Conservative Scientists & its Consequences

[bryman]

In other words, the IPCC estimate of the high range ECS of 4.5 is pretty much spot on? Nothing different from what I've heard as of late. You have a fine knack for data sir, and I am serious when I say that.

[jai mitchell]

So you have no direct evidence, just so-called polls you have witnessed?

isn't that implied in the term "informal polls", again I see we are experiencing your reading comprehension difficulties.

Kind of convenient, don't you think? According to various documented surveys of climate scientist, their estimates are nowhere near that high.

about which topics?  you have a real problem with specifics, this makes every one of your supposed arguments suspect.  please post these "various" "documented" surveys.

As far as aerosol forcing  over the arctic is concerned, that was well-accounted for on a recent study that concluded the region could warm up to 8 degrees Celsius by 2100.

Is that all you got in response to my post?  some random study that is looking at weak-tea CMIP5 modeled arctic warming response based on the more recent understanding that the aerosol forcing mechanism is MASSIVE up there?

you have yet to mention the fact that a loss of summer sea ice, occurring in Midsummer is the GLOBAL equivalent of an additional 2.5 Watts per meter squared (inferred from Caldeira, K. and I. Cvijanovic 2014 here:  http://dge.stanford.edu/labs/caldeiralab/Caldeira_research/Caldeira_SeaIce.html

In addition, the "Documented surveys" tend to show that the 100 GtC of frozen soils emissions is about 350% less than what the actual scientists expect.

In Nature's December issue of 2011, Edward Schuur and Benjamin Abbot, two scientists in the Permafrost Carbon Network, a cross-disciplinary group of researchers, wrote that they had surveyed leading experts of permafrost for their opinions on total carbon loss by 2100. The answer came back with striking similarity across the field, 232 to 380 GtC by 2100 under an RCP6.0-like scenario.  http://www.fairfaxclimatewatch.com/blog/2013/02/what-the-models-dont-show-part-2.html

With the additional decomposition from microbial heating of (hollesen et. al. 2015) http://www.popsci.com/microbes-arctic-are-heating-permafrost-1  factored in the weak-tea CMIP5 arctic forcing (that does not include the massive midsummer ice free arctic temperature response on the Siberian tundra)  decomposition of permafrost becomes front loaded on the timeline as compared to the "pure forcing" model BY OVER 40 YEARS.  So their "up to" 52 kg of CO2 per square meter of permafrost is likely underestimated by a factor of 2.  So what is a 100kg of CO2 per square meter of permafrost give us by 2100???  (yes I am saying that the depth profile by 2100 will likely be 6 meters, not 3)

And you seem to be comfortable making a lot of assumptions, which is something AbruptSLR does not do. And how do you know we won't contain emissions.

The nature of this exercise is to ascertain how the RCP 8.5, BAU analysis is significantly understating the risks of climate change.  I guess you are pretty new here and maybe didn't take the time to read the appropriate threads involved before you started opening your mouth.

Now, let's see, in all of your assertions about my statements, you have made unspecific assertions, posted very little reference material, glommed onto what I would guess is my least scientific assertion (though based on real anecdotal observation) and this out of over 640 posts on this forum. 

so I have to ask you, how did I earn such wonderful exposure to your "Serengeti Strategy" accusations?  I mean, of ALL of my posts, why did you pick that single one (which by the way you misrepresented as being related to temperature) that has such an obvious, back of the napkin assertion to take deference to?  It seems very suspicious to me.

And your assertion that the IPCC 4.5 high end estimate is within range in response to AbruptSLR's comment on this thread shows that you either do not have the intellectual faculty to understand what he just took a considerable amount of time writing (doubtful) or are simply downplaying what he said because of some kind of agenda.

so one must ask, bry-kid

when are you going to contribute something unique, insightful or otherwise useful to this forum?

because what I have been getting from you so far is a low-grade English language reading comprehension.

[AbruptSLR]

In other words, the IPCC estimate of the high range ECS of 4.5 is pretty much spot on? Nothing different from what I've heard as of late. You have a fine knack for data sir, and I am serious when I say that.

First, Schmidt's 2015 RealClimate estimate that the recent ECS is between 2 and 5C is clearly higher than AR5's estimated range of 1.5 to 4.5C.  Furthermore, Marvel's 2015 finding that the thunderhead clouds are observed to be moving to higher altitudes by the satellite record since 1983 indicates that the recent observed ECS is probable closer to 4.5C than the 3C median canonized by the IPCC; which indicates a likely 50% in the IPCC global mean surface temperature increase projections for any of the RCP scenarios used in AR5 (without considering acceleration of the "slow response" Earth System Sensitivity mechanisms).

Second, as previously posted in the "IPCC possible scenario: 9C over a century or so" thread; the following extract from Fasullo (2015), indicates that the reconstructions of sea level indicate that estimates of ECS based strictly on the instrument records contain a higher degree of uncertainty associated with long-term natural variability than previously recognized, thus indicating a greater risk that ECS may be at the higher than estimated based strictly on the instrument record, as a large fraction of the extra heat was being sequestered in the ocean (since at least 1900) as recent reconstructions steric sea level rise contributions have been higher than previously recognized:

http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/Talks/Fasullo_23032015.pdf

Extract: "What are the implications?
Larger uncertainty for ECS estimates from the instrumental record? Confirmation of Stevens et al. 2015?

…

- Interpreting climate sensitivity from the instrumental record depends critically on separating forced changes from internal variability - assumptions regarding internal variability are key, model dependent, and challenging to validate.

- The unprecedented observing system in place during the 2000’s hiatus provides a unique opportunity to understand its causes and evaluate the fidelity of simulated internal variability - though challenges remain.

- Strong parallels exist between the Grand Hiatus and the 2000’s (PDO, GMSL). While multiple generations of climate models have reproduced the hiatus mainly as a forced response, sea level reconstructions suggest that the planetary imbalance was persistent during the event.

- TWS cannot account for the sustained increase in GMSL during the Grand Hiatus. Estimation of cryospheric melt using MDD also does not suggest a major cryospheric contribution."

[AbruptSLR]

As a follow on to my last Reply #752, I re-post the following extract from Sherwood's (2015) Ringberg presentation, which expands on the role of aerosols (most significantly from the coal emissions that fueled China's recent economic growth, as indicated by the attached image, which implies a lot more aerosol emission since the early 1980's) in masking a probable high ECS value (in addition to the masking from the heat sequestered in the ocean as noted by Fasullo (2015) Ringberg):

http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/Talks/Sherwood_24032015.pdf

The Sherwood (2015) presentation focuses on the influence of aerosols on the radiative forcing over the Southern Ocean (which were not previously recognized).  The third attached image show how sulfates can have a big impact on radiative forcing associated with cloud cover over the Southern Ocean; and the fourth image shows that aerosols that caused the ozone hole over Antarctica have caused an increase in cloud cover over the Southern Ocean since the late 1970's (when the ozone hole formed).  This indicates that as both the ozone hole heals itself and as anthropogenic sulfate emissions are reduced (due to air pollution control), that we can expect the rate of observed global mean surface temperature increase to accelerate as this major masking factor associated with aerosol emissions is reduced.

Extract: "- We should not assume aerosol effects can only be in the northern hemisphere.
- Possible that greenhouse forcing in SH-extratropics has been negated by aerosol (or sea-ice) increases for some time. Deserves further attention?
- Would help to explain both (a) sluggish recent warming and (b) weird SH-NH contrast since 1979.
- Ozone depletion is the most likely culprit for the wind increase—would make this a rapid adjustment to ozone forcing."

[jai mitchell]

estimates of ECS based strictly on the instrument records contain a higher degree of uncertainty associated with long-term natural variability than previously recognized

and when the few atmospheric aerosol modellers finally realize the secondary aerosol forcing parameter is also driving the negative PDO phase?  Whence does ECS translate from there?

I will, second Bry-kid's assertion that you keep this forum on an unprecedented higher-order level of discourse probably unseen outside of a private university or think-tank generated forum.

[AbruptSLR]

estimates of ECS based strictly on the instrument records contain a higher degree of uncertainty associated with long-term natural variability than previously recognized

and when the few atmospheric aerosol modellers finally realize the secondary aerosol forcing parameter is also driving the negative PDO phase?  Whence does ECS translate from there?

I will, second Bry-kid's assertion that you keep this forum on an unprecedented higher-order level of discourse probably unseen outside of a private university or think-tank generated forum.

jai,

Thank you very much. 

It may be too late to act effectively by the time that the general public (including bryman) realize that ECS (even without considering the probable acceleration of "slow response" feedback mechanisms) is not constant, and can increase beyond 4.5C with continued radiative forcing as indicated by the Geoffroy & Sherwood (2015) Ringberg presentation entitled (see the linked reference below):

"Tropical fingerprints of low and high sensitivities in CMIP5 models"

http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/Talks/Geoffroy_25032015.pdf

And as you note the coming positive PDO phase and the likely strong El Nino this year will serve to accelerate the rate of global mean surface temperature increase for some time to come.

Best,
ASLR

[bryman]

estimates of ECS based strictly on the instrument records contain a higher degree of uncertainty associated with long-term natural variability than previously recognized

and when the few atmospheric aerosol modellers finally realize the secondary aerosol forcing parameter is also driving the negative PDO phase?  Whence does ECS translate from there?

I will, second Bry-kid's assertion that you keep this forum on an unprecedented higher-order level of discourse probably unseen outside of a private university or think-tank generated forum.

And you seem more like Jai Bitchell. Hurts when someone calls you out for the exaggerated doomsday you are, doesn't it? And by the way, when I asked Gavin about your post, I said CLIMATE IMPACTS, NOT TEMPERATURE. And he basically laughed his butt off at your unfounded claim. And I got a 3.9 GPA in university, so if anyone's dumb it's you. I'll take the word of a respected climate scientist over some doomsday moron any day.

[Neven]

Okay, so everyone blew off some steam. Now back to the no name-calling and the agreeing to disagree. 

[TeaPotty]

Climate Action "supporters" who undermine the urgency to stave off our looming catastrophe have become more dangerous than the now-discredited blatant deniers. It is also most likely a shift of focus by the very same forces that financed all the Climate Denialism to date.

Unfortunately, Climate Change is not a belief, and positive feedbacks are increasingly outnumbering negative feedbacks in both models and observations.

Also, if Gavin Schmidt wishes to continue tarnishing his reputation by dismissing methane release potential with outdated & insubstantial data, so be it. His authority in science is a weak excuse for the lack of evidence for his position. I'm not suggesting catastrophic release is likely, but the truth is we don't have enough data to even make a decent guesstimate of probability. The most important point to note is AbruptSLR's argument of a dynamic ECS, which vastly changes the nature of discussion on most feedbacks (If I am understanding this correctly).

