Conservative Scientists & its Consequences

[Laurent]

ASLR posted a link to a new paper in the Conservative Scientists & its Consequences thread yesterday.
http://forum.arctic-sea-ice.net/index.php/topic,1053.msg70113.html#msg70113
If someone has access to that paper I would love to read it.

Strange you are speaking of yourself as ASLR !? Are you referring to this link : http://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0417.1 ? it isn't locked !?

[magnamentis]

that was sleepy writing that, check the title. at least that's how i understand it, let's see :-)

[Sleepy]

ASLR posted a link to a new paper in the Conservative Scientists & its Consequences thread yesterday.
http://forum.arctic-sea-ice.net/index.php/topic,1053.msg70113.html#msg70113
If someone has access to that paper I would love to read it.

Strange you are speaking of yourself as ASLR !? Are you referring to this link : http://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0417.1 ? it isn't locked !?

That was me asking ASLR, the paper was locked then, it has been unlocked for a while now. Not much in it for me since I was/am primarily interested in what creates the NAO, such as the QBO. I think the NAO is a poor index to use for forecasts.

The NAO was also another reason for my speculations about a slowdown in the extent in the IJIS thread in May, the forecasted -NAO did not become as strong as predicted in early June.
And as for ktonines earlier question to ASLR and little review of RS and deniers, I was actually called a denier in that thread after that. I don't care really, I've been called much worse by real deniers for years.

And for the QBO (and this thread), here's a press release from ECMWF from last year that might help, and a couple of qoutes:
http://www.ecmwf.int/en/about/media-centre/news/2015/why-quasi-biennial-oscillation-matters

Although the basic physics of the QBO is well known, the quantitative details and balances of the different processes are still rather unclear. Worse, many of the models used for numerical weather prediction (NWP) or climate modelling are unable to produce a QBO, or they produce a QBO which looks very different from observations. For example, only 4 of more than 30 models used for the last IPCC report have any sort of QBO.

At ECMWF, the IFS does have sufficient vertical resolution and physics to allow a reasonable simulation of the QBO, for example as seen in ECMWF’s ERA-20CM, a set of extended model runs covering the 20th century. Our seasonal forecasts also have skill in predicting the future evolution of the QBO signal. However, we would like to improve the accuracy and skill of the IFS, so we are working with other members of the international scientific community to better understand and model the processes driving the QBO.

My bold.

Why is the QBO important? It is certainly relevant for seasonal prediction, where the state of stratospheric winds affects interactions between the tropics and the mid-latitudes, and may also affect the tropical troposphere directly and possibly how the solar cycle interacts with the atmosphere. For those groups working on climate, the QBO has a role in modulating transport out of the tropical stratosphere to higher altitudes, thus influencing the concentration of gases in the stratosphere, which in turn might lead to further climate feedbacks.

The poor representation of the QBO in climate change models means that no-one knows what will happen to the QBO in the decades ahead – will it remain largely unchanged, will its period lengthen, or will it change more radically?

My bold again. And now we have seen a change in this (previously) clockwork oscillation.

[AbruptSLR]

I am reposting the following from the aerosol thread, because it implies that ECS is likely higher than consensus science assumes, because during the faux hiatus aerosols were likely more effective at masking the higher sensitivity than previously realized:

The linked reference concludes with regards to the faux hiatus and implications of aerosol reductions in the future that: "Our results suggest that a slowdown in GMST trends could have been predicted in advance, and that future reduction of anthropogenic aerosol emissions, particularly from China, would promote a positive PDO and increased GMST trends over the coming years."

Doug M. Smith, Ben B. B. Booth, Nick J. Dunstone, Rosie Eade, Leon Hermanson, Gareth S. Jones, Adam A. Scaife, Katy L. Sheen & Vikki Thompson (2016), "Role of volcanic and anthropogenic aerosols in the recent global surface warming slowdown", Nature Climate Change, doi:10.1038/nclimate3058

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3058.html

Abstract: "The rate of global mean surface temperature (GMST) warming has slowed this century despite the increasing concentrations of greenhouse gases. Climate model experiments show that this slowdown was largely driven by a negative phase of the Pacific Decadal Oscillation (PDO), with a smaller external contribution from solar variability, and volcanic and anthropogenic aerosols. The prevailing view is that this negative PDO occurred through internal variability. However, here we show that coupled models from the Fifth Coupled Model Intercomparison Project robustly simulate a negative PDO in response to anthropogenic aerosols implying a potentially important role for external human influences. The recovery from the eruption of Mount Pinatubo in 1991 also contributed to the slowdown in GMST trends. Our results suggest that a slowdown in GMST trends could have been predicted in advance, and that future reduction of anthropogenic aerosol emissions, particularly from China, would promote a positive PDO and increased GMST trends over the coming years. Furthermore, the overestimation of the magnitude of recent warming by models is substantially reduced by using detection and attribution analysis to rescale their response to external factors, especially cooling following volcanic eruptions. Improved understanding of external influences on climate is therefore crucial to constrain near-term climate predictions."

