Conservative Scientists & its Consequences

[AbruptSLR]

Climate sensitivity under-estimated?
http://onlinelibrary.wiley.com/doi/10.1002/2015GL064119/abstract?utm_content=buffer3428e&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

"Despite decades of climate research and model development, two outstanding problems still plague the latest global climate models (GCMs): The double-intertropical convergence zone (ITCZ) bias and the 2−5°C spread of equilibrium climate sensitivity (ECS). Here we show that the double-ITCZ bias and ECS in 44 GCMs from Coupled Model Intercomparison Project Phases 3/5 are negatively correlated. The models with weak (strong) double-ITCZ biases have high (low) ECS values of ~4.1(2.2)°C. This indicates that the double-ITCZ bias is a new emergent constraint for ECS based on which ECS might be in the higher end of its range (~4.0°C) and most models might have underestimated ECS. In addition, we argue that the double-ITCZ bias can physically affect both cloud and water vapor feedbacks (thus ECS) and is a more easily measured emergent constraint for ECS than previous ones. It can be used as a performance metric for evaluating and comparing different GCMs."

Lennart,

It is interesting that the research presented by Andrews et al at the Ringberg 2015 workshop both shows that models that more accurately match the Eastern Pacific SST record associate with El Nino events (see the center panel in the attached image) result in projected values of ECS of about 5C.  Furthermore, Andrews et al (2015) conclude that: "... emergent constraints do not rely on simple linear feedback model, and give higher ECS estimates (e.g. Sherwood et al, Fasullo & Trenberth), unifies models and various observational ECS estimates ..."

http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/Talks/Andrews_23032015.pdf

While such preliminary findings come together with uncertainties; nevertheless, the support the concern that as we now in a phase of increasingly positive PDO condition, that at the effective ECS values could likely move toward the high end of estimates.

[Laurent]

And this is really where we have our problem with you.  Place a glass of ice water under a heat lamp.  place a thermometer inside that water glass.

I guarantee you that that glass will be at zero degrees centigrade until the moment the last bit of ice melts.  Then it will start to rise rapidly.

Does the models take care of that ? The reality is that the glass is so big that it does not melt completely at once, but on the spots that do melt completely then the temps are rising fast and high in temps. So I see it a positive feedback if the models do not take care of that. (Just my 2 cents, trying to follow from far away)

[jai mitchell]

And this is really where we have our problem with you.  Place a glass of ice water under a heat lamp.  place a thermometer inside that water glass.

I guarantee you that that glass will be at zero degrees centigrade until the moment the last bit of ice melts.  Then it will start to rise rapidly.

Does the models take care of that ? The reality is that the glass is so big that it does not melt completely at once, but on the spots that do melt completely then the temps are rising fast and high in temps. So I see it a positive feedback if the models do not take care of that. (Just my 2 cents, trying to follow from far away)

Only recently has NASA determined the change in absorbed solar radiation.  Since the models show only regional forcing effects and hold sea ice to be largely present though 2060, I highly doubt that the solstice ice-free system is being correctly modeled.

http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4245

[AbruptSLR]

Per the following article, US Oil & Gas related methane emissions are rising, when the lower RCP scenarios assume that they should already be falling; showing that scientists err on the side of least drama when projection anthropogenic radiative forcing:

http://theenergycollective.com/edfenergyex/2217976/methane-emissions-oil-gas-are-rise-confirm-latest-epa-data

[jai mitchell]

climate crocks produced this very good video to help explain the background and science of what is happening in the arctic today.

[AbruptSLR]

The linked Alley et al (2015) reference states (see extract) that if/when the Thwaites Glacier reaches conditions that will support a sustained Jakobshavn-type retreat mechanism that the WAIS could collapse on a decadal timescale.  Furthmore, Pollard, DeConto & Alley (2015) doi:10.1016/j.epsl.2014.12.035, so that mid-Pliocene like conditions are sufficient to trigger such a decadal timeframe collapse of the WAIS; and as I have presented considerable evidence that ECS may already be around 4.1C, and as Mann (2014) implies that for such an ECS the Earth could reach mid-Pliocene like conditions circa 2040.  Therefore, in addition to the probable reduction in Arctic albedo (including the reduction in Greenland albedo that Neven points to) that jai provides evidence for; it is also quite plausible that before 2100 climate models will need to add the change in albedo from a WAIS collapse to their projections of effective ECS.

Alley, R.B., S. Anandakrishnan. K. Christianson, H.J. Horgan, A. Muto, B.R. Parizek, D. Pollard and R.T. Walker (2015) "Oceanic forcing of ice-sheet retreat: West Antarctica and more", Ann. Rev. Earth Plan. Sci., 43, 7.1-7.25, doi:10.1146/annurev-earth-060614-105344.



http://www.annualreviews.org/doi/abs/10.1146/annurev-earth-060614-105344?journalCode=earth


Extract: "If Thwaites Glacier experiences a sustained Jakobshavn-type ice-shelf loss and retreats into the central basins beneath the West Antarctic Ice Sheet that reach >2,000 m below sea level, the resulting cliff would almost surely be highly unstable. If any mélange produced were sufficiently weak, the resulting cliff failure might cause the glacier to retreat much more rapidly than simulated by models lacking this process. Pollard et al. (2014) found that a parameterization for this process increased the instability and collapse rate of the West Antarctic Ice Sheet and of marine portions of the East Antarctic Ice Sheet, with this parameterization and the forcing adopted causing West Antarctic Ice Sheet collapse to occur on decadal timescales once initiated. No fully physical model now exists that includes this process, and given the dependence on poorly known fracture mechanics of ice, a quantitatively well-constrained model appears unlikely in the near future."

[Michael Hauber]

The 3.0 Watts per meter squared is the value from the referenced paper (really, this is the fourth time you have been shown this now!)  It is the value of forcing that occurs if one completely removes all arctic sea ice from the models for a full year.  Since the amount of forcing due to a total loss of sea ice by June 21 is a significant portion of that forcing I estimate the forcing value to be about 2.2 Watts per meter squared.

really, why do I even bother talking to you when you don't bother to read the things I write or the papers that I share with you to show the scientific background to what I am saying?

Thanks for answering my question on where the 2.2 came from.  There was no need to be rude about it.

   

• Reduction in Ocean DMS production - .4C
• Reduction in Lowngwave IR emissivity of ice in arctic - .13C
• Loss of the Amazon Forest - .5C
• Accelerated loss of permafrost due to sea ice loss (with microbial decomposition) - .7C by 2100
• Loss of boreal forest and boreal peat - .4C in black carbon and GHG
• Decreased arctic ocean albedo due to algae increase - .3C
• total loss of arctic summer solstice sea ice by 2065 - 1.8C

you are trying to argue a small portion of this list,

Because the warming for loss of arctic summer sea ice is obviously wrong.  I'm currently not interested in looking at the other issues.

you decide to move the goalposts and argue about TCR when you lose the argument about ECS and refuse to acknowledge when you are being corrected in your arguments.

You show you have no idea of the definition of equilibrium climate sensitivity when you use it to calculate the amount of warming for loss of sea ice by 2065.

Once its all melted there is no more albedo reduction, and so no further reasons for the temperature to go up except lags, so the temperature increase will gradually approach equilibrium.

And this is really where we have our problem with you.  Place a glass of ice water under a heat lamp.  place a thermometer inside that water glass.

I guarantee you that that glass will be at zero degrees centigrade until the moment the last bit of ice melts.  Then it will start to rise rapidly.

The portion of the globes energy balance that is tied up in melting sea ice is insignificant.  When this energy is diverted from melting sea ice to raising temperature the temperature increase will not be noticeable.  Assume the Arctic is on average 2 meters of sea ice and assume it all melts over 10 years.  That is 16000 joules of energy/cm 2 in total energy.  For an Arctic area of 10m kms, over earth area of 500m sqkm that ends up at 0.01 w/m2 of extra energy available once the ice stops melting.  That will raise the global temperature by about 0.002 degrees.

If you have a glass of ice under a heat lamp and it takes years for that ice to melt, do you think that the temperature of the glass will rise rapidly after it finishes melting?

[Michael Hauber]

climate crocks produced this very good video to help explain the background and science of what is happening in the arctic today.

That is what it looks like if we compare to the 20007 model runs.  In contrast the latest CMIP5 model runs show much faster loss of sea ice.  In particular they show ice free in September from about 2050, whereas the 2007 model runs show ice conditions still 4 million sqkm in 2050.  The Arctic sea ice is tracking the CMIP5 model runs much more closely (still maybe 10% too slow).  Hezel et al shows comparison of CMIP5 projections vs historical.

[Michael Hauber]

Three more papers showing evidence of lower sensitivity or negative feedbacks:

A large ozone-circulation feedback and its implications for global warming assessments

Ozone levels are usually prescribed in model runs.  If the ozone response is instead included as a potential feedback, then the warming response for x4 Co2 after 75 years is reduced by 1 degree.

Recent reversal in loss of global terrestrial biomass

Since 1993 we have been losing above ground carbon (i.e. trees) on average.  Since 2003 above ground carbon has increased, due to a reduction in deforestation, and increased biomass in north Australia and South Africa associated with increased rainfall.  I know that at least for north Australia there is a reasonable argument that the rainfall increase is AGW related (but it could be natural variation, models simulate a much weaker rainfall increase than is being observed.)  If the rainfall increase in North Australia is AGW related this means we have a negative feedback.

Also note above ground carbon is not the same as permafrost etc, so this doesn't mean we are not losing permafrost carbon etc.

Equilibrium climate sensitivity in light of observations over the warming hiatus

This paper calculates sensitivity with an energy balance model.  It shows that if the data used is varied from up to 1998 to up to more recent, that the calculated climate sensitivity reduces from 2.8 to 2.5.  Observations up to 2011 'effectively eliminate ECS values greater than 4'.  In contrast the lower range estimate of climate sensitivity is unchanged from close to 2 as data up to 2011 is included in the model. 

