Conservative Scientists & its Consequences

[AbruptSLR]

As this is the Arctic Sea Ice Forum, I will not go into great detail about the plausibility of an Arctic Albedo Flip by 2050.  However as James Hansen (and others) has postulated this possible Dragon King event, the four images in this post are from one of his 2013 slide shows on this topic. 

The first image indicates that this possible event begins by rapid changes in albedo associated with: (a) ASIE; (b) NH snow cover; (c) GIS albedo (ie dark ice ala Jason Box and reduction of outlet glacier surface area); and (d) decreases in land albedo (due primarily to changes in vegetation coverages and/or periodic wildfires).  The second image cites several follow-on positive feedback mechanisms including increases in CO₂ emissions from peat rich wetlands, permafrost methane emissions, permafrost nitrous oxide emissions; and methane hydrate decomposition. The third image emphasizes that reductions in Arctic snow and ice albedo occur a number of reasons including: wet snow, thin ice, melt ponds, and dark open ocean water.  The fourth attached image emphasizes the importance of the potentially large amounts of methane emissions that could be associated with an Arctic Albedo Flip Dragon King event by 2050.

Furthermore, I note that the coming warming phases of both the PDO and the AMO will teleconnect both atmospheric and oceanic heat energy directly into the Arctic for the next two to four decades.  Also, I remind the readers that the potential WAIS collapse Dragon King event discussed in Reply #649 would drive warm water from the North Pacific into the Arctic Ocean which would result in an extensive reduction in ASIE.

Finally, I provide the linked reference; which shows that anthropogenic aerosols have been masking/damping Arctic Amplification even more than it has been masking/damping the increase in mean global surface temperature.  Thus as aerosols are cleaned-up the Arctic will warm faster than previously estimated:

Najafi, M.R., et al. (2015) Attribution of Arctic temperature change to greenhouse-gas and aerosol influences, Nature Climate Change, doi:10.1038/nclimate2524

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2524.html

Abstract: "The Arctic has warmed significantly more than global mean surface air temperature over recent decades, as expected from amplification mechanisms. Previous studies have attributed the observed Arctic warming to the combined effect of greenhouse gases and other anthropogenic influences. However, given the sensitivity of the Arctic to external forcing and the intense interest in the effects of aerosols on its climate, it is important to examine and quantify the effects of individual groups of anthropogenic forcing agents. Here we quantify the separate contributions to observed Arctic land temperature change from greenhouse gases, other anthropogenic forcing agents (which are dominated by aerosols) and natural forcing agents. We show that although increases in greenhouse-gas concentrations have driven the observed warming over the past century, approximately 60% of the greenhouse-gas-induced warming has been offset by the combined response to other anthropogenic forcings, which is substantially greater than the fraction of global greenhouse-gas-induced warming that has been offset by these forcings. The climate models considered on average simulate the amplitude of response to anthropogenic forcings well, increasing confidence in their projections of profound future Arctic climate change."

See also:

http://www.carbonbrief.org/blog/2015/02/aerosols-dampen-pace-of-arctic-warming-for-now-say-scientists/

[AbruptSLR]

For my final post about plausible climate change related Dragon King events I note that an Arctic Albedo Flip together with strong anthropogenic radiative forcing until at least 2050, could possibly induce a flip in the atmosphere into an Equable pattern by 2100 (assuming that at least 800 ppm CO₂ atmospheric concentration occurred due to the combination of anthropogenic and positive feedback emissions) which would teleconnect atmospheric energy directly from the tropics to the North and/or South Polar regions (also increasing frequency of intense cyclonic activity could supplement this teleconnection). 

The first reference, and link to a pdf of a 2011 PowerPoint presentation (see also the attached figures from the pdf, where in the first figure delta T is the temperature difference between the upper atmosphere in North Pole and in the Equator, while the second figure shows that the flip to an equable climate could occur abruptly) by Prof Bill Langford (who presents both paleo and model evidence) about the possible abrupt climate change from our current three cell atmospheric circulation pattern to a single Hadley Cell (equable climate pattern).  This reference makes it very clear that the Northern Hemisphere (NH) is more likely to make this transition before the Southern Hemisphere; and that any such transition is likely to be abrupt.   I find this Langford 2011 work to be particularly disturbing, considering that the rapid loss of Arctic Sea Ice might be sufficient to adequately warm the Arctic atmosphere sufficiently (probably due to an associated rapid increase in Arctic atmosphere specific humidity):

HADLEY CELL EXPANSION IN TODAY’S CLIMATE AND PALEOCLIMATES Bill Langford; University Professor Emeritus, Department of Mathematics and Statistics; University of Guelph, Canada; Presented to the BioM&S Symposium on Climate Change and Ecology; University of Guelph; April 28, 2011


http://www.fields.utoronto.ca/programs/scientific/10-11/biomathstat/Langford_W.pdf

As additional background I provide the following link to Brian Farrell's 1990 theory which also considers changes from our current atmospheric circulation pattern to that for an equable climate (with a single Hadley cell):

http://www.seas.harvard.edu/climate/eli/research/equable/hadley.html

Furthermore a draft pdf copy of the Sagoo et al 2013 reference is available at the link provided below.  While this reference confirms that the equilibrium climate sensitivity (Charney sensitivity) would be less in an equable climate than that for our modern condition, this is not reassuring given the about of devastation that an equable climate would bring to the world.

http://www.paleo.bris.ac.uk/~ggdjl/warm_climates/sagoo_etal.pdf

"The Early Eocene equable climate problem: Can perturbations of climate model parameters identify possible solutions?" by: by Navjit Sagoo, Paul Valdes, Rachel Flecker, and Lauren Gregoire;  Royal Society Philosophical Transactions A; 2013

Abstract:
"Geological data for the early Eocene (56 Ma to 47.8 Ma) indicates extensive global warming, with very warm temperatures at both poles. However, despite numerous attempts to simulate this warmth, there are remarkable data–model differences in the prediction of these polar surface temperatures, resulting in the so called “equable climate problem”.
In this paper, for the first time an ensemble with a perturbed climate-sensitive model parameters approach has been applied to modelling the early Eocene climate. We performed more than 100 simulations with perturbed physics parameters, and identified two simulations which have an optimal fit with the proxy data. We have simulated the warmth of the early Eocene at 560 ppmv CO2 which is a much lower CO2 level than many other models. We investigate the changes in atmospheric circulation, cloud properties and ocean circulation that are common to these simulations and how they differ from the remaining simulations in order to understand what mechanisms contribute to the polar warming.  The parameter set from one of the optimal early Eocene simulations also produces a favourable fit for the Last Glacial Maximum boundary climate and outperforms the control parameter set for the present day. Although this does not “prove” that this model is correct, it is very encouraging that there is a parameter set that creates a climate model able to simulate well very different paleoclimates and the present day climate.  Interestingly, to achieve the great warmth of the early Eocene this version of the model does not have a strong future climate change Charney climate sensitivity. It produces a Charney climate sensitivity of 2.7 °C whereas the mean value of the 18 models in the AR4 is 3.26 °C ± 0.69 °C.  Thus this value is within the range and below the mean of the models included in the IPCC Fourth Assessment Report (AR4)."

The last linked reference (with a pdf), finds that more distributed warmth (poleward from the equator) promotes Hadley Cell expansion; which if continued long enough results in an equable climate as would be the case for strong radiative forcing scenarios:

http://math.nyu.edu/~gerber/pages/documents/tandon_gerber_sobel_polvani-JC-2013.pdf

Understanding Hadley Cell Expansion versus Contraction: Insights from Simplified
Models and Implications for Recent Observations; NEIL F. TANDON, EDWIN P. GERBER, ADAM H. SOBEL AND LORENZO M. POLVANI, 2013, JOURNAL OF CLIMATE; VOLUME 26

[Shared Humanity]

"In general the strongest effect of a feedback will be immediate..."

I don't know about generally, though a linky would be nice if that is an overall tendency.

The point is, though, that we are not talking about 'generally.'

We are talking about specific carbon feedbacks.

Archer and others don't think, for example, that subsea methane and other carbon feedbacks will behave in the way you describe.

We can only pray that they are the ones who are right, and not the ones doing most of the on-the-ground research in the area.

It doesn't seem likely that terrestrial permafrost will act that way, either.

...

The permafrost at the surface is the easiest to melt.  After that is melted there is then an increasing depth of insulation from soil above to slow down the melt.  Therefore permafrost melt should be the fastest right at the start. 

This is very simple for an instantaneous forcing (e.g. model experiments where Co2 is instantly doubled and then the model run to see what happens). 

A complicating issue is when temperatures change over time.  The feedback response to any specific level of forcing will still follow the above behaviour.  However over time you could get an effect where both the amount of area being melted goes up so that the feedback level increases over time, until the amount of area that totally melts out can balance out the new areas melting as the melt zone moves further north.

You need to look at the small  processes before you make such general statements. Permafrost does not melt evenly from the surface  but melt causes small collapses, the formation of thermokarsts. These thermokarsts can then grow quite rapidly as adjacent areas of permafrost collapse. As thermokarsts appear across previously contiguous permafrost, stream networks form,  accelerating the loss.

http://thermokarst.psu.edu/

[sidd]

WAIS collapse is given, we merely discuss timescale now.

[viddaloo]

Arctic Albedo Flip together with strong anthropogenic radiative forcing until at least 2050, could possibly induce a flip in the atmosphere into an Equable pattern by 2100 (assuming that at least 800 ppm CO₂ atmospheric concentration occurred due to the combination of anthropogenic and positive feedback emissions) which would teleconnect atmospheric energy directly from the tropics to the North and/or South Polar regions.

Oh my. Thanks a lot for your solid and thorough posts, AbruptSLR. Remember that a lot more people read them than comment them.

[Gray-Wolf]

To my simple mind once the Polar Jet becomes so sinuous as to 'bump into' the subtropical Jet  the floodgates are open for rapid exchange of air masses? We already see just how fast polar air can flow south inside the troughs and warmer air flow north inside the ridges? With slow moving jet patterns this allows for substantial modification of the 'native' air masses.

So what if the Arctic sheds its deep cold before the onset of spring? How does that impact the upcoming melt season? This year it appears the US is to suffer in Feb what it saw in Dec/Jan last year ( and we in the UK can look forward to the lows this then spawns as the cold hits the Atlantic) so will this impact the first phase of melt season?

[AbruptSLR]

Arctic Albedo Flip together with strong anthropogenic radiative forcing until at least 2050, could possibly induce a flip in the atmosphere into an Equable pattern by 2100 (assuming that at least 800 ppm CO₂ atmospheric concentration occurred due to the combination of anthropogenic and positive feedback emissions) which would teleconnect atmospheric energy directly from the tropics to the North and/or South Polar regions.

Oh my. Thanks a lot for your solid and thorough posts, AbruptSLR. Remember that a lot more people read them than comment them.

