IPCC possible scenario: 9 C over next century or so

[JimD]

The level of 'domestic' emissions is, of course, irrelevant.  It is a metric used by business interests in places like the US to deflect attention from us being the main problem.  Thus the typical Fox news item indicating that China is now the worlds worst polluter and that attention should be focused more on them.  "There is nothing going on here!  Move along!"  It is Orwellian.

We live in a global system.  Climate does not recognize borders.  The US chart on emissions does not matter.  The ones that matters are ones like that posted by SH. 

What matters in terms of assessing blame is consumption only.  Off shoring production of US consumed goods to China and elsewhere does not in any way absolve the consumer of responsibility for emissions from said production of goods.  And now that China is starting to off shore activities like steel production to locals which have less regulation than they do someone is sure to claim that they are working hard to make progress just like some in the US are claiming.  But it is nonsense.

Americans (or anyone living an affluent lifestyle) will not be making progress until we/they give up a large part of our consumption and standard of living.  All else is just a form of BAU - black or green, pick your poison.  In the meantime every year we are setting new records for emissions and co2 levels steadily rise.  Such is progress. 

Admitting that climate change is certain does not mean that one thinks it has occurred yet. But it has.  What one needs to come to grips with is that 'severe' climate change is certain in that it has not yet occurred, but it there is nothing we can do to stop it at this point.  What we are focused on is whether there is still the possibility of making a change in our civilizational course which will allow us to 'avoid' catastrophic climate change.

We have known for many years now that to avoid catastrophic climate change would require a massive overhaul of our civilizational model.  Absolute requirements include dramatically reduced levels of consumption, standards of living, and most importantly population levels.  Yet over all of those years there has been zero progress on any of those fronts.  Population continues to rise rapidly, all global entities are focused on economic growth, no group of people anywhere have willingly reduced their levels of consumption and given up a substantial percentage of their standard of living, and carbon emissions have continued to set records on a yearly basis.  All evidence is of a continuing pursuit of BAU.  The world "IS", so far, just continuing to pursue BAU.  We 'are' just sitting back and letting it happen.  That is what we do.  That is what we have always done.  It is in our nature.

Will this continue forever.  Of course not.  What can't, won't.  But all evidence is that it will continue until we reach the point of civilizational collapse and that will certainly fit the criteria of 'catastrophic".

If you want to prevent this.  Tear it all down now.   Whatever mess is created now will be much less painful than the mess you get the longer you wait.  We have to man up and stop being cowards.

[wili]

"Tear it all down now." Suggestions on where and how to start?

[JimD]

"Tear it all down now." Suggestions on where and how to start?

Isn't that what the Climate Change Triage thread is about?

[AbruptSLR]

Regarding his plan to colonize Mars, Elon Musk recently said: “Either we spread earth to other planets, or we risk going extinct. An extinction event is inevitable and we’re increasingly doing ourselves in.”  Perhaps Elon knows something about climate sensitivity (or not) that policymakers are not willing to admit publically.

[AbruptSLR]

I thought that I would provide the following link to a free pdf for the Tomassini et al 2014 paper (see the highlighted part of the abstract:


Tomassini, L., Voigt, A. and Stevens, B. (2014), "On the connection between tropical circulation, convective mixing, and climate sensitivity", Q.J.R. Meteorol. Soc.. doi: 10.1002/qj.2450

http://pubman.mpdl.mpg.de/pubman/item/escidoc:2007690:5/component/escidoc:2069570/qj2450.pdf

Abstract: "The connection between the large-scale tropical circulation of the atmosphere, convective mixing, and climate sensitivity is explored in a wide range of climates through a perturbed-parameter ensemble of a comprehensive Earth System Model. Four parameters related to the representation of atmospheric moist convection are found to dominate the response of the model. Their values govern the strength of the tropical circulation, the surface temperature, atmospheric humidity, and the strength of the tropical overturning circulation, largely through their influence on the atmospheric stability. The same convective parameters, albeit in different combinations, also have a strong influence on the equilibrium climate sensitivity of the model, which ranges from a little over 3 °C to more than 10 °C. The importance of the most poorly represented processes in determining important aspects of the behaviour of the model argues for the need to move beyond statistical approaches to estimating climate sensitivity and to focus on the development of a better understanding and representation of convective mixing, particularly in the Tropics."

[AbruptSLR]

The linked 2013 reference by Meraner et al confirms that Equilibrium Climate Sensitivity, ECS, increase robustly under global warming:

Meraner, K., T. Mauritsen, and A. Voigt (2013), "Robust increase in equilibrium climate sensitivity under global warming",  Geophys. Res. Lett., 40, doi:10.1002/2013GL058118

http://onlinelibrary.wiley.com/doi/10.1002/2013GL058118/pdf

Abstract: "Equilibrium climate sensitivity (ECS) is a widely accepted measure of Earth’s susceptibility to radiative forcing. While ECS is often assumed to be constant to a first order of approximation, recent studies suggested that ECS might depend on the climate state. Here it is shown that the latest generation of climate models consistently exhibits an increasing ECS in warmer climates due to a strengthening of the water vapor feedback with increasing surface temperatures. The increasing ECS is replicated by a one-dimensional radiative-convective equilibrium model, which further shows that the enhanced water vapor feedback follows from the rising of the tropopause in a warming climate. This mechanism is potentially important for understanding both warm climates of Earth’s past and projections of future high-emission scenarios."

[AbruptSLR]

The linked reference has a free access pdf and indicates that improved modeling of atmospheric convection results in greater model sensitivity that indicates greater (than previously projected) sea ice reductions and stronger MJO activity with continuing global warming.

Nathan Arnold, Mark Branson, Melissa A. Burt, Dorian S. Abbot, Zhiming Kuang, David A. Randall, and Eli Tziperman, (2014) "Effects of explicit atmospheric convection at high CO2", PNAS, 111(30):10943-10948.

http://www.seas.harvard.edu/climate/eli/reprints/Arnold-Branson-Burt-Abbot-Kuang-Randall-Tziperman-2014.pdf

Significance: "The representation of clouds and convection has an enormous impact on simulation of the climate system. This study addresses concerns that conventional parameterizations may bias the response of climate models to increased greenhouse gases. The broadly similar response of two models with parameterized and nonparameterized convection and clouds suggests that state-of-the-art predictions, based on parameterized climate models, may not necessarily be strongly biased in either direction (too strong or too weak warming). At the same time, large differences in simulated tropical variability and Arctic sea ice area suggest that improvement in convection and cloud representations remains essential."

Abstract: "The effect of clouds on climate remains the largest uncertainty in climate change predictions, due to the inability of global climate models (GCMs) to resolve essential small-scale cloud and convection processes. We compare preindustrial and quadrupled CO2 simulations between a conventional GCM in which convection is parameterized and a “superparameterized” model in which convection is explicitly simulated with a cloud-permitting model in each grid cell. We find that the global responses of the two models to increased CO2 are broadly similar: both simulate ice-free Arctic summers, wintertime Arctic convection, and enhanced Madden–Julian oscillation (MJO) activity. Superparameterization produces significant differences at both CO2 levels, including greater Arctic cloud cover, further reduced sea ice area at high CO2, and a stronger increase with CO2 of the MJO."