[AbruptSLR]

The following post that I made in the "IPCC possible scenario: 9 C over next century or so" last December is relevant to the heart of bryman's question; and while the following re-post does not prove anything; if the ECS is currently closer to 4.5 C than 3 C (and is increasing with increasing GHG forcing); then the possibility of an abrupt methane release from the ESAS in the next two to three decades becomes more likely, and if it were to occur, the effective ECS through 2100 could be very high (say 9C or so):

While not proving that Arctic Sea will emit significant quantities of methane in the next 100-years, the following linked reference addresses both the current, and future, situation in the West Yamal continental shelf with regards to degradation of the local subsea permafrost (and these findings will be relevant to the ESAS within two to three decades).  The Portnov et al 2014 paper shows that in the West Yamal shelf area the relict subsea permafrost (which traps methane gas beneath it and also stabilizes methane hydrates beneath it) are already degrading to the point of leaking methane gas in the 20 to 50 meter water depth range, and the reference notes that model projections indicates that in the next few decades the ocean water temperature at the seafloor in this area should likely increase from about 0.5 C to about 2.5 C, which should result in a rapid acceleration of the degradation of this relic subsea permafrost.  If indeed, the relict subsea permafrost in the Russian Arctic shelves degrade rapidly due to the introduction of warm ocean currents along the seafloor from the North Atlantic Current (and/or from reduced sea ice cover and associated water column mixing due to storm activity), within the next few decades then the world could experience a very large positive feedback, first from the associated release of free methane gas from beneath the previously impermeable permafrost and second from the destabilization of the methane hydrates that were kept in a quasi-stable condition since the last ice age due to the melting of the degrading permafrost keeping the hydrates in a transient low temperature condition.

Portnov, A., J. Mienert, and P. Serov (2014), Modeling the evolution of climate-sensitive Arctic subsea permafrost in regions of extensive gas expulsion at the West Yamal shelf, J. Geophys. Res. Biogeosci., 119, 2082–2094, doi:10.1002/2014JG002685.

http://onlinelibrary.wiley.com/doi/10.1002/2014JG002685/abstract

Abstract: "Thawing subsea permafrost controls methane release from the Russian Arctic shelf having a considerable impact on the climate-sensitive Arctic environment. Expulsions of methane from shallow Russian Arctic shelf areas may continue to rise in response to intense degradation of relict subsea permafrost. Here we show modeling of the permafrost evolution from the Late Pleistocene to present time at the West Yamal shelf. Modeling results suggest a highly dynamic permafrost system that directly responds to even minor variations of lower and upper boundary conditions, e.g., geothermal heat flux from below and/or bottom water temperature changes from above permafrost. Scenarios of permafrost evolution show a potentially nearest landward modern extent of the permafrost at the West Yamal shelf limited by ~17 m isobaths, whereas its farthest seaward extent coincides with ~100 m isobaths. The model also predicts seaward tapering of relict permafrost with a maximal thickness of 275–390 m near the shoreline. Previous field observations detected extensive emissions of free gas into the water column at the transition zone between today's shallow water permafrost (<20 m) and deeper water nonpermafrost areas (>20 m). The model adapts well to corresponding heat flux and ocean temperature data, providing crucial information about the modern permafrost conditions. It shows current locations of upper and lower permafrost boundaries and evidences for possible release of methane from the seabed to the hydrosphere in a warming Arctic."

Also see:

http://phys.org/news/2014-12-methane-leaking-permafrost-offshore-siberia.html

Extract: "Portnov used mathematical models to map the evolution of the permafrost, and thus calculate its degradation since the end of the last ice age. The evolution of permafrost gives indication to what may happen to it in the future.
If the bottom ocean temperature is 0,5°C, the maximal possible permafrost thickness would likely take 9000 years to thaw. But if this temperature increases, the process would go much faster, because the thawing also happens from the top down.
"If the temperature of the oceans increases by two degrees as suggested by some reports, it will accelerate the thawing to the extreme. A warming climate could lead to an explosive gas release from the shallow areas."
Permafrost keeps the free methane gas in the sediments. But it also stabilizes gas hydrates, ice-like structures that usually need high pressure and low temperature to form.
"Gas hydrates normally form in water depths over 300 meters, because they depend on high pressure. But under permafrost the gas hydrate may stay stable even where the pressure is not that high, because of the constantly low temperatures."
Gas hydrates contain huge amount of methane gas, and it is destabilization of these that is believed to have caused the craters on the Yamal Peninsula."

On a related matter, the linked article reported (see the following quote) on the findings from cores that indicated two carbon pulses during the PETM, with the first one smaller than the second; which raises the possibility the with strong forcing, positive feedback mechanisms (particularly from methane hydrates) may be stronger than previously thought:

http://www.nbcnews.com/science/environment/earths-future-ancient-warming-gives-ominous-peek-climate-change-n268721

[jai mitchell]

estimates of ECS based strictly on the instrument records contain a higher degree of uncertainty associated with long-term natural variability than previously recognized

and when the few atmospheric aerosol modellers finally realize the secondary aerosol forcing parameter is also driving the negative PDO phase?  Whence does ECS translate from there?

I will, second Bry-kid's assertion that you keep this forum on an unprecedented higher-order level of discourse probably unseen outside of a private university or think-tank generated forum.

jai,

Thank you very much. 

It may be too late to act effectively by the time that the general public (including bryman) realize that ECS (even without considering the probable acceleration of "slow response" feedback mechanisms) is not constant, and can increase beyond 4.5C with continued radiative forcing as indicated by the Geoffroy & Sherwood (2015) Ringberg presentation entitled (see the linked reference below):

"Tropical fingerprints of low and high sensitivities in CMIP5 models"

http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/Talks/Geoffroy_25032015.pdf

And as you note the coming positive PDO phase and the likely strong El Nino this year will serve to accelerate the rate of global mean surface temperature increase for some time to come.

Best,
ASLR

With regard to B-K's Strato-sulfur loading comment.  I have absolutely no doubt that as China experiences a global economic slowdown and shifts rapidly away from sulfate emissions that we will experience a resumption of catastrophic warming, with a severe jump back up to the 4.5 curve in Mann's "false hope" graphic.  (attached).  It is at this point that a global dimming project will be initiated and we will begin to aggressively move away from CO2 emissions. 

Either that or the rapid warming of this next decade will lead to catastrophic, cascading system failure due to regional climate-driven destabilization. 

When the arctic is ice free during the summer solstice that will add an additional 2.75 watts per meter squared to the Earth's energy imbalance.

When we stop burning fossil fuels the anthropogenic aerosol forcing will go away and this will result in an additional 1-2 watts per meter squared forcing.

The decadal rate of longwave forcing increases is about 2.1 watts per meter squared.

our current top of atmosphere forcing is just about 1.2 watts per meter squared or roughly double the TOA as determined by Hansen and Sato 2010 (median 2007 value).

What this means is that, if the Earth's average surface temperature was held constant and no other forcing changes took place AND we continue to emit CO2 at current rates that by 2055 or so the top of atmosphere forcing will be somewhere between 6 and 10 watts per meter squared.

obviously we have a significant amount of warming locked in over the next few decades.

[Steven]

First, Schmidt's 2015 RealClimate estimate that the recent ECS is between 2 and 5C is clearly higher than AR5's estimated range of 1.5 to 4.5C.

I think the range from 2 to 5°C mentioned in the RealClimate article refers to the ECS estimates from CMIP5 climate models.  The CMIP5 model spread in Equilibrium Climate Sensitivity ranges from 2.1°C to 4.7°C, e.g. see here, page 745.  This doesn't contradict the IPCC range of 1.5-4.5°C, because the latter is based on several lines of evidence, including climate models, paleoclimate evidence, and observed climate change.

Furthermore, Marvel's 2015 finding that the thunderhead clouds are observed to be moving to higher altitudes by the satellite record since 1983 indicates that the recent observed ECS is probable closer to 4.5C than the 3C median canonized by the IPCC

What makes you think that Dr. Marvel's work "indicates that the recent observed ECS is probably closer to 4.5°C than 3°C"?  Could you provide a quote to support your claim?

...ECS (even without considering the probable acceleration of "slow response" feedback mechanisms) is not constant, and can increase beyond 4.5C with continued radiative forcing as indicated by the Geoffroy & Sherwood (2015) Ringberg presentation entitled (see the linked reference below):
... 

http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/Talks/Geoffroy_25032015.pdf

Which part of the presentation are you referring to?  I don't see anything there about an ECS "increase beyond 4.5C with continued radiative forcing".

[Shared Humanity]

estimates of ECS based strictly on the instrument records contain a higher degree of uncertainty associated with long-term natural variability than previously recognized

and when the few atmospheric aerosol modellers finally realize the secondary aerosol forcing parameter is also driving the negative PDO phase?  Whence does ECS translate from there?

I will, second Bry-kid's assertion that you keep this forum on an unprecedented higher-order level of discourse probably unseen outside of a private university or think-tank generated forum.

And you seem more like Jai Bitchell. Hurts when someone calls you out for the exaggerated doomsday you are, doesn't it? And by the way, when I asked Gavin about your post, I said CLIMATE IMPACTS, NOT TEMPERATURE. And he basically laughed his butt off at your unfounded claim. And I got a 3.9 GPA in university, so if anyone's dumb it's you. I'll take the word of a respected climate scientist over some doomsday moron any day.

Ahhhhhh.....while I am certain this is of no interest or cause for concern to you, this comment has  now earned you the honor of being placed on my ignore list. This saves me the aggravation of reading your arrogant drivel and the time spent scanning past comments totally lacking in merit.

[bryman]

Climate Action "supporters" who undermine the urgency to stave off our looming catastrophe have become more dangerous than the now-discredited blatant deniers. It is also most likely a shift of focus by the very same forces that financed all the Climate Denialism to date.

Unfortunately, Climate Change is not a belief, and positive feedbacks are increasingly outnumbering negative feedbacks in both models and observations.

Also, if Gavin Schmidt wishes to continue tarnishing his reputation by dismissing methane release potential with outdated & insubstantial data, so be it. His authority in science is a weak excuse for the lack of evidence for his position. I'm not suggesting catastrophic release is likely, but the truth is we don't have enough data to even make a decent guesstimate of probability. The most important point to note is AbruptSLR's argument of a dynamic ECS, which vastly changes the nature of discussion on most feedbacks (If I am understanding this correctly).