To elaborate on the points made in my previous posts which provided selected evidence that the Earth, either has recently, or will shortly, leave a quasi-static equilibrium state achieved during the Holocene (which many people feel that they are entitled to assume will remain the case), I provide the following discussion based largely on Hansen's thinking about Albedo Flip and WAIS/GIS collapse.

Hansen suggests that until the 2000 - 2010 timeframe (at which point the global temperature matched the previous Holocene peak, see the first attached image) the global temperature remained just below the level required to initiate the "albedo flip" mechanism (which historically would include the collapse of the WAIS in both the Holsteinian and Eemian interglacial periods with SLR finger prints that would have push warm North Pacific water into the Arctic Ocean).  If the evidence presented by Hansen et al (2012) is correct that as soon as global-mean temperatures approximately exceed 0.7 C above that for the year 2000, a bifurcation in climate sensitivity could occur with either new net positive feedbacks, and/or faster response rates for existing net positive feedbacks.

Caption for the attached image: "Global temperatures relative to peak Holocene temperature. (per Hansen and Sato, 2012).

Therefore, it is critical to correctly account for the various feedbacks into an Earth's System Model analysis, as if it is true that some "Slow" feedbacks will act as "Fast" feedbacks then some researchers (Previdi et.al. 2013), believe that climate sensitivity may be about 6 C, which would imply a climate feedback parameter of 0.6 W m-2C-1.  As it has been estimated (Hansen et al., 2010) that the global temperature has already increased above pre-industrial temperatures by about 0.8 C, this may only leave a safe remaining global surface temperature increase of about 0.7 C.  Considering that delta Q is currently estimated to be 0.85 +/- 0.15 W m-2 and if the climate feedback parameter were to be 0.6 W m-2C-1 (corresponding to a climate sensitivity of 6 C) this implies that global temperatures would increase by another 1.4 C without any further increase in radiative forcing (note that CESM – H showed a 1.2 C increase due to 367 ppm CO₂ in the atmosphere).

AR5 GCM temperature projections assumed the incorporation of feedback mechanisms similar to what has been documented for the past several thousand years, when for example the Arctic permafrost has been relatively stable.  However, Schuur and Abbott 2011 report that due to carbon emission from permafrost thawing associated with the man-induced global mean temperature change associated with the 95% CL* of RCP 8.5, that the global mean temperature change will increase another approximately 30% (or 2.25 C).  But Schuur and Abbott 2011 estimate that about 2.7% of the carbon released from the permafrost thawing will be in the form of methane, which they take to have 25 times more warming potential than CO2 averaged over 100-years (note that this correlated to 72 times averaged over 20 years).  While in 2011 NASA determined that due to interactions between methane and nitrous oxide that methane actually has 105 times the warming potential of CO2 averaged over 20-years (note that nitrous oxide is currently available in the atmosphere to be stabilized by methane at levels well above historical levels due to man-induced introduction of nitrogen into the environment largely as a fertilizer).  This demonstrates that effective climate sensitivity varies in magnitude depending on the strength, rate, and number, of feedback mechanisms that are active for any given climate condition, and that the AR5 global mean temperature projections need to be corrected for such factors as changes in the thawing of the permafrost, and the interactions of methane and nitrous oxide, until the numerous earth system feedback mechanisms are correctly modeled by state-of-the-art ESM projections (e.g. the ACME project).

Hansen, J.E., and Sato, M. (2012), "Paleoclimate implications for human-made climate change", Climate Change: Inferences from Paleoclimate and Regional Aspects. A. Berger, F. Mesinger, and D. Šijački, Eds. Springer, pp. 21-48, doi:10.1007/978-3-7091-0973-1_2.

Hansen, J., Kharecha, P. and Sato, M., (2013), "Climate forcing growth rates: Doubling down on our Faustian bargain", Environ. Res. Lett., 8, 011006, doi:10.1088/1748-9326/8/1/011006.

Hansen, J., Sato, M., Russell, G. and Kharecha, P., (2013), "Climate sensitivity, sea level, and atmospheric carbon dioxide", Phil. Trans. R. Soc. A, 371, 20120294, doi:10.1098/rsta.2012.0294.

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

[AbruptSLR]

While I have previously indicated that both Frequentist and Bayesian statistical methodologies are equally valuable tools when applying the Scientific Method; I have also previously indicated that focusing on the correct application Bayesian methodology can help decision makers to more quickly deal with the uncertainties associated with climate change, if they want to take appropriate action in a timely fashion.  However, as many people have stated that they do not understand what I mean by Bayesian statistical methodology I present the following brief discussion.

There is a continuing debate among statisticians, over the proper definition of probability.  The frequentist definition sees probability as the long-run expected frequency of occurrence. P(A) = n/N, where n is the number of times event A occurs in N opportunities.  The Bayesian view of probability is related to degree of belief.  It is a measure of the plausibility of an event given incomplete knowledge.  The two schools of thought disagree over how to describe a prior distribution to represent ignorance.

Bayesian philosophy is based on the idea that more may be known about a physical situation than is contained in the data from a single observation, or measurement.  Bayesian methods can be used to combine results from different observations, or measurements, for example.  In other situations, there may be sound reasons, based on physics, to restrict the allowable values that can be assigned to a parameter.  Bayesian techniques can help to determine allowable values, as often the data can be sparse, noisy or biased, or all of these.

Bayes' Theorem begins with a statement of knowledge prior to performing the observation, or measurement.  Usually this prior is in the form of a probability density.  It can be based on physics, on the results of other experiments, on expert opinion, or any other source of relevant information.  Now, it is desirable to improve this state of knowledge, and an experiment is designed and executed to do this.  Bayes' Theorem is the mechanism used to update the state of knowledge to provide a posterior distribution.  Both the prior (often a projection) and the experimental results (or evidence) have a joint distribution, since they are both different views of reality.

Let the experiment be A and the projection be B. Both have occurred, AB. The probability of both A and B together is P(AB). The law of conditional probability says that this probability can be found as the product of the conditional probability of one, given the other, times the probability of the other.  That is:

P(A|B) x P(B) = P(AB) = P(B|A) x P(A)
if both P(A) and P(B) are non-zero.

Simple algebra shows that:
P(B|A) = P(A|B) x P(B) / P(A)

This last equation is Bayes' Theorem; which says that the posterior probability of B (the updated projection) is the product of the conditional probability of the experiment, given the influence of the parameters being investigated, times the prior probability of those parameters.  (Division by the total probability of A assures that the resulting quotient falls on the [0, 1] interval, as all probabilities must.)

The attached first image is a Venn diagram (see caption below) that can help to illustrate the principle behind Bayes’ Theorem.

Caption for the first attached image: "Venn Diagram illustrating Unconditional, Conditional, and Joint Probabilities.  (Note that the conditional probability of A, given B is not, in general, equal to the conditional probability of B, given A)."

The previous mathematics assumes that events A and B each have a single probability.  While true in many cases, in most situations the events are better described with probability densities.  The underlying idea is still the same, but the arithmetic can become tedious rapidly, and it is best to leave such math to computer programs run by statisticians (or scientists).

Nevertheless, the concept of Bayesian Learning using PDFs can be understood using the second attached image showing the results of representative Bayesian Learn climate change analysis where: (a) the top graphs for Data from the 1961-1998 show on the left panel two blue Priors together with a red curve of observations resulting in the Posterior in the panel on the right; and (b) the middle graphs for Data from 1970 to 1998 show on the left panel the same two Priors as in the top graphs together with more recent observations indicated by a red curve to the right of the red curve in the top graph; which result in the Posterior shown in the right middle panel with the new probability curve shifted to the right of the curve in the top left panel; and (c) the bottom graphs for Data from 1980 to 1998 show the same two Priors together with still more recent observations shown by the red curve in the bottom left panel, which after Bayesian Learning analysis results in the Posterior in the bottom right panel which is still further to the right of the Posterior shown in the middle right panel.  This example illustrates how in a non-stationary situation (like our current climate change situation) that Bayesian methodology can help to identify the stronger response using more recent observations (shown in the bottom graphs) as opposed to the weaker response when using older and averaged data (shown in the top graphs).

Caption for the second image: "Three Representative Examples of Bayesian Learning Using New Observations to Transform Old Probability Density Priors into New Probability Density Posteriors."

[AbruptSLR]

To my simple mind once the Polar Jet becomes so sinuous as to 'bump into' the subtropical Jet  the floodgates are open for rapid exchange of air masses? We already see just how fast polar air can flow south inside the troughs and warmer air flow north inside the ridges? With slow moving jet patterns this allows for substantial modification of the 'native' air masses.

So what if the Arctic sheds its deep cold before the onset of spring? How does that impact the upcoming melt season? This year it appears the US is to suffer in Feb what it saw in Dec/Jan last year ( and we in the UK can look forward to the lows this then spawns as the cold hits the Atlantic) so will this impact the first phase of melt season?

Gray-Wolf,

Making forecasts about the possible timing of a possible flip into an equable climate is tricky business; and it is possible that I may (or may not) have chosen to err on the side of least drama; and you may be correct that instabilities in the jet streams may (or may not) lead to a possible flip to an equable climate with far less forcing than I have indicated (i.e. about 800 ppm CO2-e).  The truth of the matter is that such a potential flip is highly dependent on the final pathway for radiative forcing that the world follows and what chaotic events occur simultaneously, and what boundary conditions that the Earth Systems are subject to.  In this regards, I am concerned that the recent hiatus period was a "perfect storm" of temporary negative feedbacks (temporary spurts of vegetation growth driven by greater warmth and CO2) and masking factors (aerosols); while I am concerned that we are now be entering a period which may prove to be a "perfect storm" of strong anthropogenic radiative forcing (e.g. rapid economic growth of the non-Chinese developing world, etc), and strong temporary positive feedback mechanisms (e.g. rapid permafrost degradation, wildfires, shrub driven reductions in Arctic albedo; warming phases of the PDO and AMO, collapse of marine glaciers and ice sheets; etc.); which could temporarily drive the effective climate sensitivity up to 6 C for periods of multiple decades. 

Thus if my worst fear is correct, then you may be correct that the atmosphere could flip into an equable climate closer to 2050 (than to my circa 2100 date); not only due to temporary instabilities with the jet streams; but also potentially due to a possible rash of extreme cyclonic events carrying large amounts of tropic heat to the polar regions.  Only time will tell which pathway we follow and how sensitive the Earth Systems are to change.

Best,
ASLR

[AbruptSLR]

While this thread tends to focus on IPCC WGI (Science of Climate Change), there is also: WGII (Impacts, Adaptation and Vulnerability), WGIII (Mitigation of Climate Change) and a Task Force on Greenhouse Gas Inventories.  Furthermore, the IPCC was established in 1988 to assess the scientific, technical and socio-economic information relevant for the understanding of human induced climate change, its potential impacts and options for mitigation and adaptation.  However, as risk is equal to probability times consequences it is inappropriate to focus on WGI at the expense of WGII & WGIII, as they all influence the risk that society may collapse due to the IPCC choosing to err on the side of least drama, not only with regard to probabilities of back events but also with regard to likely impacts and with regard to possible mitigation measures.  Thus in a series of posts (starting with this one), I plan to briefly discuss the appropriateness of the 2 C limit that the IPCC has recommended, and whether the IPCC scientists may have erred on the side of least drama by recommending such a relatively high limit.

