Climate Sensitivity and What Lewis and Curry 2014 Has to Say About It 12

[rconnor]

Ah yes, it’s that time again folks. A paper is released, in this case Lewis and Curry 2014, that says climate sensitivity is on the low end of the spectrum and the “skeptic” community starts banging pots and pans claiming the ACC theory is dead. Well, like most things in the field of climate science, it's not nearly that simple. Let's look at the entire story.

Equilibrium Climate Sensitivity (ECS) and Transient Climate Response (TCR)
Equilibrium Climate Sensitivity (ECS) – the amount the planet will warm in response to a doubling of atmospheric CO2 concentration (the base is usually taken from preindustrial levels of 280 ppm). ECS includes both fast and slow feedbacks, so ECS is not fully realized for decades or centuries after CO2 is held constant.

Transient Climate Response (TCR) – similar to ECS but only includes fast responding feedbacks. In other words, TCR is the temperature rise at the time atmospheric concentrations hit 2x the baseline, not where it will settle out to. As slow responding feedbacks tend to be positive, TCR is smaller than ECS.

These two are not the same and should not be confused. Many “skeptic” arguments prey on this confusion, be careful.

The Body of Knowledge on Climate Sensitivity
First, here’s a good list of the spectrum of peer reviewed literature addressing climate sensitivity. If you actually want to understand the topic (instead of cherry picking things that fit your viewpoint), it’s import to look at the body of work, that’s kinda how science works. Here’s a graphical representation, from AR5 WG1 Fig Box 12.2-1:
[image

http://www.climatechange2013.org/images/figures/WGI_AR5_FigBox12.2-1.jpg

]

To claim that a single paper can definitely set climate sensitivity, is false. While on the low side, Lewis and Curry 2014 does sit within the spectrum of other estimates.

Lewis and Curry 2014
Now to the paper itself. Lewis and Curry 2014 (LC14) is very similar to Otto et al 2013 (they both take the energy balance model approach), just with different heat uptake rates and reference periods.

LC14 has a heat uptake rate (0.36 Wm^-2) that is almost half of Otto et al 2013 (0.65 Wm^-2). The uptake rate used in LC14 comes from a single model, not an ensemble mean, and is, surprise, surprise, a very low value (which leads to lower ECS).

The ending reference period (1995-2011) was selected to “avoid major volcanic activity”. Although this seems odd considering Vernier et al. 2011 found that volcanic activity greatly affected the 2000’s. Furthermore, it is well known that the last decade has been a La Nina dominated period which would further add a cooling bias to their ending reference period, and thus artificially lower their ECS and TCR estimates.

Now new evidence (Durack et al 2014) suggests that “observed estimates of 0-700 dbar global warming since 1970 are likely biased low. This underestimation is attributed to poor sampling of the Southern Hemisphere”. Using the results of Durack et al 2014, the ECS would rise (15% according to a tweet from Gavin Schmidt).

The paper makes no mention of Cowtan & Way 2013 which demonstrates and corrects the cooling bias in HadCRUT caused by a lack of coverage in the heavily warming Arctic. Therefore, much of the recent warming which is occurring in the Arctic is unaccounted for in this paper. This would cause an artificially lower value of ECS and TCR.

The paper also ignores Shindell 2014 and Kummer & Dessler 2014 (most likely because they are too recent). Both of these papers highlight the inhomogeneities in aerosol forcing which may cause energy balance models to underestimate ECS and TCR.

Finally, the rather simplistic technique used in LC14 (and Otto et al 2013 as well) ignores all non-linearities in feedbacks and inhomogeneities in forcings. The exclusion of these elements leads to a lowering bias in TCR and ECS. Due to the fact the sample period and technique used introduce lowering biases into the results, LC14 may be useful in establishing the lower bound of sensitivity but in no way offers a conclusive value for the median or best estimate.

