relation between soil dust aerosols and cloud cover."

So it is far from clear cut."

2011-10-09 02:42:46
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Dana,

This is great!  I do have some comments, but it might be difficult for me to find some time to post them.  What is the timeline for this post?

2011-10-09 03:06:44
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Good comments guys, thanks.  Kevin - the albedo section was needling at the back of my mind all night.  I definitely need to clarify it.

Alby - thanks, no specific timeline.  Monday might be a good day to post this, since Pielke apparently will have some new questions for us at that point.  I'll add a bit on that glaciation effect, but not too much detail.

2011-10-09 03:11:46
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Hi Dana,

OK great.  Yeah, don't get bogged down in aerosols it is an eveolving field and the values in question here are not high.

Something seems odd with Pielke's corrected column-- if we are correcting him, shouldn't we also correct his value of CH4 and double counting of O3 and his SW alebdo effect?  It then is essentrially the same as TAR with exception of the 0.2 for indirect aerosol effects...

More at some point, my girls need me.....

2011-10-09 03:44:39Pielke corrected
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Yeah I had to think about what to include in that column.  Like you say, if I corrected everything, it would be almost the same as the TAR.  I thought it would be more useful to just include the math corrections (double counting and rounding), since the other columns essentially correct his wrong values for methane, ozone, etc.

I could change the column heading to "Pielke's math corrected" or something like that if it would help.

2011-10-09 04:38:45revised
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Okay, text revised to incorporate the comments above, plus a beefing-up of the albedo section (that one really kicks Pielke's ass now), plus I added a bit on the aerosol glaciation effect.  Which was really confusing - there's direct and indirect and semi-direct effects, bah!  I also updated the table so the second column is now called "Pielke Math Corrected".

2011-10-09 07:34:40
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Hi Dana,

I will write more about this later tonight, I see some problems that need addressing.

2011-10-09 11:18:45
Tom Curtis

t.r.curtis@gmail...
112.213.174.221

With regard to the albedo section, the changes in albedo represent  an approx -1 W/m^2  change to the Earth's radiative balance, which is about the radiative imbalance as calculated by Trenberth et al, 2008.  We can expect some of our resident deniers to pick up on this and argue climate sensitivity is low.  It would be appropriate to take some of the steam out of this by arguing that an increase in albedo due to an increase in clouds would have been accompanied by an increase in the GH effect due to that increase in clouds.  That means the net effect is even more uncertain than is indicated by the albedo data alone, and may (probably is based on other studies), be opposite in sign to that indicated by the albedo only studies.

 

Further, if the albedo change is anthropogenic, then it is a feedback, or at least most of it is.  If it is not a feedback, then it is not anthropogenic.  So, either Pielke should not have included it as anthropogenic, or he should not have included it in the calculation at all (because it is not a forcing).  You mention the fact that the albedo change may be a feedback, but do not expand on the logical implications.

It should probably be noted somewhere for the pedants that "radiative forcing" is used instead of the more correct "change in radiative forcing" (or cognates) for simplicity of language.

2011-10-09 13:57:22
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Good points Tom, changes made.  Except for the cognates.  They can suck it if they're going to be that nitpicky ;-)

2011-10-09 16:23:24
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Hi all,

Bunch of comments to follow.  I'm playing devil's advocate here Dana and being nit picky...

"Below we discuss some problems SkS has identified in Dr. Pielke's estimate"


I'd say "..we discuss several problems...".

Before I forget, some words of wisdom from Isaac Held when conversing with Pielke that is relevant here.

"I think it is very generally recognized that, for the same global mean forcing, aerosols perturb the mean precipitation field more than do the well-mixed greenhouse gases (WMGGs). So if, up to the present, anthropogenic aerosols and WMGGs have had comparable effects on regional precipitation, say, the WMGG effect will undoubtedly grow and will be essentially irreversible on the time scale of several centuries, in the absence of geoengineering, while the aerosol effect will likely be bounded by its current magnitude, and the WMGGs will dominate."

2011-10-09 16:45:32
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Albedo

Some suggestions here. 