[Michael Hauber]

The linked 2013 reference by Meraner et al confirms that Equilibrium Climate Sensitivity, ECS, increase robustly under global warming:

Meraner, K., T. Mauritsen, and A. Voigt (2013), "Robust increase in equilibrium climate sensitivity under global warming",  Geophys. Res. Lett., 40, doi:10.1002/2013GL058118

http://onlinelibrary.wiley.com/doi/10.1002/2013GL058118/pdf

Abstract: "Equilibrium climate sensitivity (ECS) is a widely accepted measure of Earth’s susceptibility to radiative forcing. While ECS is often assumed to be constant to a first order of approximation, recent studies suggested that ECS might depend on the climate state. Here it is shown that the latest generation of climate models consistently exhibits an increasing ECS in warmer climates due to a strengthening of the water vapor feedback with increasing surface temperatures. The increasing ECS is replicated by a one-dimensional radiative-convective equilibrium model, which further shows that the enhanced water vapor feedback follows from the rising of the tropopause in a warming climate. This mechanism is potentially important for understanding both warm climates of Earth’s past and projections of future high-emission scenarios."

A higher ECS in a warmer world, is the same as a cooler ECS in a cooler world.  Compared to much of geologic past the current world is on the cool side (but certainly not as cool as the glacial).  In particular a favourite paleo-sensitivity estimate of the doomers is the high sensitivity estimates based on the Paleo-eocene thermal maximum.  As this started from a much warmer start than current conditions this paper suggests that ECS for today's world would be lower than that of the PTM.

[Michael Hauber]

The linked reference has a free access pdf and indicates that improved modeling of atmospheric convection results in greater model sensitivity that indicates greater (than previously projected) sea ice reductions and stronger MJO activity with continuing global warming.

Nathan Arnold, Mark Branson, Melissa A. Burt, Dorian S. Abbot, Zhiming Kuang, David A. Randall, and Eli Tziperman, (2014) "Effects of explicit atmospheric convection at high CO2", PNAS, 111(30):10943-10948.

http://www.seas.harvard.edu/climate/eli/reprints/Arnold-Branson-Burt-Abbot-Kuang-Randall-Tziperman-2014.pdf

Significance: "The representation of clouds and convection has an enormous impact on simulation of the climate system. This study addresses concerns that conventional parameterizations may bias the response of climate models to increased greenhouse gases. The broadly similar response of two models with parameterized and nonparameterized convection and clouds suggests that state-of-the-art predictions, based on parameterized climate models, may not necessarily be strongly biased in either direction (too strong or too weak warming). At the same time, large differences in simulated tropical variability and Arctic sea ice area suggest that improvement in convection and cloud representations remains essential."

Abstract: "The effect of clouds on climate remains the largest uncertainty in climate change predictions, due to the inability of global climate models (GCMs) to resolve essential small-scale cloud and convection processes. We compare preindustrial and quadrupled CO2 simulations between a conventional GCM in which convection is parameterized and a “superparameterized” model in which convection is explicitly simulated with a cloud-permitting model in each grid cell. We find that the global responses of the two models to increased CO2 are broadly similar: both simulate ice-free Arctic summers, wintertime Arctic convection, and enhanced Madden–Julian oscillation (MJO) activity. Superparameterization produces significant differences at both CO2 levels, including greater Arctic cloud cover, further reduced sea ice area at high CO2, and a stronger increase with CO2 of the MJO."

Also from this paper:

This study addresses concerns that conventional parameterizations may bias the response of climate models to increased greenhouse gases. The broadly similar response of two models with parameterized and nonparameterized convection and clouds suggests that state-of the-art predictions, based on parameterized climate models, may not necessarily be strongly biased in either direction (too strong or too weak warming). At the same time, large differences in simulated tropical variability and Arctic sea ice area suggest that improvement in convection and cloud representations remains essential.

This paper does not support your view that the model projections made by the IPCC are underestimates.  It supports my view that the IPCC projections are accurate.

[AbruptSLR]

Also from this paper:

This study addresses concerns that conventional parameterizations may bias the response of climate models to increased greenhouse gases. The broadly similar response of two models with parameterized and nonparameterized convection and clouds suggests that state-of the-art predictions, based on parameterized climate models, may not necessarily be strongly biased in either direction (too strong or too weak warming). At the same time, large differences in simulated tropical variability and Arctic sea ice area suggest that improvement in convection and cloud representations remains essential.

This paper does not support your view that the model projections made by the IPCC are underestimates.  It supports my view that the IPCC projections are accurate.

When the quote you provide indicates that "... large differences in simulated tropical variability and Arctic sea ice area suggest that improvements in convection and cloud representation remain essential.", you seem to like the approach where you stop analyzing just as soon a you get the answer that you like rather incorporating essential refinements, like getting atmospheric convention modeling right, that might well contribute to non-linear positive feedback with further global warming.

[AbruptSLR]

The linked 2013 reference by Meraner et al confirms that Equilibrium Climate Sensitivity, ECS, increase robustly under global warming:

Meraner, K., T. Mauritsen, and A. Voigt (2013), "Robust increase in equilibrium climate sensitivity under global warming",  Geophys. Res. Lett., 40, doi:10.1002/2013GL058118

http://onlinelibrary.wiley.com/doi/10.1002/2013GL058118/pdf

Abstract: "Equilibrium climate sensitivity (ECS) is a widely accepted measure of Earth’s susceptibility to radiative forcing. While ECS is often assumed to be constant to a first order of approximation, recent studies suggested that ECS might depend on the climate state. Here it is shown that the latest generation of climate models consistently exhibits an increasing ECS in warmer climates due to a strengthening of the water vapor feedback with increasing surface temperatures. The increasing ECS is replicated by a one-dimensional radiative-convective equilibrium model, which further shows that the enhanced water vapor feedback follows from the rising of the tropopause in a warming climate. This mechanism is potentially important for understanding both warm climates of Earth’s past and projections of future high-emission scenarios."

A higher ECS in a warmer world, is the same as a cooler ECS in a cooler world.  Compared to much of geologic past the current world is on the cool side (but certainly not as cool as the glacial).  In particular a favourite paleo-sensitivity estimate of the doomers is the high sensitivity estimates based on the Paleo-eocene thermal maximum.  As this started from a much warmer start than current conditions this paper suggests that ECS for today's world would be lower than that of the PTM.

No where in my post was I referring to the PETM, so why both quoting my post when you want to talk about a different topic (note: I concur that climate sensitivity was clearer higher during the PETM than today or for any plausible climate state in the 21st century).