I echo that sentiment but claiming that climate scientists as a whole think that impacts will be 150-400% greater than IPCC estimates when no independent evidence exists to prove that point is unwise. The Vergehhen et al survey does not support this view, and a general review of most studies does not either. In some cases, impacts could match up with Jai's numbers, but not all will. Obviously these events need to be planned for, but trumpeting catastrophe as a certainty when evidence is iffy on that does not help things. Considering such cases in a range of possibilities is the best way, and will serve action and planning well. And we don't know if SLR is right on ECS. He or she may be, but evidence is lacking in certainty on that point. I agree that there is some truth in Jai's assessment of where things stand and may go in the future, but it is doubtful that all of what he says will come to pass. That doesn't mean it shouldn't be duly considered and planned for though. With that, I take my leave of my debate with Jai. You have proven a worthy adversary, and I hope that we can agree to disagree. Clearly you will not budge from your position and neither will I lol.

[bryman]

estimates of ECS based strictly on the instrument records contain a higher degree of uncertainty associated with long-term natural variability than previously recognized

and when the few atmospheric aerosol modellers finally realize the secondary aerosol forcing parameter is also driving the negative PDO phase?  Whence does ECS translate from there?

I will, second Bry-kid's assertion that you keep this forum on an unprecedented higher-order level of discourse probably unseen outside of a private university or think-tank generated forum.

And you seem more like Jai Bitchell. Hurts when someone calls you out for the exaggerated doomsday you are, doesn't it? And by the way, when I asked Gavin about your post, I said CLIMATE IMPACTS, NOT TEMPERATURE. And he basically laughed his butt off at your unfounded claim. And I got a 3.9 GPA in university, so if anyone's dumb it's you. I'll take the word of a respected climate scientist over some doomsday moron any day.

Ahhhhhh.....while I am certain this is of no interest or cause for concern to you, this comment has  now earned you the honor of being placed on my ignore list. This saves me the aggravation of reading your arrogant drivel and the time spent scanning past comments totally lacking in merit.

And yet you ignore Jai's insults and resort to attacking the messenger yourself. You are no better than I, sir, and you completely ignored Neven's post above. How noble of you

[Neven]

Is it a full moon over where you guys live? 

[bryman]

Is it a full moon over where you guys live? 

I don't know man. Anyway, if anyone wants to carry on the debate, hit up my Twitter account under the name ArgonneForest. Anyone wishing to dispute my points can go there.

[Neven]

Is it a full moon over where you guys live? 

I don't know man. Anyway, if anyone wants to carry on the debate, hit up my Twitter account under the name ArgonneForest. Anyone wishing to dispute my points can go there.

Actually, I would appreciate it if you could use just one name de plume over here and on the ASIB. It's difficult enough for me to keep track of who's saying what to whom, during these digital brawls.

[jai mitchell]

Is it a full moon over where you guys live? 

I don't know man. Anyway, if anyone wants to carry on the debate, hit up my Twitter account under the name ArgonneForest. Anyone wishing to dispute my points can go there.

Points?

Except for the fact that the Wadhams long-term warming potential of a 50GT methane spike is based on the forcing potential of the oxidized CO2 product after 30 years under hydroxyl reduction (and you pass over the 3C pulse warming from the methane forcing) I really didn't see much point at all.  But you know, I am a fan of "knives sharpening each other" I just wish you spent some time reading and reflecting and asking questions, instead of glomming onto single issue points.  You obviously care about this stuff and you should have all kinds of access to varied points of view.  I do agree that my views are based on a multi-discipline synthesis of various parameters that do not normally group together.  For instance, did you realize that the ocean acidification feedback response on ocean aerosols is expected to produce an additional 0.5C of warming by 2100 just on its own?  where has that been included in the analyses that you have seen?

http://www.nature.com/news/rising-ocean-acidity-will-exacerbate-global-warming-1.13602

Or that the climactic response of the loss of the Amazon rainforest also produces an additional forcing factor (not albedo) related to reduced DMS emissions.  That this forest loss is happening at a current rate that is about 300% faster than the worst-case scenarios and the 2015 EL Nino will exacerbate this forest loss.

http://onlinelibrary.wiley.com/doi/10.1002/2014GB004969/abstract

Elevated but highly variable DMS mixing ratios were observed within the canopy, showing clear evidence of a net ecosystem source to the atmosphere during both day and night in both the dry and wet seasons. Periods of high DMS mixing ratios lasting up to 8 h (up to 160 parts per trillion (ppt)) often occurred within the canopy and near the surface during many evenings and nights. Daytime gradients showed mixing ratios (up to 80 ppt) peaking near the top of the canopy as well as near the ground following a rain event. The spatial and temporal distribution of DMS suggests that ambient levels and their potential climatic impacts are dominated by local soil and plant emissions. A soil source was confirmed by measurements of DMS emission fluxes from Amazon soils as a function of temperature and soil moisture. Furthermore, light- and temperature-dependent DMS emissions were measured from seven tropical tree species. Our study has important implications for understanding terrestrial DMS sources and their role in coupled land-atmosphere climate feedbacks.

Where have you seen THAT included in modeled warming projections???

[AbruptSLR]

First, Schmidt's 2015 RealClimate estimate that the recent ECS is between 2 and 5C is clearly higher than AR5's estimated range of 1.5 to 4.5C.

I think the range from 2 to 5°C mentioned in the RealClimate article refers to the ECS estimates from CMIP5 climate models.  The CMIP5 model spread in Equilibrium Climate Sensitivity ranges from 2.1°C to 4.7°C, e.g. see here, page 745.  This doesn't contradict the IPCC range of 1.5-4.5°C, because the latter is based on several lines of evidence, including climate models, paleoclimate evidence, and observed climate change.


Response: The exact quote by Schmidt given in Reply #748 w.r.t. the 2 to 5C range was: "While the workshop wasn’t designed to produce a new assessment of the evidence, we did spend time specifying the problems there would be if equilibrium sensitivity was less than 2ºC or greater than 5ºC. Specifically, what would have to be true for all the evidence to fit? This was useful at underlining the challenge in shifting or constraining the ‘classic’ range by very much."  I used bold font to emphasize that Schmidt feels that the 2 to 5C range best reflects all of the available data discussed by experts in the field at Ringberg and not just that best fits the CMIP5 projections.  Therefore, I maintain my position, which to me indicates that Schmidt is leaning towards a median value for ECS of 3.5C which is mid-way between 2 and 5C.

Furthermore, Marvel's 2015 finding that the thunderhead clouds are observed to be moving to higher altitudes by the satellite record since 1983 indicates that the recent observed ECS is probable closer to 4.5C than the 3C median canonized by the IPCC

What makes you think that Dr. Marvel's work "indicates that the recent observed ECS is probably closer to 4.5°C than 3°C"?  Could you provide a quote to support your claim?

Response: When Dr. Marvel states (see Reply #748): "So these big thunderheads that you would see, like convective clouds in the tropics, those are rising, those are going higher in ways that are predicted very robustly by a lot of the climate models and some of the physics underlying them, which is incredible." It is my opinion that see is at least referring to physics presented by Sherwood, S.C., Bony, S. and Dufresne, J.-L., (2014) "Spread in model climate sensitivity traced to atmospheric convective mixing", Nature; Volume: 505, pp 37–42, doi:10.1038/nature12829; which presents some of the most definitive physics on this matter, and Sherwood et al (2014) indicates that ECS could likely exceed 4 C. 

 

...ECS (even without considering the probable acceleration of "slow response" feedback mechanisms) is not constant, and can increase beyond 4.5C with continued radiative forcing as indicated by the Geoffroy & Sherwood (2015) Ringberg presentation entitled (see the linked reference below):
... 

http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/Talks/Geoffroy_25032015.pdf

Which part of the presentation are you referring to?  I don't see anything there about an ECS "increase beyond 4.5C with continued radiative forcing".

Response: As illustrated by the attached figure from Geoffroy & Sherwood Ringberg (2015) the non-linear climate response could have low/normal sensitivity or high sensitivity depending on the climate state.  As my evidence cited above (plus Schmidt et al Ringberg (2015)'s recommendation to increase the median TCR/ECS based on observed instrument data by 35 to 60%), indicates that we show use the Geoffroy et al (2013) graph shown in the lower right corner of the attached figure (labeled high sensitivity), which has a vertical axis of 2 X ECS vs the Tropical Feedback Factor on the horizontal axis.  Furthermore, Trenberth, K. E., J. T. Fasullo, C. O'Dell, and T. Wong (2010), Relationships between tropical sea surface temperature and top-of-atmosphere radiation, Geophys. Res. Lett., 37, L03702, doi:10.1029/2009GL042314, cite a reasonable value for the Tropical Feedback Factor of about 1.25 W m^{-1 K-1}, thus the Geoffroy et al (2013) graph indicates that currently 2 X ECS is about 8C so ECS is about 4C; & this graph indicates that with more forcing 2 X ECS could change to about 10C.

[AbruptSLR]

Or that the climactic response of the loss of the Amazon rainforest also produces an additional forcing factor (not albedo) related to reduced DMS emissions.  That this forest loss is happening at a current rate that is about 300% faster than the worst-case scenarios and the 2015 EL Nino will exacerbate this forest loss.

http://onlinelibrary.wiley.com/doi/10.1002/2014GB004969/abstract

Elevated but highly variable DMS mixing ratios were observed within the canopy, showing clear evidence of a net ecosystem source to the atmosphere during both day and night in both the dry and wet seasons. Periods of high DMS mixing ratios lasting up to 8 h (up to 160 parts per trillion (ppt)) often occurred within the canopy and near the surface during many evenings and nights. Daytime gradients showed mixing ratios (up to 80 ppt) peaking near the top of the canopy as well as near the ground following a rain event. The spatial and temporal distribution of DMS suggests that ambient levels and their potential climatic impacts are dominated by local soil and plant emissions. A soil source was confirmed by measurements of DMS emission fluxes from Amazon soils as a function of temperature and soil moisture. Furthermore, light- and temperature-dependent DMS emissions were measured from seven tropical tree species. Our study has important implications for understanding terrestrial DMS sources and their role in coupled land-atmosphere climate feedbacks.

Where have you seen THAT included in modeled warming projections???