 

1) I still think that the following comments  are relevant and will really hammer home our point:

i) Fours years is simply too short a time frame.From Loeb et al. (2007a, J. Climate):

"Commonly used statistical tools applied to the CERES Terra data reveal that in order to detect a statistically significant trend of magnitude 0.3 W m−2 decade−1 in global SW TOA flux, approximately 10 to 15 yr of data are needed. "

 

ii) Also, subsequent research does not support the clim of a significant decline in albedo. From Loeb et al. (2007b, GRL):

"In contrast, the global CERES observations show a small decrease of 2 Wm-2 in shortwave reflected flux between 2000 and 2004 [Wielicki et al., 2005]. More recently, Loeb et al. [2007] used a revised version of the CERES data to show that no statistically significant changes in the Earth’s albedo have occurred between 2000 and 2005.

 

2) Caveat about EarthShine data:

I am a little nervous about using the EarthShine data, and would not enourage people hanging their hat on it, because they have issues and are not as accurate as other measures.   in Loeb et al. (2007b) highlight the problems:

"The ground-based Earthshine data show an order-ofmagnitude more variability in annual mean SW TOA flux
than either CERES or ISCCP, while ISCCP and CERES SW TOA flux variability is consistent to 40%. Most of the
variability in CERES TOA flux is shown to be dominated by variations global cloud fraction, as observed using
coincident CERES and MODIS data. Idealized Earthshine simulations of TOA SW radiation variability for a
lunar-based observer show far less variability than the ground-based Earthshine observations, but are still a factor
of 4–5 times more variable than global CERES SW TOA flux results. Furthermore, while CERES global albedos
exhibit a well-defined seasonal cycle each year, the seasonal cycle in the lunar Earthshine reflectance simulations is highly variable and out-of-phase from one year to the next."

Also, the figure you show, shows a slight decrease in the albedo from the CERES data.  It is moot, but he might say  "Hey, see the trend in CERES data is slightly negative". 

 

3) "However, we should also note that an albedo increase due to increasing cloudcover would also be accompanied by an increased greenhouse effect, making the net effect on the climate even more uncertain."

This sentence makes me nervous-- if you have a reference, then great.  Otherwise, I do not think that we need it, it might just give him something to nit pick or argue about.

 

4) "Ultimately, for this calculation, Dr. Pielke's 0.5 W/m2 albedo forcing estimate is unjustified."

I would go further "...is unjustified and not supported by more recent observations and scientific literature"

2011-10-09 17:17:07
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Tropospheric Ozone

1) "Thus Dr. Pielke's estimate of 0.65 W/m2 appears too high."

I would maybe add that "....is in all likelihood much too high". 

 It is almost double the value supported by the literature! 

 

Aerosol Glaciation Indirect Effect [needs to change]

We have to tread very carefully here.  I have been reading the papers very quickly and it is not my field of expertise-- so am not confident that we have a good handle on this.  The literature is also confusing and it appears that the sign of the forcing depends on the type of aerosol (e.g., sulfate versus black carbon).

1) He actually mentions two effects, and the subsection title should reflect that (I would also suggest making the row headers in the Table more explicit as simply stating "glaciation" or "aersols"); as it is not clear right now and how we ended up chasing our tails in the fist place, so let us not repeat his poor communicaton skills):

i) The semi-direct effect, which he says is a positive forcing.

ii) The glaciation effect in mixed-phase clouds which he says is positive.

Re the semidirect effect, from AR4:

"The TAR did not include any assessment of the semi-direct effect (e.g., Hansen et al., 1997; Ackerman et al., 2000a; Jacobson, 2002; Menon et al., 2003; Cook and Highwood, 2004; Johnson et al., 2004), which is the mechanism by which absorption of shortwave radiation by tropospheric aerosols leads to heating of the troposphere that in turn changes the relative humidity and the stability of the troposphere and thereby influences cloud formation and lifetime. In this report, the semi-direct effect is not strictly considered an RF because of modifications to the hydrological cycle"

Now this is confusing b/c Lohmann et al state that:

"The semi-direct effect refers to temperature changes due to absorbing aerosols that can cause evaporation of cloud droplets, as was shown in a large eddy model simulation study that used black carbon concentrations measured during the Indian Ocean Exper15iment (Ackerman et al., 2000). It ranges from 0.1 to –0.5Wm-2 in global simulations
(Lohmann and Feichter, 2005)."