[Michael Hauber]

When the quote you provide indicates that "... large differences in simulated tropical variability and Arctic sea ice area suggest that improvements in convection and cloud representation remain essential.", you seem to like the approach where you stop analyzing just as soon a you get the answer that you like rather incorporating essential refinements, like getting atmospheric convention modeling right, that might well contribute to non-linear positive feedback with further global warming.
[/quote]

Essential for what though?  The paper states that the difference in modelling approach makes no difference for overall climate sensitivity.  But obviously it is important to get the details correct for regional projections etc.

Your approach seems to be to find a detail which you like and ignore the fact that the overall summary goes against the conclusion you want to draw.

[AbruptSLR]

Essential for what though?  The paper states that the difference in modelling approach makes no difference for overall climate sensitivity.  But obviously it is important to get the details correct for regional projections etc.

Your approach seems to be to find a detail which you like and ignore the fact that the overall summary goes against the conclusion you want to draw.

Essential because the IPCC AR5 GCM projections are not adequate to accurately model possible highly non-linear feedbacks and interactions; which would require a state-of-the-art type of Earth Systems Model such as ACME by the DOE.  Alternately, do you think that the DOE is just milking the US citizens just to keep a small group of scientists employed?

[Michael Hauber]

Essential because the IPCC AR5 GCM projections are not adequate to accurately model possible highly non-linear feedbacks and interactions; which would require a state-of-the-art type of Earth Systems Model such as ACME by the DOE.  Alternately, do you think that the DOE is just milking the US citizens just to keep a small group of scientists employed?

All models are wrong.  Some are useful.  The IPCC AR5 GCM models are the best we have to predict future climate change.

[jai mitchell]

Essential because the IPCC AR5 GCM projections are not adequate to accurately model possible highly non-linear feedbacks and interactions; which would require a state-of-the-art type of Earth Systems Model such as ACME by the DOE.  Alternately, do you think that the DOE is just milking the US citizens just to keep a small group of scientists employed?

All models are wrong.  Some are useful.  The IPCC AR5 GCM models are the best we have to predict future climate change.

Except the C4MIP carbon cycle inputs have as much variance in feedback emissions as there is between RCP 8.5 and RCP 2.6 emissions.  AND they don't include carbon cycle and frozen soil feedbacks in any of the model runs except RCP 8.5 and we know that they have severely underestimated those emissions since they predict summer sea ice to maintain through 2065.

The simple fact that they underestimate western U.S. droughts and arctic sea ice extents by nearly 40 years is enough to confirm that, even if their mid-value of ECS is good, even if they Don't severely underestimate aerosol secondary cloud-effects (they do!) then we would know from direct observations that the models are about 40 years too slow for major climate responses.

I know we have talked about these things and, while you agreed that they were true, you still hold fast to the faith-based assertion that the IPCC GCMs are "accurate".

[Michael Hauber]

Some regional impacts may be ahead of model projections.  But the global temperature is currently behind model projections (even if only slightly).  Obviously then some regional impacts are ahead, and others are behind.  It is not smart to focus only on the impacts that are ahead to try and prove that the models always underestimate everything.

Further discussion on CMIP and carbon cycle issues I will limit to the Conservative sciences thread.

I do not recall seeing any good evidence for an underestimation of aerosol secondary effects.  I remember someone made such a claim in this forum and posted a paper in support, but the claim was made nowhere in the paper, and if you compared the number that the paper put on the effect to what was in the latest IPCC it was about the same.

[jai mitchell]

I do not recall seeing any good evidence for an underestimation of aerosol secondary effects. 

Somehow, I doubt that you have looked.

claiming that globally averaged temperatures over a 10 years span is somehow indicative of the veracity of the GCMs makes you sound just like a denialist from Watts.  The temperature projections are well within the variability of solar cycle intensity, aerosol emissions and ocean decadal oscillation regimes.

However, with regard to overarching feedback inputs, there is nothing even close in the GCMs that compares with the Great Drying that is occurring in the Amazon and the SouthWest U.S. nor is there any doubt that the intensity of boreal forest fires and arctic ice loss are happing well in advance of the most aggressive GCM results.

These are the feedbacks that I am talking about.  These are the real world, directly observable instances that are directly attributable to climate change, each with intensely active impacts on the rest of the biosphere with regard to carbon sequestration (or lack thereof) and carbon emissions and loss of albedo.

For your ease I will list them for you:

• Amazonian Basin Drought- turning into Savannah
• South Western State mega drought (the Great Drying) and loss of mountain snowpack
• Boreal forest fires (and now peat fires)
• Arctic sea ice collapse

If you can address these and explain how they are NOT operating well and in excess of the model results and/or show how they are not POSITIVE contributions to further warming, well, I am listening. . .

[AbruptSLR]

With the stellar list of conveners I hope to see slides or proceedings from the 2015 WCRP Grand Challenge Workshop on Earth's Climate Sensitivities:

http://www.mpimet.mpg.de/en/science/the-atmosphere-in-the-earth-system/ringberg-workshop/ringberg-2014.html

WCRP Grand Challenge Workshop: Earth's Climate Sensitivities
March 23-27, 2015
Schloss Ringberg
3700 Rottach-Egern, Germany
 
Conveners:   
Bjorn Stevens, Ayako Abe-Ouche, Sandrine Bony, Gabi Hegerl, Gavin Schmidt, Steve Sherwood and Mark Webb

Overview:
Ringberg 2015 is the third of a series of workshops organized at Ringberg under the auspices of the World Climate Research Programmes (WCRP) and with the support of the Max Planck Institute for Meteorology in Hamburg, Germany.

Ringberg 2015 revisits the question of Earth's climate sensitivity and its transient response to forcing. Coming on the heels of the fifth assessment report, in which many perceived very little progress to have been made in bounding how Earth responds to forcing, the workshop brings together an international group of experts to look at the different facets of Earth's response to forcing. Through coordinated experiments and a critical assessment of the story lines for a surprisingly large, or small, climate sensitivity the workshop aims to more clearly summarize the current state of understanding as to how Earth responds to forcing, and identify fruitful research directions for further narrowing uncertainty. In so doing a particular focus will be placed on seemingly contradictory lines of evidence, as well as possible early warning signals for a larger or smaller than anticipated climate sensitivity.

[Sleepy]

Thanks, ASLR. It will be interesting to follow the outcome of that one. With a special little interest towards one of my countrymens contributions. Hmm...

[Michael Hauber]

claiming that globally averaged temperatures over a 10 years span is somehow indicative of the veracity of the GCMs makes you sound just like a denialist from Watts.  The temperature projections are well within the variability of solar cycle intensity, aerosol emissions and ocean decadal oscillation regimes.

Have a look at my thread in the science section of this forum.  I do not talk about 10 year trends, but rather 30 years or so.  The fact remains that while the trend is well within variability due to a bunch of factors, it is still below that projected by the models for many (but not all) different time frames.  This makes it hard to justify a projection of twice the speed that the models are projecting (i.e. 9 deg over next century).  Simply pointing out that there are reasons why warming might be higher is not enough.  Is the extra warming enough to push the temperature trend up to the modelled trend?  Or is it enough to push it higher?