It should be noted that the results of Lewis and Curry 2104 implicitly accept and endorse the core of the Anthropogenic Climate Change theory; namely that increases in atmospheric CO2 will result in increases in global temperatures and that feedbacks will amplify the effect. For example, if you feel that the recent rise in global temperatures is due to land use changes and not CO2, then the TCR and ECS to a doubling of CO2 should be near zero. Or, if you feel that "it's the sun" and not CO2 then the TCR and ECS to a doubling of CO2 should be near zero. The recent change in climate is "just natural" and not CO2 you say? Well then TCR and ECS should, again, be near zero. So, if you've found yourself claiming any of the preceding and now find yourself trumpeting the results of LC14 as proof for your side, then you, unfortunately, are deeply confused. If you want to accept LC14's value for TCR of 1.33 K as THE value for TCR (which it isn't), then you also accept that majority of global warming is due to anthropogenic CO2 emissions.

What About Other Papers that Claim Lower Sensitivity?
As I stated from the outset, Lewis and Curry 2014 is hardly the only paper to address climate sensitivity. Beyond that, it’s hardly the only paper to suggest that climate sensitivity is on the lower end of the IPCC spectrum. I’ve addressed a few already but there are more (Lindzen 2001, Spencer & Braswell 2008, etc.). However, almost all of these papers have been found to have some significant flaws that cast doubt on their conclusions. Various peer reviewed rebuttals to these papers are listed below. I’d welcome readers to review the rebuttals and the original authors response to them.
[image

http://static.guim.co.uk/sys-images.../11/1397174224604/lowSensitivityRebuttals.jpg

]

...But What if Climate Sensitivity WAS Lower Than Expected
Let’s ignore all this for a second and pretend that, with Lewis and Curry, we can definitively say that climate sensitivity is lower than expected. Then what? Does this completely debunk the ACC theory? Does this mean rising CO2 levels really aren’t a concern? Well, many “skeptics” would say “YES!” but they do so without ever actually examining the issue.

According to Myles Allen, head of the Climate Dynamics group at Oxford:

A 25 per cent reduction in TCR would mean the changes we expect between now and 2050 might take until early 2060s instead…So, even if correct, it is hardly a game-changer…any revision in the lower bound on climate sensitivity does not affect the urgency of mitigation

.

The issue is that, with atmospheric CO2 levels rising as quickly as they are, a lower TCR does not mean anything significant. It just means that the effects will be delayed slightly. So even if “skeptics” were correct in saying that climate sensitivity is definitely at the lower end of the IPCC range (which they’re not), it would have no substantial impact on future global temperatures or the need to control CO2 emissions.

So, Lewis and Curry 2014 is:
1) Inconclusive to definitely say that climate sensitivity is on the low end of the IPCC spectrum
2) The results are suspect and appear to include numerous biases that would lead to lower TCR and ECS
3) Even if it were conclusive and accurate, it would still not suggest that reductions in CO2 emissions are unnecessary. In fact, it adds to the scientific body of knowledge that temperatures will continue to rise to unsafe levels if we continue with the status-quo, just maybe a decade later than other estimates.

(Note: I’ve started this new thread to discuss climate sensitivity specifically. It is an important topic that popped up in another thread and I felt it merited its own discussion. I would, as much as possible, like to keep the conversation on this subject…although this is likely wishful thinking)

 

[IRstuff]

"Perhaps if your concern is with climate change (regardless of the source) affecting "poor people", maybe we should enrich them? We could start by providing them with efficient, reliable, non-polluting (in the common sense of the term, not the carbon pollution bs) sources of energy. "

Not my issue, but not relevant either. Not all of the people going to be affected by climate change are even remotely contributing to the problem. Bangladesh, while most likely burning fossil fuels, is probably a relatively small problem, compared to the US and China. Yet, Bangladesh's climate warming problems will probably make ours look insignificant.