In related research, the linked reference confirms that aerosol precursors from forests play an important part in currently partially suppressing mean global temperatures (due to cloud formation); however, as forests are projected to sustain possibly severe stress from climate change; this temporary climate change masking factor (forest emitted aerosol precursors) may start to decline in a few decades:

Francesco Riccobono, Siegfried Schobesberger, Catherine E. Scott, Josef Dommen, Ismael K. Ortega, Linda Rondo, João Almeida, Antonio Amorim, Federico Bianchi, Martin Breitenlechner, André David, Andrew Downard, Eimear M. Dunne, Jonathan Duplissy, Sebastian Ehrhart, Richard C. Flagan, Alessandro Franchin, Armin Hansel, Heikki Junninen, Maija Kajos, Helmi Keskinen, Agnieszka Kupc, Andreas Kürten,Alexander N. Kvashin, Ari Laaksonen, Katrianne Lehtipalo, Vladimir Makhmutov, Serge Mathot, Tuomo Nieminen, Antti Onnela, Tuukka Petäjä, Arnaud P. Praplan, Filipe D. Santos, Simon Schallhart, John H. Seinfeld, Mikko Sipilä, Dominick V. Spracklen, Yuri Stozhkov, Frank Stratmann, Antonio Tomé, Georgios Tsagkogeorgas, Petri Vaattovaara, Yrjö Viisanen, Aron Vrtala, Paul E. Wagner, Ernest Weingartner, Heike Wex, Daniela Wimmer, Kenneth S. Carslaw, Joachim Curtius, Neil M. Donahue, Jasper Kirkby, Markku Kulmala, Douglas R. Worsnop and Urs Baltensperger, (2014), "Oxidation Products of Biogenic Emissions Contribute to Nucleation of Atmospheric Particles",  Science 16 May 2014: Vol. 344 no. 6185 pp. 717-721. DOI: 10.1126/science.1243527

http://www.sciencemag.org/content/344/6185/717

Abstract: "Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations."

[AbruptSLR]

Jean-Pascal van Ypersele is professor of climatology and environmental sciences at the Université catholique de Louvain in Belgium. He has held the position of vice-chair of the Intergovernmental Panel on Climate Change (IPCC) for seven years and is now running for the role of chair, to succeed Dr Rajendra Pachauri; and per the following extract from the linked interview, the topic that excites him the most is the uncertainty associated with the feedback associated with clouds and their impact on ECS.  Some people think that high uncertainty entitles society to continue BAU emissions; however, uncertainty is not societies friend, it is an enemy that increases risk.  Hopefully, the first stage of the ACME program (to be completed in another 2.5 years) will reduce this uncertainty before society follows a pathway that it comes to regret.



http://www.carbonbrief.org/blog/2015/04/the-carbon-brief-interview-jean-pascal-van-ypersele/

Extract: "CB: So, as a climate scientist, what areas of new research excite you the most, which questions would you like to see more than any others?

JY: Probably one of the key questions is the role of clouds. I mean, the main reason behind, let's face it, the large range in the climate sensitivity, the equilibrium climate sensitivity - sorry for using jargon here, but probably the readers of this will know what we're talking about - climate sensitivity is simply the amount of warming that you get at equilibrium when you double the amount of CO2 in the atmosphere. But the range for the number has been basically [the same] for the last 40 years; 1.5 to 4.5C with some fluctuations. It's a situation with nuances, but basically it's a large range - it's a factor of three. It would make a big difference to reduce that range and to know better if, for a doubling of the concentration, the warming would be 2C, 3C, or 4C. It would make a big difference for policymakers as well when they discuss risk management because the risk would be better known. And the main factor behind that is cloud microphysics and the way clouds interact with other elements in the climate system. And relatively little progress has been made actually. When Charney published in 1975 his first assessment of the range of climate sensitivity, it was 1.5 to 4.5 and it's still the same today. So little progress has been made, and the main factor is the uncertainties around clouds.

CB: So, my understanding of clouds - cloud feedbacks - is that there's quite a lot of evidence that there is a positive feedback, which means it would amplify the warming that you would get just purely for a doubling of carbon dioxide. There are suggestions that it might be a negative feedback, but there isn't a lot of evidence to support that, in fact I'm not sure of any. Having identified clouds as an issue, does that lessen the possibility that's it's at the lower end of that range?

JP: Things are even a little more complicated than that. Because it's true that overall water vapour - and clouds is one of the manifestations of water vapour - increase the warming for an increase in the CO2 concentration, so overall the feedback is positive. But inside that big envelope there are different behaviours for different kinds of clouds. I'm not a cloud expert, but still, I know that, for example, high-level clouds like cirrus, have a warming effect if there's an increase in their number. Low-lying clouds, low in the atmosphere, on the contrary, have a cooling effect because they reflect more sunlight to space, while the upper clouds have a larger greenhouse effect by trapping heat radiation. So, when you talk about clouds, clouds is not just a large cloud - let's use that word! - of water vapour in different forms. The altitude and type of clouds and the microphysics is quite different for different levels in the atmosphere. And to understand the overall effects of clouds and changing cloudiness in warming climates depends on the understanding, the detail of the understanding, of the microphysics of those individual layers of clouds at different layers. For some layers, it's a positive feedback and for some layers it's a negative feedback. And the balance is positive indeed, but how positive? How to quantify that depends on the details of the microphysics of clouds, and there there is still much progress to do. One difficulty being that it's very hard to observe what is happening inside clouds at their level, and the other difficulty - or one other difficulty - is the difficulty to model with high resolution - the high resolution that would be needed to resolve clouds. It's very difficult to do that in climate models because we are limited by computer power, and that's one of the difficulties."

[AbruptSLR]

While it is not clear what value Schmidt et al (2015) Ringberg mean when they recommend that the median value of ECS determined by instrument observation be multiplied by 1.35 to 1.60 to determine the true value of ECS; however, the most recent reference that I could find that reports this instrument observations determined value of ECS is Johansson et al (2015); which give a value of 2.5C.  If Schmidt et al (2015) Ringberg are considering this value then their recommendation gives a range for the true value of ECS of from 3.375 to 4C.

Daniel J. A. Johansson, Brian C. O’Neill, Claudia Tebaldi & Olle Häggström (2015), "Equilibrium climate sensitivity in light of observations over the warming hiatus", Nature Climate Change, doi:10.1038/nclimate2573

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2573.html

Abstract: "A key uncertainty in projecting future climate change is the magnitude of equilibrium climate sensitivity (ECS), that is, the eventual increase in global annual average surface temperature in response to a doubling of atmospheric CO2 concentration. The lower bound of the likely range for ECS given in the IPCC Fifth Assessment Report (AR5) was revised downwards to 1.5 °C, from 2 °C in its previous report, mainly as an effect of considering observations over the warming hiatus—the period of slowdown of global average temperature increase since the early 2000s. Here we analyse how estimates of ECS change as observations accumulate over time and estimate the contribution of potential causes to the hiatus. We find that including observations over the hiatus reduces the most likely value for ECS from 2.8 °C to 2.5 °C, but that the lower bound of the 90% range remains stable around 2 °C. We also find that the hiatus is primarily attributable to El Niño/Southern Oscillation-related variability and reduced solar forcing."

[TeaPotty]

After adding the poster's twitter account to my personal list of Climate Deniers, they block me. Feels like a paranoid knee-jerk response from someone who has been called a denier many times. I rest my case.

[AbruptSLR]

This post is a follow-up to my Reply # 772 where I calculate a possible range of 3.375 to 4C for the true median value of ECS (i.e. that is comparable to the median ECS of 3C).

When considering the uncertainties associated with applying Schmidt et. al. (2015) Ringberg's guidance of multiplying the median TCR/ECS based on instrument observations by 1.35 to 1.6 to estimate the range of true median TCR/ECS, one needs to remember:

(1) Different researches use different data sets and process the raw data differently, and thus report different median instrument values (e.g. Johansson et al 2015 report a median instrument based ECS of 2.5C while other researchers report different median values).

(2) The cloud monitoring satellite records roughly began in the early 1980's, which results in a relatively limit data set, when trying to correct for multi-decadal atmospheric/oceanic oscillations, like the PDO/IPO (e.g. Johannsson et al (2015) report a median instrument based ECS of 2.8C without the hiatus impact vs 2.5C with the hiatus impact; while the record does not account for the impact of the 20 to 30-year positive PDO phase that is likely to have started just last year).

(3) Corrections for a potential large number of temporary masking factors have at best only been partially made to currently reported values.  Such masking mechanisms include: (a) aerosol effects over the Southern Ocean identified by Sherwood (2015) Ringberg; (b) aerosol impact on the ENSO cycle; (c) aerosol impacts on Arctic Amplification; (d) North Hemisphere vs Southern Hemisphere aerosol distribution effect (see Shindell 2014); (e) DMS and VOC from the ocean & forests; (f) the recent short-term growth spurt of vegetation that will return the temporarily sequestered carbon to the atmosphere due to fires, droughts, floods, forest degradation, insect attack, heat stress etc.; (g) temporarily accelerated sequestration of heat in the oceans.

(4) There is a lag time for the ocean to interact with the atmosphere leading to increases in ECS, thus we are already committed to higher ECS values and we are continuing on a BAU pathway through at least 2020 when the voluntary CoP21 pledges kick-in.

(5) We are only talking here about the median value of ECS and not about the fat-tail and/or right-skewed PDF, nor are we talking about the effective ECS due to the acceleration of "slow-response" feedback mechanisms (including multiple carbon cycle mechanisms, mainly albedo mechanism, etc.)

[AbruptSLR]

The following is a re-post from the "Sea Level Rise and Social Cost of Carbon" thread in the consequence folder.  I provide it here as it should help some readers to realize the implications of Fasullo (2015) Ringberg's presentation on reconstructed sea level rise, SLR, & ECS, as Hay et al (2015) show that SLR has risen about 25% more rapidly, since 1900, than previously thought due to greater heat sequestration in the ocean, during this period, than previously thought.  Of course this implies that before the SLR satellite era, ECS was at least 25% greater than previously thought:

The linked reference finds that the acceleration in sea level rise seen in recent decades is more rapid (by about 25% since 1990, see the first attached plot & caption, while the second attached image is a variation of the first developed by Rahmstorf on RealClimate) than scientists previously thought:

Hay CC, Morrow E, Kopp RE, Mitrovica JX, (2015) "Probabilistic reanalysis of twentieth-century sea-level rise", Nature. 2015 Jan 14. doi: 10.1038/nature14093

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14093.html

Abstract: "Estimating and accounting for twentieth-century global mean sea-level (GMSL) rise is critical to characterizing current and future human-induced sea-level change. Several previous analyses of tide gauge records—employing different methods to accommodate the spatial sparsity and temporal incompleteness of the data and to constrain the geometry of long-term sea-level change—have concluded that GMSL rose over the twentieth century at a mean rate of 1.6 to 1.9 millimetres per year. Efforts to account for this rate by summing estimates of individual contributions from glacier and ice-sheet mass loss, ocean thermal expansion, and changes in land water storage fall significantly short in the period before 1990. The failure to close the budget of GMSL during this period has led to suggestions that several contributions may have been systematically underestimated. However, the extent to which the limitations of tide gauge analyses have affected estimates of the GMSL rate of change is unclear. Here we revisit estimates of twentieth-century GMSL rise using probabilistic techniques and find a rate of GMSL rise from 1901 to 1990 of 1.2 ± 0.2 millimetres per year (90% confidence interval). Based on individual contributions tabulated in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, this estimate closes the twentieth-century sea-level budget. Our analysis, which combines tide gauge records with physics-based and model-derived geometries of the various contributing signals, also indicates that GMSL rose at a rate of 3.0 ± 0.7 millimetres per year between 1993 and 2010, consistent with prior estimates from tide gauge records. The increase in rate relative to the 1901–90 trend is accordingly larger than previously thought; this revision may affect some projections of future sea-level rise."