Amazonian Basin Drought- turning into Savannah
South Western State mega drought (the Great Drying) and loss of mountain snowpack
Boreal forest fires (and now peat fires)
Arctic sea ice collapse

If you can address these and explain how they are NOT operating well and in excess of the model results and/or show how they are not POSITIVE contributions to further warming, well, I am listening. . .

[/url]
Reasons for less warming also need to be considered.  As an example CMIP models project a statistically significant decline in Antarctic sea ice.  However no such decline is happening and so albedo feedbacks in the Antarctic are currently less than models predict.  Until reasons for both less and more warming are considered then any analysis is biased.

[jai mitchell]

the models are right at the trends.  you are obviously getting your talking points from watts.

[jai mitchell]

fyi

The overall magnitude of the changes in forcing from the
two models indicates that ACI contributions from sulfate
are a near zero global forcing agent over the last decade of
less than ±0.1 Wm−2. This compares to a positive anthropogenic
greenhouse gas forcing of +0.35Wm−2. Other
agents can easily account for this, including oceans heat
uptake (−0.2Wm−2, Trenberth et al. (2014)), stratospheric
water vapor decreases (−0.1Wm−2, Solomon et al. (2010)),
recent volcanoes (−0.1Wm−2, Solomon et al. (2011)), and
effects from variations in solar flux over the 11 year solar
cycle and ENSO variability (Kosaka and Xie 2013).

http://www.cgd.ucar.edu/staff/andrew/papers/gettelman2015aerorecent.pdf

Impact of aerosol radiative effects on 2000–2010 surface
temperatures
A. Gettelman · D. T. Shindell · J. F. Lamarque
DOI 10.1007/s00382-014-2464-2

[AbruptSLR]

The linked reference discusses the significance of short-lived halogens with regard to global warming and depletion of stratospheric ozone (citing an immediate need for increased regulations):

R. Hossaini, M. P. Chipperfield, S. A. Montzka, A. Rap, S. Dhomse & W. Feng, (2015), "Efficiency of short-lived halogens at influencing climate through depletion of stratospheric ozone", Nature Geoscience, doi:10.1038/ngeo2363


http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2363.html


Abstract: "Halogens released from long-lived anthropogenic substances, such as chlorofluorocarbons, are the principal cause of recent depletion of stratospheric ozone, a greenhouse gas. Recent observations show that very short-lived substances, with lifetimes generally under six months, are also an important source of stratospheric halogens. Short-lived bromine substances are produced naturally by seaweed and phytoplankton, whereas short-lived chlorine substances are primarily anthropogenic. Here we used a chemical transport model to quantify the depletion of ozone in the lower stratosphere from short-lived halogen substances, and a radiative transfer model to quantify the radiative effects of that ozone depletion. According to our simulations, ozone loss from short-lived substances had a radiative effect nearly half that from long-lived halocarbons in 2011 and, since pre-industrial times, has contributed a total of about −0.02 W m−2 to global radiative forcing. We find natural short-lived bromine substances exert a 3.6 times larger ozone radiative effect than long-lived halocarbons, normalized by halogen content, and show atmospheric levels of dichloromethane, a short-lived chlorine substance not controlled by the Montreal Protocol, are rapidly increasing. We conclude that potential further significant increases in the atmospheric abundance of short-lived halogen substances, through changing natural processes or continued anthropogenic emissions, could be important for future climate."

[Sleepy]

Just browsed through some of the talks from the 2015 WCRP Grand Challenge Workshop at Ringberg.
http://www.mpimet.mpg.de/en/science/the-atmosphere-in-the-earth-system/ringberg-workshop/ringberg-2014/talks.html

Does anyone know if there will be a presentation or more of the discussions presented there soon?

[AbruptSLR]

Just browsed through some of the talks from the 2015 WCRP Grand Challenge Workshop at Ringberg.
http://www.mpimet.mpg.de/en/science/the-atmosphere-in-the-earth-system/ringberg-workshop/ringberg-2014/talks.html

Does anyone know if there will be a presentation or more of the discussions presented there soon?

Sleepy,
Thank you very much for the link to the 2015 WCRP Grand Challenge Workshop at Ringberg presentations.  Based on my initial review it seems to me that the presenters at the workshop were roughly divided into two camps:
(1) Those who choose to continue the AR5 climate sensitivity assumptions that erred on the side of least drama, in order minimize confrontations with policy makers who wish to make positive happy talk; and

(2) Those who believe that the AR5 climate sensitivity assumptions are biased on the low side, and are working towards presenting a consistent paradigm to match the instrumentation record with more accurate physics of the complex Earth Systems.

As AR5 more than adequately represents the position of the first camp, I only summarize three presentations of researchers in the second camp in the following

The Andrews, Webb & Gregory (2015) presentation correlates different SST patterns [most significantly dominated by the ENSO, where greater El Nino frequency/magnitudes (see the first attached image) result in slower global SST rates of increase and much higher ECS values (up to 5C) due to associated changes in cloud cover in the tropics] have a big impact on modeled ECS values (see the second image & the following extract):

Extract: "- Targeted AGCM experiments with various SST patterns – traceable to AOGCM transient behavior and observations – are a valuable tool in understanding the mechanisms and processes related to time varying feedbacks

- Feedbacks are very sensitive to warming patterns: I can get ECS values from 1.3 to 5K just by changing the warming pattern in HadGEM2!

- HadGEM2--‐A results give some insight into why cloud feedback varies with SST patterns, relates to LTS change for low clouds.

- CMIP5 AMIP experiments forced with observed SST variations give feedback and ECS estimates (~1--‐2K) in agreement with observations.

- Perhaps no discrepancy between models and observational estimates of climate sensitivity after all, its just the historical record estimates are biased low because of variability in SST patterns

- Interesting 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?

- Much more to understand and do. Detailed results mostly from a single model. Some of these experiments have been proposed for CMIP6 and/or CFMIP3 – please do them, they are cheap runs, early multi--‐model pilot study welcome!"

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

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


The following extract from Fasullo (2015), indicates that the reconstructions of sea level indicate that estimates of ECS based strictly on the instrument records contain a higher degree of uncertainty associated with long-term natural variability than previously recognized, thus indicating a greater risk that ECS may be at the higher than estimated based strictly on the instrument record.:

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

…

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

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

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

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

Very best,
ASLR

[AbruptSLR]

The linked draft reference (with a free pdf) uses statistical methods on direct observations from 1964 to 2010 in order to correct (disentangle) estimates of Transient Climate Sensitivity, TCS, from this influence of aerosol cooling.  This draft reference finds that TCS is likely higher than that assumed in AR5, and that one third of the measured warming of continental surface temperatures, during this timeframe was masked by the cooling effect of aerosols (see also the link at the end of this post to other post-AR5 papers related to climate sensitivity):