TTFN
faq731-376

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[TGS4]

IRstuff - your response, to me, represents all that is wrong with the alarmist/warmist perspective. When there is "blame" for a issue such as this, the focus is on blaming and restitution and not actually solving the problem. The real solution is to set the conditions for the Bangladeshis to enrich themselves and therefore better able to handle whatever is thrown at them. Your solution is to punish the West, make energy more expensive for everyone, keep the Bangladeshis poor and somehow this is "better".

 

[IRstuff]

I was merely answering your point "providing them with efficient, reliable, non-polluting (in the common sense of the term, not the carbon pollution bs) sources of energy" which you apparently ignored to make your your own agenda point, which is apparently some sort of orphaned, paternalistic "trickle down" concept.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

Of course I can. I can do anything. I can do absolutely anything. I'm an expert!

 

[2dye4]

Let me sum up this discussions two points.

1 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population
and it would be prudent to curtail entertainment consumption of fossil fuels at this point until we know what will happen and how to manage it.


2 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population
BUT it will harm our economy and standard of life to do any meaningful reductions in carbon fuel usage so it seems prudent to gamble on the
optimistic outcome materializing.

 

[TGS4]

IRstuff - so what exactly is your point then? That you don't want the poor to have reliable abundant energy? You don't want to enrich them so that their communities are more robust to handle any weather calamities? What's paternalistic about wanting people to succeed on their own and able to support and sustain themselves? It's paternalistic to require them to stay poor and dependent on the West as we "pay for our sins".

2dye4 - it's probably best that you stay out of the discussion - these are grown up concepts that you apparently cannot fathom or comprehend. Your ideology also blinds you to reality. If the sensitivity (ECS or TCR) is low, then there is no catastrophe (there's always the potential for catastrophe - celestial objects crashing down, vulcanism, infectious diseases, etc). Of all you can contribute is the precautionary principle, then it's best that you leave the adult discussion to the likes of rconnor.

 

[2dye4]

A few unprintable words for you TGS4. Use your imagination.
I also don't think much of your input but I will withhold juvenile insults.

I simply though this perspective is lacking in much of the discussion. Participants mostly
belong to one or the other camp depending on how they WISH to view the probabilities and likely outcomes
with skeptics being by far the most emotionally entangled and illogical.

I would ask you what in my post you take issue with but then again I could not possible care less.

I think instead of quibbling over minor scientific details that we are not in any way qualified
to judge as well as the scientists who actually do this for their day job , we might just
think about the boundaries to the what ifs and how much we would be willing to sacrifice for
a given quantity of peace of mind.

Remember the USA uses 2X per capita fossil fuel than many other first world nations. I don't think
it is so terrible to live in these other places, do you.

 

[TGS4]

2dye4 - your simplistic approach/summary is unbecoming and engineer. If the ECS/TCR a is low, then the timeframe for adaption is much longer and the potential for catastrophe is so much less. What can you not grasp of that?

And, no, I am not buying the authority of these so-called scientists. I suspect that I know more about computational modeling than the vast majority of them, so I think that I am eminently qualified to render an opinion, especially on their use or misuse of computational models. And you - what do you bring to the table?

That you think that these are minor scientific quibbles shows your total lack of understanding. At least rconnor understands and appreciates some of these subtleties. This disagreement about ECS/TCR is part of the heart of the discussion. If you have nothing technical to add to the discussion, then I say "good day".

 

[rconnor]

Temperature baseline period – pre-industrial, 1851-1900.

“Investigative journalists” op-ed disagrees with the thousands of peer-reviewed papers and NASA, NOAA, National Academy of Sciences, Royal Society, etc… - you don’t say! I never knew that Donna Laframboise thought otherwise! Compelling argument!

What will happen at 3 deg C that won’t happen at 2 deg C? – For a very good explanation, read this report published by the National Academy of Sciences. IPCC reports also detail this descriptively and graphically. It’s important to note that it’s a scale, not an “on/off” issue.