Caption: "Time series of global mean sea level for the period 1900-2010. Figure shows estimates of sea level from the two methods used in this study: 'KS' (blue line) and 'GPR' (black line), and two methods used in the latest IPCC report: 'Ref.4' (purple line) from Church et al. ( 2011) and 'Ref. 3' (red line) from Jevrejeva et al. ( 2008). Inset table shows trends for three different time periods. Source: Hay et al. (2015)"

See also:
http://www.carbonbrief.org/blog/2015/01/global-sea-levels-rising-faster-than-previously-thought-study-shows/
http://in.reuters.com/article/2015/01/14/climatechange-seas-idINL6N0US3IZ20150114

[jai mitchell]

Of course this implies that before the SLR satellite era, ECS was at least 25% greater than previously thought:

I have been considering the paper on Aerosol forcing from this period.  It seems to me that the dominant anthropogenic aerosol forcing during the 1880-1930 period was from low-temp coal combustion.  It seems to me that the predominance of home-heating coal consumption would produce a significantly different altitude loading profile of aerosols.  That modern high thermal efficiency consumption of coal in industrial and electric power generation would produce a much higher loading in the upper atmosphere.

Since rain washout rates of sulfates are much more rapid at lower atmosphere.  It seems reasonable to conclude that the aerosol loading and forcing parameter in the 1880-1930 period would produce about 1/2 to 2/3 of the modern equivalent on a per-unit emissions case.

Since Bjorn Steven's recent paper did not consider this, as well as the Hay et al 2014 sea level rise info posted by SLR directly above, then this confirms again the ECS parameter being higher than 3 and being biased low by an underestimation of the aerosol forcing value.  (bjorn paper here:  http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00656.1 )

[AbruptSLR]

Since Bjorn Steven's recent paper did not consider this, as well as the Hay et al 2014 sea level rise info posted by SLR directly above, then this confirms again the ECS parameter being higher than 3 and being biased low by an underestimation of the aerosol forcing value.  (bjorn paper here:  http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00656.1 )

jai,
Thanks for your insights on some of the possible short-comings of Bjorn Steven's thinking as expressed in:

Bjorn Stevens (2015), "Rethinking the lower bound on aerosol radiative forcing", Journal of Climate; e-View, doi: http://dx.doi.org/10.1175/JCLI-D-14-00656.1

While the first two web-links verify that Stevens is not a denialist; his own words verify that he is a firm supporter of the "err-on-the-side-of-least-drama" type of AR5 thinking (& he was one of the AR5 authors), and that he seeks to influence policy makers to take ineffective action against climate change by seeking to maintain the validity that ECS may likely currently be between 2 & 3.5C as expressly stated in his Ringberg presentation (found at the third link below). 

Stevens' Ringberg presentation (see first image) admits that the CMIP5 estimates of ECS have a comprehensive range of 2.08 to 4.67C with a median valued of 3.45C (which supports Gavin Schmidt's range of probably ECS values); nevertheless, his linear calculations of "Robust Feedbacks" indicate a likely range of only 2.2 to 3.4C (see the first image).  The second image indicates that Stevens' believes that the CMIP5 values are likely too high because he believes the models have too many shallow tropical clouds that dissipate with global warming, while his third image provides some selected evidence that the observed shallow tropical clouds are currently less evident in the sky by a factor of five as to that indicated by the CMIP5 projections.  In the fourth attached image, Stevens then proceeds to propose (not entirely convincingly as indicated by the question marks in his title) that this apparent inconsistency can be resolved by decreasing the amount of modeled negative forcing from anthropogenic aerosols.

Now, in addition to your (jai's) questioning of the efficacy of the 1880-1930 aerosols assumed by Stevens in his (2015), "Rethinking the lower bound on aerosol radiative forcing" paper, I would like to make the additional following points as to why policy makers should not accept his proposal that ECS is likely between 2 & 3.5C:

- He ignores the Schmidt et al 2015 Ringberg satellite findings that the high altitude tropical clouds are increasing due to deep atmospheric mixing (see also Sherwood et al 2014).

- He ignores the Falluso 2015 Ringberg finding that the recently reconstructed SLR data shows that between 1900 and 1990 more heat has been sequestered in the ocean than he assumes.

- He ignores Sherwood 2015 Ringberg findings that aerosols are masking radiative forcing over the Southern Ocean.

- He short-changes recent research that Asian anthropogenic aerosols are masking both Arctic Amplification and ENSO contributions to global warming (the ENSO masking helps to explain why the ocean has been sequestering more heat than previously expected due to more strong La Nina activity).

- He short-changes the non-linear effect of the tropical high altitude cloud cover on promoting high ECS values (see Geoffroy & Sherwood 2015 Ringberg).

I only hope that the first phase of the ACME project is completed in time for associate papers to be included in AR6, so that policy makers will not give inappropriate weight to such incomplete thinking as presented by Stevens (who is proposing that aerosol forcing is less negative than considered by CMIP5 and presumably by ACME):

Bjorn Stevens' statement against the denalist's distortion of his research findings:

http://www.mpimet.mpg.de/fileadmin/grafik/presse/News/AerosolForcing-Statement-BjornStevens.pdf

See also:
http://mediamatters.org/blog/2015/04/03/climate-scientist-no-my-study-is-not-a-death-bl/203166


Bjorn Stevens' Ringberg presentation entitled: "Some (not yet entirely convincing) reasons why 2.0 < ECS < 3.5" is linked below:

http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/Talks/Stevens_Ringberg_Talk.pdf

Best,
ASLR

[AbruptSLR]

The linked Wired article indicates that the Amazon Rainforest is getting "clobbered" harder than AR5 expected (which will likely increase the effective value of ECS in a relatively short period of time):

http://www.wired.com/2015/04/global-warming-already-clobbering-amazon/

Extract: "For now, the Amazon is still sucking up more carbon than it’s releasing. But the Rainfor data suggests that a tipping point is coming. As skeptics have long asserted and scientists themselves suspected, models of the future of Earth’s climate did indeed get it wrong. But not in the way anyone would hope. As Phillips puts it: They were “too optimistic.”"

[AbruptSLR]

The linked (open access) reference demonstrates that large declines (exceeding climate model projections) in NH snow cover extent from 1971 to 2014, have contributed to strong polar amplification (which will likely accelerate still further as Asian aerosols are reduced in the coming decades):

Marco A Hernández-Henríquez et al (2015), "Polar amplification and elevation-dependence in trends of Northern Hemisphere snow cover extent, 1971–2014", Environ. Res. Lett. 10 044010
doi:10.1088/1748-9326/10/4/044010


http://iopscience.iop.org/1748-9326/10/4/044010/article


Abstract: "Recent years (i.e., 2007–2014) have exhibited large declines in snow cover extent (SCE) in the Northern Hemisphere (NH), marked by earlier snowmelt in the springtime. In Northern latitudes, the snow-albedo feedback (SAF) is most pronounced in the spring and may be contributing to these decreasing trends in SCE. Rising surface air temperatures and changes in precipitation patterns could also vary the declining trends in SCE depending on latitude and elevation. Previous trend analyses of NH SCE are extended here to cover the period 1 October 1971 to 30 September 2014 using observed data from the National Oceanic and Atmospheric Administration snow chart climate data record. Trends in snow coverage (significant when p < 0.05) with latitude and elevation are investigated using the Mann–Kendall test. Over the 43 year period, strong polar amplification of negative trends in snow cover are observed. The majority of statistically significant negative trends are found in the mid- to high-latitudes, reaching a maximum reduction at 75.5°N. There is also elevation dependence of SCE over time as statistically significant negative trends occur at most elevations, with the strongest observed at 3950 m a.s.l. These significant negative trends exhibited in the mid- to high-latitudes and mid- to high-elevations provide evidence of polar amplification and elevation dependence of trends in snow cover in a warming climate, suggesting a leading role of the SAF on the recent retreat of NH snow cover."

[AbruptSLR]

While a few months old the following Skeptical Science post by Kevin Cowtan includes the following extract (and attached image, where the height of the bars indicates the relative importance of the factor in Cowtan's opinion) noting that climate sensitivity from the 20th century could exceed those from climate models and as my last post notes that the median value for ECS of the CMIP5 projections was 3.45C; this adds support to my contention that ECS may currently be 4C or greater.  Unfortunately, the Carbon Budget provided to policy makers by the IPCC is not based on the CMIP5 projections (which may likely be too low per Cowtan) but rather on IPCC expert evaluation of a likely range for TCRE (warming per 1000 PgC) of from 0.8 to 2.5C.  Therefore, our policy makers are likely not fully aware of the risks that they are exposing society to:

http://www.skepticalscience.com/kevin_cowtan_agu_fall_2014.html

Extract: "If we order the factors affecting climate sensitivity by their importance, the list probably looks like this:
1.   The size of the aerosol cooling effect.
2.   Coverage bias in the early temperature record.
3.   Thermal inertia.
4.   Hiatus factors (volcanoes, solar cycle and industrial emissions).
Put all of these together, and estimates of climate sensitivity from 20th century temperatures could exceed those from climate models. And given that transient sensitivity (TCR) is important for policy, we would expect political and public discourse to be dominated by those same factors."

Edit: I forgot to note that per the extracted comment by Robert Way (of Cowtan & Way) to Nic Lewis, from the linked RealClimate article, the global mean temperature coverage bias show that TCR/ECS may be 10% greater than values determined on uncorrected data (such as TCR/ECS values reported in AR5).

http://www.realclimate.org/index.php/archives/2014/10/climate-response-estimates-from-lewis-curry/

“There are three available datasets that go back to 1850. CW2014, Hadcrut4v2 and BEST. Both CW2014 and BEST show about 10% more warming using your preferred base and final periods (1859-1882; 1995-2011). Is the rationale for not including coverage bias or either of these datasets discussed in more detail anywhere?”