Recent research has shown that models which give a more accurate presentation of clouds produce a higher climate sensitivity.  The recently discussed paper on the double ITCZ seems to be a variation on this issue, as the effect is likely tied up with cloud and water vapor processes.  However the energy balance model results show that models with a lower climate sensitivity are going to give a better match to global temperature trends.  Intuitively I'd expect the match to global temperature trends to be more significant and climate sensitivity to be in the lower range, however we have a good explanation of this contradiction there will be uncertainty as to which method for estimating climate sensitivity is more accurate.

[jai mitchell]

336,000 joules to melt one kg of ice.

one cubic meter of ice weighs 1000 kg
one square meter of an ice sheet that is 2 meters thick weighs 2,000 kg.

Total energy to melt that square meter of ice sheet (neglecting energy to warm ice to the point of melt)  = 672,000,000 joules

specific heat capacity of water = 4,181.3 joules per kg to raise ocean one degree C. 
specific heat capacity of air at 1 atmosphere = 1,006.1 joules per kg to raise air one degree C

according to NASA the change in insolation in the Beaufort Sea due to ice loss from JUNE JULY and AUGUST is 45 Watts per square meter  that equals 349,920,000 additional joules of energy per meter, deposited in those regions for those months.

[AbruptSLR]

Three more papers showing evidence of lower sensitivity or negative feedbacks:

A large ozone-circulation feedback and its implications for global warming assessments

Ozone levels are usually prescribed in model runs.  If the ozone response is instead included as a potential feedback, then the warming response for x4 Co2 after 75 years is reduced by 1 degree.

Recent reversal in loss of global terrestrial biomass


Since 1993 we have been losing above ground carbon (i.e. trees) on average.  Since 2003 above ground carbon has increased, due to a reduction in deforestation, and increased biomass in north Australia and South Africa associated with increased rainfall.  I know that at least for north Australia there is a reasonable argument that the rainfall increase is AGW related (but it could be natural variation, models simulate a much weaker rainfall increase than is being observed.)  If the rainfall increase in North Australia is AGW related this means we have a negative feedback.

Also note above ground carbon is not the same as permafrost etc, so this doesn't mean we are not losing permafrost carbon etc.

Equilibrium climate sensitivity in light of observations over the warming hiatus

This paper calculates sensitivity with an energy balance model.  It shows that if the data used is varied from up to 1998 to up to more recent, that the calculated climate sensitivity reduces from 2.8 to 2.5.  Observations up to 2011 'effectively eliminate ECS values greater than 4'.  In contrast the lower range estimate of climate sensitivity is unchanged from close to 2 as data up to 2011 is included in the model. 

Recent research has shown that models which give a more accurate presentation of clouds produce a higher climate sensitivity.  The recently discussed paper on the double ITCZ seems to be a variation on this issue, as the effect is likely tied up with cloud and water vapor processes.  However the energy balance model results show that models with a lower climate sensitivity are going to give a better match to global temperature trends.  Intuitively I'd expect the match to global temperature trends to be more significant and climate sensitivity to be in the lower range, however we have a good explanation of this contradiction there will be uncertainty as to which method for estimating climate sensitivity is more accurate.

MH,

Thank you for the linked references; however, I have the following responses:

First, as per the first two linked articles below studying the impacts of stratospheric ozone is complex & it is not clear to me that the research by Peer J. Nowack, N. Luke Abraham, Amanda C. Maycock, Peter Braesicke, Jonathan M. Gregory, Manoj M. Joshi, Annette Osprey & John A. Pyle  (2015), "A large ozone-circulation feedback and its implications for global warming assessments", Nature Climate Change, Volume: 5, Pages: 41–45, doi:10.1038/nclimate2451; indicates in any way that climate sensitivity tends towards the low end of the uncertainty range:

http://www.giss.nasa.gov/research/features/200402_tango/

http://www.ucsusa.org/global_warming/science_and_impacts/science/ozone-hole-and-gw-faq.html#.VUcoN6Pn9Ms

Second, per the following linked article by James Hansen, it is a Faustian Bargain to rely on the recent increase in aboveground biomass carbon (as documented by Yi Y. Liu, Albert I. J. M. van Dijk, Richard A. M. de Jeu, Josep G. Canadell, Matthew F. McCabe, Jason P. Evans & Guojie Wang  (2015), "Recent reversal in loss of global terrestrial biomass", Nature Climate Change, Volume: 5, Pages: 470–474, doi:10.1038/nclimate2581) as any indications that the effective ECS might range to the low end of the uncertainty range:

http://www.columbia.edu/~jeh1/mailings/2013/20130329_FaustianBargain.pdf

Third (regarding 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, Volume: 5, Pages: 449–453, doi:10.1038/nclimate2573), I believe that relying on the impacts of the recent ENSO phase driven hiatus period to indicate that climate sensitivity will remain near the low end of the uncertainty range is even more of a Faustian Bargain than relying on the recent increase in aboveground biomass carbon. 
ASLR

[BornFromTheVoid]

/r/science on reddit is hosting an AMA (questions and answers session) with John Cook today.

https://www.reddit.com/r/science/comments/34tcge/science_ama_series_i_am_john_cook_climate_change/

Hi r/science, I study Climate Change Science and the psychology surrounding it. I co-authored the college textbook Climate Change Science: A Modern Synthesis, and the book Climate Change Denial: Heads in the Sand. I've published papers on scientific consensus, misinformation, agnotology-based learning and the psychology of climate change. I'm currently completing a doctorate in cognitive psychology, researching the psychology of consensus and the efficacy of inoculation against misinformation.
I co-authored the 2011 book Climate Change Denial: Heads in the Sand with Haydn Washington, and the 2013 college textbook Climate Change Science: A Modern Synthesis with Tom Farmer. I also lead-authored the paper Quantifying the Consensus on anthropogenic global warming in the scientific literature, which was tweeted by President Obama and was awarded the best paper published in Environmental Research Letters in 2013. In 2014, I won an award for Best Australian Science Writing, published by the University of New South Wales.
I am currently completing a PhD in cognitive psychology, researching how people think about climate change. I'm also teaching a MOOC (Massive Online Open Course), Making Sense of Climate Science Denial, which started last week.
I'll be back at 5pm EDT (2 pm PDT, 11 pm UTC) to answer your questions, Ask Me Anything!

[jai mitchell]

The Arctic sea ice is tracking the CMIP5 model runs much more closely (still maybe 10% too slow).  Hezel et al shows comparison of CMIP5 projections vs historical.

This is interesting and I must thank you for showing some documentation that (kind of) supports your perspective. 

Here are the graphics from the paper you cite (Hezel et. al. (2014) Modeled Arctic sea ice evolution through 2300 in CMIP5 extended RCPs

The first is the modeled sea ice extent.  It is important to see that the CMIP5 multi-model mean (the red curve for RCP 8.5) starts out below the observed extent in previous years and ends up above the observed extent line in current years.



What is even more interesting from this paper (and extremely thread topic relevant) is that there is a model run that is at the extreme top of the range.  For September sea ice minimum extent it shows that current sea ice minimums are 11 Million square kilometers.  Now this is interesting, since even in 1979 the minimum extent was slightly over half that value. 

AND YET the authors decided to include this model run in the scenario which moved the CMIP5 model average run higher.  This model run should not have been included in the mean.

So the models for extent are certainly overestimating future values and the multimodel mean value includes an outlier that has absolutely NO objective scientific basis for inclusion in the mean.  Even if you meant to say that the model runs UNDERESTIMATE ice loss by 10% (It seems that you intended to say it OVERESTIMATES) this shows that the models underrepresent future ice loss by closer to 40%.  AND even if the outlier model run is excluded the MMM (multi-model mean) would still overestimate sea ice extent by 20%.

This is the September ice volume chart, it shows even more striking departure from the modeled mean.



What is striking about this display is that none of the models are even close to approximate correlation to observed values.  The models that show recent values hindcast much lower historic values.  Models that have good hindcast results end up with much higher near term values.

In addition the variation of the models shows that the multi-model mean has very high statistical uncertainty as each of those models exists within a range of probability outcomes.

Finally, and this is where the crux lies, the CMIP5 runs does not include the appropriate anthropogenic aerosol forcing values that have been identified as having MASSIVE regional (negative) forcing effects in the arctic that are far different from the modeled effects in lower latitudes.  See: Zhao & Garrett (2015)  http://onlinelibrary.wiley.com/doi/10.1002/2014GL062015/full 

During episodes of high surface haze aerosol concentrations and cloudy skies, both the net warming and net cooling are amplified, ranging from +12.2 Wm−2 in February to −11.8 Wm−2 in August.

This anthropogenic aerosol forcing effect is also evidenced from the historical trends.

[Michael Hauber]

336,000 joules to melt one kg of ice.

one cubic meter of ice weighs 1000 kg
one square meter of an ice sheet that is 2 meters thick weighs 2,000 kg.

Total energy to melt that square meter of ice sheet (neglecting energy to warm ice to the point of melt)  = 672,000,000 joules

specific heat capacity of water = 4,181.3 joules per kg to raise ocean one degree C. 
specific heat capacity of air at 1 atmosphere = 1,006.1 joules per kg to raise air one degree C

according to NASA the change in insolation in the Beaufort Sea due to ice loss from JUNE JULY and AUGUST is 45 Watts per square meter  that equals 349,920,000 additional joules of energy per meter, deposited in those regions for those months.

And when you include the insolation for the other parts of the Arctic, consider both positive and negative feedbacks, and what happens for the rest of the year and average it out for the entire globe does it come out at 3w/m2?