Diurnal/seasonal fluctuations vs average fluctuations - …sigh...you know the answer to this (at least you ought to). This is likely just Gish Gallop. Diurnal and seasonal fluctuations have been happen for a little while now on Earth. The biosphere is quite well adjusted to it. Furthermore, the Holocene has not experienced a long term, significant change in temperature. However, in the Anthropocene we will experience long term, significant changes in temperature that the biosphere will likely not have time to adapt via evolution. Furthermore, you know the whole “it’s changed before” argument? Well when climate went through significant changes in average temperature, the biosphere went through large scale changes (and extinctions). You know ice ages and such. Periods that were warmer than pre-industrial levels were great for lizards and not great for mammals…and likely not great for humans that have evolved and developed through the Holocene.

Furthermore, areas have been quite dependant on a consistent climate from year to year. One year you might get a drought, which affects agriculture and other aspects. Another year, you might experience flooding which affects cities and agriculture. Normally you can ride out the short term extremes, as it usually balances out over the long term. However, when you consistently have more draughts (of greater severity) in some areas and consistently have more floods (of greater severity) in other areas, it begins to have a serious impact.

mitigation v adaptation – you think (i.e. believe based off very little evidence) adaptation will be better. Just like you thought the tropics weren’t warming. Just like you thought humidity wasn’t increasing. Just like you thought BC carbon tax had not reduce emissions. Just like you thought sensitivity estimates were definitively dropping. And just like in all those other cases, I’ve presented some evidence (6 papers…and there are many more) that says otherwise.

If the ECS/TCR a is low, then the timeframe for adaption is much longer and the potential for catastrophe is so much less.

Without mitigation, the time frame is pushed out by ~10 years if we assume a TCR of 1.33 K (LC14 value) instead of 1.8 K. That’s not significant.

Without mitigation, atmospheric CO2 concentrations will be ~940 ppm in 2100. Using a TCR of 1.33 K or 1.8 K, it really doesn’t matter – the warming will be very severe.

actually makes a liar out of you. Your integrity is really on the line here...

YOU made the assertion, YOU need to support it. That should be the end of this story. However, instead of just asking you to support your position through evidence, I’ve dug up the evidence for you (list of papers below). Why my “integrity is really on the line” is baffling.

While one cannot definitively say that the trend is increasing (and admittedly my linear trend should never have been included), neither can one definitively say that the trend is decreasing. The correlation is far too weak. Furthermore, three of the latter data points are based off simplistic energy balance models which introduce assumptions and inherent biases that lead to artificially lower sensitivity values. This skews the end of the data series downward while not being reflective of the body of various techniques. Therefore, there is even less confidence in the accuracy or usefulness of the trend. As it stands, there is almost no valid support of the assertion that climate sensitivity estimates have been decreasing as our understanding grows.

Before any evidence was brought forth or analyzed, both GregLocock and TGS4 made such statements. This was done based off a narrow review of recent simple energy budget model techniques. I’ve demonstrated issues with these techniques and have yet to hear any defense of them. The fact that the basis of their assertion is in question seems to cast more doubt on its accuracy.

Of key importance to climate change policy is the question is there substantial evidence to suggest that the sensitivity is outside the lower bound of the IPCC range? Nothing in the body of evidence suggests that answer is yes. A single study, ripe with assumptions and biases that lead to artificially lower values, proves nothing. A single technique, with inherent biases that lead to lower values, proves nothing. The body of knowledge, across numerous techniques, numerous sample periods, numerous data sources and numerous authors, suggests that the IPCC range is valid. You must prove otherwise or drop the argument.