Certainly, the IPCC did not work in a vacuum when developing this target, as policy makers, economists, the media and the public at large, influenced what limit the Assessment Report, AR, authors found to be overly dramatic.  Also subsequent to AR4, a group of authors unsuccessfully pushed for a 1.5 C limit for AR5, and individual scientists such has Hansen have advocated for a 1 C limit above pre-industrial levels.  Furthermore, the IPCC won the Nobel Peace Prize for its AR4 work, so obviously the Nobel selection committee must have believed that the IPCC showed higher moral fiber than society-at-large (note that the IPCC was not particularly lauded for AR5); however, as Wlodarski et al (2015) show this is not saying too much (see the Extract below from the Economist magazine) as based on science it appears that the majority of humans are not wired to deal well with the climate change challenge:

Rafael Wlodarski, John Manning , R. I. M. Dunbar, (2015), "Stay or stray? Evidence for alternative mating strategy phenotypes in both men and women", Biology Letters, Volume: 11 Issue: 2, DOI: 10.1098/rsbl.2014.0977

http://rsbl.royalsocietypublishing.org/content/11/2/20140977

http://rsbl.royalsocietypublishing.org/content/roybiolett/11/2/20140977.full.pdf

See also:

http://www.economist.com/news/science-and-technology/21642000-promiscuity-and-fidelity-seem-be-specific-biological-adaptations-their

Extract: "Dr Wlodarski and his colleagues calculate that cads outnumber dads by a ratio of 57:43. Loose women, by contrast, are outnumbered by their more constant sisters, but by only 53:47. Each of these ratios tends in the direction of received wisdom. Both, though, are close enough to 50:50 for that fact to need an explanation.

…

If their analysis is correct, Dr Wlodarski and his colleagues have probably stumbled on a type of equilibrium known to biologists as an evolutionarily stable strategy, in which a way of behaving becomes more advantageous as it gets rarer, and less so as it gets commoner. Cads succeed when dads are frequent, and vice versa. Neither can conquer and neither can vanish. Such equilibria are part of a branch of math called game theory—"

The Wlodarski et al 2015 work adds some scientific clarity for understanding the nature of the "Tyranny of the Commons" problem for climate change; as "Climate Cads" (CCs), with a high tolerance for risk for emitting GHG, constitutes about 53 to 57% of the general population; while "Climate Dads" (CDs), who prefer to husband the Earth's Systems for the benefit of future generations, constitutes only 43 to 47% of the general population. Furthermore, when "CDs" work towards a relatively stable society (such as now), "CCs" benefit and become more numerous; while when climate change eventually destabilizes society "CDs" will become more valuable and for some generations to come may out-number "CCs".

Wlodarski et al 2015's work adds perspective on why society pressures scientists (who may have a higher percentage of Dads than society-at-large) to set a relatively high/risky limit of 2 C; as due to thermal inertia in the Earth Systems "Climate Cads" can inappropriately advocate that they have emitted GHG for decades without any consequences, while "Climate Dads" have been overly cautious when they advocate for a lower limit.  Due to such uncertainties (as cited by the "CCs") it is not possible to definitively predict how much damage would result from temperature rises projected by AR5 (putting aside the concern that these projections may well be too low); thus "CCs" have pressured the IPCC to set higher limits as "CCs" are in the voting majority and they have high risk-tolerance.   

However, the central claim of the Weitzman's 2009a paper is that the probability distribution of potential losses from global warming is “fat-tailed,” or includes high enough odds of very large amounts of warming, that Weitzman argues that there is a one percent chance of temperature increase equal to, or greater than, 20 C over the next two centuries (i.e. by 2200).  The IPCC's, AR4 and AR5, probability distributions for potential warming include no measurable probability for warming anywhere near this level for any considered radiative forcing scenario, and most authorities are not prepared to start considering such extreme scenarios for planning purposes.

Furthermore, Weitzman 2010 states: "The issue of how to deal with deep structural uncertainties of climate change would be completely different and immensely simpler if systemic inertias, such as the time required for the system to naturally remove extra atmospheric CO2, were short, as is the case for many airborne pollutants like sulfur dioxide, nitrous oxides, and particulates.  An important component of an optimal strategy might be along the lines of "wait and see."  With strong reversibility, an optimal climate change policy would logically involve (among other elements) waiting to learn how far out on the bad fat tail the planet will end up, followed by midcourse corrections if we seem to be headed for a disaster.  Alas, the problem of climate change seems bedeviled at almost every turn by significant stock-accumulation inertias ---- in atmospheric CO2, in the absorption of heat or CO2 by the oceans, and in many other relevant physical and biological processes ---- that are slow to respond to attempts at reversal.
…
Qualitatively, fat tails favor more aggressive policies to lower GHGs than "standard" BCA (Benefit Cost Analysis).  Alas, the quantitative implications are less clear.  As this article has stressed, the natural consequence of fat-tailed uncertainty should be to make economists less confident about climate change BCA and to make them adopt a more modest tone that befits less robust policy advice.  My own conclusion is that the sheer magnitude of the deep structural uncertainties concerning catastrophic outcomes, and the way we express this in our models, is likely to influence plausible application of BCA to the economics of climate change for the foreseeable future."

Also Weitzman (2014) states: "A fat tail for rare disasters has the potential to dominate economic calculations like the SCC (Social Cost of Carbon). Therefore, analysis of a situation that might potentially be catastrophic cannot afford to ignore tail behavior. It is not enough in such situations to look just at measures of central tendency or even just at thin-tailed probability distributions.  Ignorance of the potential fatness of an extreme bad tail is not an excuse for ignoring the potential fatness of an extreme bad tail. This warning is the main message of the “dismal theorem.”"

Weitzman, M., (2007), "The Stern Review of the economics of climate change", Journal of Economic Literature, 45, pp. 703-724.

Weitzman, M., (2009a), "On Modeling and Interpreting the Economics of Catastrophic Climate Change," Review of Economics and Statistics, 91, pp. 1-19.

Weitzman, M., (2009b), "Additive damages, fat-tailed climate dynamics, and uncertain discounting"; Economics - The Open-Access, Open-Assessment E-Journal, 3, pp. 1-29.

Weitzman, M., (2010), "Risk-Adjusted Gamma Discounting"; Journal of Environmental Economics and Management, 60, pp. 1-13.

Weitzman, M. L. (2014) "Fat Tails and the Social Cost of Carbon", American Economic Review, 104(5): 544-46, DOI: 10.1257/aer.104.5.544

https://www.aeaweb.org/articles.php?doi=10.1257/aer.104.5.544

http://scholar.harvard.edu/files/weitzman/files/aer.104.5.544fattailsandthesocialcostofcarbon.pdf

Abstract: "At high enough greenhouse gas concentrations, climate change might conceivably cause catastrophic damages with small but non-negligible probabilities. If the bad tail of climate damages is sufficiently fat, and if the coefficient of relative risk aversion is greater than one, the catastrophe-reducing insurance aspect of mitigation investments could in theory have a strong influence on raising the social cost of carbon. In this paper I exposit the influence of fat tails on climate change economics in a simple stark formulation focused on the social cost of carbon. I then attempt to place the basic underlying issues within a balanced perspective."

Thus it appears that WGI & WGII have erred on the side of least error when estimating the probabilities of occurrence for fat-tailed climate change PDFs (if for no other reason but that they ignore the influence of "CCs"), and also the impacts of  such "fat-tailed" PDFs by either ignoring the tail effect or by so heavily discounting such future possibilities as to effectively ignore this fat-tailed risk, which Weitzman proves should actually dominate economic calculations (thus the IPCC cannot say that at least some economists did not warn them of the actual societal risks).  In my next post I plan to discuss how such "conservative" (i.e. societally risky) guidance from the IPCC could actually be misguiding policy makers and could actually be serving to increase the probabilities of societal collapse due to climate stress.

Edit: Note that Weitzman only evaluates Black Swan types of tail risk and not Dragon King types of tail risk.

Second Edit: For those who are willing to buy a book you may want to consider buying "Climate Shock" By Gernot Wagner & Martin L. Weitzman, 2015.

http://gwagner.com/books/climate-shock/

[Lennart van der Linde]

ASLR,
Thanks for pointing to Climate Shock, which I had not read about yet.

Also see what Nicholas Stern said in 2013:
http://personal.lse.ac.uk/sternn/128NHS.pdf

"Scientists describe the scale of the risks from unmanaged climate change as potentially immense. However, the scientific models, because they omit key factors that are hard to capture precisely, appear to substantially underestimate these risks. Many economic models add further gross underassessment of risk because the assumptions built into the economic modeling on growth, damages and risks, come close to assuming directly that the impacts and costs will be modest and close to excluding the possibility of catastrophic outcomes. A new generation of models is needed in all three of climate science, impact and economics with a still stronger focus on lives and livelihoods, including the risks of large-scale migration and conflicts."

Unfortunately the economics profession in general seems slow in taking up this advise, so far.

And is there any way in which we can overcome the apparent tyranny of evolutionary stable strategies (other than possibly by extinction)?

[Lennart van der Linde]

Maybe Gus Speth has the answer:
http://www.thenation.com/article/196217/how-i-became-radical#

'Radicalism'?

[AbruptSLR]

Maybe Gus Speth has the answer:
http://www.thenation.com/article/196217/how-i-became-radical#

'Radicalism'?

Lennart,

I am a bit busy at the moment, but when I get time I will post my response in the following thread that JimD set-up on: "Climate Change Triage - cutting out the rot and the fat".


http://forum.arctic-sea-ice.net/index.php/topic,1099.0.html#lastPost


Best,
ASLR

[AbruptSLR]

As a follow-up to Reply #659:

Previously, I have noted that chaotic Earth Systems, such as ENSO, can reach resonance under certain conditions (such as we may be approaching in the coming decades) resulting in a "quasi-equilibrium" ratcheting type of amplification such as that shown in the attached image, which could lead to a Dragon King event.  Also, chaotic bee colony systems can also be subjected to a comparable type of "quasi-equilibrium" ratcheting type of resonance leading to a premature Dragon King-type of collapse (see the linked Perry et al 2015 reference below). In a fashion similarly to the beehive collapse syndrome, our chaotic modern international economic system is subject to climate change induced accelerated collapse.

Furthermore, such a climate change induced international societal collapse can be accelerated by the poor guidance provided by the IPCC; which can encourage inappropriate types and levels of investments that do not match the nature of the problem.  Therefore, the sooner that the IPCC chooses to stop erring on the side of least drama, the more robust (anti-fragile) our international societal/economic system will be.