So they claim it is most likely a negative forcing or cooling feedback. But the important part is the last sentence form that AR4 quote:

"In this report, the semi-direct effect is not strictly considered an RF because of modifications to the hydrological cycle".

NB: Also in AR4 they say that the semidirect effect can be positive of negative and is likley of "small" magnitude.  They say the glaciation efect is "positive" with a "medium" magnitide.  Interestingly Pielke has them of the same magnitude.  So consider mentioning that.

 

2) "Lohmann et al. (2007) note that the aerosol indirect glaciation effect is negligible. Perlwitz and Mller (2010) conclude"

Yes, so Perlwitz and Miller (not Mller) (well actually [Storelvmo et al., 2008]) seem to contradict Lohmann et al. (2008).  But that you are indicating that is not clear right now.

 

3) I would conclude with:

"In short, the magnitude and roles of the semi-direct and glaciation effects in terms of radiaive frocing remain far from clear.

Or something along those lines.

 

An aside-- this sentence really confuses me:

"Whether or not the glaciation effect can partly offset the warm indirect aerosol effect depends on the competition between the ice nucleating abilities of the natural and anthropogenic freezing nuclei (Lohmann and Diehl, 2006)."

How can a positive forcing offset the "warm indirect aerosol effect"?!

2011-10-09 17:31:33
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Carbon Dioxide

1) "Dr. Pielke's estimate for the CO2 radiative forcing is also outdated, originating from the IPCC TAR (1.46 W/m2), but either rounding it down or eyeballing the radiative forcing graphic in order to estimate it at 1.4 W/m2."

This sentence needs some tweaking.  How about:

"Dr. Pielke's estimate for the CO2 radiative forcing is both outdated and not consistent with the value in the IPCC TAR (1.46 W/m2); it appears that he either rounding down or eyeballed the radiative forcing graphic in order to estimate the CO2 radiative forcing at 1.4 W/m2."

 

2) "...but the CO2 forcing has changed as a result of rapidly increasing CO2 emissions and atmospheric concentrations."

I would not harp on this t oo much.  He'll probably say "Yeah but deapite the CO2 forcing increasing so much 0-700 m OHC has not increased so the models are useless and EQS is low".  So consider deleting that part.

 

3)  "This rapidly increasing radiative forcing is..."

Same here.  Maybe use Isaac Held's line of reasoning that I quoted above here.  And maybe start with "This sustained increase in radiative frocing from lon-lived GHGs is the reason why..."

 

Estimated CO2 Contribution

1) "The second column corrects Dr. Pielke's estimates by eliminating the double counting of methane, and correcting rounding errors for the CO2 and solar forcings."

I would suggesting inlcude the correct value for CH4 as well so as to be consistent with the AR4 report that he is citing.  That brings the relative contribution of radiative forcing from CO2 value up to 31.7% for total, and for anthro only to 34%.  Change text below table accordingly.

And again, I would suggest using more explicit titles for some of the row headers and is it possible to ahve a nicer looking table?  Nit picky I know, but a HQ table would be nice :)

2011-10-09 17:37:28
Tom Curtis

t.r.curtis@gmail...
112.213.174.221

Albatross @4:45 PM, (3), I think it is straightforward that in addition to reflecting SW radiation, clouds absorb and re-emit LW radiation from the surface.  As the cloud tops are cooler than the surface, that means they introduce a greenhouse effect.  If Pielke wants to make a fool of himself by challenging that, let him.  What we do not know, but do not claim to know is the relative strength of this effect. 

2011-10-09 17:55:57
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Human Contribution to Global Surface Warming

1) "we return to our original question to Dr. Pielke on this subject"

Would it be too snarky to point out that he has avoided answering this question?  To use Neal's chess analogy, this is a key piece on the table and our queen is threatening one of his key pieces, so he wants us and onlookers to ignore it by hand waiving and shouting "Squirrel!".  Let us not please not ignore the elephant in the room.

2) "Using the Skeie et al. 2011 CO2 forcing best estimate of 1.82 W/m2,"

Replace with:

"Using the Skeie et al. (2011) CO2 forcing best estimate of 1.82 W/m2 for 2010,..."

3) "his corresponds to a CO2 contribution of 0.64 to 1.28°C, with a best estimate of 0.79°C warming of average global surface temperature."