But anyways, see the list of papers I used below. It certainly is not all-encompassing but it’s arguably representative. If you want to add papers, feel free to do so.
Manabe and Wetherald 1967
Manabe 1971
Rasool and Schneider 1971
Sellers 1973
Sellers 1974
Weare and Snell 1974
Manabe 1975
Manabe and Wetherald 1975
Ramanathan 1975
Temkin and Snell 1976
Augustsson and Ramanathan 1977
Ohring and Adler 1978
Manabe and Stouffer 1979
Manabe and Wetherald 1980
Idso 1980
Ramanathan 1981
Chou et al. 1982
Hall and Cacuci 1982
Nicoli and Visconti 1982
Gilliland and Schneider 1984
Hansen et al. 1984
Washington and Meehl 1984
Wetherald and Manabe 1986
Wilson and Mitchell 1987
Mitchell et al. 1989
Noda and Tokoika 1989
Schlesinger et al. 1989
Washington and Meehl 1989
Wetherald and Manabe 1989
Oglesby and Saltzman 1990
McAvaney et al. 1991
Boer et al. 1992
Hoffert and Covey 1992
Mahfouf et al. 1993
Manabe and Stouffer 1993
Lambert 1995
Thompson and Pollard 1995
Chen and Ramaswamy 1996
Gordon and O'Farrell 1997
Hegerl et al. 1997
MacKay et al. 1997
Schlesinger et al. 1997
Bertrand 1998
Delworth et al. 1999
Roeckner et al. 1999
Wolbarst 1999
Boer et al. 2000
Washington et al. 2000
Dai et al. 2001
Wetherald et al. 2001
Boer and Yu 2003
Shaviv and Veizer 2003
Stern 2005
Sumi 2005
Goosse et al. 2006
Hegerl et al. 2006
Schmittner et al 2011
Hargreaves et al. 2012
PALAEOSENS Project 2012
Bitz et al. 2012
Masters 2013
Lewis 2013
Otto et al. 2013
Lewis and Curry 2014

 

[TGS4]

Typical warmist obfuscation rconnor. You plotted data (and I am actually taking your word that you gathered the information correctly) and I asked for the data. You replied with a list of papers. Not the data that you used - should be in an excel file (unless you don't know how to use that like Phil Jones...) that can be easily uploaded. Actually, you said that I was wrong to say that recent studies were driving the ESC/TCR values down. You produced data to support that, except your data doesn't support that. Either you were wrong or I was wrong. But sure, I certainly see why you wouldn't share the data when I can use it to demonstrate that you're wrong. This little back-and-forth, for me, demonstrates all that is wrong with the scientific discourse on this topic. You are so obstinate that you can't admit to even once being wrong. Whereas I can man-up and admit where and when I am wrong. Now, whose the man of science and who looks more like a man of religion in that interaction?

You might as well add another paper to that list: Harde 2014 which says 0.6°C/CO2 doubling.

Re Donna Laframboise - have you even read her work? Her critique is about the integrity of the people and the papers involved in the IPCC (she makes no claim about the "science"). It's a corrupt organization that has been infiltrated with biased NGOs. But, better to plug your fingers in your ears than to actually listen to dissenting voices.

Re diurnal and seasonal fluctuations - are you really going to go all hockey-stick again? Our recent history has been filled with rapid and severe fluctuations in the average - and what we have experienced thus far is well within the range of what has happened in the past. Indeed warmer might be worse for warm-blooded creatures if the temperature exceeds their normal temperature. However for mankind, we have little inventions, like air conditioning and other refrigeration. Have you ever wondered how people live today in places such as the middle eastern deserts - air conditioning. I guess, however, if you want us all to live a subsistence lifestyle without reliable energy, then maybe we'll have to go without those modern conveniences. I have zero concern that mankind will survive and thrive in any environment - we already do!

And where does this 940ppm come from? As I said before:

Of course, to get to 940ppm from our current 400ppm, the concentration will have to increase by 540ppm in the next 85 years. That's a rate (linearized, I know - so shoot me) of 6.35ppm/yr. It's currently at about 2ppm/yr. So, to achieve your number, the rate of increase will itself have to be tripled. Business-as-usual indeed...