Clint J. Perry, Eirik Søvik, Mary R. Myerscough, and Andrew B. Barron, (2015), "Rapid behavioral maturation accelerates failure of stressed honey bee colonies", PNAS, doi: 10.1073/pnas.1422089112

http://www.pnas.org/content/early/2015/02/04/1422089112.abstract

Abstract: "Many complex factors have been linked to the recent marked increase in honey bee colony failure, including pests and pathogens, agrochemicals, and nutritional stressors. It remains unclear, however, why colonies frequently react to stressors by losing almost their entire adult bee population in a short time, resulting in a colony population collapse. Here we examine the social dynamics underlying such dramatic colony failure. Bees respond to many stressors by foraging earlier in life. We manipulated the demography of experimental colonies to induce precocious foraging in bees and used radio tag tracking to examine the consequences of precocious foraging for their performance. Precocious foragers completed far fewer foraging trips in their life, and had a higher risk of death in their first flights. We constructed a demographic model to explore how this individual reaction of bees to stress might impact colony performance. In the model, when forager death rates were chronically elevated, an increasingly younger forager force caused a positive feedback that dramatically accelerated terminal population decline in the colony. This resulted in a breakdown in division of labor and loss of the adult population, leaving only brood, food, and few adults in the hive. This study explains the social processes that drive rapid depopulation of a colony, and we explore possible strategies to prevent colony failure. Understanding the process of colony failure helps identify the most effective strategies to improve colony resilience."

[AbruptSLR]

In my last two posts I commented briefly on IPCC WG I, II & III; but I have not commented yet on the IPCC Task Force on National Greenhouse Gas Inventories, TFI, with regard to questions of the validity of the IPCC radiative forcing scenarios (RCP or the WG III Baseline scenarios).

In this regards, the linked reference addresses the Terms of Reference for Technical Assessment of IPCC Inventory Guidelines for the year 2015 from the Expert Meeting on Systematic Assessment of TFI Products from 25-27 August 2014 in Ottawa, Canada.  The extract below addresses key issues:

https://redremedia.files.wordpress.com/2015/01/attachment_i_tor_2015_technical_assessment.pdf

Extract: "Significance and prioritization criteria
- Significance of the source/sink and the gas within the sector on a global scale. Sources significant only for a limited number of particular countries currently or in the foreseeable future may not meet this criterion. The adequacy of the existing guidance for a particular category should be considered, as should the likelihood that new information would lead to a definite improvement in the IPCC Guidelines.
- Availability of relevant new scientific results.
- Sufficient data availability and maturity of scientific advances since 2006 to provide a basis for methodological development or refinement, including:
   1 Ability to develop new or updated default emission/removal factors
   2 Feasibility of obtaining the necessary data to implement the methods
- Emergence of new sources or gases meeting these criteria."
This information not only raises questions about whether the old guidelines are adequate to monitor individual GHG source/sink information, and whether we need new criteria for new GHGs like new members of the HCF family; but the work of the TFI raises other questions including:

A. Most likely there will be not AR6, but instead after 2015 smaller annual reports will be issued, which may (or may not) include TFI monitoring and reporting on whether COP participants meet their pledged GHG emission reduction targets, and as noted in the Ottawa document above the reporting from some particular countries may not meet the new Terms of Reference for Technical Assessment.

B. The RCP and the WG III Baseline scenario include many assumptions about what levels of control on GHG emissions will be achieved until 2100 and it is not clear to me whether the TFI findings for the past few years match these assumptions particularly with regard to methane emissions from hydro-fracking and other anthropogenic methane sources (rice, livestock, coal mines, etc.) as the measured atmospheric concentrations of methane in the past few years have been higher than expected, and may well increase more in the future.  Furthermore, see the discussion in the following linked thread (and the linked Schwartz et. al 2014 reference, & see the associated attached figure) about how the emissions uncertainties made for AR5 (using RCP scenarios) differ from those made for AR4 (using SRES scenarios).

http://forum.arctic-sea-ice.net/index.php/topic,1011.50.html

http://onlinelibrary.wiley.com/doi/10.1002/2014EF000273/pdf

C.   When the annual IPCC reports are issued will that assume the use of RCP scenarios or will they try to update the radiative forcing scenarios to reflect state-of-the-art understandings of both anthropogenic and natural source/sink emissions (including permafrost degradation, deforestation, hydrofracking etc.)?  Furthermore, future actual emissions may be temporarily worsened by such considerations as: (a) adaptive infrastructure say to resist SLR that could rise associated emissions for decades; (b) increase economic activity associated with higher population projections since the RCP scenarios were developed (including higher food production requirements); (c) possible increased warfare and defense against terrorist activities; and (d) increased investment in sustainable infrastructure not foreseen in the RCP scenarios that could again boost GHG emissions for several up-coming decades.

[AbruptSLR]

The attached images are from the linked IPCC AR5 Synthesis Report, and indicates that the WGIII Baseline Global Mean Surface Temperature Increase (above pre-industrial) that reflect the Cancun commitments are lower than that for the mean RCP 8.5 scenario by 2100 (even for the same cumulative GHG emissions because RCP 8.5 emits the GHG faster; and remember that we are currently exceeding the mean RCP 8.5 emission rates).

http://www.ipcc.ch/pdf/assessment-report/ar5/syr/SYR_AR5_LONGERREPORT_Final.pdf

Edit: Note that I believe that these projections err on the side of least drama, even when considering the variability of climate sensitivity.

Second Edit: Also note that the projections in these figures do not include the influence of the range of variability in climate sensitivity.  See Reply #645 which includes the following IPCC WG III quote: "Baseline scenarios, those without additional mitigation, result in global mean surface temperature increases in 2100 from 3.7 °C to 4.8 °C compared to pre-industrial levels (median values; the range is 2.5 °C to 7.8 °C when including climate uncertainty, see Table SPM.1) (high confidence)."

[AbruptSLR]

The first linked IPCC report on the impact of aviation on global warming indicates that contrail formation is one of the largest aircraft-induced radiative forcing factors, and that it is also one of the largest areas of scientific uncertainty in predicting aircraft-induced climate effects (see the IPCC extract).  While the second linked reference by Irvine et al 2015 indicates that: "Ice-supersaturation (ISS) in the upper-troposphere and lower stratosphere is important for the formation of cirrus cloud and long-lived contrails. We analyse projected changes to 250 hPa ISS distribution and frequency over the twenty-first century using data from the RCP8.5 simulations of a selection of CMIP5 models. The models show a global-mean annual-mean decrease in ISS frequency of 4% by the end of the twenty-first century, relative to the present-day period 1979–2005."  This indicates that following RCP 8.5 that contrails will be significant positive forcing mechanism.

http://www.ipcc.ch/ipccreports/sres/aviation/064.htm

IPCC Extract: "At present, the largest aircraft forcings of climate are through CO2, NOx, and contrail formation.
…
The largest areas of scientific uncertainty in predicting aircraft-induced climate effects lie with persistent contrails, with tropospheric ozone increases and consequent changes in methane, with potential particle impacts on "natural" clouds, and with water vapor and ozone perturbations in the lower stratosphere (especially for supersonic transport)."

Irvine, E. A. and Shine, K. P., (2015), "Ice-supersaturation and the potential for contrail formation in a changing climate", Earth Syst. Dynam. Discuss., 6, 317-349, doi:10.5194/esdd-6-317-2015

http://www.earth-syst-dynam-discuss.net/6/317/2015/esdd-6-317-2015.pdf

Abstract: "Ice-supersaturation (ISS) in the upper-troposphere and lower stratosphere is important for the formation of cirrus cloud and long-lived contrails. We analyse projected changes to 250 hPa ISS distribution and frequency over the twenty-first century using data from the RCP8.5 simulations of a selection of CMIP5 models. The models show a global-mean annual-mean decrease in ISS frequency of 4% by the end of the twenty-first century, relative to the present-day period 1979–2005. Changes are analysed in further detail for three sub-regions where air traffic is already high and increasing (Northern Hemisphere mid-latitudes) or expected to increase (tropics and Northern Hemisphere polar regions). The largest change is seen in the tropics, where a reduction of around 9% in ISS frequency by the end of the century is driven by the strong warming of the upper troposphere. In the Northern Hemisphere mid-latitudes the multi-model mean change is an increase in ISS frequency of 1%; however the sign of the change is not only model-dependent but also has a strong latitudinal and seasonal dependence. In the Northern Hemisphere polar regions there is an increase in ISS frequency of 5% in the annual-mean. These results suggest that over the 21st century climate change may have large impacts on the potential for contrail formation; actual changes to contrail cover will also depend on changes to the volume of air traffic, aircraft technology and flight routing."

[AbruptSLR]

As a follow-up on my posts in Replies #649 to 651 about possible climate change related Dragon King events:

While a Venus-type runaway situation would probably require in excess of 30,000 ppm atmospheric CO₂ (which is not likely to happen before the Sun starts to expand in over a billion years-time); nevertheless, we are already at 480 ppm CO₂e and per the IPCC WG III Baseline we could easily be at 1,000 ppm CO₂e well before 2100.  The last time Earth was at 1,000 ppm CO₂ was during the early Paleogene (∼65–35 Mya) (which includes the PETM), and the linked Caballero & Huber (2013) reference indicates that the fact that the past Earth System behavior was non-fragility near 1,000 ppm CO₂ is no guarantee that at higher rates of radiative forcing (such as for RCP 8.5) that we might not experience an abrupt increase in effective climate sensitivity as: (a) slow response feedbacks can change due to changes in model boundary conditions; (b) the radiative forcing od CO₂ deviates from the normally assumed pure logarithmic behavior in the range of 1,000 ppm; and (c) fast (Charney) feedback mechanisms can increase sharply with global warming (as projected by Sherwood et al 2014).

Caballero R, and Huber M (2013), "State-dependent climate sensitivity in past warm climates and its implications for future climate projections", Proc Natl Acad Sci USA 110: 14162–14167, doi: 10.1073/pnas.1303365110.

http://www.pnas.org/content/110/35/14162.full

Abstract: "Projections of future climate depend critically on refined estimates of climate sensitivity. Recent progress in temperature proxies dramatically increases the magnitude of warming reconstructed from early Paleogene greenhouse climates and demands a close examination of the forcing and feedback mechanisms that maintained this warmth and the broad dynamic range that these paleoclimate records attest to. Here, we show that several complementary resolutions to these questions are possible in the context of model simulations using modern and early Paleogene configurations. We find that (i) changes in boundary conditions representative of slow “Earth system” feedbacks play an important role in maintaining elevated early Paleogene temperatures, (ii) radiative forcing by carbon dioxide deviates significantly from pure logarithmic behavior at concentrations relevant for simulation of the early Paleogene, and (iii) fast or “Charney” climate sensitivity in this model increases sharply as the climate warms. Thus, increased forcing and increased slow and fast sensitivity can all play a substantial role in maintaining early Paleogene warmth. This poses an equifinality problem: The same climate can be maintained by a different mix of these ingredients; however, at present, the mix cannot be constrained directly from climate proxy data. The implications of strongly state-dependent fast sensitivity reach far beyond the early Paleogene. The study of past warm climates may not narrow uncertainty in future climate projections in coming centuries because fast climate sensitivity may itself be state-dependent, but proxies and models are both consistent with significant increases in fast sensitivity with increasing temperature."