T. Storelvmo, T. Leirvik, U. Lohmann, P. C. B. Phillips, M. Wild (2015), "Disentangling Greenhouse Warming and Aerosol Cooling to Reveal Earth’s Transient Climate Sensitivity", Draft submitted for publication


http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/ClimSens_Mar2015.pdf


Extract: "Earth’s climate sensitivity has been the subject of heated debate for decades, and recently spurred renewed interest after the latest IPCC assessment report suggested a downward adjustment of the most likely range of climate sensitivities. Here, we present an observation-based study based on the time period 1964 to 2010, which is unique in that it does not rely on global climate models (GCMs) in any way. The study uses surface observations of temperature and incoming solar radiation from approximately 1300 surface sites, along with observations of the equivalent CO2 concentration (CO2,eq) in the atmosphere, to produce a new best estimate for the transient climate sensitivity of 1.9K (95% confidence interval 1.2K – 2.7K). This is higher than other recent observation-based estimates, and is better aligned with the estimate of 1.8K and range (1.1K – 2.5K) derived from the latest generation of GCMs. The new estimate is produced by incorporating the observations in an energy balance framework, and by applying statistical methods that are standard in the field of Econometrics, but less common in climate studies. The study further suggests that about a third of the continental warming due to increasing CO2,eq was masked by aerosol cooling during the time period studied."


For other relevant post-AR5 papers on climate sensitivity see:

http://www.mpimet.mpg.de/en/science/the-atmosphere-in-the-earth-system/ringberg-workshop/ringberg-2014.html

[jai mitchell]

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

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

If so, this is incredibly disturbing, we already know that the OHC in the northern hemisphere has been negligible since the beginning of the Chinese sulfate rampup.  This would be consistent with my own analysis that indicates that the cumulative GHG forcing and Aerosol forcing has both been significantly understated.

[AbruptSLR]

If so, this is incredibly disturbing, we already know that the OHC in the northern hemisphere has been negligible since the beginning of the Chinese sulfate rampup.  This would be consistent with my own analysis that indicates that the cumulative GHG forcing and Aerosol forcing has both been significantly understated.

I suspect that by the time that the researchers (including those working on ACME) have detangled the various interactions of aerosols, global warming and multi-annual to multi-decadal oscillations such as: ENSO/AMO/IPO/PDO/etc. on: (a) OHC distribution, (b) tropical atmospheric deep convection and other circulation patterns, (c) regional cloud cover (with altitude), (d) Arctic & Antarctic amplification, (e) direct & indirect negative forcing; etc (and their combined influence on TCR, ECS & ESS) we will be so far down the rabbit-hole that it will be impossible to control non-linear positive feedback mechanisms (activated in the next couple of decades) even with aggressive application of SRM.

[LRC1962]

Another issue that has come up many times, at least for me and the number of clips I have seen, is the totally unpredictable step. That is where you have a nice trend going on then something dramatic happens and you continue on with the same trend slope except on a whole new level. It is that step which can be the biggest problem. It has not always happened historically. The size of the step is always different, and the time period in which it is happening is never the same.
Let us take as an example. Right now we are on an increase temperature curve. Take it out to 2100 and you get a certain number. What if you have in the mean time a step up of say 3-4 degrees, not in a nice curve, in in a surge over 10 years, 5 years, or maybe even one year. Then you proceed on the same kind of curve, but a whole new level. Not only that it doesn't happen only once, but 2-3 times during that time period.
Historically CO2 follows temp changes, granted about 300 years apart, but the curves match. In our current state. the CO2 levels are leading at levels far exceeding temperature change ever in the history of known time. That means we are putting a lot of stress to the system. Anytime nature gets too stressed out it reacts very dramatically. The more stress the more violent and suddenness of the reaction. Such as earthquakes. The unanswerable question is how stressed is nature over the CO2-temp imbalance, how sudden and how much change will occur to fix that imbalance? Then of course since everything in nature is interconnected to everything else, the imbalance adjustment in one spot will cause extra stress somewhere else and that will have to be fix and on and on it goes until we return back to the CO@-temp imbalance that has now returned to excess stress and another step.
Nature left alone will fix things in time with the best all round results, but man and his mind and impatience is guaranteed to step in and try and help out. Sometimes with good results, but most often with disastrous results.
My take on it will be man will finally come to realization that action will be need, but instead of doing little things, such as changing farming practices after the dust bowl and thereby avoiding a repeat in the 50's, will do something to try and bring down temps artificially rather then just taking CO2 out and add more stresses and and out with causing even greater problems.

[Sleepy]

Took some time this morning and went through them all and I think ASLR made a nice summary above. I definately vote for the second camp, but it doesn't really matter, todays warming is too much as it is.

My little side interest was in Bengtssons talk. Compared to the absurd political opinions he expresses here in newspapers and social media, that one was a joy to read...

[AbruptSLR]

Another issue that has come up many times, at least for me and the number of clips I have seen, is the totally unpredictable step. That is where you have a nice trend going on then something dramatic happens and you continue on with the same trend slope except on a whole new level. It is that step which can be the biggest problem. It has not always happened historically. The size of the step is always different, and the time period in which it is happening is never the same.
Let us take as an example. Right now we are on an increase temperature curve. Take it out to 2100 and you get a certain number. What if you have in the mean time a step up of say 3-4 degrees, not in a nice curve, in in a surge over 10 years, 5 years, or maybe even one year. Then you proceed on the same kind of curve, but a whole new level. Not only that it doesn't happen only once, but 2-3 times during that time period.
Historically CO2 follows temp changes, granted about 300 years apart, but the curves match. In our current state. the CO2 levels are leading at levels far exceeding temperature change ever in the history of known time. That means we are putting a lot of stress to the system. Anytime nature gets too stressed out it reacts very dramatically. The more stress the more violent and suddenness of the reaction. Such as earthquakes. The unanswerable question is how stressed is nature over the CO2-temp imbalance, how sudden and how much change will occur to fix that imbalance? Then of course since everything in nature is interconnected to everything else, the imbalance adjustment in one spot will cause extra stress somewhere else and that will have to be fix and on and on it goes until we return back to the CO@-temp imbalance that has now returned to excess stress and another step.
Nature left alone will fix things in time with the best all round results, but man and his mind and impatience is guaranteed to step in and try and help out. Sometimes with good results, but most often with disastrous results.
My take on it will be man will finally come to realization that action will be need, but instead of doing little things, such as changing farming practices after the dust bowl and thereby avoiding a repeat in the 50's, will do something to try and bring down temps artificially rather then just taking CO2 out and add more stresses and and out with causing even greater problems.

In GCM, & ESM, projections, researchers have looked for the type of stepped temperature increases that you discuss (& which have occurred in the paleo-record), and as of yet they have not been able to identify any such stepped occurrence before 2100 given modern conditions and plausible anthropogenic forcing scenarios.  That said, the DOE is sufficiently concerned that we do not adequately understand all of the positive/negative forcing/feedback mechanisms yet so they are currently spending hundreds of millions of dollars to build & calibrate the state-of-the-art ESM: ACME (with both new hardware & software).  Furthermore, the Ringberg presentations that I cited certainly raise the prospect that ECS could be 4C to 5C right now (but masked), and that as more positive feedback mechanisms are triggered this could increase to above 6C before the end of this century.