Speaking of the BC carbon taxes and emission, is there any updates on the data? I can only find data to July 2012. :-(

 

[CELinOttawa]

YOU should all drop the sand and play nice...

I think I'm going to have to stop reading these threads. Useless bickering and responses which are clearly ignoring half of what other posters say is all I seem to find here.

 

[TGS4]

I think that you're right CEL. I'd have better luck converting ISIL militants to Judaism. I see why zdas04 took a hiatus. Not that our bickering back and forth will change any outcome at the global or country level, but the stakes are huge. If I'm right, yet they destroy the economy for nothing, that's a bad outcome. If they're roght, yet we do nothing, they see that as a bad outcome, too. If they're right, and we destroy the economy we just might trade one bad outcome for another. And if I'm right and we do nothing, we're fine. This is why Dr. Curry refers to this as a wicked problem.

That said - 2dye4: I apologize for insulting you.

 

[beej67]

Let me sum up this discussions two points.

1 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population
and it would be prudent to curtail entertainment consumption of fossil fuels at this point until we know what will happen and how to manage it.


2 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population
BUT it will harm our economy and standard of life to do any meaningful reductions in carbon fuel usage so it seems prudent to gamble on the
optimistic outcome materializing.

3 GHG will warm the planet and cause unknown but potentially catastrophic changes to our currently built out civilization and population,
but the chances of it being *only* caused by fossil fuels and none of the other vast array of ways mankind affects our environment are fairly small, so any climate strategy that focuses entirely or even primarily on fossil fuels is doomed to failure anyway.

Which is why we can't craft policy around science that can't get the sensitivity numbers right.

Carbon is probably about a third of the problem. That's why the low end models have a sensitivity of about a third of the high end models. The high end models are erroneously attributing other anthropogenic warming effects to carbon, while the low end models are attributing the correct impact to carbon without specifically explaining the other warming sources.

And we go round in circles, while nobody talks about anthropogenic changes in land cover.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[rb1957]

i'm good with we add "other vast array of ways mankind and nature (ie non-mankind) affects our environment"

another day in paradise, or is paradise one day closer ?

 

[2dye4]

Nobody said *only*

Do you people realize how silly you sound with this never ending picking at the theory. It's like birds picking at an elephant to try to move it.

Hey if any of you skeptics really have something solid and substantial to say about climate change theory weakness then write up a proposal
and send it to BP, Exxon, Haliburton...They would fork over half a million dollars in less than a few hundred milliseconds for science solid
enough to cast some doubt. So get to work....

 

[rb1957]

for me it's a central tenet of the "global warming" "argument" ... that AGHG are solely responsible for climate change being experienced.

another day in paradise, or is paradise one day closer ?

 

[beej67]

Nobody said *only*

The policy is crafted around a presumption of "only."



Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[GregLocock]

"never ending picking at the theory"

Oh, well as rconnors has failed, perhaps you could write 'the theory' down, including numbers. Sadly the scientists involved have been unable to write 'the theory' down. What we have at the moment is a bunch of hypothesese.

Incidentally you obviously don't believe the more extreme predictions since you calculated that your carbon footprint is twice as large as that that would maintain the status quo, and seem content with that.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[rconnor]

“and I am actually taking your word that you gathered the information correctly” – Please don’t. Do your own independent research, which you should have done prior to making such an assertion such that you could actually support that assertion.

However, I’ve listed the papers I used which you're welcome to use by going to the abstracts, grabbing the numbers and creating your own plot. You have all the necessary information to double check my plot, now you just need to put in the effort. Or not. I certainly could send the excel file but the only added good it would do would be to save you the time and effort of double checking the numbers. While in the past I’ve allowed you to lean on me to do put in the time to do the research for you, after you called me a liar, I’m not willing to be so generous this time.