Perhaps the best way to see what Caballero & Huber (2103) are indicating is to review the accompanying commentary paper by Pierrehumbert (2013) and to focus on the area to the left of point "D" in the attached two images (which are the upper and lower portions of the same figure, respectively).

R. T. Pierrehumbert, "Hot climates, high sensitivity", 14118–14119 | PNAS | August 27, 2013 | vol. 110 | no. 35

www.pnas.org/cgi/doi/10.1073/pnas.1313417110

https://geosci.uchicago.edu/~rtp1/papers/PNASHotClimates2013.pdf

Per Pierrehumbert the attached images show: "The temperature of the Earth is determined by the point at which the curve representing infrared loss to space [Outgoing Longwave Radiation (OLR)] as a function of temperature crosses the curve representing the amount of solar radiation absorbed; the latter depends on temperature through changes in clouds and ice cover. Increasing CO2 brings down the OLR curve by an amount delta F—the radiative forcing. The planet must then warm up to bring the energy budget back into balance. Climate sensitivity is determined by the relative slopes of the two curves at the crossing point; when the curves are nearly parallel, a large warming is required to make up for a given delta F. Linear, or state independent, sensitivity analysis treats the OLR and solar absorption curve as straight lines, whereas curvature allows the sensitivity to depend on the unperturbed state. In ref. 2 (Caballero & Huber 2013), the state dependence arises primarily from curvature in the solar absorption curve, which in turn is tied to dissipation of low clouds when temperature increases. This situation is represented in Fig. 1, Upper, where it is seen that even if each doubling of CO2 produced equal radiative forcing delta F, the warming in going from state A to A′ in the first doubling is less than that going from A′ to A″ in the second doubling.
….
The transition to the less cloudy state needs not be smooth as depicted in Fig. 1, Upper.  If the dependence of cloud albedo is sufficiently sharp, one gets a bifurcation or tipping point leading to multiple equilibrium states, in a manner analogous to the Snowball bifurcation (5), which arises from temperature- dependent ice-albedo feedback. In Fig. 1, Lower, a moderate increase in CO₂ leads to a smooth transition from state A to state A′, but a further increase causes the continuation of A′ to cease existing, whereafter the climate makes a discontinuous transition to the much warmer state C″. It is not clear yet whether the transition in ref. 2 is more like the upper or lower panel, but the character of the behavior is one of the things that are likely to differ from one model to another and would tend to cloud inferences of climate sensitivity from hothouse climates."


Extract: "Hothouse states may have different climate sensitivity per doubling of CO2 than the present state."

Since the time that Caballero & Huber (2103) and Pierrehumbert (2013) were published, findings such as CESM – H (2015) indicate the Earth's System subjected to high (ala RCP 8.5 which we are currently exceeding) may well follow the pathway indicated by the second (LOWER) attached image which indicates a relatively high (say 6 C) effective climate sensitivity before 2100.

[AbruptSLR]

The linked reference about increased upwelling with increasing global warming could lead to increased "stratification," or the horizontal layering of ocean water of different temperatures. The result could be a warm, near-surface layer and a deep, cold layer.  Stratification of the oceans would lead to wide spread hypoxia and eventually possible sulfur dioxide emissions from the ocean into the atmosphere.  AR5 does not contain adequate guidance to avoid such possible abrupt changes in the ocean.

Intensification and spatial homogenization of coastal upwelling under climate change by Daiwei Wang, Tarik C. Gouhier, Bruce A. Menge and Auroop R. Ganguly published in Nature, 518, 390–394 (19 February 2015) doi:10.1038/nature14235
http://www.nature.com/nature/journal/v518/n7539/full/nature14235.html

[AbruptSLR]

As a follow-up to my post Reply 667, the attached image is from the IPCC WG III and it clearly indicates that their Baseline emissions scenario is on track to equal or exceed 1,000 ppm CO2e by 2100.

[sidd]

How can increased upwelling lead to stratification ? I would imagine the opposite, and the paper does not reach any conclusion as to degree of stratification.

[AbruptSLR]

How can increased upwelling lead to stratification ? I would imagine the opposite, and the paper does not reach any conclusion as to degree of stratification.

sidd,

Thanks for double checking as I should have said that solar heating can lead to ocean stratification and that then the upwelling can lead to hypoxia, see below:

http://www.sciencedaily.com/releases/2015/02/150218093005.htm

Extract: "However, solar heating due to greenhouse warming may also increase the persistence of "stratification," or the horizontal layering of ocean water of different temperatures. The result could be a warm, near-surface layer and a deep, cold layer.
If this happens to a significant extent, it could increase global "hypoxic," or low-oxygen events, decouple upwelling from the supply of nutrient-rich water and pose a significant threat to the global function of fisheries and marine ecosystems."

Durack shows that the upper ocean is warming faster than expected while short-term impacts (such as the possible collapse of the WAIS and Antarctic ice shelves; and/or Agulhas ocean current 'leakage' from the Indian into the Atlantic Ocean) could slow the global oceanic conveyor belt which can slow sequestering of heat into the deep ocean (so it stays relatively cool).

http://www-pcmdi.llnl.gov/about/staff/Durack/dump/oceanwarming/141130a_Duracketal_UpperOceanWarming.pdf

[AbruptSLR]

sidd,

While the exact timing and impact of climate change on the Agulhas Leakage, AL, and its impact on the slowing of the AMOC, is not well understood, due to the increasing Westerly wind velocities (due to both the Antarctic ozone hole and increasing GHG concentrations, the Southern Ocean Subtropical Front is moving Southward; which is resulting in more AL; which per the linked reference & the attached image should slow the AMOC; which could contribute to ocean 'stratification'.

Gianluca Marino and Rainer Zahn, (2015), "The Agulhas Leakage: the missing link in the interhemispheric climate seesaw?", PAGES MAGAZINE ∙ VOLUME 23 ∙ NO 1 

http://www.pages-igbp.org/download/docs/magazine/2015-1/PAGESmagazine_2015(1)_22-23_Marino.pdf

Extract: "The Agulhas Leakage is a key component of the Atlantic Meridional Overturning Circulation. Unraveling the past patterns of leakage variability and associated heat and salt anomalies into the Atlantic Ocean holds clues for their role in ocean and climate changes."

[AbruptSLR]

With the attached image from the AR5 Final Synthesis Report showing the deforestation is continuing to contribution to global warming, it seems difficult for me to believe that afforestation will be an effective form of geoengineering to suck CO2 out of the air when we are not even willing to spend enough money to save the forests that we already have.


See also:
http://iopscience.iop.org/1748-9326/10/2/021001/pdf/1748-9326_10_2_021001.pdf

[AbruptSLR]

As a follow-up to Reply #672:

The linked article adds support to the idea that periods of deglaciation (such as we are in now) that hypoxia could  become a problem in the ocean in the future.

Moffitt SE, Moffitt RA, Sauthoff W, Davis CV, Hewett K, et al. (2015), "Paleoceanographic Insights on Recent Oxygen Minimum Zone Expansion: Lessons for Modern Oceanography", PLoS ONE 10(1): e0115246. doi:10.1371/journal.pone.0115246


http://www.plosone.org/article/fetchObject.action?uri=info:doi/10.1371/journal.pone.0115246&representation=PDF


Abstract: "Climate-driven Oxygen Minimum Zone (OMZ) expansions in the geologic record provide an opportunity to characterize the spatial and temporal scales of OMZ change. Here we investigate OMZ expansion through the global-scale warming event of the most recent deglaciation (18-11 ka), an event with clear relevance to understanding modern anthropogenic climate change. Deglacial marine sediment records were compiled to quantify the vertical extent, intensity, surface area and volume impingements of hypoxic waters upon continental margins.  By integrating sediment records (183-2,309meters below sea level;mbsl) containing one ormore geochemical, sedimentary or microfossil oxygenation proxies integrated with analyses of eustatic sea level rise, we reconstruct the timing, depth and intensity of seafloor hypoxia. Themaximum vertical OMZ extent during the deglaciation was variable by region: Subarctic Pacific (~600-2,900 mbsl), California Current (~330-1,500 mbsl), Mexico Margin (~330-830 mbsl), and the Humboldt Current and Equatorial Pacific (~110-3,100 mbsl). The timing of OMZ expansion is regionally coherent but not globally synchronous. Subarctic Pacific and California Current continental margins exhibit tight correlation to the oscillations of Northern Hemisphere deglacial events (Termination IA, Bølling-Allerød, Younger Dryas and Termination IB). Southern regions (Mexico Margin and the Equatorial Pacific and Humboldt Current) exhibit hypoxia expansion prior to Termination IA (~14.7 ka), and no regional oxygenation oscillations. Our analyses provide new evidence for the geographically and vertically extensive expansion of OMZs, and the extreme compression of upper-ocean oxygenated ecosystems during the geologically recent deglaciation."

[jai mitchell]

sidd,

While the exact timing and impact of climate change on the Agulhas Leakage, AL, and its impact on the slowing of the AMOC, is not well understood, due to the increasing Westerly wind velocities (due to both the Antarctic ozone hole and increasing GHG concentrations, the Southern Ocean Subtropical Front is moving Southward; which is resulting in more AL; which per the linked reference & the attached image should slow the AMOC; which could contribute to ocean 'stratification'.

Gianluca Marino and Rainer Zahn, (2015), "The Agulhas Leakage: the missing link in the interhemispheric climate seesaw?", PAGES MAGAZINE ∙ VOLUME 23 ∙ NO 1 

http://www.pages-igbp.org/download/docs/magazine/2015-1/PAGESmagazine_2015(1)_22-23_Marino.pdf

Extract: "The Agulhas Leakage is a key component of the Atlantic Meridional Overturning Circulation. Unraveling the past patterns of leakage variability and associated heat and salt anomalies into the Atlantic Ocean holds clues for their role in ocean and climate changes."

Does reduced Amazonian basin rainfall compensate for this somewhat?