Certainly, I concur with your concern that the state elites may very well resort to geoengineering (both NET & SRM) circa 2050, and that if they do, there is a fair possibility that they could make matters worst.  As there is only one Earth, I believe that we will all find out what is going to actually happen together (unless Elon Musk gets his colony set-up on Mars first).

[AbruptSLR]

The linked reference (with a free author's proof linked) reviews both AR4's & AR5's treatment (see the attached images) of both ECS and TCR and recommend a new parameter the ratio TCR:ECS, or realized warming fraction (RWF).  While the paper concludes that the AR5 generation of GCM projections do not indicate that scenario with low TCRs and high RWFs occur (and the authors call for more research to verify these low drama findings); I point out that the GCM projection clearly identify numerous cases with relatively high TCRs and low RWFs which are high drama cases that have been ignored by AR5 so as to intentionally err on the side of least drama (while callously exposing the public to unstated risks).

Richard J. Millar, Alexander Otto, Piers M. Forster, Jason A. Lowe, William J. Ingram, Myles R. Allen (2015), "Model structure in observational constraints on transient climate response", Climate Change, DOI 10.1007/s10584-015-1384-4


http://link.springer.com/article/10.1007/s10584-015-1384-4

http://www.mpimet.mpg.de/fileadmin/atmosphaere/WCRP_Grand_Challenge_Workshop/Ringberg_2015/Millar_etal_2015.pdf

Abstract: "The transient climate response (TCR) is a highly policy-relevant quantity in climate science. We show that recent revisions to TCR in the IPCC 5th Assessment Report have more impact on projections over the next century than revisions to the equilibrium climate sensitivity (ECS). While it is well known that upper bounds on ECS are dependent on model structure, here we show that the same applies to TCR. Our results use observations of the planetary energy budget, updated radiative forcing estimates and a number of simple climate models. We also investigate the ratio TCR:ECS, or realised warming fraction (RWF), a highly policy-relevant quantity. We show that global climate models (GCMs) don’t sample a region of low TCR and high RWF consistent with observed climate change under all simple models considered. Whether the additional constraints from GCMs are sufficient to rule out these low climate responses is a matter for further research."

[AbruptSLR]

The linked reference discusses the importance of correctly modeling tropical low clouds when GCMs estimate values of climate sensitivity.  I suspect that as more models are improved (especially by state-of-the-art climate models like ACME) to more correctly account for this positive feedback factor (including w.r.t. the ENSO & AMO cycles) that estimates of both TCR and ECS will be increased.

Florent Brient, Tapio Schneider, Zhihong Tan,Sandrine Bony (2015), "Shallowness of tropical low clouds as a predictor of climate models' response to warming", Climate Dynamics, submitted.

http://www.clidyn.ethz.ch/papers/Brient-et-al-2015.pdf

Abstract: "How tropical low clouds change with climate remains the dominant  source of uncertainty in global warming projections. An analysis of an ensemble of CMIP5 climate models reveals that about half of the spread in the models' climate sensitivity can be accounted for by differences in the climatological shallowness of tropical low clouds in weak subsidence regimes: models with shallower low clouds in weak subsidence regimes tend to have a higher climate sensitivity than models with deeper low clouds. The dynamical mechanisms responsible for the model differences are analyzed, and competing effects of parameterized boundary-layer turbulence and shallow convection are found to be essential."

[AbruptSLR]

The linked article by Joe Romm makes the case that global mean temperatures will likely jump relatively abruptly by 0.2 to 0.3 of a degree centigrade.

http://thinkprogress.org/climate/2015/04/02/3640842/global-warming-jump-imminent/

[AbruptSLR]

The linked reference expands on the findings of the Andrews, Gregory & Webb presentation discussed in Reply #225:

Timothy Andrews, Jonathan M. Gregory, and Mark J. Webb (2015), "The Dependence of Radiative Forcing and Feedback on Evolving Patterns of Surface Temperature Change in Climate Models", J. Climate, 28, 1630–1648, doi: http://dx.doi.org/10.1175/JCLI-D-14-00545.1

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-14-00545.1

Abstract: "Experiments with CO2 instantaneously quadrupled and then held constant are used to show that the relationship between the global-mean net heat input to the climate system and the global-mean surface air temperature change is nonlinear in phase 5 of the Coupled Model Intercomparison Project (CMIP5) atmosphere–ocean general circulation models (AOGCMs). The nonlinearity is shown to arise from a change in strength of climate feedbacks driven by an evolving pattern of surface warming. In 23 out of the 27 AOGCMs examined, the climate feedback parameter becomes significantly (95% confidence) less negative (i.e., the effective climate sensitivity increases) as time passes. Cloud feedback parameters show the largest changes. In the AOGCM mean, approximately 60% of the change in feedback parameter comes from the tropics (30°N–30°S). An important region involved is the tropical Pacific, where the surface warming intensifies in the east after a few decades. The dependence of climate feedbacks on an evolving pattern of surface warming is confirmed using the HadGEM2 and HadCM3 atmosphere GCMs (AGCMs). With monthly evolving sea surface temperatures and sea ice prescribed from its AOGCM counterpart, each AGCM reproduces the time-varying feedbacks, but when a fixed pattern of warming is prescribed the radiative response is linear with global temperature change or nearly so. It is also demonstrated that the regression and fixed-SST methods for evaluating effective radiative forcing are in principle different, because rapid SST adjustment when CO2 is changed can produce a pattern of surface temperature change with zero global mean but nonzero change in net radiation at the top of the atmosphere (~−0.5 W m−2 in HadCM3)."

[AbruptSLR]

Gavin Schmidt posted an article on the Ringberg workshop at RealClimate a couple of days ago (see link).  While Gavin leans toward supporting the common AR5 message, the extract below (and associated image indicating that the climate sensitivity parameter is not constant, particularly due to cloud, and also aerosol, interactions) indicates that he is reasonably open to changing the current AR5 message given sufficient evidence.  I keep my fingers crossed that the next generation of ESMs (& GCMs) will shine a light to reduce the remaining uncertainties that denialist (like Nick Lewis) hide behind.

http://www.realclimate.org/index.php/archives/2015/04/reflections-on-ringberg/

Extract: "The variation in climate sensitivity in models seems to be dominated by the simulations of low clouds (which are a net cooling to the climate) which have a tendency to disappear as the climate warms. Whether this can be independently constrained in the observations is unclear.
The conversations around these issues got into multiple connected areas, including aerosol forcings, observational uncertainty, climate model tuning and independence, the nature of probability, Bayesian updating, detection and attribution, and internal variability. It looks like there will be some interesting upcoming papers on many of these aspects that will help clarify matters.

While the workshop wasn’t designed to produce a new assessment of the evidence, we did spend time specifying the problems there would be if equilibrium sensitivity was less than 2ºC or greater than 5ºC. Specifically, what would have to be true for all the evidence to fit? This was useful at underlining the challenge in shifting or constraining the ‘classic’ range by very much."