Harde 2014 – Oh boy. Firstly, tell me whether it’s ECS or TCR? Actually don’t bother, the model is so grossly simplistic that it can’t discern a difference between ECS and TCR. It says it incorporates feedbacks but then it makes assumptions and simplifications that negates all positive feedbacks. Cloud feedbacks are assumed to be strongly negative (based on what I’m not sure…wait! I looked at the references and, as expected, it’s based off Lindzen’s discredited Iris effect. Very fitting.). Furthermore, a sensitivity around 0.6 deg C means that past climate changes could never have happened (at least to nowhere near the scale they did). Unfortunately, they did happen, as many “it’s changed before”ers will tell us (including yourself…in the very same post) and, you know, the entire field of paleoclimatology.

So this paper has completely flipped climate sensitivity on its head, undoes all the research suggesting a strongly positive water vapour feedback, rewrites the book on cloud feedbacks and completely dismantles paleoclimatology (and, in doing so, silences the “it’s changed before”ers). Wow! What a paper! Where would such a landmark and momentous paper get published? Nature? No, too small! Science? No way, too obscure! The only journal suitable for such a grandiose paper is…ah, let me make sure I get this right…Open Journal of Atmospheric and Climate Change (sound trumpets!)! The only other place I’ve seen this publisher (Scientific Online) mentioned is Jeffrey Beall’s list of Predatory Publishers (#403).

Interesting, related article.

Donna Laframboise – If I linked you a bunch of Moon Landing Hoax books, articles and website by “investigative journalists”, does that mean they have something valid to say?

”I have zero concern that mankind [sic] will survive and thrive in any environment - we already do!” – because the biosphere can sustain us (for now). I have no doubt that humankind will survive a 3 deg (or higher, for that matter) increase in temperature. My concern is that effects on the biosphere will create hardships for humans. You continually stress the economic turmoil that mitigation will cause (without any numbers or supporting evidence) while completely ignoring any practical economic, social or moral issues that will result if we wait to adapt. For example, sea level rises and coastal cities in developing regions are forced to relocate. Physically that’s no problem. Economically, socially, culturally, politically and morally it is. Mass forced immigration is a massive problem that has historically lead to huge, lasting issues. These issues may not show up in any cost/benefit analysis as they are mainly social/moral issues. Again, I’ve provided sources that state the cost/benefit of mitigation v no mitigation. You’ve just kept responding by saying “we’ll adapt!”. I don’t doubt that but at what cost? (economically, socially, morally)

”where does 940 ppm come from?” – RCP8.5. ppm per year is increasing over time. Using the old emission scenarios, CO2 emissions trended closest to A1F1 which leads to an atmospheric CO2 concentration of ~960 ppm. And note that A1F1 assumes that emissions/year will slow down in 2050 and decline in 2080. RCP8.5 assumes that emissions/year will rise until 2060, when they being to slow down and eventual plateau around 2090. Without mitigation efforts, both these pathways are realistic.

Also, it is odd that on one hand you'd argue that China and India are going to continue to increase their CO2 emissions and then on the other hand say that CO2 emissions won't continue to rise. Which is it?

BC Carbon tax new numbers – Can’t find an updated (2013) report either.

GregLocock wrt “well as rconnor has failed, perhaps you could write “the theory” down, including numbers” – What are you looking for? I keep answering this question and then you folks keep going “nope, that’s not what I wanted” but never state what, specifically, you want. I’ve provided some numbers, do you want others? If so, which ones? Ask me to “define the theory” and I’ll do, and have done, just that. Ask me to “provide numbers” (without specifying which ones) and I’ll do, and have done, just that. Provide me with a specific question and you’ll get a specific answer.

 

[jgailla]

An article about the effects of CFCs on the ozone layer. The anti-GW folks used the same methods back then as they are using now.

http://www.wunderground.com/resources/climate/ozone_skeptics.asp?MR=1

 

[TGS4]

Have you even read Laframboise's work on the IPCC? Before dismissing it out-of-hand?