Figure 1. Simulated percentage change in precipitation due to 2000–2050 business-as-usual deforestation of the Amazon basin. a, Wet season; b, dry season. Stippling denotes regions where the simulated precipitation anomaly differs from the present-day (1998–2010) rainfall by more than 1 s.d. The Amazon (black) and Rio de la Plata (red) basins are marked. Source: Spracklen and colleagues research article

http://www.terra-i.org/terra-i/news/news-A-world-without-Amazon.html

[AbruptSLR]

Does reduced Amazonian basin rainfall compensate for this somewhat?

jai,

I don't know how much changes in the Amazon rainfall will impact the AMOC; however the linked 2014 PowerPoint presentation shows a lot of variations in rainfall forecasts for the Amazon Basin between the different CMIP5 models (see the attached image for the RCP 8.5 forecasts from 2040 – 2059).  The ESM CMIP5 models assumed the amounts of deforestation indicated in the second slide.  This research also found that: (a) RCP 8.5 resulted in larger increases in regional temperature and larger decreases in regional rainfall than RCP 2.6; (b) Increasing deforestation above the assumed rates resulted in still larger decreases in regional rainfall; and (c) the less-than-state-of-the-art CMIP5 ESMs forecast greater increases in regional temperature than did the CMIP5 AOGCMs.

http://www.biosfera.dea.ufv.br/sage2014/arquivos/apresentacoes/13_1030_GilvanSampaio.pdf

[AbruptSLR]

As a follow-up to my Reply #650 about the risk of a possible Arctic Albedo Flip, in 1985 70% of the Arctic sea ice extent was multi-year ice and 30% first year ice; while by 2012 these percentages were reversed.  Now, I have come to realize that for multi-year ice the melt ponds pool between the elevated ridges, which leaves a fair amount of multi-year ice uncovered by ponds (& thus maintain relatively high albedo).  However, melt ponds spread much more uniformly across first-year sea ice; resulting in a much greater albedo flip when the melt ponds form early enough for solar radiance to have an impact.

Thus while 2013 & 2014 had delayed formation of melt ponds; another roll of the weather dice could result in early melt pond formation any year now, which would result in a much greater annual albedo flip than in past decades (even without changes in sea ice extent, snow fall, shrub growth, or dark snow due to aerosols).

[AbruptSLR]

The linked reference (with an open access pdf) about Surface Air Temperature, SAT, projections for the critical Northern Eurasia area (which has an important influence on Albedo Flip risks) indicates: (a) the limitations of the CMIP5 projections without Bayesian modeling averaging; (b) the value of employing Bayesian methodology to enhance projections; and (c) a 9.46 C increase per hundred years in DJF (which most influences the risk of an Albedo Flip, see the attached plot), which probably errs on the side of least drama as compared to what I expect the ACME model will eventually project.

Chiyuan Miao et al (2014), "Assessment of CMIP5 climate models and projected temperature changes over Northern Eurasia", Environ. Res. Lett. 9 055007, doi:10.1088/1748-9326/9/5/055007

http://iopscience.iop.org/1748-9326/9/5/055007/pdf/1748-9326_9_5_055007.pdf

http://iopscience.iop.org/1748-9326/9/5/055007/article

Abstract: "Assessing the performance of climate models in surface air temperature (SAT) simulation and projection have received increasing attention during the recent decades. This paper assesses the performance of the Coupled Model Intercomparison Project phase 5 (CMIP5) in simulating intra-annual, annual and decadal temperature over Northern Eurasia from 1901 to 2005. We evaluate the skill of different multi-model ensemble techniques and use the best technique to project the future SAT changes under different emission scenarios. The results show that most of the general circulation models (GCMs) overestimate the annual mean SAT in Northern Eurasia and the difference between the observation and the simulations primarily comes from the winter season. Most of the GCMs can approximately capture the decadal SAT trend; however, the accuracy of annual SAT simulation is relatively low. The correlation coefficient R between each GCM simulation and the annual observation is in the range of 0.20 to 0.56. The Taylor diagram shows that the ensemble results generated by the simple model averaging (SMA), reliability ensemble averaging (REA) and Bayesian model averaging (BMA) methods are superior to any single GCM output; and the decadal SAT change generated by SMA, REA and BMA are almost identical during 1901–2005. Heuristically, the uncertainty of BMA simulation is the smallest among the three multi-model ensemble simulations. The future SAT projection generated by the BMA shows that the SAT in Northern Eurasia will increase in the 21st century by around 1.03 °C/100 yr, 3.11 °C/100 yr and 7.14 °C/100 yr under the RCP 2.6, RCP 4.5 and RCP 8.5 scenarios, respectively; and the warming accelerates with the increasing latitude. In addition, the spring season contributes most to the decadal warming occurring under the RCP 2.6 and RCP 4.5 scenarios, while the winter season contributes most to the decadal warming occurring under the RCP 8.5 scenario. Generally, the uncertainty of the SAT projections increases with time in the 21st century."

[AbruptSLR]

The linked Insider Climate news article discusses the plausibility of implementing a net-zero carbon goal within various timeframes ranging from 35 to 80+ years:

http://insideclimatenews.org/news/20022015/net-zero-carbon-goal-rescue-climate-plausible

While we can all hope for the best (noting that: "The road to Hell is paved with good intensions"); in keeping with the theme of this thread I will only note that even the most aggressive plan proposed by "Plan B" to reach Net-Zero-Carbon-Emissions by 2035, would still require a massive carbon capture and sequestering program (afforestation only would not be sufficient) after 2050 in order to avoiding exceeding 2 C because the Carbon Budget used to calculate the 2 C value assumes a TCRE of about 2.5 C; while the median ECS is at least 3.1 C; and the difference between 3.1 (at least) and 2.5 would need to be accommodated by a carbon capture and sequestering program (as acknowledged by Hansen and others).  Furthermore, my above statements ignore the probability that before 2100 the actual effective climate sensitive will be greater than 3.1 C.

[AbruptSLR]

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 radiative forcing by 2030 cited in the linked reference, means that we should progressively be getting a clearer understanding of what the future will hold (conveniently just in time for the policy makers to decide whether NRC numerical model research on geoengineering should be extended into field studies):

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."

[AbruptSLR]

While scientists distinguish themselves from other professionals in that they generally care more about revealing the truth than about conforming to the social expectations of the moment.  Nevertheless, as denialist were challenging the Nobel Peace Prize winning IPCC-AR4 panel, it appears that the IPCC-AR5 panel decided to frequently err on the side of least drama in order to maintain the authority of their professionalism. Unfortunately, all "… isms" (whether: materialism, atheism, Islamism, Catholicism, Buddhism, narcissism, Fascism, hedonism, capitalism, opportunism, nihilism, alarmism, denialism, authoritarianism,  Communism, Socialism, etc.) are characterized by their predetermined central value systems; and the professionalism of scientists is no exception.  For example, the answers that scientists provide to the military under top-secret circumstances have a different type of bias than the type of answers that they provide in an open forum like AR5, and this is an unavoidable systemic phenomena. 

Thus, as the US National Research Council, NRC, has recently recommended that geoengineering be actively researched (for the next two to three decades); it is becoming increasingly likely that unless GHG emissions are reduced significantly, very quickly, that governments (lead by their military branches) will likely implement geoengineering sometime after 2050.  If so this will require scientists to develop climate change projections without erring on the side of least drama in order to allow such governments [implemented by their military branches) to regulate/monitor such geoengineering programs as best that they can (unfortunately individual governments, and/or coalitions of governments will likely remain biased in their county('s) favor(s)].

[ritter]

Thus, as the US National Research Council, NRC, has recently recommended that geoengineering be actively researched (for the next two to three decades); it is becoming increasingly likely that unless GHG emissions are reduced significantly, very quickly, that governments (lead by their military branches) will likely implement geoengineering sometime after 2050.  If so this will require scientists to develop climate change projections without erring on the side of least drama in order to allow such governments [implemented by their military branches) to regulate/monitor such geoengineering programs as best that they can (unfortunately individual governments, and/or coalitions of governments will likely remain biased in their county('s) favor(s)].

I wonder, will this be 25 years too late? Stomach turning to consider, either way.

[AbruptSLR]

Thus, as the US National Research Council, NRC, has recently recommended that geoengineering be actively researched (for the next two to three decades); it is becoming increasingly likely that unless GHG emissions are reduced significantly, very quickly, that governments (lead by their military branches) will likely implement geoengineering sometime after 2050.  If so this will require scientists to develop climate change projections without erring on the side of least drama in order to allow such governments [implemented by their military branches) to regulate/monitor such geoengineering programs as best that they can (unfortunately individual governments, and/or coalitions of governments will likely remain biased in their county('s) favor(s)].

I wonder, will this be 25 years too late? Stomach turning to consider, either way.

ritter,

First, I would like to point-out that the reference Myhre et al 2015 cited in Reply #680 indicates that the expected relatively rapid reduction in air pollution (anthropogenic aerosols) in Asia until 2030 is giving scientists a chance to calibrate their models for Solar Radiation Management, SRM, as air pollution is unintended SRM. 

Second, the US DOE will not be finished with the ACME program until 2025.  Therefore, implementing a SRM program before at least these two steps (probably pluse some field trials between 2030 and 2050) would be premature.

Third, as there will be winning countries and losing countries under any SRM plan; therefore, implementing such a plan would be an act of aggression against the losing countries.  Therefore, implementing any such SRM plan would require actual damage (like Pearl Harbor in WWII) before such an act of aggression would be acceptable to coalition partners.

Yes, the situation that we face is stomach churning; but I think that it is best to face such situations with ones eyes open rather than to close ones eyes and hope for the best.

Best,
ASLR

[ritter]

I think that it is best to face such situations with ones eyes open rather than to close ones eyes and hope for the best.

Best,
ASLR

Absolutely. Thanks for all your efforts to inform us.

[AbruptSLR]

The linked reference (with an open access pdf) indicates that continued ocean acidification of the Southern Ocean under dynamic light conditions will result in a reduction in CO₂ sequestration into the Southern Ocean; thus indicating that greater dependence on an intense use of solar radiation management, SRM, will be likely in order to counter this trend.  Unfortunately, the most likely form of SRM accelerates ocean acidification which would require still more dependence on heavy SRM use; resulting in a likely anthropogenic positive feedback driving atmosphere CO₂ levels upward even if/when geoengineering is applied (say after 2050):

Hoppe, C. J. M., Holtz, L.-M., Trimborn, S. and Rost, B. (2015), Ocean acidification decreases the light-use efficiency in an Antarctic diatom under dynamic but not constant light. New Phytologist. doi: 10.1111/nph.13334

http://onlinelibrary.wiley.com/doi/10.1111/nph.13334/abstract?utm_content=bufferbc7d4&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

• Summary: "There is increasing evidence that different light intensities strongly modulate the effects of ocean acidification (OA) on marine phytoplankton. The aim of the present study was to investigate interactive effects of OA and dynamic light, mimicking natural mixing regimes.
• The Antarctic diatom Chaetoceros debilis was grown under two pCO2 (390 and 1000 μatm) and light conditions (constant and dynamic), the latter yielding the same integrated irradiance over the day. To characterize interactive effects between treatments, growth, elemental composition, primary production and photophysiology were investigated.
• Dynamic light reduced growth and strongly altered the effects of OA on primary production, being unaffected by elevated pCO2 under constant light, yet significantly reduced under dynamic light. Interactive effects between OA and light were also observed for Chl production and particulate organic carbon quotas.
• Response patterns can be explained by changes in the cellular energetic balance. While the energy transfer efficiency from photochemistry to biomass production (Φe,C) was not affected by OA under constant light, it was drastically reduced under dynamic light. Contrasting responses under different light conditions need to be considered when making predictions regarding a more stratified and acidified future ocean."