[AbruptSLR]

In Reply #780, I criticized AR5's likely TCRE (warming per 1000 PgC) range of 0.8 to 2.5 C for their Carbon Budget, as most likely being too low.  However, I believe that a further elaboration of reasons as to why AR5's Carbon Budget is insufficient guidance is warranted.  Besides, the influence of cloud altitude (particularly tropical thunderheads) [ala: Sherwood, Geoffroy, Marvel & others], coverage bias of the instrument record [ala: Cowtan & Way], masking influence of aerosols [ala Sherwood, Shindell & others], long-term sequesterization of heat in the ocean [ala: Fasullo (2015) Ringberg], Earth system state time (e.g. hiatus timing due to ENSO, PDO, volcanoes, solar cycles, etc.) [ala: Mann, English, Trenberth , & others] and lag-time [on the order of 20 to 50 years]; these reason include:

1. In Copenhagen many scientists advocated for the adoption of a 1.5C global mean temperature rise limit (while Hansen has promoted a 1C limit); which the state elite, to which the IPCC reports, rejected; not only for reasons of uncertainty, but also to limit liability lawsuits from under-developed countries who plan to file claims (to the developed countries) as soon as the limit is exceeded.

2. All scenarios to achieve a limit of 2C, or less, are highly dependent on the use of carbon capture & sequestration, CCS, negative emission technology, NET, and solar radiation management, SRM; all of which will be difficult to implement and all of which will have uncertain side-effects, which will increase societal risk compared to a policy of simply reducing GHG emissions.

3. Krasting, J. P., J. P. Dunne, E. Shevliakova, and R. J. Stouffer (2014), Trajectory sensitivity of the transient climate response to cumulative carbon emissions, Geophys. Res. Lett., 41, 2520–2527, doi:10.1002/2013GL059141; makes it explicitly clear that TCRE is highly dependent on the rate of carbon emissions (which Bjorn Stevens (2015) Ringberg totally ignored).  Using a ESM (Geophysical Fluid Dynamics Laboratory-ESM2G), Krasting et al found that TCRE ranged from 1.52 to 2.08C/1000 PgC for carbon emission rates ranging from 2 to 25 GtC/yr, where TCRE is largest for both low (2 GtC/yr) and high (25 GtC/yr) emissions and smallest for the recent/present-day emissions (5–10 GtC/yr).  Furthermore, Kasting et al state: " Unforced climate variability hinders precise estimates of TCRE for periods shorter than 50 years for emission rates near or smaller than present day values.  Even if carbon emissions would stop, the prior emissions pathways will affect the future climate responses."  I note that our current carbon emission rate is above 10 GtC per year (or above 36.7 CO2 equiv. per year), which per Krasting et al 2014 has a relatively low TCRE; but by about 2060 following RCP 8.5 the carbon emissions per year will be about 25 GtC per year (or about 91.75 CO2 equiv. per year), which had the highest TCRE evaluated by Krasting et al (also note that 1ppm Atmospheric CO2 ~ 2.12 GtCarbon).

4. TCR/ECS do not include the probable acceleration of many "slow response" positive feedback mechanisms this century (e.g.: carbon cycle changes, etc. [see other examples below])
4a. The following reference discusses a recent doubling of the carbon cycle sensitivity to tropical temperature variations (such as those induced by the ENSO cycle):
Xuhui Wang, Shilong Piao, Philippe Ciais, Pierre Friedlingstein, Ranga B. Myneni, Peter Cox, Martin Heimann, John Miller, Shushi Peng, Tao Wang, Hui Yang, Anping Chen. A two-fold increase of carbon cycle sensitivity to tropical temperature variations. Nature, 2014; DOI: 10.1038/nature12915


See also the discussion at:  http://www.independent.co.uk/news/science/climate-change-rainforest-absorption-of-co2-becoming-erratic-9086304.html

4b. The linked paper shows that climate sensitivity is likely higher than assumed in most prior GCM projections:

http://onlinelibrary.wiley.com/doi/10.1002/qj.2165/abstract;jsessionid=ED7BA33BAD69F5B1E7BCFD85EAC3DF89.d02t01

Previdi, M., B.G. Liepert, D. Peteet, J. Hansen, D.J. Beerling, A.J. Broccoli, S. Frolking, J.N. Galloway, M. Heimann, C. Le Quéré, S. Levitus, and V. Ramaswamy, 2013: Climate sensitivity in the Anthropocene. Q. J. R. Meteorol. Soc., 139, 1121-1131, doi:10.1002/qj.2165.

4c. The following linked reference indicates that most climate sensitivity feedback mechanisms are non-linear (particularly with regard to the influence of water vapor).

http://www.earth-syst-dynam.net/4/253/2013/esd-4-253-2013.html

Schaller, N., Cermak, J., Wild, M., and Knutti, R.: The sensitivity of the modeled energy budget and hydrological cycle to CO2 and solar forcing, Earth Syst. Dynam., 4, 253-266, doi:10.5194/esd-4-253-2013, 2013

4d. The following reference indicates that use of only an equilibrium climate sensitivity, ECS, value within a GCM is too simplistic to capture the influence of hydrologic cycle and its response to different types of forcing.  This implies that any GCM projections dependent on a simple ECS value should be given a greater range of uncertainty values; and Earth System Models should be calibrated to account for the different types of sensitivities to various types of forcings.

http://www.earth-syst-dynam-discuss.net/4/853/2013/esdd-4-853-2013.pdf


A simple explanation for the sensitivity of the hydrologic cycle to global climate change;
by: A. Kleidon and M. Renner; Earth Syst. Dynam. Discuss., 4, 853–868, 2013; www.earth-syst-dynam-discuss.net/4/853/2013/; doi:10.5194/esdd-4-853-2013

[AbruptSLR]

The first linked reference (by Gibson et al 2015) presents paleo-evidence that atmospheric teleconnections can lead to abrupt climate change. The second linked reference (by Barker et al 2015) indicates that numerous Dansgaard–Oeschger events (with abrupt climate change) were not exclusively triggered armadas of icebergs launched into the North Atlantic (which are not expected for our modern condition), but rather by nonlinear response of the atmospheric/oceanic system.  While these paleo-studies both consider Earth conditions different than those for modern times, nevertheless, they both demonstrate the strong nonlinearity of the atmospheric-oceanic system due to teleconnection of energy from the tropics to the polar regions.  As El Nino events, atmospheric river events, and hurricanes/cyclones/typhoons, can all teleconnect large amounts of energy from the tropics to the polar regions, I do not think that we should have too much confidence that the CMIP5 projections provide must assurance that we will not experience abrupt climate change by 2100 if we continue following a BAU pathway for even a few more decades.

First reference:

Gibson, K. A., R. C. Thunell, E. J. Tappa, L. C. Peterson, and M. McConnell (2015), "The influence of rapid, millennial scale climate change on nitrogen isotope dynamics of the Cariaco Basin during marine isotope stage 3", Paleoceanography, 30, 253–268. doi: 10.1002/2014PA002684.

http://onlinelibrary.wiley.com/doi/10.1002/2014PA002684/abstract

Abstract: "Understanding changes to the marine nitrogen cycle on millennial and shorter time scales can help determine the influence of rapid climate change on the fixed N pool and its sources and sinks. Rapid changes in denitrification have been observed in the eastern tropical North Pacific (ETNP) and Arabian Sea; however, millennial scale δ15N records in regions influenced by N2 fixation are sparse. We present a sedimentary δ15N record from the Cariaco Basin during marine isotope stage (MIS) 3 (~35–55 ka). The δ15N record displays a pattern of millennial scale variability that tracks the Greenland ice core Dansgaard-Oeschger cycles, with higher values observed during interstadial periods, lower values during stadial periods, and abrupt transitions in between. Conditions during interstadials are similar to those at present in the Cariaco Basin, with the sedimentary δ15N signal reflecting a combination of local processes and an imported regional signal. If interpreted to reflect regional processes, the interstadial δ15N values (average ~5.1‰) support the argument that N2 fixation did not increase in the tropical North Atlantic during the last glacial. The lower δ15N values during stadials, when lower sea level resulted in increased physical isolation of the basin, can be explained primarily by local processes. In spite of the importance of local processes, striking similarity is observed between the Cariaco record and millennial scale δ15N records from the ETNP and Arabian Sea. The apparent synchronicity of changes observed in all three regions suggests an atmospheric teleconnection between the three sites and high-latitude climate forcing during MIS 3."

Second reference:

Stephen Barker, James Chen, Xun Gong, Lukas Jonkers, Gregor Knorr and David Thornalley (2015), "Icebergs not the trigger for North Atlantic cold events", Nature, DOI 10.1038/nature14330

http://www.nature.com/nature/journal/v520/n7547/full/nature14330.html

Abstract: "Abrupt climate change is a ubiquitous feature of the Late Pleistocene epoch. In particular, the sequence of Dansgaard–Oeschger events (repeated transitions between warm interstadial and cold stadial conditions), as recorded by ice cores in Greenland, are thought to be linked to changes in the mode of overturning circulation in the Atlantic Ocean. Moreover, the observed correspondence between North Atlantic cold events and increased iceberg calving and dispersal from ice sheets surrounding the North Atlantic has inspired many ocean and climate modelling studies that make use of freshwater forcing scenarios to simulate abrupt change across the North Atlantic region and beyond. On the other hand, previous studies identified an apparent lag between North Atlantic cooling events and the appearance of ice-rafted debris over the last glacial cycle, leading to the hypothesis that iceberg discharge may be a consequence of stadial conditions rather than the cause. Here we further establish this relationship and demonstrate a systematic delay between pronounced surface cooling and the arrival of ice-rafted debris at a site southwest of Iceland over the past four glacial cycles, implying that in general icebergs arrived too late to have triggered cooling. Instead we suggest that—on the basis of our comparisons of ice-rafted debris and polar planktonic foraminifera—abrupt transitions to stadial conditions should be considered as a nonlinear response to more gradual cooling across the North Atlantic. Although the freshwater derived from melting icebergs may provide a positive feedback for enhancing and or prolonging stadial conditions, it does not trigger northern stadial events."

[AbruptSLR]

The linked article indicates that the albedo of Greenland has been dropping (see first image), much faster than projected by AR5 for all RCP scenarios.  This will clearly accelerate climate change above projections.

http://www.carbonbrief.org/blog/2015/04/darkening-ice-speeds-up-greenland-melt-new-research-suggests/

[jai mitchell]

The linked article indicates that the albedo of Greenland has been dropping (see first image), much faster than projected by AR5 for all RCP scenarios.  This will clearly accelerate climate change above projections.

http://www.carbonbrief.org/blog/2015/04/darkening-ice-speeds-up-greenland-melt-new-research-suggests/

if my understanding of the arctic effects of chinese sulfates is correct, we are going to see unprecedented melt this season. 

[Csnavywx]

Again, the biggest shortcomings in Stevens' work are the way he handles BC forcing and volcanic rebound forcing in the 1910-1950 period. He effectively waves them off. As a result, I can't recommend that approach over something like Wilcox et al (2013).

It's a more minor issue, but he should also really be using mean CCL (convective condensation level) height as the overwhelming cloud type in the tropics are cumiliform clouds and do not tend to form at the LCL unless there is moderate-strong low level forcing.