[jai mitchell]

336,000 joules to melt one kg of ice.

one cubic meter of ice weighs 1000 kg
one square meter of an ice sheet that is 2 meters thick weighs 2,000 kg.

Total energy to melt that square meter of ice sheet (neglecting energy to warm ice to the point of melt)  = 672,000,000 joules

specific heat capacity of water = 4,181.3 joules per kg to raise ocean one degree C. 
specific heat capacity of air at 1 atmosphere = 1,006.1 joules per kg to raise air one degree C

according to NASA the change in insolation in the Beaufort Sea due to ice loss from JUNE JULY and AUGUST is 45 Watts per square meter  that equals 349,920,000 additional joules of energy per meter, deposited in those regions for those months.

And when you include the insolation for the other parts of the Arctic, consider both positive and negative feedbacks, and what happens for the rest of the year and average it out for the entire globe does it come out at 3w/m2?

Yes but this is if there was no ice for the entire year.

In our model, nearly one-third of the change in the climate feedback parameter caused by sea ice response is due to the longwave component of this feedback parameter. Furthermore the contribution of sea ice response to the climate feedback parameter can be decomposed into two terms, one related to changes in sea ice area with increasing temperature and another related to changes in sea ice radiative forcing per unit change in sea ice area.

Results obtained here indicate that in this configuration of CESM (CAM4 coupled to a slab ocean and the dynamic–thermodynamic sea ice model CICE4), approximately 3 × 1012 m2 of sea ice is lost for each kelvin of global mean warming and approximately 0.1 W m−2 of “sea ice radiative forcing” is produced by each 1012 m2 of sea ice loss, yielding a value of −0.3 W m−2 K−1 for the sea ice contribution to the overall climate feedback parameter. Because sea ice area in the 1×CO2 control simulation is approximately 30 × 1012 m2, this suggests that complete loss of all sea ice from the 1×CO2 state would produce a radiative forcing of about 3 W m−2, which is somewhat less than, but of the same order of magnitude as, the regressed radiative forcing from a doubling of atmospheric CO2.

However, it is not clear how their model treats the far infrared spectrum, since the discovery of open water being less radiative than sea ice for that spectrum then it is likely that they did not capture that effect in the model and the longwave feedback will add more positive forcing.  The 2.2 Watts per meter squared for June 21 sea ice loss is also expecting significant extent loss starting in early may so, as the sun rises, albedo is already being affected significantly. 

In addition, just a SUMMER ice free arctic is shown to produce a forcing of 75 Watts per meter squared of regional forcing in CMIP5 model revisions.   http://onlinelibrary.wiley.com/doi/10.1002/grl.50768/abstract?wol1URL=/doi/10.1002/grl.50768/abstract

Karlsson & Svenson (2013)
Consequences of poor representation of Arctic sea-ice albedo and cloud-radiation interactions in the CMIP5 model ensemble

abstract: 

    First published: 19 August 2013Full publication history
    DOI: 10.1002/grl.50768View/save citation
    Cited by: 5 articlesRefresh citation countCiting literature
    Article has an altmetric score of 15

Abstract

[1] Clouds significantly influence the Arctic surface energy budget and a realistic representation of this impact is a key for proper simulation of the present-day and future climate. Considerable across-model spread in cloud variables remains in the fifth phase of Coupled Model Intercomparison Project ensemble and partly explains the substantial across-model spread in the surface radiative effect of the clouds. In summer, the extensive model differences in sea-ice albedo, which sets the potential of the cloud-albedo effect, are strongly positively correlated to their cloud radiative effect. This indicates that the model's sea-ice albedo not only determines the amount, but also the sign of its cloud radiative effect. The analysis further suggests that the present-day annual amplitude of sea-ice cover depends inversely on the model's sea-ice albedo. Given the present-day across-model spread in sea-ice albedo and coverage, a transition to a summer ice-free Arctic ocean translates to a model-span of increased surface shortwave absorption of about 75 W m−2.

[Michael Hauber]

First, as per the first two linked articles below studying the impacts of stratospheric ozone is complex & it is not clear to me that the research by Peer J. Nowack, N. Luke Abraham, Amanda C. Maycock, Peter Braesicke, Jonathan M. Gregory, Manoj M. Joshi, Annette Osprey & John A. Pyle  (2015), "A large ozone-circulation feedback and its implications for global warming assessments", Nature Climate Change, Volume: 5, Pages: 41–45, doi:10.1038/nclimate2451; indicates in any way that climate sensitivity tends towards the low end of the uncertainty range:

http://www.giss.nasa.gov/research/features/200402_tango/

http://www.ucsusa.org/global_warming/science_and_impacts/science/ozone-hole-and-gw-faq.html#.VUcoN6Pn9Ms

The paper finds 20% less warming after 75 years with the ozone effect, compared to without it.  That could translate very roughly to a 0.5 degree reduction in climate sensitivity.  I do have some skepticism as to whether such a large effect could really be missed after decades of climate research.  I also note there may be similar issues to the lack of inclusion of methane feedbacks in IPCC projections.  While the model runs do not explicitly include the ozone calculations, they do include a prescribed ozone concentration, which may indirectly account for some of this effect.

[/quote]
Second, per the following linked article by James Hansen, it is a Faustian Bargain to rely on the recent increase in aboveground biomass carbon (as documented by Yi Y. Liu, Albert I. J. M. van Dijk, Richard A. M. de Jeu, Josep G. Canadell, Matthew F. McCabe, Jason P. Evans & Guojie Wang  (2015), "Recent reversal in loss of global terrestrial biomass", Nature Climate Change, Volume: 5, Pages: 470–474, doi:10.1038/nclimate2581) as any indications that the effective ECS might range to the low end of the uncertainty range:

http://www.columbia.edu/~jeh1/mailings/2013/20130329_FaustianBargain.pdf
[/quote]
Aerosol cooling is a clear faustian bargain issue - there is no reasonable doubt (that I know of) that once coal burning stops the aerosols will clear and the warming that is hidden by aerosols will be realised. 

The situation with above ground carbon is not so clear.  There is no definite reason to expect that above ground carbon sequestered due to carbon dioxide fertilisation will not remain for as long as the extra carbon dioxide will remain in the air.  However this storage is certainly not reliable and it could change in the future.  For instance drought effects could overtake Co2 fertilisation effects.  Also if Co2 effects are causing an increase in above ground carbon in forests this carbon may be lost again to future deforestation.

Third (regarding 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, Volume: 5, Pages: 449–453, doi:10.1038/nclimate2573), I believe that relying on the impacts of the recent ENSO phase driven hiatus period to indicate that climate sensitivity will remain near the low end of the uncertainty range is even more of a Faustian Bargain than relying on the recent increase in aboveground biomass carbon. 
ASLR

The study does not say that the hiatus period supports only a climate sensitivity near the low end.  It says that the hiatus period suggests that a climate sensitivity near the high end is unlikely.  It specifically states that a climate sensitivity near the middle range is still quite consistent with the hiatus period.

I certainly would not use any of these papers (or all three together) to argue that sensitivity is in the low end of the range, but I do hold them up as examples of research that is providing evidence of a lower sensitivity.  My claim is that some research gives evidence of a higher sensitivity, some for a lower.  An unbiased assessment of climate sensitivity should consider both types of paper, and not just the papers that fit a preconceived belief of either a high or low climate sensitivity.

[AbruptSLR]

MH,

To briefly respond to your Reply #915.  We can both rest assured that the modelers are doing their best to include all appropriate positive and negative feedbacks, and that when the first phase of the ACME projections are issued around 2017 they will address all of your areas of concern to the best of their abilities.

That said, the ozone model results you cite do not appear to consider the chemistry of many important factors including that ozone interacts with methane so by ignoring the resent increase in methane they are downplaying an important warming feedback mechanism.  The only way to tell what the true impact of the stratospheric ozone is to include it in a full state-of-the-art Earth Systems Model like ACME and then do the math.

The article about aboveground biomass carbon ignores the recent finding (cited earlier in this thread) that a bottleneck of nutrients in the soil will significantly limit the influence of this effect with continued GHG forcing in the future.

The article about the observed data from the hiatus period looks at too narrow of a timeframe, and as we gather more data over the next 20 to 30 years during the positive PDO phase, the statistics will most likely shift towards higher values for climate sensitivity.  Furthermore, the only reason that this paper would imply  that their finding "rule-out" higher values of climate sensitivity is because they do not adequately account for the influence of such temporary masking factors as aerosols, vegetation blooms, ocean heat uptake, incomplete data coverage, and multi-decadal ocean-atmospheric oscillations.

ASLR

[jai mitchell]

Just a quick note, I have been looking at some of the more recent papers on Secondary Organic Aerosols.  The impact of these organic oxidation elements on the nucleation of mid and lower troposphere cloud nucleation had been previously underestimated by 1,000% in models and has only recently become better understood http://www.atmos-chem-phys.net/14/3831/2014/acp-14-3831-2014.pdf

while my understanding of this portion of the science is still extremely limited, due to the intensely complex atmospheric chemistry involved, there is one thing that I have come to understand and believe is share-worthy.



As the current tropical forest zones are pushed into the temperate regions, the production of Secondary Organic Aerosols will also shift toward the poles, this will greatly reduce the radiative forcing parameters of tropical clouds and shift this cloud formation toward the poles.  The net effect of this will be a trend toward reduced albedo as solar intensity at the equator is higher than at mid-latitude.

recent modeling in china found that SOA forcing parameters at the Top of Atmosphere are quite large.