[AbruptSLR]

The linked reference indicates that the UN estimates of deforestation in the humid tropics have significantly erred on the side of least drama, and that instead of decelerating (by 25%) such deforestation is actually accelerating (by 62%).  Before accepting UN estimates, it is a good idea to follow the old adage: "Let the buyer beware."

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/enhanced/doi/10.1002/2014GL062777/?campaign=wlytk-41855.5282060185


Abstract: "Using a consistent, twenty-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 (FAO) Forest Resource Assessment (FRA). 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 2000-2005 and decelerated afterward. The acceleration of humid tropical deforestation we report contradicts the assertion that losses decelerated from the 1990s to the 2000s."

[AbruptSLR]

In my opinion, the linked Carbon Brief article indicates that during their recently completed meeting in Nairobi, the IPCC "punted" on making significant improvements to the timing and impact of their reporting process (see extract).  I have relatively low expectations from the IPCC process on issuing useful guidance for policymakers to improve our current situation; but this makes it even more clear that the IPCC prefers a BAU approach:

http://www.carbonbrief.org/blog/2015/02/five-decisions-the-ipcc-made-today-about-its-future/

Extract: "Will we see shorter, more focused IPCC reports from now on?
The short answer is no. At least, not as a general rule."

[AbruptSLR]

The linked open access reference indicates that peatlands are more vulnerable to both moderate water table drops (predicted by models) and wildfires than previously understood:

"Moderate drop in water table increases peatland vulnerability to post-fire regime shift." Scientific Reports 5, Article number: 8063 DOI: 10.1038/srep08063


http://www.nature.com/srep/2015/150127/srep08063/full/srep08063.html

Abstract: "Northern and tropical peatlands represent a globally significant carbon reserve accumulated over thousands of years of waterlogged conditions. It is unclear whether moderate drying predicted for northern peatlands will stimulate burning and carbon losses as has occurred in their smaller tropical counterparts where the carbon legacy has been destabilized due to severe drainage and deep peat fires. Capitalizing on a unique long-term experiment, we quantify the post-wildfire recovery of a northern peatland subjected to decadal drainage. We show that the moderate drop in water table position predicted for most northern regions triggers a shift in vegetation composition previously observed within only severely disturbed tropical peatlands. The combined impact of moderate drainage followed by wildfire converted the low productivity, moss-dominated peatland to a non-carbon accumulating shrub-grass ecosystem. This new ecosystem is likely to experience a low intensity, high frequency wildfire regime, which will further deplete the legacy of stored peat carbon."

[AbruptSLR]

The linked article indicates that peat fires emit brown carbon (as opposed to black carbon); which is bad because brown carbon absorbs incoming solar radiation in the shorter (visible & near ultraviolet) wavelengths; which will contribute to global warming via a previously underestimated mechanism:

Washington University in St. Louis. "Peat fire emissions may shed light on climate change." ScienceDaily. ScienceDaily, 16 January 2015.


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

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

Extract: ""When you see the yellowish or brown color, it implies that the brown carbon is reflecting all light but the blue violet wavelengths, and that's what it's absorbing," Chakrabarty says. "That has significant implications because we know that black carbon is much less in terms of mass emissions compared to organic carbon. And if organic carbon has absorption right near visible or near ultraviolet light when the solar spectrum starts to peak, it will add further warming on top of black carbon, and we don't know how much.""

Edit:

The linked PowerPoint pdf confirms that global warming from brown carbon aerosols are currently not accounted for in current projections, and it also identifies other sources for brown carbon emissions that burning peat:


http://www.epa.gov/ncer/events/calendar/2014/mar04/schauer.pdf

[AbruptSLR]

The reason that I provide the following link and extracts to Paul Krugman's article on "the-closed-minds-problem" in economics, is because it is relevant to both the "Tyranny of the small decisions" and the "Tyranny of the Commons" problems with regards to climate change.  Krugman points-out that academic economics has become deeply politicized, and I can say the same thing about both the science and policymaking of climate change.
One of the fundamental insights of game theory (Google how game theory applies to the "Tyranny of the small decisions) is that agents must keep secrets; as an agent who divulges too much has lost some autonomy and thus is subject to manipulation by other agents who act to further their own welfare/agendas.  In the modern world of 24-7 media coverage and the Internet, one of the most efficient ways to keep secrets is to close people's minds by means of sowing doubts/uncertainties about (and generally politicizing) economic theory, scientific theory and mitigation policy for climate change.
Krugman advocates that in order to break-through such political manipulations of the truth, it is not sufficient to write in academic prose (such as that used by the IPCC Assessment Reports), or to politely point-out the errors of such truth distorters (as currently some activist scientists do); instead Krugman advocates that academics (including scientists) must point-out the errors of the wrong doers in a manner that stigmatize the truth distorters. Krugman further points-out that the purpose of stigmatizing the denialists is not to change their minds (which will not happen easily), but rather to deter third parties (voters, policymakers, investors, etc.) from associating with the political camp of the denalist (see my prior discussion about "Climate Cads"), if such third parties do not want to become stigmatized themselves.
 

http://krugman.blogs.nytimes.com/2015/02/27/the-closed-minds-problem/?_r=0

Extract: "… academic economics, which still has pretenses of being an arena of open intellectual inquiry, appears to be deeply infected with politicization.
So what should those of us who really wanted to be part of what we thought this enterprise was about do? That’s the question Brad DeLong has been asking.
I see three choices:
1. Continue to write and speak as if we were still having a genuine intellectual dialogue, in the hope that politeness and persistence will make the pretense come true.

…

 2. Point out the wrongness, but quietly and politely. This has the virtue of being honest, and useful to anyone who reads it. But nobody will.
3. Point out the wrongness in ways designed to grab readers’ attention — with ridicule where appropriate, with snark, and with names attached. This will get read; it will get you some devoted followers, and a lot of bitter enemies. One thing it won’t do, however, is change any of those closed minds.
So is there a reason I go for door #3, other than simply telling the truth and having some fun while I’m at it? Yes — because the point is not to convince Rick Santelli or Allan Meltzer that they are wrong, which is never going to happen. It is, instead, to deter other parties from false equivalence."

[Sigmetnow]

...  3.  ...with snark...

Snark.  I like it.   

Sou uses it to good effect against climate change deniers, at the HotWhopper blog:  http://blog.hotwhopper.com/2015/03/paranoia-runs-riot-at-cfact-and-wuwt.html

[bryman]

The linked reference (with an open access pdf) indicates that continued ocean acidification of the Southern Ocean under dynamic light conditions will result in a reduction in CO₂ sequestration into the Southern Ocean; thus indicating that greater dependence on an intense use of solar radiation management, SRM, will be likely in order to counter this trend.  Unfortunately, the most likely form of SRM accelerates ocean acidification which would require still more dependence on heavy SRM use; resulting in a likely anthropogenic positive feedback driving atmosphere CO₂ levels upward even if/when geoengineering is applied (say after 2050):

Hoppe, C. J. M., Holtz, L.-M., Trimborn, S. and Rost, B. (2015), Ocean acidification decreases the light-use efficiency in an Antarctic diatom under dynamic but not constant light. New Phytologist. doi: 10.1111/nph.13334

http://onlinelibrary.wiley.com/doi/10.1111/nph.13334/abstract?utm_content=bufferbc7d4&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

• Summary: "There is increasing evidence that different light intensities strongly modulate the effects of ocean acidification (OA) on marine phytoplankton. The aim of the present study was to investigate interactive effects of OA and dynamic light, mimicking natural mixing regimes.
• The Antarctic diatom Chaetoceros debilis was grown under two pCO2 (390 and 1000 μatm) and light conditions (constant and dynamic), the latter yielding the same integrated irradiance over the day. To characterize interactive effects between treatments, growth, elemental composition, primary production and photophysiology were investigated.
• Dynamic light reduced growth and strongly altered the effects of OA on primary production, being unaffected by elevated pCO2 under constant light, yet significantly reduced under dynamic light. Interactive effects between OA and light were also observed for Chl production and particulate organic carbon quotas.
• Response patterns can be explained by changes in the cellular energetic balance. While the energy transfer efficiency from photochemistry to biomass production (Φe,C) was not affected by OA under constant light, it was drastically reduced under dynamic light. Contrasting responses under different light conditions need to be considered when making predictions regarding a more stratified and acidified future ocean."

I have to disagree with your statement on SRM speeding up ocean acidification. Reports from the NRC and others state that SRM does nothing to address the situation, not accelerate it. And according to this study, the effects of suphate use would be slight.
 http://rsta.royalsocietypublishing.org/content/370/1974/4317#sec-11
CO2-induced ocean acidification could be exacerbated if sulphate aerosols were used for SRM, due to their effect on precipitation pH. Such impacts would probably be slight, since the quantity of sulphur that, in theory, would need to be added to the stratosphere for geoengineering (1–5 million tonnes per year) [140] is at least an order of magnitude less than that currently added to the total atmosphere by industrial activities and volcanic emissions.

[Bruce Steele]

Bryman, Welcome aboard.  SRM will cause more diffuse light but to what degree that modifies increased light intensity under acidified conditions I don't know. The other complication is what effect OA has on other plankton communities like coccoliths and how SRM may effect them. The study is important however because it shows diatoms responding differently than other studies have indicated them reacting.
"“Diatoms fulfil an important role in the Earth’s climate system. They can absorb large quantities of carbon dioxide, which they bind before ultimately transporting part of it to the depths of the ocean. Once there, the greenhouse gas remains naturally sequestered for centuries,” explains Dr Clara Hoppe, a biologist at the AWI and first author of the present study (learn more about the role of diatoms in this interview with Dr Clara Hoppe).


Scientists have so far worked under the assumption that the progressive acidification of the ocean could promote growth in diatoms, primarily because the additional carbon dioxide in the water can have a fertilising effect.

However, previous studies on the topic have overlooked an important aspect: the light environment. The previous experiments used stable unchanging light conditions. But constant light is hard to come by in nature, especially in the Southern Ocean, where storms mix the upper water layers. As Hoppe elaborates, “Several times a day, the wind and currents transport diatoms in the Southern Ocean from the uppermost water layer to the layers below, and then back to the surface – which means that, in the course of a day, the diatoms experience alternating phases with more and with less light.”

Under these conditions, the diatoms suffer most from insufficient light when they are in deeper water layers; this is why they grow more slowly in changing compared to constant light. So here they spend less time under optimal light conditions and have to constantly adjust from more light to less. But these conditions were not taken into account in experiments on ocean acidification so far.