[AbruptSLR]

Again, the biggest shortcomings in Stevens' work are the way he handles BC forcing and volcanic rebound forcing in the 1910-1950 period. He effectively waves them off. As a result, I can't recommend that approach over something like Wilcox et al (2013).

It's a more minor issue, but he should also really be using mean CCL (convective condensation level) height as the overwhelming cloud type in the tropics are cumiliform clouds and do not tend to form at the LCL unless there is moderate-strong low level forcing.

Csnavywx,

Thanks for your insights. 

But your comments highlight for me that among other things one thing that particularly bothers me about the IPCC process, is that once papers like Stevens' get published in a peer reviewed journal they are then given equal weight as more conscientious works; which then has the effect of dragging down the mean value of climate sensitivity used on the Carbon Budget that influences policy makers. 

It seems to me that climate skeptics/denalists (Nic Lewis, etc.) are intentionally taking advantage of this loophole in the IPCC process to game the system to get the results that they want, rather than what nature has determined to be the case.

Best,
ASLR

[AbruptSLR]

The linked Lin et al (2015) reference states: "We find that the variations in the Brewer-Dobson circulation are strongly correlated with those in the tropical mean surface temperature through changes in the upper tropospheric temperature and zonal winds."  Therefore, if indeed Geoffroy & Sherwood (2015) Ringberg is correct and deep atmospheric convective mixing in the equatorial tropics is increasing (and will continue to increase) tropical surface temperatures with increasing global warming; then the Brewer-Dobson circulation will increasingly transfer this extract energy to poleward extratropical locations (see the linked Wiki article & extract & image of the Brewer-Dobson circulation), with continued anthropogenic global warming.  This helps to explain how increasing deep atmospheric convective mixing may contribute effectively to higher (say 4 to 5C mean ECS depending on period considered this century, which is more than AR5 assumes) ECS values.

http://en.wikipedia.org/wiki/Brewer-Dobson_circulation

Wiki extract about Brewer-Dobson circulation: "It is a simple circulation model that posits the existence of a slow current in the winter hemisphere which redistributes air from the tropics to the extratropics. The Brewer-Dobson circulation is driven by atmospheric waves and may be speeding up due to climate change."

Pu Lin, Yi Ming, V. Ramaswamy (2015), "Tropical climate change control of the lower stratospheric circulation", Geophysical Research Letters, DOI: 10.1002/2014GL062823


http://onlinelibrary.wiley.com/doi/10.1002/2014GL062823/abstract


Abstract: "The behavior of the Brewer-Dobson circulation is investigated using a suite of global climate model simulations with different forcing agents, in conjunction with observation-based analysis. We find that the variations in the Brewer-Dobson circulation are strongly correlated with those in the tropical mean surface temperature through changes in the upper tropospheric temperature and zonal winds. This correlation is seen on both interannual and multidecadal time scales, and holds for natural and forced variations alike. The circulation change is relatively insensitive to the spatial pattern of the forcings. Consistent changes in the Brewer-Dobson circulation with respect to those in the tropical mean surface temperature prevail across time scales and forcings, and constitute an important attribution element of the atmospheric adjustment to global climate change."

[Neven]

I saw this one today on Carbon Brief and thought it might fit in well (if not already mentioned somewhere):

Projections

Tedesco and his colleagues used models to see how Greenland ice sheet albedo could change in the future. Model projections suggest the ice sheet will continue to darken over this century. All the models and scenarios Tedesco ran showed a decrease in albedo, as you can see in the graph below. Brown shaded areas are where the projections overlap.



Observed and projected change in Greenland albedo changes, from 1990 to 2100. Red line shows satellite observations, and black line shows how the models reproduce the satellite observations (as a test of their accuracy). Blue, light green and red areas show albedo projections for three models, shading shows spread of results between a moderate (RCP4.5) and high emissions scenario (RCP8.5). Brown, dark green and purple areas show where the projections from different models overlap. Source: Tedesco et al. (2015).

The projections only account for the increasing grain size and exposure of bare ice, not the increase in particles of dust and soot on the surface. This means the projections probably underestimate the drop in albedo over this century, Tedesco says.

The satellite observations (red line) shows the albedo dropped very low in 2012, which was a record melt year for Greenland. Data collected since then suggest albedo has recovered in the last two years, with albedo in 2014 around the same level as 2011.

There are many processes that contribute to ice melt on Greenland, and Tedesco says his team can't yet calculate the specific contribution from the ice sheet getting darker. But they hope to in time for next year's EGU, he says.

[Csnavywx]

Again, the biggest shortcomings in Stevens' work are the way he handles BC forcing and volcanic rebound forcing in the 1910-1950 period. He effectively waves them off. As a result, I can't recommend that approach over something like Wilcox et al (2013).

It's a more minor issue, but he should also really be using mean CCL (convective condensation level) height as the overwhelming cloud type in the tropics are cumiliform clouds and do not tend to form at the LCL unless there is moderate-strong low level forcing.

Csnavywx,

Thanks for your insights. 

But your comments highlight for me that among other things one thing that particularly bothers me about the IPCC process, is that once papers like Stevens' get published in a peer reviewed journal they are then given equal weight as more conscientious works; which then has the effect of dragging down the mean value of climate sensitivity used on the Carbon Budget that influences policy makers. 

It seems to me that climate skeptics/denalists (Nic Lewis, etc.) are intentionally taking advantage of this loophole in the IPCC process to game the system to get the results that they want, rather than what nature has determined to be the case.

Best,
ASLR

What's particularly damning to me is that using Stevens' aerosol estimate with Lewis' methodology yields a ridiculously low ECS around 1.4C as a median estimate, which is completely inconsistent with both paleoclimate and recent observations, even using years during the "hiatus". This indicates to me that one of these is virtually certain to be wrong, and probably both are wrong. They simply can't both be right.

[AbruptSLR]

I saw this one today on Carbon Brief and thought it might fit in well (if not already mentioned somewhere):

Projections

Tedesco and his colleagues used models to see how Greenland ice sheet albedo could change in the future. Model projections suggest the ice sheet will continue to darken over this century. All the models and scenarios Tedesco ran showed a decrease in albedo, as you can see in the graph below. Brown shaded areas are where the projections overlap.



Observed and projected change in Greenland albedo changes, from 1990 to 2100. Red line shows satellite observations, and black line shows how the models reproduce the satellite observations (as a test of their accuracy). Blue, light green and red areas show albedo projections for three models, shading shows spread of results between a moderate (RCP4.5) and high emissions scenario (RCP8.5). Brown, dark green and purple areas show where the projections from different models overlap. Source: Tedesco et al. (2015).

The projections only account for the increasing grain size and exposure of bare ice, not the increase in particles of dust and soot on the surface. This means the projections probably underestimate the drop in albedo over this century, Tedesco says.

The satellite observations (red line) shows the albedo dropped very low in 2012, which was a record melt year for Greenland. Data collected since then suggest albedo has recovered in the last two years, with albedo in 2014 around the same level as 2011.

There are many processes that contribute to ice melt on Greenland, and Tedesco says his team can't yet calculate the specific contribution from the ice sheet getting darker. But they hope to in time for next year's EGU, he says.

In the linked article Dr. Marco Tedesco confirms that the already bad darkening of the GIS is projected to get worse (compared to the AR5 projections) with continued global warming:

http://www.ccny.cuny.edu/news/marco-tedesco-egu-vienna-conference.cfm

Extract: "Darkening of the Greenland Ice Sheet is projected to continue as a consequence of continued climate warming, Dr. Marco Tedesco, a City College of New York scientist, said at the European Geosciences Union (EGU) General Assembly in Vienna today."

[AbruptSLR]

Given the current discussion in the "Arctic Wildfire" thread, I thought that I would point out that peatlands are not limited to Arctic regions and contain fuels that make up nearly three-fourths of earth's land mass and are believed to be the largest emitter of carbon from wildfires to the atmosphere.  In addition to begin an underestimate source of GHG emissions in AR5, peat smoke also emits brown carbon that more strongly absorbs shorter light-wavelengths and/or near ultraviolet light than black carbon; and this fact is not considered at all by AR5.

http://www.sciencedaily.com/releases/2015/01/150116134537.htm

Summary: "Researchers are beginning a study of the climatic effects of peat fire emissions. "This project is going to provide the much-needed information on peat smoke aerosol properties for integration in satellite retrieval algorithms and climate models," the lead researcher says. "Based on my initial findings, I hypothesize the peat smoke is made up of brown carbon and not black carbon. Brown carbon is a class of organic carbon aerosol which, unlike black carbon, strongly absorbs incoming solar radiation in the shorter wavelengths, or near ultraviolet.""

The following second link provides a summary table of current & projected wildfire extents for different regions of the world:

http://www.earth-policy.org/images/uploads/graphs_tables/fire.htm

[jai mitchell]

fuels that make up nearly three-fourths of earth's land mass

this needs a slight clarification, I think   

[AbruptSLR]

fuels that make up nearly three-fourths of earth's land mass

this needs a slight clarification, I think   

I took the quote directly from this NASA grant page (see first link), without checking it; while the attached extract from the book at the second link indicates that peatlands make-up about 3.8% of the world's ice-free land area, which is closer to the current situation.  However, if you consider the melting of the permafrost (see the third link to a Wiki discussion of the permafrost) then this area of extent of burnable peatland could get much larger:

http://news.wustl.edu/news/Pages/nasa-grant-funds-peat-fire-research.aspx

Book reference on the Earth in transition including a discussion on peatlands:
https://books.google.com/books?id=CSHInNHPc_0C&pg=PA66&lpg=PA66&dq=peatland++three-fourths+of+earth%27s+land+mass&source=bl&ots=DXvBBqOAd0&sig=OwBzwXbHOqyNSUtS7EDL748poxc&hl=en&sa=X&ei=gHs1VanKD-HGygPE7IDYAQ&ved=0CCUQ6AEwAQ#v=onepage&q=peatland%20%20three-fourths%20of%20earth's%20land%20mass&f=false

http://en.wikipedia.org/wiki/Permafrost

[jai mitchell]

(perhaps you meant total non-frozen biomas carbon pool?) 

total land mass is a VERY large number, I have heard of 500+ gigatonnes of carbon contained in the boreal peat mass.  However, I would not compare it to the mass of the earth, or land or ocean, I would compare it to atmospheric abundance, emission scenarios and fossil fuel reserves.  The quote is 3/4 of total peat not 3/4 of total land mass.

according to this source total peat contains 600 Gt of carbon

http://pubman.mpdl.mpg.de/pubman/item/escidoc:2060512/component/escidoc:2062321/PAGESmagazine_2014%282%29_92_Yu.pdf

peatlands represent the largest carbon (c) pool in the terrestrial biosphere. In the form of peat (organic soils) they store at present ~600 Pg c, accumulated mostly since the Last Glacial Maximum.

also

Global Vulnerability of peatlands to fire and carbon loss

http://www.nature.com/ngeo/journal/v8/n1/full/ngeo2325.html

Turetsky et al. (2015)

abstract: Globally, the amount of carbon stored in peats exceeds that stored in vegetation and is similar in size to the current atmospheric carbon pool. Fire is a threat to many peat-rich biomes and has the potential to disturb these carbon stocks. Peat fires are dominated by smouldering combustion, which is ignited more readily than flaming combustion and can persist in wet conditions. In undisturbed peatlands, most of the peat carbon stock typically is protected from smouldering, and resistance to fire has led to a build-up of peat carbon storage in boreal and tropical regions over long timescales. But drying as a result of climate change and human activity lowers the water table in peatlands and increases the frequency and extent of peat fires. The combustion of deep peat affects older soil carbon that has not been part of the active carbon cycle for centuries to millennia, and thus will dictate the importance of peat fire emissions to the carbon cycle and feedbacks to the climate.