The domain averaged simulated ASOA direct SW radiative forcing at surface and at the top of atmosphere (TOA) are −1.21 and −0.66 W m−2. For BSOA, the surface and TOA SW DRF are −0.75 and −0.46 W m−2.

http://www.tellusb.net/index.php/tellusb/article/view/24634
Assessment of direct radiative forcing due to secondary organic aerosol over China with a regional climate model
Yin et. al. (2015)

abstract: 

Using the regional climate model (RegCM4), optical depth and shortwave (SW) direct radiative forcing (DRF) of secondary organic aerosol (SOA) are investigated over China during the summer period. The biogenic emission and gas phase chemistry modules are updated to investigate α-pinene and limonene emissions and their reactions with atmosphere oxidants. The VBS (volatility basis set) model is implemented into RegCM4 to illustrate gas-particle partition process. During the study period (July 2006), the mean surface concentration and column burden of anthropogenic SOA (ASOA) over China are 1.90 µg m−3 and 4.50 mg m−3, respectively. The ones of biogenic SOA (BSOA) are 2.00 and 3.35 mg m−3, respectively. Monthly mean calculated optical depths (at 550 nm) are 0.020 and 0.013 for ASOA and BSOA. The domain averaged simulated ASOA direct SW radiative forcing at surface and at the top of atmosphere (TOA) are −1.21 and −0.66 W m−2. For BSOA, the surface and TOA SW DRF are −0.75 and −0.46 W m−2. The errors induced by applying optical parameters of primary organic aerosol for SOA DRF modelling are also accessed. For DRF at TOA, it will increase by 156 and 161% for ASOA and BSOA. Though the optical parameters applied in this study are still rough, especially for intermediate SOA, this is a first step to apply explicit optical parameters for both ASOA and BSOA in DRF estimation.

[AbruptSLR]

As discussed last year in the Antarctic folder:

In an interview regarding the recently published article: Evidence for negative climate feedback: warming increases aerosol number concentrations, Paasonen, P., et. al. 2013 (in  Nature Geoscience doi: 10.1038/NGEO1800) contains the following excerpt:


"The effect of enhanced plant gas emissions on climate is small on a global scale – only countering approximately 1 percent of climate warming, the study suggested. “This does not save us from climate warming,” says Paasonen. However, he says, “Aerosol effects on climate are one of the main uncertainties in climate models. Understanding this mechanism could help us reduce those uncertainties and make the models better.”
The study also showed that the effect was much larger on a regional scale, counteracting possibly up to 30% of warming in more rural, forested areas where anthropogenic emissions of aerosols were much lower in comparison to the natural aerosols. That means that especially in places like Finland, Siberia, and Canada this feedback loop may reduce warming substantially.
The researchers collected data at 11 different sites around the world, measuring the concentrations of aerosol particles in the atmosphere, along with the concentrations of plant gases, the temperature, and reanalysis estimates for the height of the boundary layer, which turned out to be a key variable. The boundary layer refers to the layer of air closest to the Earth, in which gases and particles mix effectively. The height of that layer changes with weather. Paasonen says, “One of the reasons that this phenomenon was not discovered earlier was because these estimates for boundary layer height are very difficult to do. Only recently have the reanalysis estimates been improved to where they can be taken as representative of reality.”


However, is not pointed out in out in either the preceding reference nor either of the two following linked research that as current estimates of "climate sensitivity" do not include this negative feedback; in order for Global Circulation Models, GCM's including this negative feedback to match historical records they will need to utilize higher effective "climate sensitivity" values; which should resulting in higher projections of global temperature increase, if plant growth/activity does not keep pace with the rate of future green house gas, GHC, emissions.

Mikael Ehn, Joel A. Thornton, Einhard Kleist, Mikko Sipilä, Heikki Junninen, Iida Pullinen, Monika Springer, Florian Rubach, Ralf Tillmann, Ben Lee, Felipe Lopez-Hilfiker, Stefanie Andres, Ismail-Hakki Acir, Matti Rissanen, Tuija Jokinen, Siegfried Schobesberger, Juha Kangasluoma, Jenni Kontkanen, Tuomo Nieminen, Theo Kurtén, Lasse B. Nielsen, Solvejg Jørgensen, Henrik G. Kjaergaard, Manjula Canagaratna, Miikka Dal Maso et al (2014), " A large source of low-volatility secondary organic aerosol", Nature, 506, 476–479, doi:10.1038/nature13032


http://www.nature.com/nature/journal/v506/n7489/full/nature13032.html

Also, see:
http://www.bbc.com/news/science-environment-26340038


Abstract: "Forests emit large quantities of volatile organic compounds (VOCs) to the atmosphere. Their condensable oxidation products can form secondary organic aerosol, a significant and ubiquitous component of atmospheric aerosol, which is known to affect the Earth’s radiation balance by scattering solar radiation and by acting as cloud condensation nuclei. The quantitative assessment of such climate effects remains hampered by a number of factors, including an incomplete understanding of how biogenic VOCs contribute to the formation of atmospheric secondary organic aerosol. The growth of newly formed particles from sizes of less than three nanometres up to the sizes of cloud condensation nuclei (about one hundred nanometres) in many continental ecosystems requires abundant, essentially non-volatile organic vapours, but the sources and compositions of such vapours remain unknown. Here we investigate the oxidation of VOCs, in particular the terpene α-pinene, under atmospherically relevant conditions in chamber experiments. We find that a direct pathway leads from several biogenic VOCs, such as monoterpenes, to the formation of large amounts of extremely low-volatility vapours. These vapours form at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles. Our findings could help to improve assessments of biosphere–aerosol–climate feedback mechanisms, and the air quality and climate effects of biogenic emissions generally."

Also, see the link to the following related reference:

Paasonen, P., et. al. (2013), "Evidence for negative climate feedback: warming increases aerosol number concentrations,", Nature Geoscience, 6, Pages: 438–442, doi: 10.1038/NGEO1800

http://www.nature.com/ngeo/journal/v6/n6/full/ngeo1800.html

[jai mitchell]

The image that I provided was a ratio diagram of non-volatile SOA vs. SOA 

NVSOA are non-condensable.

see: http://www.cesm.ucar.edu/working_groups/Chemistry/Presentations/2014/shrivastava.pdf

It was the determination that many Secondary Organic Aerosols (SOA) have a much longer life before condensation that spurred a new revision to the impact of these elements in cloud formation.  Note that this paper was produced well after the cut off date for the IPCC AR5.

http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50160/abstract

Implications of low volatility SOA and gas-phase fragmentation reactions on SOA loadings and their spatial and temporal evolution in the atmosphere
M. Shrivastava et. al. (2013)
DOI: 10.1002/jgrd.50160

Abstract:

[1] We investigate issues related to volatility and multi-generational gas-phase aging parameterizations affecting the formation and evolution of secondary organic aerosol (SOA) in models. We show that when assuming realistic values for the mass accommodation coefficient, experimentally observed SOA evaporation rates imply significantly lower “effective volatility” than those derived from SOA growth in smog chambers, pointing to the role of condensed phase processes and suggesting that models need to use different parameters to describe the formation and evolution of SOA. We develop a new, experimentally driven paradigm to represent SOA as a non-absorbing semi-solid with very low “effective volatility.” We modify both a box model and a 3D chemical transport model, to include simplified parameterizations capturing the first-order effects of gas-phase fragmentation reactions and investigate the implications of treating SOA as a non-volatile, non-absorbing semi-solid (NVSOA). Box model simulations predict SOA loadings decrease with increasing fragmentation, and similar SOA loadings are calculated in the traditional, semi-volatile (SVSOA) approach and with the new paradigm (NVSOA) before evaporation reduces loadings of SVSOA. Box-model-calculated O:C ratios increase with aging in both the SVSOA and the NVSOA paradigms. Consistent with box model results, 3D model simulations demonstrate that predicted SOA loadings decrease with the addition of fragmentation reactions. The NVSOA paradigm predicts higher SOA loadings compared to the SVSOA paradigm over nearly the entire 3D modeling domain, with larger differences close to the surface and in regions where higher dilution favors SVSOA evaporation.

[Michael Hauber]

However, is not pointed out in out in either the preceding reference nor either of the two following linked research that as current estimates of "climate sensitivity" do not include this negative feedback; in order for Global Circulation Models, GCM's including this negative feedback to match historical records they will need to utilize higher effective "climate sensitivity" values;

My argument is that some evidence points to higher feedbacks, other evidence points to lower feedbacks.  The counter is that anything pointing to a higher feedback means more warming in the future and a higher climate sensitivity.  Anything pointing to a lower feedback means more warming in the past to offset this feedback and still means a higher climate sensitivity.

However the fact is that the warming rate in the past is lower than what the models show (if only slightly).  If there is evidence of a higher feedback the question needs to be asked whether there is an additional negative feedback that has operated in the past and so sensitivity is unchanged.  If there is evidence of a lower feedback then this suggests a better match between model calculations and historical temperature trends.

Reminder:  GISS observed trend from 1975 to now: 1.7 deg/century
CMIPt modelled trend from 1975 to now:  2.3 deg/century

which should resulting in higher projections of global temperature increase, if plant growth/activity does not keep pace with the rate of future green house gas, GHC, emissions.

This feedback is not related to plant growth or activity, but to additional vaporisation of volatile organic compounds in warmer temperatures.  This effect is weakened by anthropogenic pollution, and the feedback is actually positive in highly polluted regions.  The result is that as anthropogenic aerosol pollution weakens in the future this negative feedback will increase in strength.  Obviously if we lose a significant amount of our total vegetation the effect will decrease, but plant growth does not have to keep pace with future GHG etc for this effect to continue.  And of course this feedback is only enough to reduce the effect of global warming by about 1%, and so even if the effect doubles in strength that's not a lot of warming being offset.