The new study shows: This shifting light intensity significantly affects the reaction to ocean acidification. “Our findings show for the first time that our old assumptions most likely fall short of the mark. We now know that when the light intensity constantly changes, the effect of the ocean acidification reverses. All of a sudden, lower pH values don’t increase growth, like studies using constant light show; instead, they have just the opposite effect,” says Dr Björn Rost from the AWI, co-author of the study.

In experiments conducted at the Alfred Wegener Institute in Bremerhaven, the researchers investigated how the Antarctic diatom species Chaetoceros debilis grows in constant and in shifting light, respectively – and how the effects of the different light conditions change in todays as well as more acidic seawater.

The new study effectively demonstrates that there are surprising interactions between changing light conditions and ocean acidification. As a result, in a future scenario characterised by more acidic water under changing light intensities, diatoms’ biomass production could be drastically reduced.

The results also reveal that under ocean acidification the diatoms are especially sensitive when subjected to phases of higher light levels. As Hoppe relates, “At a certain intensity, the light actually begins to shut down and even destroy part of the photosynthesis chain, a phenomenon referred to as high-light stress. In these phases, the algae cells have to invest a great deal of energy to undo the damage done by the light. This point, at which enough light becomes too much light, is more quickly reached in acidic water.”

For their experiments, Hoppe’s team examined the diatom species Chaetoceros debilis. “Though it’s always difficult to generalise for all species on the basis of just one, Chaetoceros is one of the most important groups of diatoms and is often dominant in algal communities. Further, previous studies have shown that its responses to ocean acidification are fairly typical for other diatom species,” Hoppe explains.

http://www.awi.de/en/news/press_releases/detail/item/a_question_of_light_ocean_acidification_slows_algae_growth_in_the_southern_ocean/?cHash=00de8ea4c830991a157f3a3ea365be63

[AbruptSLR]

Further to Bruce's post, I would like to add that while many SRM approaches do not increase ocean acidification, OA, sulfate aerosols do (to some extent see the links below), and as sulfate SRM plans are relatively inexpensive, they may well be implemented by desperate governments in the future.

Furthermore, as industrial sulfate emissions are projected to drop sharply in coming decades as Asia and Africa implement tighter air pollution regulations; thus any sulfate SRM plan will need to be sufficiently aggressive to make-up for this projected reduction in negative forcing (due to reduced industrial emissions).  Also, as we do not know whether ECS is closer to 4.5C than to 3C and whether third world development will push the world on a BAU GHG emissions pathway; we do not know how aggressive any final sulfate SRM plan may have to be.  Thus as Bruce points out that significant amounts of plankton are sensitive to OA, it is possible that a sulfate SRM plan (which would be implemented to allow high CO2 levels to remain in the atmosphere for at least decades) could be the straw that broke the camel's (plankton's) back.

For geoengineering see also:
http://en.wikipedia.org/wiki/Climate_engineering
http://en.wikipedia.org/wiki/Stratospheric_sulfate_aerosols_(geoengineering)
http://en.wikipedia.org/wiki/Solar_radiation_management

[AbruptSLR]

...  3.  ...with snark...

Snark.  I like it.   

Sou uses it to good effect against climate change deniers, at the HotWhopper blog:  http://blog.hotwhopper.com/2015/03/paranoia-runs-riot-at-cfact-and-wuwt.html

As Sigmetnow likes the idea of snarky posts:

I propose that before any scientist, or economist, be allowed to work on AR6 (now that the IPCC has decided to pass on issuing annual reports) that they should all be required to take a class on morals and ethics and then they should be required to pass a test or required to take the class again.  While I do not question the integrity of the vast majority of scientists (I am less certain about the majority of economists), it appears clear to me that before they should be allowed to advise policymakers on matters of public, and environmental, safety that they need to sharpen their collective moral compasses and possibly take the equivalent of a medical doctor's Hippocratic oath to do no damage.  Advising policymakers is a profession and most professionals involved in matters of public safety must learn appropriate rules and guidance, which AR5 indicates that these scientist/economists have not yet learned.

For example, per Weitzman 2009a&b, societies willingness to pay (WTP) to avoid damage from extreme climate changes associated with fat-tailed (or dragon-trailed) PDFs should morally constitute all of output produced by modern society, but instead the AR5 economists applied such heavy discount factors for future fat-tailed risks that they ignored them completely.

For another example all civil engineering infrastructure projects are first evaluated with one set of criteria for benefit/cost ratios to determine project approvals for governments with limited budgets; but then they design the projects to higher public safety standards than that applied during the project approval phase.  Unfortunately, the SPM for AR5 only includes the lower environmental loading criteria for infrastructure economic project approval, and do not state environmental loading criteria appropriate for public safety (which requires an understanding of the fat-tailed PDFs).

Hopefully, scientists working on AR6 will realize that while application of the scientific method does not require any particular moral compass with regard to public safety, professional guidance to policymakers does, and that it is both unethical and amoral to ignore this professional obligation that they are not normally used to shouldering.


Weitzman, M., (2009a), "On Modeling and Interpreting the Economics of Catastrophic Climate Change," Review of Economics and Statistics, 91, pp. 1-19.

Weitzman, M., (2009b), "Additive damages, fat-tailed climate dynamics, and uncertain discounting"; Economics - The Open-Access, Open-Assessment E-Journal, 3, pp. 1-29.

[bryman]

Further to Bruce's post, I would like to add that while many SRM approaches do not increase ocean acidification, OA, sulfate aerosols do (to some extent see the links below), and as sulfate SRM plans are relatively inexpensive, they may well be implemented by desperate governments in the future.

Furthermore, as industrial sulfate emissions are projected to drop sharply in coming decades as Asia and Africa implement tighter air pollution regulations; thus any sulfate SRM plan will need to be sufficiently aggressive to make-up for this projected reduction in negative forcing (due to reduced industrial emissions).  Also, as we do not know whether ECS is closer to 4.5C than to 3C and whether third world development will push the world on a BAU GHG emissions pathway; we do not know how aggressive any final sulfate SRM plan may have to be.  Thus as Bruce points out that significant amounts of plankton are sensitive to OA, it is possible that a sulfate SRM plan (which would be implemented to allow high CO2 levels to remain in the atmosphere for at least decades) could be the straw that broke the camel's (plankton's) back.

For geoengineering see also:
http://en.wikipedia.org/wiki/Climate_engineering
http://en.wikipedia.org/wiki/Stratospheric_sulfate_aerosols_(geoengineering)

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

The study I refer to says there could be significant secondary effects from sulfates. Is that what you're referring to?

[bryman]

Bryman, Welcome aboard.  SRM will cause more diffuse light but to what degree that modifies increased light intensity under acidified conditions I don't know. The other complication is what effect OA has on other plankton communities like coccoliths and how SRM may effect them. The study is important however because it shows diatoms responding differently than other studies have indicated them reacting.
"“Diatoms fulfil an important role in the Earth’s climate system. They can absorb large quantities of carbon dioxide, which they bind before ultimately transporting part of it to the depths of the ocean. Once there, the greenhouse gas remains naturally sequestered for centuries,” explains Dr Clara Hoppe, a biologist at the AWI and first author of the present study (learn more about the role of diatoms in this interview with Dr Clara Hoppe).
Thanks, Bruce.  I guess, what I'm asking is, is deploying sulfates feasible? I believe so, since they have secondary effects on ocean acidification and SRM could potentially regulate the amount of light hitting the ocean.


Scientists have so far worked under the assumption that the progressive acidification of the ocean could promote growth in diatoms, primarily because the additional carbon dioxide in the water can have a fertilising effect.

However, previous studies on the topic have overlooked an important aspect: the light environment. The previous experiments used stable unchanging light conditions. But constant light is hard to come by in nature, especially in the Southern Ocean, where storms mix the upper water layers. As Hoppe elaborates, “Several times a day, the wind and currents transport diatoms in the Southern Ocean from the uppermost water layer to the layers below, and then back to the surface – which means that, in the course of a day, the diatoms experience alternating phases with more and with less light.”

Under these conditions, the diatoms suffer most from insufficient light when they are in deeper water layers; this is why they grow more slowly in changing compared to constant light. So here they spend less time under optimal light conditions and have to constantly adjust from more light to less. But these conditions were not taken into account in experiments on ocean acidification so far.

The new study shows: This shifting light intensity significantly affects the reaction to ocean acidification. “Our findings show for the first time that our old assumptions most likely fall short of the mark. We now know that when the light intensity constantly changes, the effect of the ocean acidification reverses. All of a sudden, lower pH values don’t increase growth, like studies using constant light show; instead, they have just the opposite effect,” says Dr Björn Rost from the AWI, co-author of the study.

In experiments conducted at the Alfred Wegener Institute in Bremerhaven, the researchers investigated how the Antarctic diatom species Chaetoceros debilis grows in constant and in shifting light, respectively – and how the effects of the different light conditions change in todays as well as more acidic seawater.

The new study effectively demonstrates that there are surprising interactions between changing light conditions and ocean acidification. As a result, in a future scenario characterised by more acidic water under changing light intensities, diatoms’ biomass production could be drastically reduced.

The results also reveal that under ocean acidification the diatoms are especially sensitive when subjected to phases of higher light levels. As Hoppe relates, “At a certain intensity, the light actually begins to shut down and even destroy part of the photosynthesis chain, a phenomenon referred to as high-light stress. In these phases, the algae cells have to invest a great deal of energy to undo the damage done by the light. This point, at which enough light becomes too much light, is more quickly reached in acidic water.”

For their experiments, Hoppe’s team examined the diatom species Chaetoceros debilis. “Though it’s always difficult to generalise for all species on the basis of just one, Chaetoceros is one of the most important groups of diatoms and is often dominant in algal communities. Further, previous studies have shown that its responses to ocean acidification are fairly typical for other diatom species,” Hoppe explains.

http://www.awi.de/en/news/press_releases/detail/item/a_question_of_light_ocean_acidification_slows_algae_growth_in_the_southern_ocean/?cHash=00de8ea4c830991a157f3a3ea365be63

[Sigmetnow]

A great idea, ASLR; hardly snarky at all.  A disparate international group needs a unified, realistic approach in order to override outside influences demanding a palatable result.  (Whew!)

[LRC1962]

A have a question about IPCC. Do we not have to acknowledge the fact the reports published are in fact political and not scientific? The Politicians try and couch it in scientific terms, but it is non the less a political report. Given that the IPCC then tends to select a panel that is more conservative by nature and or more political attuned to what is wanted. The reason for my thinking is I have heard more then once the the released report must be signed of by all counties and they haggle over everything in it on a very political level. And it is not the scientist that are doing the negotiating, but the lawyers and civil servants answerable to the governing powers of their respective countries.
Granted in end it is the scientist that are demanded to carry the waste bucket. but I am not convinced they in the end had any real say in the report. I doubt you would ever find anyone on the panel coming out and agreeing with it because of all those contractual obligations they must sign off on.