It is not clear to me what you did here.  I think you explained it better in the thread.  Clarity is always better than brevity and confusion.  And ac ontribution of X C to what? Isn't it better to say "....potentially resulting in an expected warming of 0.64 to 1.28 C over pre-industrial temperatures, compared to an obsrved increase of ~0.8 C."

4) "Skeie et al. estimated the net anthropogenic radiative forcing at 1.4 W/m2, and the IPCC AR4 estimated it at 1.6 W/m2.  Using these two estimates and the Padilla transient sensitivity range yields a net anthropogenic warming of 0.49 to 1.12°C with a central estimate of 0.65°C warming of average global surface temperature."

Again, a little more detail, one might also wish to clarify how this calculation differs from that in the previous par., it not immediately evident that we are looking at expected  warming from “CO2 only” versus warming from “net anthro forcing” Something like:

"Now considering the expected warming for the net anthropogenic forcing, Skeie et al. (2011) estimated the net anthropogenic radiative forcing at 1.4 W/m2, and the IPCC AR4 estimated it at 1.6 W/m2.  Using these two estimates and the Padilla et al. (2011) transient sensitivity range yields a net anthropogenic warming of 0.49 to 1.12°C with a central estimate of 0.65°C warming of average global surface temperature."

And lastly a note about uncertainties.  Skeptics love to talk about error bars etc.  The IPCC have done so, Pielke has not.  He states his values with high certainty and confidence, yet some are more certain than others.  Make it clear that we are using the best estimates for the forcings (GHGs, etc.) from the latest literature.

2011-10-09 18:27:14
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.35.36

Under the "Methane" heading you have "to not" - should be "do not"

Very informative and a thumbs up from me.

2011-10-10 05:44:45aerosols
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Alby, is the semi-direct effect Pielke's "aerosols", and the indirect effect his "glaciation"?

2011-10-10 05:50:58
nealjking

nealjking@gmail...
91.33.110.134

Albatross:

"1) "we return to our original question to Dr. Pielke on this subject"

Would it be too snarky to point out that he has avoided answering this question?  To use Neal's chess analogy, this is a key piece on the table and our queen is threatening one of his key pieces, so he wants us and onlookers to ignore it by hand waiving and shouting "Squirrel!".  Let us not please not ignore the elephant in the room."

I would phrase it along the lines of, "We are still interested in Dr. Pielke's answer to our original question, ..."

The word "still" makes the point, while the tone is courteous.

2011-10-10 06:00:13
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Dana,

"Alby, is the semi-direct effect Pielke's "aerosols", and the indirect effect his "glaciation"?"

 

Yes :)

2011-10-10 06:55:29updated
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Okay good comments Alby.  Making a lot of work for me though! :-)

Post updated, have another look.

2011-10-10 08:06:55
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Hi Dana,

Sorry about that.  If it is any consolaton it was a lot of work for me too ;)  And again, you are under no obligation whatsoever to incorporate or accept my suggestions, I am very, very far from omniscient.

Is there any chance of this going live before tomorrow am Mountain Time (maybe even tonight your time)?  We want to try and keep Pielke on the back foot-- if he sees this it can't excatly boost his confidence and it will make him asking more questions look very much like trying to obfuscate and detract from his misearble accounting and unjustified assumptions.

I'm committed to doing some stuff with my family right now, but I'll do my best to have a quick looklater.  Hopefully Tom, Rob and John C. et al. will also weight in.

2011-10-10 08:50:06going live
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Yeah, we can publish this tonight as long as everyone is satisfied with it.  I just looked it over a few more times and caught a few typos and such.  I think it's in really good shape.  A major Pielke asswhooping, frankly.

You also deserve to be named as co-author on this, Alby.  I only hesitate because you scared Pielke off last time, but you put in so much work that I hate to take all the credit.  Let me know if you want to be added and I'll put you on as co-author.  It's all pretty polite so Pielke shouldn't be able to squirm out of responding.

2011-10-10 09:30:56
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Hi Dana,

Got a few mintes here.

Re co-author, thanks Dana, much appreciated.  I am OK with that, but Pielke does not like me it seems.  So I, again, do not wish to compromise things, and if adding my name does that then better not doing so.  I'll let the group decide and I am OK either way with what is decided.  I'll also feel a lot better should John C sign off on this.