[AbruptSLR]

The linked reference indicates that CMIP5 projections (which err on the side of least drama) estimates that due to anthropogenic forcing the Earth systems are now moving into a regime of increasing global mean temperature increase rates that are unprecedented for at least the past 1,000 years.

Steven J. Smith, James Edmonds, Corinne A. Hartin, Anupriya Mundra & Katherine Calvin (2015), "Near-term acceleration in the rate of temperature change", Nature Climate Change, Volume: 5, Pages: 333–336, doi:10.1038/nclimate2552


http://www.nature.com/nclimate/journal/v5/n4/full/nclimate2552.html


Abstract: "Anthropogenically driven climate changes, which are expected to impact human and natural systems, are often expressed in terms of global-mean temperature. The rate of climate change over multi-decadal scales is also important, with faster rates of change resulting in less time for human and natural systems to adapt. We find that present trends in greenhouse-gas and aerosol emissions are now moving the Earth system into a regime in terms of multi-decadal rates of change that are unprecedented for at least the past 1,000 years. The rate of global-mean temperature increase in the CMIP5 archive over 40-year periods increases to 0.25 ± 0.05 °C (1σ) per decade by 2020, an average greater than peak rates of change during the previous one to two millennia. Regional rates of change in Europe, North America and the Arctic are higher than the global average. Research on the impacts of such near-term rates of change is urgently needed."

[Richard Rathbone]

Gavin Schmidt posted an article on the Ringberg workshop at RealClimate a couple of days ago (see link).  While Gavin leans toward supporting the common AR5 message, the extract below (and associated image indicating that the climate sensitivity parameter is not constant, particularly due to cloud, and also aerosol, interactions) indicates that he is reasonably open to changing the current AR5 message given sufficient evidence.  I keep my fingers crossed that the next generation of ESMs (& GCMs) will shine a light to reduce the remaining uncertainties that denialist (like Nick Lewis) hide behind.

You'd get a better picture of the uncertainty by drawing a tangent rather than a chord on that graph. We don't know what the equilibrium temperature is for our current imbalance and are extrapolating to it in various different ways, rather than knowing what it is and being uncertain about what the path to it will be.

[AbruptSLR]

Gavin Schmidt posted an article on the Ringberg workshop at RealClimate a couple of days ago (see link).  While Gavin leans toward supporting the common AR5 message, the extract below (and associated image indicating that the climate sensitivity parameter is not constant, particularly due to cloud, and also aerosol, interactions) indicates that he is reasonably open to changing the current AR5 message given sufficient evidence.  I keep my fingers crossed that the next generation of ESMs (& GCMs) will shine a light to reduce the remaining uncertainties that denialist (like Nick Lewis) hide behind.

You'd get a better picture of the uncertainty by drawing a tangent rather than a chord on that graph. We don't know what the equilibrium temperature is for our current imbalance and are extrapolating to it in various different ways, rather than knowing what it is and being uncertain about what the path to it will be.

Richard,
Your point about considering the uncertainty associated with the changing (with time) tangent of the non-linear sensitivity curve by Gregory, is well taken.  Furthermore, I realize that in complex non-linear dynamic modeling analysis that one wants to be as accurate with regards to input and modeling mechanisms as is practicable (rather than just erring on the side of precaution during the modeling); and that it is challenging to get all of this to be reasonable accurate given the AR5 situation of knowledge, computer power, money, and model code.  Therefore, I draw your attention to Replies #739 & #740 in the "Conservative Scientists & its Consequences" thread (see link & the re-posts below) about the use of dynamical system theory to reduce the uncertainties associated with estimating climate sensitivity from the paleo-record; and I ask whether you believe that use of this approach will soon result in a reduction in these uncertainties?  If not, we may need to wait about 10-years until the ACME project is complete before the uncertainties of the climate change model projections are low enough for good policy makers to ignore the "Precautionary Principle".

http://forum.arctic-sea-ice.net/index.php/topic,1053.700.html

Reply #739
"The linked reference cites that despite variable time lags for the complex non-linear paleo climate record, dynamical system theory proves that the paleo-record confirms that internal Earth systems mechanisms included marked positive feedback effect from temperature variability on greenhouse-gas concentrations.  Hopefully, this new insight will allow researchers to better use paleo-data to reduce the uncertainties associated with estimating climate sensitivities.

Egbert H. van Nes, Marten Scheffer, Victor Brovkin, Timothy M. Lenton, Hao Ye, Ethan Deyle & George Sugihara (2015), "Causal feedbacks in climate change", Nature Climate Change, doi:10.1038/nclimate2568

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2568.html


Abstract: "The statistical association between temperature and greenhouse gases over glacial cycles is well documented, but causality behind this correlation remains difficult to extract directly from the data. A time lag of CO2 behind Antarctic temperature—originally thought to hint at a driving role for temperature—is absent at the last deglaciation, but recently confirmed at the last ice age inception and the end of the earlier termination II. We show that such variable time lags are typical for complex nonlinear systems such as the climate, prohibiting straightforward use of correlation lags to infer causation. However, an insight from dynamical systems theory now allows us to circumvent the classical challenges of unravelling causation from multivariate time series. We build on this insight to demonstrate directly from ice-core data that, over glacial–interglacial timescales, climate dynamics are largely driven by internal Earth system mechanisms, including a marked positive feedback effect from temperature variability on greenhouse-gas concentrations."

See also:
http://www.laboratoryequipment.com/news/2015/03/confirmed-positive-feedback-occurs-climate-change

Edit: Also see:

http://www.reportingclimatescience.com/news-stories/article/evidence-found-of-climate-change-positive-feedback.html
"

Reply #740
"Ref 8. in the van Nes paper (doi:10.1038/NCLIMATE2568)  is to Sugihara (2012, doi:10.1126/science.1227079) which also is a very nice paper, about detecting causal relations in ecosystems. I was waiting for someone to use the technique in paleoclimate. They are both very recommended reading, the van Nes paper moves me to use the Sugihara technique in one of my little projects also.


Read em both, they're sweet.

sidd"

Best,
ASLR

[Laurent]

What a pity to do not have access to this doc ...
Great stuff : Am i reading Kyears on the left axis ?

[AbruptSLR]

What a pity to do not have access to this doc ...
Great stuff : Am i reading Kyears on the left axis ?

At least you have access to the Supplementary material at the following link (you can see the time scale clearly on the images in this material):

http://www.nature.com/nclimate/journal/vaop/ncurrent/extref/nclimate2568-s1.pdf

Also, the following link has some background discussion on this matter:

http://www.exeter.ac.uk/news/research/title_444193_en.html

[sidd]

in the van Nes paper, there are also the results for sodium and dust. The sodium is thought to come from sea ice ...

"More interestingly, we also find negative displacements for CCM
associated with a ‘proxy’ link from the salt (Na) content of the ice
record to GHGs (Supplementary Fig. 9). Sea salt in the ice cores
is probably a proxy for sea-ice extent, as the salt mainly originates
from wind erosion of the sea-ice surface[Ref 27] . Thus CCM results for Na
are consistent with the view that the Pleistocene climate fluctuations
were driven largely by the effects of expanding and shrinking ice
caps, both on land and sea, modulating the accumulation and release
of a large store of carbon in the deep ocean."