[AbruptSLR]

MH,

You sound like a defense attorney in a civil damage torte case trying to convince a jury that not only is your client innocent until proven guilty, but also that the case against your client must be proven beyond a shadow of a doubt.  In a civil damage case (such as the likely damage that is going to be done to society due to ignoring high climate sensitivity) one only needs to prove that the accused is guilty as shown by the preponderance (51%) of the evidence. 

With a complex Earth System one can only adequately estimate the impacts of non-linear synergistic feedbacks in a dynamic state-of-the-art Earth System Model with an ensemble of runs; which we will not have until at least the first phase of the ACME program is complete.

So while neither one of us can provide a final answer, developing countries like the Philippines which is getting hammered by climate change energized Typhoons, while soon (in a couple of decades) will be able to file lawsuits showing that the high fossil fuel emitted countries (typically the developed countries) should have known the true risk of a high climate sensitivity for reasons including:

- With high rates of radiative forcing (BAU) the effective climate sensitivity is higher than in quasi-equilibrium cases for reasons including that the land and ocean biomass cannot adjust fast enough, which not only will decrease CO2 absorption but will decrease the negative forcing associated with BVOC emissions from this biomass.

- Severe flood & drought cycles will stress the biomass and expose it to increased risks of attack by pests and by wildfires (which can impact not only the rainforests but also the tundra and high latitude boreal forests thereby accelerating permafrost degradation).

- Any substantial new boreal forest growth tracking northward into the tundra will have a negative impact on albedo and a positive impact on higher effective climate sensitivity.

- The number of positive feedbacks far exceed the negative feedbacks, so that as we continue further down the BAU pathway previously negligible positive feedbacks will (on balance) become much more significant (which is why the IPCC sets up temperature increase limits of either 2C to maybe 1.5C, because the risks of exceeding such a tipping point(s) is serious).

ASLR

[AbruptSLR]

IEA Energy Technology Perspective 2015 Executive Summary can be found at the following link.  It indicates that while technology based decarbonization is underway, at its current pace society will fail to achieve a 50%-50% chance of remaining below a 2C temperature increase (by 2050) assuming an ECS of about 3C.  The report assures policymakers that if they buckle-down they can improve the chances of achieving this 50%-50% target; however, it is not clear to me that: (a) ECS is about 3C or lower; (b) that positive Earth System feedback factors will not further increase the effective climate sensitivity well before 2050; and (c) that policymakers have the willpower to reduce anthropogenic radiative forcing down to appropriate levels considering the likely consequences of failing.  Furthermore, I believe that the target should be reduced to 1.5C (or even 1C) global mean surface temperature increase, considering that Gavin Schmidt already believes that the mean value for ECS (in his conservative GCM models) is 3.5C; and thus the developing world (like the Philippines) will soon be able to sue the largely developed world for damages due to neglect of due diligence.

http://www.iea.org/publications/freepublications/publication/EnergyTechnologyPerspectives2015ExecutiveSummaryEnglishversion.pdf


For the importance of minimizing the temperature increase, see also:
http://www.rtcc.org/2015/05/06/2c-warming-goal-is-a-defence-line-governments-told/

[AbruptSLR]

The linked article discusses the findings of a University of Bristol study (see extract below) of how deniers are having some degree of success in waging a coordinated psychological campaign to get climate scientists to mute their message about the risks of climate change.  This is yet another reason why the majority of climate scientists err on the side of least drama:

http://www.lighthousenewsdaily.com/climate-change-deniers-affecting-scientists/561/


Extract: “The University of Bristol has recently conducted a study on this matter, planning to comprehend just how it has come to this situation.  They conclude that there are three main factors that constitute the pillars of the deniers’ strategy: “pluralistic ignorance”, “stereotype threat” and “the third-person effect”, which have waged a synergistic effect on the scientific population."

[AbruptSLR]

The article at the first linked website reports that: "A new NASA study reports the hole in the ozone layer over Antarctica will be permanently smaller around the year 2040." The website also provides a beautiful video of how the Antarctic ozone hole formed; which indicates that much of the chlorofluorocarbons (CFCs) that causes this ozone hole remains in circulation today in the atmosphere both over Antarctica and in a separate ring over the Southern Ocean (which points to the research on aerosols presented by Sherwood at the 2015 Ringberg workshop on climate sensitivity, see the second link).

Furthermore, I would like to note that as the Antarctic ozone hole heals itself, the projected increase in GHG concentrations over Antarctica should keep the westerly wind velocities over the Southern Ocean in appropriate range to accelerate the advection of warm Circumpolar Deep Water, CDW, towards the groundlines of numerous Antarctic marine glaciers thus promoting rapid SLR.

http://www.nationaljournal.com/energy/watch-how-the-antarctic-ozone-hole-formed-in-this-beautiful-nasa-animation-20150508

Link to Sherwood (2015) presentation at the Ringberg workshop:

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).

[AbruptSLR]

The linked reference shows that prior UN estimates of the deforestation in the humid tropics erred on the side of least drama, while the actual rate of deforestation has accelerated (by 62%) through the 1990s and 2000s.

Do-Hyung Kim, Joseph O. Sexton & John R. Townshend (2015), "Accelerated deforestation in the humid tropics from the 1990s to the 2000s", Geophysical Research Letters, DOI: 10.1002/2014GL062777


http://onlinelibrary.wiley.com/doi/10.1002/2014GL062777/full

Abstract: "Using a consistent, 20 year series of high- (30 m) resolution, satellite-based maps of forest cover, we estimate forest area and its changes from 1990 to 2010 in 34 tropical countries that account for the majority of the global area of humid tropical forests. Our estimates indicate a 62% acceleration in net deforestation in the humid tropics from the 1990s to the 2000s, contradicting a 25% reduction reported by the United Nations Food and Agriculture Organization Forest Resource Assessment. Net loss of forest cover peaked from 2000 to 2005. Gross gains accelerated slowly and uniformly between 1990–2000, 2000–2005, and 2005–2010. However, the gains were overwhelmed by gross losses, which peaked from 2000 to 2005 and decelerated afterward. The acceleration of humid tropical deforestation we report contradicts the assertion that losses decelerated from the 1990s to the 2000s."

[Laurent]

Overlooked evidence - global warming may proceed faster than expected
http://www.theguardian.com/environment/climate-consensus-97-per-cent/2015/apr/30/overlooked-evidence-global-warming-may-proceed-faster-than-expected

[AbruptSLR]

Conventional high-end, high-speed computers for ESM projections can cost around $20 million per year to run thus limiting the ability of most researchers (besides the ACME program) to run the high-resolution models required to verify where ECS and ESS are actually higher than traditionally believed.  There the following 2014 paper (see the two links at the end of this post to learn about more development & work by Palem & Palmer), indicates that the use of inexact hardware design can significantly reduce operational costs (electricity costs) for such state-of-the-art high-resolution ESM runs.  While many researchers are concerned about the probable inaccuracies introduced by inexact computing; however, from information theory, the Shannon "noisy-channel coding theorem" states that reliable communication is possible over noisy channels provided that the rate of communication is below a certain threshold, called the channel capacity. The channel capacity can be approached in practice by using appropriate encoding and decoding systems.  Thus by increasing the number of model runs using inexact computing it should be possible to converge on the same accuracy of conventional high-speed computing, while still saving annual operational costs.

Düben PD, Joven J, Lingamneni A, McNamara H, De Micheli G, Palem KV, Palmer TN. (2014), "On the use of inexact, pruned hardware in atmospheric modelling", Philos Trans A Math Phys Eng Sci. 2014 Jun 28; 372(2018):20130276; doi:10.1098/rsta.2013.0276.

http://www.ncbi.nlm.nih.gov/pubmed/24842031

Abstract: "Inexact hardware design, which advocates trading the accuracy of computations in exchange for significant savings in area, power and/or performance of computing hardware, has received increasing prominence in several error-tolerant application domains, particularly those involving perceptual or statistical end-users. In this paper, we evaluate inexact hardware for its applicability in weather and climate modelling. We expand previous studies on inexact techniques, in particular probabilistic pruning, to floating point arithmetic units and derive several simulated set-ups of pruned hardware with reasonable levels of error for applications in atmospheric modelling. The set-up is tested on the Lorenz '96 model, a toy model for atmospheric dynamics, using software emulation for the proposed hardware. The results show that large parts of the computation tolerate the use of pruned hardware blocks without major changes in the quality of short- and long-time diagnostics, such as forecast errors and probability density functions. This could open the door to significant savings in computational cost and to higher resolution simulations with weather and climate models."

See also:
http://www.nytimes.com/2015/05/12/science/inexact-computing-global-warming-supercomputers.html?ref=earth&_r=0

http://www.houstonchronicle.com/news/houston-texas/houston/article/Rice-scientist-sees-a-trade-off-Cutting-6239769.php

Extract: "Rice University's Krishna Palem's idea for inexact computing states that you can trade accuracy in computer calculations for energy savings."

[AbruptSLR]

The linked discussion of a Comment piece published in the May 7 2015 issue of Nature indicates that climate scientists are subjected to pressure by politicians and government offices to err inappropriately far (to the point of losing their integrity) on the side of least drama (see extract below).

http://phys.org/news/2015-05-german-climate-scientists-kowtow-politicians.html

Extract: "Oliver Geden, a researcher with the German Institute for International and Security Affairs has published a Comment piece in the journal Nature, warning of the dire consequences of climate scientists bowing to pressure exerted by politicians and government officials. His admonitions come just a month before the UN is to meet to discuss and report on the progress of the 2C goal."