[crandles]

perhaps you meant

That

"These high-moisture-containing fuels make up nearly three-fourths of earth’s land mass "

seems to come from Beth Miller at Washington University in St. Louis
http://www.newswise.com/articles/peat-fire-emissions-may-shed-light-on-climate-change

bit of a difference between 3.8% and 75% oops
picked up from wrong line by mistake and failed to apply some common sense?

[AbruptSLR]

perhaps you meant

That

"These high-moisture-containing fuels make up nearly three-fourths of earth’s land mass "

seems to come from Beth Miller at Washington University in St. Louis
http://www.newswise.com/articles/peat-fire-emissions-may-shed-light-on-climate-change

bit of a difference between 3.8% and 75% oops
picked up from wrong line by mistake and failed to apply some common sense?

crandles,

While indeed I did pick-up and repeat the line: "These high-moisture-containing fuels make up nearly three-fourths of earth’s land mass ...."  As to whether I failed to apply common sense when I reposted it, or whether you are failing to apply common sense now, can be discussed over the next series of posts as I have very little time at the moment. 

Very likely, the phrase: "high-moisture-containing fuels" is not limited to peatlands and clearly includes the large amounts of organics contained in permafrost in the Arctic, Antarctic & alpine regions; and likely includes wetlands (note that scientists (such as Rajan Chakrabarty) applying for funding typically nuance their choice of words very carefully to put the burden on the reader to apply strict logic).  Furthermore, I suspect that when Rajan Chakrabarty cited "earth's land mass" he was referring to the volume of soil (see the Wiki definition of soil at the link below), based on the fact that he did not capitalize the "e" in earth and "earth" is a common name for soil.

http://en.wikipedia.org/wiki/Soil

Thus if we were to be charitable to Rajan Chakrabarty's point, the Earth's soil contains a high fraction of moist organic fuels that could burn to produce brown carbon instead of black carbon, as the Earth continues to warm and as permafrost (that contain moist organics to considerable depth) defrost, as ice-sheet retreat and as wetland dry-up.

Very best,
ASLR

[crandles]

I was attributing it as a mistake to Beth Miller. Did Rajan Chakrabarty produce that phrase? If so I may be mis-attributing it by not tracing it far enough.


I took 'earth's land mass' to mean area of land on earth (in which case 3.8% wouldn't be right either) but perhaps mass really did mean soil mass as you suggest. I added a question mark to 'failed to apply common sense' making it a question and your answer would seem to indicate possibly not. That does seem to be a interpretation that looks rather charitable.

[AbruptSLR]

I was attributing it as a mistake to Beth Miller. Did Rajan Chakrabarty produce that phrase? If so I may be mis-attributing it by not tracing it far enough.


I took 'earth's land mass' to mean area of land on earth (in which case 3.8% wouldn't be right either) but perhaps mass really did mean soil mass as you suggest. I added a question mark to 'failed to apply common sense' making it a question and your answer would seem to indicate possibly not. That does seem to be a interpretation that looks rather charitable.

While it is plausible that Beth Miller misinterpreted Rajan Chakrabarty's work, and that she (& I by extension) implied to the reader that 75% of the existing soil mass of the earth was peat (for which your/my extant non-frozen peat surface area value of 3.8% would be more relevant in the short-term); I believe that in the long-term (centuries) it is important to consider all of the Earth's soil with "high-moisture-containing fuel", as the permafrost (both NH & SH with different timeframes) & the wetlands are even more important plausible sources of brown carbon emissions with continued global warming.

The first link (and the first attached image) shows that:  "Permafrost comprises 24% of Northern Hemisphere land …" by surface area (not volume).  The second link (and abstract & second attached image) shows that there is substantial permafrost in Antarctica that may be exposed with continued warming.  The third link (& the third attached image & extract) shows that wetlands (swamps, marshes, lakes, etc.) comprise a large fraction of the Earth's surface area and this area is decreasing relatively rapidly due to human pressure that frequently drain wetlands and frequently burn the organics in the exposed land for farming purposes.

http://www.wunderground.com/resources/climate/melting_permafrost.asp

Extract: "Permafrost comprises 24% of Northern Hemisphere land (Figure 1), and is also found, to a lesser extent, in the Southern Hemisphere."

http://erth.waikato.ac.nz/antpas/pdf/BOCKHEIM-PRINT.pdf

Abstract: " Active-layer dynamics, permafrost and ground-ice characteristics, and selected periglacial features are summarized from recent published literature and unpublished data by the authors for three eco-climatic regions of continental Antarctica: the Antarctic Peninsula and its offshore islands (c. 61–72°S), maritime East Antarctica (c. 66–71°S), and the Transantarctic Mountains (c. 71–87°C). Active-layer thickness and depth to ice-cemented permafrost are related to regional climate, proximity to glaciers, and albedo of surface rocks. In the McMurdo Dry Valleys, the active layer is commonly underlain by dry permafrost, which can be detected only from frost tubes or temperature measurements.  Permafrost thickness ranges from zero near thermally stratified saline lakes in dry valleys and beneath parts of the Antarctic Ice Sheet to ~1000 m.  Permafrost temperature measurements are scant and range between –14 and –24°C at a depth of 50 m. Ground ice is present as rock glaciers along the polar plateau and in upland valleys and as ice-cored moraines, buried glacial ice, and ice wedges near the coast. Cryoplanation and nivation are evident along the Antarctic Peninsula. Recommendations are made for future periglacial work in the region."

Caption for second image: "The map shows permafrost distribution in continental Antarctica and locations of areas mentioned in the text. Permafrost exists throughout the ice-free areas (shown in black). Subglacial permafrost beneath the Antarctic ice sheet may be restricted to the shaded areas.43 Subglacial lakes are depicted with a cross; ice coring sites in Marie Byrd Land are identified with a circle containing a dot; and the Taylor Dome borehole is denoted by a triangle with a dot (base map after Bockheim7). The –8°C and –1°C mean annual air temperature isotherms are taken from Weyandt."

http://phys.org/news/2012-05-population-pressure-impacts-world-wetlands.html

Extract: "The area of the globe covered by wetlands (swamps, marshes, lakes, etc.) has dropped by 6% in fifteen years. This decline is particularly severe in tropical and subtropical regions, and in areas that have experienced the largest increases in population in recent decades. These are the conclusions of a study conducted by CNRS and IRD researchers from the Laboratoire d'étude du rayonnement et de la matière en astrophysique, Laboratoire d'études en géophysique et oceanography spatiales and the start-up Estellus. To obtain these results, the scientists performed the first worldwide mapping of the wetlands and their temporal dynamics, for the years 1993 to 2007. This study, which has just been published in the journal Geophysical Research Letters, emphasizes the impact of population pressure on water cycles.

Caption for third image: "Areas of the world covered by wetlands. Data shown is the annual average for the period between 1993 and 2007, estimated from satellite data (areas are given in km2; each pixel represents 773km2)."


see also:
Changes in land surface water dynamics since the 1990s and relation to population pressure, Prigent, C., F. Papa, et al., Geophys. Res. Lett., doi:10.1029/2012GL051276 , (2012).

http://www.sciencedaily.com/releases/2012/05/120511122101.htm

[AbruptSLR]

Climate change skeptics frequently point to the recent bloom of vegetation (including in degrading permafrost regions) due to recent global warming and increased atmospheric CO₂ concentrations; however, the linked reference indicates that limited nutrients may keep plants from growing as fast as scientists thought in AR5 (see also the second link & extract).  Furthermore, while not discussed in this reference the recent acceleration of shrub growth in degrading permafrost areas is both increasing albedo and increasing the risks of associated wildfires, both of which will likely accelerate the degradation of the permafrost and increase the risk that this moist organic rich soil could burn and emit brown carbon.

William R. Wieder, Cory C. Cleveland, W. Kolby Smith & Katherine Todd-Brown (2015), "Future productivity and carbon storage limited by terrestrial nutrient availability", Nature Geoscience, doi:10.1038/ngeo2413

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2413.html


Abstract: "The size of the terrestrial sink remains uncertain. This uncertainty presents a challenge for projecting future climate–carbon cycle feedbacks. Terrestrial carbon storage is dependent on the availability of nitrogen for plant growth, and nitrogen limitation is increasingly included in global models. Widespread phosphorus limitation in terrestrial ecosystems may also strongly regulate the global carbon cycle, but explicit considerations of phosphorus limitation in global models are uncommon. Here we use global state-of-the-art coupled carbon–climate model projections of terrestrial net primary productivity and carbon storage from 1860–2100; estimates of annual new nutrient inputs from deposition, nitrogen fixation, and weathering; and estimates of carbon allocation and stoichiometry to evaluate how simulated CO2 fertilization effects could be constrained by nutrient availability. We find that the nutrients required for the projected increases in net primary productivity greatly exceed estimated nutrient supply rates, suggesting that projected productivity increases may be unrealistically high. Accounting for nitrogen and nitrogen–phosphorus limitation lowers projected end-of-century estimates of net primary productivity by 19% and 25%, respectively, and turns the land surface into a net source of CO2 by 2100. We conclude that potential effects of nutrient limitation must be considered in estimates of the terrestrial carbon sink strength through the twenty-first century."

See also:
http://news.sciencemag.org/climate/2015/04/plants-may-not-protect-us-against-climate-change

Extract: "Plants are one of the last bulwarks against climate change. They feed on carbon dioxide, growing faster and absorbing more of the greenhouse gas as humans produce it. But a new study finds that limited nutrients may keep plants from growing as fast as scientists thought, leading to more global warming than some climate models had predicted by 2100."