[AbruptSLR]

in the van Nes paper, there are also the results for sodium and dust. The sodium is thought to come from sea ice ...

"More interestingly, we also find negative displacements for CCM
associated with a ‘proxy’ link from the salt (Na) content of the ice
record to GHGs (Supplementary Fig. 9). Sea salt in the ice cores
is probably a proxy for sea-ice extent, as the salt mainly originates
from wind erosion of the sea-ice surface[Ref 27] . Thus CCM results for Na
are consistent with the view that the Pleistocene climate fluctuations
were driven largely by the effects of expanding and shrinking ice
caps, both on land and sea, modulating the accumulation and release
of a large store of carbon in the deep ocean."

As the Pleistocene has been dated from 2.588 million (±.005) to 11,700 years before present (BP), it is likely that such CCM results will tell us little about our risk this century.

[Richard Rathbone]

ASLR: re your reply #239 above.

I am unconvinced that there is anything in those papers that will narrow sensitivity estimates to a significant degree. Maybe 10 years will suffice to get the models to a state where a consensus can emerge, but I think the lack is in detailed modern data rather than sparse paleo data. When you are basically fitting noise, fancier methods of fitting noise don't help.

When I see models that hold up well as modern data comes in rather than the performance revealed in the AR5 cycle I'll start to think there's value in paleo work for these pathway considerations rather than exemplars of possible system states. The biasses in individual terms of the radiation balance need to come down by an order of magnitude before I'd expect outputs from the models to show reliability or consistency.

Paleo is a valuable counterpoint for those who think that the earth can't possibly get into a state significantly different from its current one, but the current one needs to be modelled a whole lot better before we'll have decent predictive ability about the pathway it will take.

[AbruptSLR]

Richard,

I generally concur with the points in your Reply #244; which means at best the converging trends of better understanding feedback mechanisms via such tools as the ACME project which will be complete by 2025 together with an increased understanding of the TCR due to the better understanding of modern radiative forcing by 2030 cited in the linked Myhre et.al. (2015) reference, means that we should progressively be getting a clearer understanding of what the future will hold, just in time for the policy makers to decide whether geoengineering should be extended into field studies, for possible full deployment by 2045-2050:

Gunnar Myhre, Olivier Boucher, François-Marie Bréon, Piers Forster & Drew Shindell, (2015), "Declining uncertainty in transient climate response as CO2 forcing dominates future climate change", Nature Geoscience, doi:10.1038/ngeo2371

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2371.html

Abstract: "Carbon dioxide has exerted the largest portion of radiative forcing and surface temperature change over the industrial era, but other anthropogenic influences have also contributed. However, large uncertainties in total forcing make it difficult to derive climate sensitivity from historical observations. Anthropogenic forcing has increased between the Fourth and Fifth Assessment Reports of the Intergovernmental Panel of Climate Change (IPCC) although its relative uncertainty has decreased. Here we show, based on data from the two reports, that this evolution towards lower uncertainty can be expected to continue into the future. Because it is easier to reduce air pollution than carbon dioxide emissions and because of the long lifetime of carbon dioxide, the less uncertain carbon dioxide forcing is expected to become increasingly dominant. Using a statistical model, we estimate that the relative uncertainty in anthropogenic forcing of more than 40% quoted in the latest IPCC report for 2011 will be almost halved by 2030, even without better scientific understanding. Absolute forcing uncertainty will also decline for the first time, provided projected decreases in aerosols occur. Other factors being equal, this stronger constraint on forcing will bring a significant reduction in the uncertainty of observation-based estimates of the transient climate response, with a 50% reduction in its uncertainty range expected by 2030."

Best,
ASLR

[sidd]

That van Nes/sugihara combo also shows the way to imputing causation at any timescale, not just kiloyear in pleistocene, as long as variables belong to the same dynamic system. Indeed the first paper in 2012 by sugihara looks at the case for (among other things) ecosystem consisting of didinium and paramecium on a timescale of days and sardine/anchovy on scale of decades. That is such a nice paper.

 To stretch those ideas further, i am looking at how CCM could measure evolution of the dynamic system also, as indeed we see our climate evolving under anthro stress.

sidd

[AbruptSLR]

The linked article indicates that between 2007 and 2012 HFC emissions increase by 54 percent.

http://www.carbonbrief.org/blog/2015/04/hydrofluorocarbon-emissions-up-54-percent-with-air-conditioning-on-the-rise/

[Sleepy]

I would like to quote this from ASLR's post above about HFC emissions.

what Prof Paul Blowers, professor of chemical engineering at the University of Arizona, who wasn't involved in the study, tells Carbon Brief that he's not surprised reported emissions don't match the study's findings:

"While there are regulations in place in different parts of the world, they are far from uniform, and it is unclear what penalties there are when emissions do occur. I am surprised that the cancellation of errors occurs, though. That is just sheer luck."

Sweden has over 1M heat pumps in a population of 9M people.
The sales boom started in 2000, in 2003 we had 244000 heat pumps, in 2013 we had 1 138 000 installed heat pumps, 96% of them are residential. The most common is the air to air heat pump (an AC more or less optimized for heating), those numbers are not accurate since that type of heat pumps are not reported very well in sales here. The numbers are estimates, I think they are higher.

The attachment below shows the HFC-32 measurements from the study. Those units I wrote about above primarily uses R-410a, it's a blend of 50/50 HFC-32/HFC-125. HFC-125 which is the ugly part of the blend, is just a fire depressant and Earth destroyer.
http://www.epa.gov/ozone/geninfo/gwps.html
There is no way to apply penalties on any of those units who leak, and most of them will do so.

The European Union has an updated f-gas regulation (517/2014), in effect since January. Great? Single split air conditioning systems containing less than 3 kg of f-gases, with GWP of 750 or more won't be affected until 2025.

And guess what, the "new blue" from the refrigeration oligopoly is R-32 (HFC-32).
All of this is nonsense, they should have been banned a long time ago.

[Neven]

Holy cr*p, I didn't know the 0.7 kg of R-134a refrigerant of my heat pump had "global warming potential". I'm saving a lot of kWh, but will it be enough to offset?

Man, it seems impossible to do things right, however hard one tries....

[Richard Rathbone]

Holy cr*p, I didn't know the 0.7 kg of R-134a refrigerant of my heat pump had "global warming potential". I'm saving a lot of kWh, but will it be enough to offset?

Man, it seems impossible to do things right, however hard one tries....

Provided 1) you are buying dirty power, 2) it remains sealed during its lifetime, 3) its scrapped with refrigerant recovery at the end of its life, you are doing things right.

If 1) your power is all wind, solar, hydro, 2) it requires regular top ups, 3) it gets dismantled by a scrapper thats only interested in the metal and lets the refrigerant escape, you aren't.