See:

http://www.nature.com/news/policy-climate-advisers-must-maintain-integrity-1.17468

[AbruptSLR]

The linked website article discusses that a key “Structured Expert Dialogue” (SED) between IPCC scientists and UNFCCC negotiators has just released its technical summary report, and finds that policy makers should be targeting a global mean temperature rise of 1.5C and should not be targeting 2C.

http://www.ecoequity.org/

For a short clear summary pdf see:

http://climateanalytics.org/files/climate_analytics_briefing_sed_may2015.pdf

For a large pdf of the original UN report see:

http://unfccc.int/resource/docs/2015/sb/eng/inf01.pdf

Extract from the SED technical summary report: "“We are therefore of the view that Parties would profit from restating the long-term global goal as a ‘defence line’ or ‘buffer zone’, instead of a ‘guardrail’ up to which all would be safe. This new understanding would then probably favor emission pathways that will limit warming to a range of temperatures below 2 °C. In the very near term, such aspirations would keep open as long as possible the option of a warming limit of 1.5 °C, and would avoid embarking on a pathway that unnecessarily excludes a warming limit below 2 °C."

See also:
http://climateanalytics.org/

[Michael Hauber]

From the recent on climate sensitivity (Stevens):

'Some (not yet entirely convincing) reasons why Equilibrium sensitivity is between 2.0 and 3.5'
'the reasons are not, yet, entirely convincing...but perhaps good enough for policymakers'

I went through each presentation, and I note that while some argued for lower sensitivity, and others argued against lower sensitivity, there was not one single presentation that argued for higher sensitivity.

Of course that is just part of the conspiracy that stops the climate scientists from actually saying anything about climate sensitivity being on the upper end, even though their papers are being constantly quoted on this forum to 'prove' that climate sensitivity is in the higher end.

[AbruptSLR]

Further to my Reply #929 that a key “Structured Expert Dialogue” (SED) technical report about dialogue between IPCC scientists and UNFCCC negotiators, finds that policy makers should be targeting a global mean temperature rise of 1.5C and should not be targeting 2C.

Some people might take this to imply that key IPCC scientists are acknowledging that ECS might actually be (2/1.5)x3.1C = 4.1C; however, this SED technical report recommendation to change in the targeted global mean surface temperature rise from 2C to 1.5C is actual more frightening than merely implying that ECS may be in the 4.1C range.

The SED technical report essentially assumes that ECS is still about 3.1C but that the various Earth System responses that were discounted by AR5 (such as the permafrost and ice sheet response to global warming) should not have been discounted so much; and that the IPCC "Expect" scientists want to reserve the right to acknowledge at some undefined future (when more data is available) that ECS is actually higher than 3.1C.  This is important because the SED technical report concluded that it is still possible to limit global mean surface temperature rise to 1.5C with strict emission policies; however, if/when such "Expert" scientist finally decide that that have enough information to publically acknowledge a higher ECS then policy maker would be obliged to consider implementing more aggressive geoengineering measures, or to accept that the climate response will be more than what modern society can tolerate.

Hopefully, the opinion of lone wolf scientists such as Stevens will not distract the CoP21 policy makers from heeding the well reasoned advice of the SED technical report, before it is too late to spare modern society a large measure of otherwise unnecessary suffering.

[AbruptSLR]

The linked article discusses the findings of a University of Bristol study (see extract below) of how deniers are having some degree of success in waging a coordinated psychological campaign to get climate scientists to mute their message about the risks of climate change.  This is yet another reason why the majority of climate scientists err on the side of least drama:

http://www.lighthousenewsdaily.com/climate-change-deniers-affecting-scientists/561/


Extract: “The University of Bristol has recently conducted a study on this matter, planning to comprehend just how it has come to this situation.  They conclude that there are three main factors that constitute the pillars of the deniers’ strategy: “pluralistic ignorance”, “stereotype threat” and “the third-person effect”, which have waged a synergistic effect on the scientific population."

Here is more on the Unversity of Bristol study on the impact of denalists on scientists that I cited in Reply # 923:

http://insideclimatenews.org/news/11052015/climate-denial-takes-toll-scientists%E2%80%94and-science

Extract: "Scientists spend time and resources addressing denialists' debunked claims in a way the scientific community has never done, said Stephan Lewandowsky, a cognitive scientist at the University of Bristol in England and lead author of the new study, published in the journal Global Environmental Change. Researchers also often downplay future climate risks to avoid being labeled an "alarmist" by climate contrarians.

"Scientists are reticent to begin with, and if they know that everyone wants to ream at them for being alarmists, that adds to their reticence," Lewandowsky said. "They are human, just like you and I...and some of the actions by deniers can be quite nasty." He said hate mail and complaints directed to their research institutions are common."

[Michael Hauber]

As I've said before, the last resort of those who have the weight of scientific evidence is to claim that the scientific process is biased.

In his latest article, Lewandowsky still refers to this study to claim that scientists are systematically underestimating  climate change.  The more prominent claims in this paper are the underestimation of temperature rise, arctic ice and sea level rise.  The underestimation of temperature rise is supported by reference to a 2007 paper, when recent global warming trends have been at their highest, despite the fact that the paper was written in 2013 and the cool years of 2008 and 2011 that caused the large share of the recent slowdown had already happened.  The current rate of warming from 1975 is 1.7 deg/century, compared to a modelled rate of 2.3 deg/century.  Arctic sea may have been underestimated, particularly in the fourth report, but the 5th report has a significantly faster Arctic ice loss which is probably closer to the observations than the current temperature trend is.  There is also the Antarctic ice.  We are currently gaining ice in the Antarctic, but the IPCC 4th and 5th assessments projection is for a loss.  Sea level rise is probably the one area of significant underestimate by the IPCC, although it is interesting to note the first report actually overestimated the sea level rise.

Once more up to date data and other factors besides those cherry picked for that study are considered the appearance of systematic under prediction by the IPCC of current trends is gone.

[Anne]

Peace, Michael, and if you have some spare cash why not invest in some Florida condos?

[jai mitchell]

As I've said before, the last resort of those who have the weight of scientific evidence is to claim that the scientific process is biased.

In his latest article, Lewandowsky still refers to this study to claim that scientists are systematically underestimating  climate change.  The more prominent claims in this paper are the underestimation of temperature rise, arctic ice and sea level rise.  The underestimation of temperature rise is supported by reference to a 2007 paper, when recent global warming trends have been at their highest, despite the fact that the paper was written in 2013 and the cool years of 2008 and 2011 that caused the large share of the recent slowdown had already happened.  The current rate of warming from 1975 is 1.7 deg/century, compared to a modelled rate of 2.3 deg/century.  Arctic sea may have been underestimated, particularly in the fourth report, but the 5th report has a significantly faster Arctic ice loss which is probably closer to the observations than the current temperature trend is.  There is also the Antarctic ice.  We are currently gaining ice in the Antarctic, but the IPCC 4th and 5th assessments projection is for a loss.  Sea level rise is probably the one area of significant underestimate by the IPCC, although it is interesting to note the first report actually overestimated the sea level rise.

Once more up to date data and other factors besides those cherry picked for that study are considered the appearance of systematic under prediction by the IPCC of current trends is gone.

Antarctica is losing ice, not gaining ice.  This is a common denialist lie/meme/talking point.  you should know better.
http://www.princeton.edu/~charig/Research_files/Harig.Simons.AntarcticaGRACE.EPSL.2015.pdf
http://www.constantinealexander.net/2015/week13/


other than that, you have reverted back to your denialist rhetorical devices of assertion without proof, straw man arguments and blatant distortions to back up your failed attempt to understand the things of which you speak.

[jai mitchell]

for example:

In his latest article, Lewandowsky still refers to this study to claim that scientists are systematically underestimating  climate change. 

Please link the Lewandowsky article, this is a common courtesy here:

The more prominent claims in this paper are the underestimation of temperature rise, arctic ice and sea level rise.  The underestimation of temperature rise is supported by reference to a 2007 paper,

Please provide the link or title of the paper, otherwise you are just making unsupported assertions.  For example, you claim that the main points are temperature, arctic ice and sea level rise.  However, the link that you did provide only shows an abstract that claims "recent papers" were used and specifically mentions antarctic ozone depletion and west Antarctica disintegration rates.  there is no mention of temperature or the arctic.

when recent global warming trends have been at their highest, despite the fact that the paper was written in 2013 and the cool years of 2008 and 2011 that caused the large share of the recent slowdown had already happened.  The current rate of warming from 1975 is 1.7 deg/century, compared to a modelled rate of 2.3 deg/century.

This is a classic example of a straw man argument, claim something was stated, provide no evidence, then claim your own takedown of that information, again with no evidence.

Arctic sea may have been underestimated, particularly in the fourth report, but the 5th report has a significantly faster Arctic ice loss which is probably closer to the observations than the current temperature trend is. 

I am sure that you have absolutely no idea what you are talking about or else you would have posted a graphic or a paper that lends some credibility to your assertion.  by the way, why would you insert a non-sequiter into your statement above (i.e. "arctic ice loss" . . probably closer to . . . the current temperature trend is)  besides just damn poor english, this has no value of information or even comparison.

There is also the Antarctic ice.

quite possibly the first true assertion that you made in your statement

We are currently gaining ice in the Antarctic

and then you revert to misinformation. . .this is definitely not the case you either are misinformed or are blatantly lying.  provide a proof to your assertions, here is a hint, when you try to find proof to your assertions, especially the ones you gather from the denialist talking point sites you appear to frequent, you will find you that there is no real scientific basis for their claims.

but the IPCC 4th and 5th assessments projection is for a loss. 

This is an example of THE BIG LIE  when you continue to state something as though it is true even though it is not and then attack those who state the truth as being false.  It is the most twisted form of propaganda, it is sad to think that you may have devolved to such a state of anti-intellectualism and/or outright despotism.

Sea level rise is probably the one area of significant underestimate by the IPCC, although it is interesting to note the first report actually overestimated the sea level rise.

again without proof of the assertion, no graphic or linked paper.  When you say the first report are you talking about the FAS published in 1990?