I would also recommend adding Tom Curtis as a co author-- he made some fine comments and has had some great insights.

Anyhow, fantastic job Dana and everyone who contributed!  I'm excited to see this go live tonight N. American time.

2011-10-10 10:06:07
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Well unfortunately we can only have 2 authors on a post.  I don't think having your name on there will compromise anything.

2011-10-10 11:10:35green light from John
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

John made a good suggestion about clarifying the difference between the table (50% due to CO2) and the human-caused warming (~100% due to CO2, because aerosols have offset the other positive forcings).  Other than that, he's still not thrilled about chasing Pielke's blimp, but likes the post and gives it a thumbs-up.

2011-10-10 11:14:00
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

OK Dana, here you go.

2011-10-10 11:30:43
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Thanks Alby.  I just added a concluding section of take-home messages per John's notes too.  Get any last comments in - I'll publish this in a few hours.

2011-10-10 13:40:39
Tom Curtis

t.r.curtis@gmail...
112.213.174.221

Dana @11:10, you need to be very carefull in wording that point.  There is no reason to think the negative forcings would counteract only the non-CO2 forcings.  Therefore CO2 accounts for only approx 48% of the observed warming, even the the magnitude of the warming is of the same size as the warming effect we would expect from CO2 alone.  In the post you state:

 

"The main points here are that CO2 is responsible for approximately 50% of the net positive radiative forcing since pre-industrial times (a percentage which will only continue to increase in the future), and is responsible for approximately 100% of the 0.8°C surface temperature warming over the past century.  This tells us that the negative forcings (primarily from human aerosol emissions) have offset approximately 50% of the net positive forcings."

The bolded section is false, and should not be included.  I doubt any advantage is gained by mentioning the parity between the expected warming from CO2 alone and the actual warming because, to do so in a non-misleading way, we would need to so many qualifiers that it would detract from the overall article.

2011-10-10 13:54:36
Tom Curtis

t.r.curtis@gmail...
112.213.174.221

"We should also note that an albedo increase/decrease due to increasing cloudcover would also..."

 

"cloudcover" should be "cloud cover"

Anyway, thumbs up from me provided the bolded phrase highlighted in my previous comment is removed.

2011-10-10 13:57:11
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Tom if the bolded text is false, then should the sentence immediately following that also be removed?

Can you suggest a better wording for that para Tom? Once this bug is fixed I think that it should be good to go.

2011-10-10 14:34:21
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Not a problem, I'll re-word that section and then publish.

2011-10-10 14:35:01
Tom Curtis

t.r.curtis@gmail...
112.213.174.221

Albatross, if we want to include discussion of negative forcings, something like this would be better:

 

""The main points here are that CO2 is responsible for approximately 50% of the net positive radiative forcing since pre-industrial times (a percentage which will only continue to increase in the future).  In the absence of negative forcings, CO2 would have contributed 0.79 degrees of the 0.8 degrees Kelvin observed temperature rise, and hence we would expect the total observed rise to be double that.  This tells us that the negative forcings (primarily from human aerosol emissions) have offset approximately 50% of the net positive forcings."

Having said that, in large part we know the negative forcings have offset approx 50% of positive forcings because the negative forcings have also been measured.  Admitedly the uncertainties are large so that is not determinate, but it has more force than mere book balancing.

 

2011-10-10 14:59:57
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

That works - have incorporated Tom's language and published.  Thanks for your work on this Alby and Tom.  I think it's a pretty major SkS smackdown on Pielke - will be interesting to see how he reacts.  He should eat some serious crow after making so many errors that it took a 2600 word blog post to correct them all.

2011-10-10 15:30:17
skywatcher

andycasely@hotmail...
122.107.164.176

superb post!  Just had a read, am now getting the popcorn and very interested in the response.  One minor typo in the methane section that has escaped through:

"Keppler et al. to not estimate the methane radiative forcing"  'to' should be 'do'

2011-10-10 15:45:17
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.101.55

Thanks skywatcher, corrected.  Hard to catch all the typos in such a long post.  I said 2600, actually it was 2754 words.  That's a long one!  Just goes to show how badly Pielke screwed up this calculation.