It is amazing to me that you are stilled allowed to post here.  There are sometimes problems with data vs. noise here but you bring a completely different dynamic of falsehood.

[jai mitchell]

Double Inter-Tropical Convergence Zone bias causes artificially low ECS response in the models

http://onlinelibrary.wiley.com/doi/10.1002/2015GL064119/full

Spread of Model Climate Sensitivity Linked to Double-Intertropical Convergence Zone Bias†
Baijun Tian
DOI: 10.1002/2015GL064119
April 30, 2015

Abstract

Despite decades of climate research and model development, two outstanding problems still plague the latest global climate models (GCMs): The double-intertropical convergence zone (ITCZ) bias and the 2−5°C spread of equilibrium climate sensitivity (ECS). Here we show that the double-ITCZ bias and ECS in 44 GCMs from Coupled Model Intercomparison Project Phases 3/5 are negatively correlated. The models with weak (strong) double-ITCZ biases have high (low) ECS values of ~4.1(2.2)°C. This indicates that the double-ITCZ bias is a new emergent constraint for ECS based on which ECS might be in the higher end of its range (~4.0°C) and most models might have underestimated ECS. In addition, we argue that the double-ITCZ bias can physically affect both cloud and water vapor feedbacks (thus ECS) and is a more easily measured emergent constraint for ECS than previous ones. It can be used as a performance metric for evaluating and comparing different GCMs.

[Michael Hauber]

Peace, Michael, and if you have some spare cash why not invest in some Florida condos?

You seem to be mistaking me for someone who thinks the climate scientists are wrong.  I believe that our climate scientists are right.  The people who think the climate scientists are wrong are the ones I'm arguing with.

[AbruptSLR]

Peace, Michael, and if you have some spare cash why not invest in some Florida condos?

You seem to be mistaking me for someone who thinks the climate scientists are wrong.  I believe that our climate scientists are right.  The people who think the climate scientists are wrong are the ones I'm arguing with.

MH,

I am so glad to hear that you concur with Tian 2015 that: "The models with weak (strong) double-ITCZ biases have high (low) ECS values of ~4.1(2.2)°C. This indicates that the double-ITCZ bias is a new emergent constraint for ECS based on which ECS might be in the higher end of its range (~4.0°C) and most models might have underestimated ECS."

ASLR

[Michael Hauber]

Please link the Lewandowsky article, this is a common courtesy here:

ASLR was the one who brought up the Lewandowsky article.  Look for the link in his post.

The more prominent claims in this paper are the underestimation of temperature rise, arctic ice and sea level rise.  The underestimation of temperature rise is supported by reference to a 2007 paper,

Please provide the link or title of the paper, otherwise you are just making unsupported assertions.  For example, you claim that the main points are temperature, arctic ice and sea level rise.  However, the link that you did provide only shows an abstract that claims "recent papers" were used and specifically mentions antarctic ozone depletion and west Antarctica disintegration rates.  there is no mention of temperature or the arctic.

Sorry I sometimes forget that I am inside the paywall and that not everyone can access the full contents.  The 2007 paper is here
 
This paper is references in the text:

In a 2007 article, Rahmstorf and colleagues compared projections of global mean temperature change, sea level rise, and atmospheric carbon dioxide concentration from IPCC's Third Assessment Report (TAR) with observations made since 1973 and concluded: “Overall, these observational data underscore the concerns about global climate change.

when recent global warming trends have been at their highest, despite the fact that the paper was written in 2013 and the cool years of 2008 and 2011 that caused the large share of the recent slowdown had already happened.  The current rate of warming from 1975 is 1.7 deg/century, compared to a modelled rate of 2.3 deg/century.

This is a classic example of a straw man argument, claim something was stated, provide no evidence, then claim your own takedown of that information, again with no evidence.

Also from the text:

Summertime melting of Arctic sea-ice has “accelerated far beyond the expectations of climate models” (Allison et al., 2009, p. 7; see also Stroeve et al., 2007). Indeed, using unusually vivid language, the authors note that the record for previous Arctic sea ice summer minimum extent was “shattered” in 2007, “something not predicted by climate models …

My previous analysis of temperature trends vers models is here

Arctic sea may have been underestimated, particularly in the fourth report, but the 5th report has a significantly faster Arctic ice loss which is probably closer to the observations than the current temperature trend is. 

I am sure that you have absolutely no idea what you are talking about or else you would have posted a graphic or a paper that lends some credibility to your assertion.  by the way, why would you insert a non-sequiter into your statement above (i.e. "arctic ice loss" . . probably closer to . . . the current temperature trend is)  besides just damn poor english, this has no value of information or even comparison.

We had this discussion about Arctic sea ice obs vs models on this thread earlier, and I'm pretty you participated.  I estimate the Arctic ice loss rate is about 10% faster than modelled.  The temperature gain is over 20% slower than modelled.

There is also the Antarctic ice.

quite possibly the first true assertion that you made in your statement

We are currently gaining ice in the Antarctic

and then you revert to misinformation. . .this is definitely not the case you either are misinformed or are blatantly lying.  provide a proof to your assertions, here is a hint, when you try to find proof to your assertions, especially the ones you gather from the denialist talking point sites you appear to frequent, you will find you that there is no real scientific basis for their claims.

I would have thought that you were smart enough to realise I am talking about Antarctic Sea Ice and not ice on land in Antarctica even though I forgot to make the distinction.  Antarctic sea ice increase in case you actually need evidence of that.

but the IPCC 4th and 5th assessments projection is for a loss. 

This is an example of THE BIG LIE  when you continue to state something as though it is true even though it is not and then attack those who state the truth as being false.  It is the most twisted form of propaganda, it is sad to think that you may have devolved to such a state of anti-intellectualism and/or outright despotism.

Are you saying IPCC project a gain in Antarctic (sea) ice?  Care to provide any evidence?  Or is it only me that has to provide links??

I specifically read both reports prior to making my post, and after all the stuff I've just looked up for your benefit I can't be bothered looking this one up again.

It is amazing to me that you are stilled allowed to post here.  There are sometimes problems with data vs. noise here but you bring a completely different dynamic of falsehood.

Go look in a mirror.

[Michael Hauber]

Peace, Michael, and if you have some spare cash why not invest in some Florida condos?

You seem to be mistaking me for someone who thinks the climate scientists are wrong.  I believe that our climate scientists are right.  The people who think the climate scientists are wrong are the ones I'm arguing with.

MH,

I am so glad to hear that you concur with Tian 2015 that: "The models with weak (strong) double-ITCZ biases have high (low) ECS values of ~4.1(2.2)°C. This indicates that the double-ITCZ bias is a new emergent constraint for ECS based on which ECS might be in the higher end of its range (~4.0°C) and most models might have underestimated ECS."

ASLR

I tend to agree with both the scientists who say that ECS might be in the lower end, and those who say it might be in higher end.  I disagree with those who cherry pick all the studies that show evidence for higher end and ignore those that show evidence of lower end.

[AbruptSLR]

Peace, Michael, and if you have some spare cash why not invest in some Florida condos?

You seem to be mistaking me for someone who thinks the climate scientists are wrong.  I believe that our climate scientists are right.  The people who think the climate scientists are wrong are the ones I'm arguing with.

MH,

I am so glad to hear that you concur with Tian 2015 that: "The models with weak (strong) double-ITCZ biases have high (low) ECS values of ~4.1(2.2)°C. This indicates that the double-ITCZ bias is a new emergent constraint for ECS based on which ECS might be in the higher end of its range (~4.0°C) and most models might have underestimated ECS."

ASLR

I tend to agree with both the scientists who say that ECS might be in the lower end, and those who say it might be in higher end.  I disagree with those who cherry pick all the studies that show evidence for higher end and ignore those that show evidence of lower end.

MH,

As far as I am concerned you are free to believe whatever you want; however, for the benefit of other readers who may be confused by some of the points that you raise; I point-out that while you imply that you are merely trying to defend the consensus view of the IPCC, the IPCC's Experts have moved on past AR5 as I indicated in both my Replies #929 and #931 (which for convenience, I re-post below).  The "Structured Expert Dialogue" (SED) between the IPCC scientists and the UNFCCC (CoP) negotiators recommends changing the CoP21 target to 1.5C rather than 2C; which can be taken as increasing the effective ECS (ie the ECS plus any accelerated ESS feedbacks) from 3.1C to 4.1C; which is in complete agreement with Tian 2015:



Re-post of Reply #929: "The linked website article discusses that a key “Structured Expert Dialogue” (SED) between IPCC scientists and UNFCCC negotiators has just released its technical summary report, and finds that policy makers should be targeting a global mean temperature rise of 1.5C and should not be targeting 2C.

http://www.ecoequity.org/

For a short clear summary pdf see:

http://climateanalytics.org/files/climate_analytics_briefing_sed_may2015.pdf

For a large pdf of the original UN report see:

http://unfccc.int/resource/docs/2015/sb/eng/inf01.pdf

Extract from the SED technical summary report: "“We are therefore of the view that Parties would profit from restating the long-term global goal as a ‘defence line’ or ‘buffer zone’, instead of a ‘guardrail’ up to which all would be safe. This new understanding would then probably favor emission pathways that will limit warming to a range of temperatures below 2 °C. In the very near term, such aspirations would keep open as long as possible the option of a warming limit of 1.5 °C, and would avoid embarking on a pathway that unnecessarily excludes a warming limit below 2 °C."

See also:
http://climateanalytics.org/
"
Re-post of Reply #931
"Further to my Reply #929 that a key “Structured Expert Dialogue” (SED) technical report about dialogue between IPCC scientists and UNFCCC negotiators, finds that policy makers should be targeting a global mean temperature rise of 1.5C and should not be targeting 2C.

Some people might take this to imply that key IPCC scientists are acknowledging that ECS might actually be (2/1.5)x3.1C = 4.1C; however, this SED technical report recommendation to change in the targeted global mean surface temperature rise from 2C to 1.5C is actual more frightening than merely implying that ECS may be in the 4.1C range.

The SED technical report essentially assumes that ECS is still about 3.1C but that the various Earth System responses that were discounted by AR5 (such as the permafrost and ice sheet response to global warming) should not have been discounted so much; and that the IPCC "Expect" scientists want to reserve the right to acknowledge at some undefined future (when more data is available) that ECS is actually higher than 3.1C.  This is important because the SED technical report concluded that it is still possible to limit global mean surface temperature rise to 1.5C with strict emission policies; however, if/when such "Expert" scientist finally decide that that have enough information to publically acknowledge a higher ECS then policy maker would be obliged to consider implementing more aggressive geoengineering measures, or to accept that the climate response will be more than what modern society can tolerate.

Hopefully, the opinion of lone wolf scientists such as Stevens will not distract the CoP21 policy makers from heeding the well reasoned advice of the SED technical report, before it is too late to spare modern society a large measure of otherwise unnecessary suffering."

[Michael Hauber]

The argument from the SED has two parts:
1) that the consequences of 1.5 degrees of warming are bad.
2) that the costs of preventing 1.5 degrees of warming are low.

A higher sensitivity has no impact on 1.  A higher sensitivity would make the costs under 2 higher and therefore weaken the SED argument.  The SED proposal has nothing to do with a changing opinion on climate sensitivity and is more likely to reflect either an increased concern of the negative of each degree of warming, or reflect a more optimistic view on the capabilities of recent advances in renewable energy to easily achieve a more ambitious target.

[TeaPotty]

The argument from the SED has two parts:
1) that the consequences of 1.5 degrees of warming are bad.
2) that the costs of preventing 1.5 degrees of warming are low.

A higher sensitivity has no impact on 1.  A higher sensitivity would make the costs under 2 higher and therefore weaken the SED argument.

Are your faculties really so lacking, or do you make such comments to troll this forum?

[AbruptSLR]

The argument from the SED has two parts:
1) that the consequences of 1.5 degrees of warming are bad.
2) that the costs of preventing 1.5 degrees of warming are low.

A higher sensitivity has no impact on 1.  A higher sensitivity would make the costs under 2 higher and therefore weaken the SED argument.  The SED proposal has nothing to do with a changing opinion on climate sensitivity and is more likely to reflect either an increased concern of the negative of each degree of warming, or reflect a more optimistic view on the capabilities of recent advances in renewable energy to easily achieve a more ambitious target.

With apologies to those who are already tired of the time spent on responding to such misconceptions; I nevertheless, provide the following responses to MH's opinions cited above:

A. When this thread points out areas that the scientific consensus (focused on IPCC positions) err on the side of least drama (see the linked article at the bottom of this post); it is primarily done to highlight the climate risks that society is subjected while the scientific consensus gathers more information about the true nature of those risks.
B. Key IPCC scientists suggested a 1.5C target at least as long at the 2009 CoP15 in Copenhagen; however, instead of pressing for that target at that time these agreed with the UNFCCC officials to jointly err on the side of least drama and to adopt a 2C target (which was reflected in the AR5 Carbon Budget calculations).
C. Saying the SED now recommends changing the target to 1.5C because:

"1) that the consequences of 1.5 degrees of warming are bad." Is to say that climate models determine consequences of global warming so there is no need for UNFCCC official to set climate sensitivity targets for ECS or ESS; but as high climate sensitivity is bad, UNFCCC official need to set a 25% lower target of 1.5C; and

"2) that the costs of preventing 1.5 degrees of warming are low." Is saying that it saved money not to adopt a 1.5C target in 2009 rather than in 2015 is ludicrous, as we have been on a BAU track from 2009 to 2015 (which we may not have been if we had not chosen to err on the side of least drama); which means that we need to institute a crash-emissions control program in CoP21 rather than a more gradual emissions control program in CoP15.

Article on scientific erring on the side of least drama:

http://www.sciencedirect.com/science/article/pii/S0959378012001215

[AbruptSLR]

Per the linked article from the US DOE's Pacific Northwest National Laboratory: "For the past 20 years, a large portion of the particles measured in the atmosphere were missing from models. At best, models were able to explain one-tenth of the carbon-rich secondary organic aerosols, or SOA, measured in the air. The problem turned out to be a series of fundamental assumptions used in the models due to a lack of experimental data."

As SOA's tend to mask global warming, the discussed improvements of the climate models to include 10 times more SOA implies that if climate change stresses the planet's biomass sufficiently to decrease future SOA emissions with continued global warming; then the world will be subjected to a higher effective ECS.

http://www.pnnl.gov/science/highlights/highlight.asp?id=3983

See also:

http://www.reportingclimatescience.com/news-stories/article/data-revises-views-on-organic-aerosols.html

Select Publications
E. Abramson, D. Imre, J. Beranek, J. Wilson, A. Zelenyuk, "Experimental determination of chemical diffusion within secondary organic aerosol particles." Physical Chemistry Chemical Physics 15 (, 2983-2991 (2013). [DOI: 10.1039/C2CP44013J]

V. Perraud, E. A. Bruns, M. J. Ezell, S. N. Johnson, Y. Yu, M. L. Alexander, A. Zelenyuk, D. Imre, W. L. Chang, D. Dabdub, J. F. Pankow, B. J. Finlayson-Pitts, "Nonequilibrium atmospheric secondary organic aerosol formation and growth." Proceedings of the National Academy of Sciences USA 109 (, 2836-2841 (2012). [DOI: 10.1073/pnas.1119909109]

P. Roldin, A. C. Eriksson, E. Z. Nordin, E. Hermansson, D. Mogensen, A. Rusanen, M. Boy, E. Swietlicki, B. Svenningsson, A. Zelenyuk, J. Pagels, "Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multilayer model ADCHAM." Atmospheric Chemistry and Physics 14 (15), 7953-7993 (2014). [DOI: 10.5194/acp-14-7953-2014]

M. Shrivastava, A. Zelenyuk, D. Imre, R. Easter, J. Beranek, R. A. Zaveri, J. Fast, "Implications of low volatility SOA and gas-phase fragmentation reactions on SOA loadings and their spatial and temporal evolution in the atmosphere." Journal of Geophysical Research Atmospheres 118 (, 3328-3342 (2013). [DOI: 10.1002/jgrd.50160]

T. D. Vaden, C. Song, R. A. Zaveri, D. Imre, A. Zelenyuk, "Morphology of mixed primary and secondary organic particles and the adsorption of spectator organic gases during aerosol formation." Proceedings of the National Academy of Sciences USA 107 (15), 6658-6663 (2010). [DOI: 10.1073/pnas.0911206107]

T. D. Vaden, D. Imre, J. Beranek, M. Shrivastava, A. Zelenyuk, "Evaporation kinetics and phase of laboratory and ambient secondary organic aerosol." Proceedings of the National Academy of Sciences USA 108 (6), 2190-2195 (2011). [DOI: 10.1073/pnas.1013391108]

J. Wilson, D. Imre, J. Beránek, M. Shrivastava, A. Zelenyuk, "Evaporation kinetics of laboratory-generated secondary organic aerosols at elevated relative humidity." Environmental Science & Technology 49 (1), 243-249 (2015). [DOI: 10.1021/es505331d]

A. Zelenyuk, J. Yang, C. Song, R. A. Zaveri, D. Imre, "A new real-time method for determining particles' sphericity and density: application to secondary organic aerosol formed by ozonolysis of α-pinene." Environmental Science & Technology 42 (21), 8033-8038 (2008). [DOI: 10.1021/Es8013562]

A. Zelenyuk, D. Imre, J. Beránek, E. Abramson, J. Wilson, M. Shrivastava, "Synergy between secondary organic aerosols and long-range transport of polycyclic aromatic hydrocarbons."

[AbruptSLR]

As jai requested a link to the discussion by Stephan Lewandowsky as to whether pressure from climate skeptics is leading climates scientists: ".. to frame climate facts as uncertain"; I provide the following link to a RTCC article:

http://www.rtcc.org/2015/05/15/are-climate-scientists-cowed-by-sceptics/

Extract: "It’s worth comparing Lewandowsky’s thesis with that put forward by Oliver Geden, a German researcher who was published in Nature last week warning climate scientists and advisors were offering false hope to politicians on averting global warming.

“Scientific advisers must resist pressures that undermine the integrity of climate science,” he wrote.

“Instead of spreading false optimism, they must stand firm and defend their intellectual independence, findings and recommendations – no matter how politically unpalatable.”

He added: “Scientific advisers should resist the temptation to be political entrepreneurs, peddling their advice by exaggerating how easy it is to transform the economy or deploy renewable technologies, for instance.”"

For Oliver Geden's article see:

http://phys.org/news/2015-05-german-climate-scientists-kowtow-politicians.html

[Laurent]

The claim that 2°C is safe, is just ridiculous. The datas show that we have never exceeded 1°C in the last million year. That should be clear enough that even reaching that limit is highly dangerous.
Now that we are at 0,8°C we are beginning to see the foolishness of such a target !!!

[Michael Hauber]

The argument from the SED has two parts:
1) that the consequences of 1.5 degrees of warming are bad.
2) that the costs of preventing 1.5 degrees of warming are low.

A higher sensitivity has no impact on 1.  A higher sensitivity would make the costs under 2 higher and therefore weaken the SED argument.

Are your faculties really so lacking, or do you make such comments to troll this forum?

I see that you have no ability to rebut my argument and so rely on insults.  If the SED was concerned about a higher sensitivity they'd lower the target for Co2 emissions, not lower the target for temperature rise.