See also:
http://www.carbonbrief.org/aerosol-emissions-key-to-the-surface-warming-slowdown-study-says

Extract: "Human-caused aerosols are, therefore, at least another factor to add to the list of those that have contributed to the global surface warming slowdown …"

[Theta]

New link by Guy Mcpherson where in the text he states that in 23 years, the mixture of aerosol decline + moistening of the upper troposphere could lead us to 23C in a few months/years

Moistening of the upper troposphere plus “other feedbacks” (of which there are many) plus loss of global dimming take Earth up to 23 C in a few months or years. Ignoring more than five dozen self-reinforcing feedback loops, that’s the highest global-average temperature Earth has attained during the last two billion years.

http://guymcpherson.com/2016/06/a-town-hall-discussion-in-chico-california-part-iii/

[AbruptSLR]

The linked reference discusses paleodata to indicate that climate sensitivity increased from 3.3 - 5.6 (mean of 4.45k) at the beginning of the PETM up to 3.7 - 6.5 K (mean of 5.1K) near the peak of the PETM; and that if we burn only the easily accessible carbon reserves then GMST could increase by about 10C.  I note these climate sensitivity values are much higher than those inherent in the CMIP5 projections:

Gary Shaffer, Matthew Huber, Roberto Rondanelli & Jens Olaf Pepke Pedersen (23 June 2016), "Deep-time evidence for climate sensitivity increase with warming", Geophysical Research Letters, DOI: 10.1002/2016GL069243

http://onlinelibrary.wiley.com/doi/10.1002/2016GL069243/full

Abstract: "Future global warming from anthropogenic greenhouse gas emissions will depend on climate feedbacks, the effect of which is expressed by climate sensitivity, the warming for a doubling of atmospheric CO2 content. It is not clear how feedbacks, sensitivity and temperature will evolve in our warming world but past warming events may provide insight. Here we employ paleo-reconstructions and new climate-carbon model simulations in a novel framework to explore a wide scenario range for the Paleocene-Eocene Thermal Maximum (PETM) carbon release and global warming event 55.8 million years ago, a possible future warming analogue. We obtain constrained estimates of CO2 and climate sensitivity before and during the PETM and of the PETM carbon input amount and nature. Sensitivity increased from 3.3 - 5.6 to 3.7 - 6.5 K (Kelvin) into the PETM. When taken together with Last Glacial Maximum and modern estimates this result indicates climate sensitivity increase with global warming."

Also see:

https://www.sciencedaily.com/releases/2016/06/160623112206.htm

Extract: ""Our results show that the amount of carbon that drove the PETM warming was about the same amount as the current 'easily accessible' fossil fuel reserves of about 4,000 billion tons. But the warming that would result from adding such large amounts of carbon to the climate system would be much greater today than during the PETM and could reach up to 10 degrees. This is partly due to the current atmosphere containing much less CO2 -- approximately 400 ppm (parts per million) -- compared to before the PETM, where the concentration was about 1,000 ppm and partly because we emit carbon into the atmosphere at a much faster rate than during the PETM. If we then also take into account the fact that climate sensitivity increases with the temperature, it means that it is all the more urgent to limit global warming as soon as possible by reducing the human-made emissions of greenhouse gases," explains Professor Gary Shaffer, who conducted the study in collaboration with researchers from Purdue University, USA, the University of Chile and the Technical University of Denmark."

Edit: Caption for attached image: "Paleo climate sensitivity study reconstructs global warming 56 million years ago and suggests future global warming could be even worse than expected. This graphic shows climate sensitivity at different global temperatures in the atmosphere. The figure shows from the right estimates for the past warm period, the PETM 56 million years ago, the period before the PETM and for the present. On the left the figure shows estimates for the Last Glacial Maximum. Courtesy: Gary Shaffer and Roberto Rondanelli"

[jai mitchell]

This paper shows that if anthropogenic aerosol emissions are changed according to recent historic patterns then a negative PDO phase sets up, leading to additional globally averaged temperature cooling.  As the title of the paper indicates, they attribute the slowdown of warming to chinese aerosol emission increases (and U.S./EURO emission reductions).

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3058.html
Role of volcanic and anthropogenic aerosols in the recent global surface warming slowdown
    Nature Climate Change
    (2016)
    doi:10.1038/nclimate3058
Published online
    20 June 2016

abstract:
The rate of global mean surface temperature (GMST) warming has slowed this century despite the increasing concentrations of greenhouse gases. Climate model experiments1, 2, 3, 4 show that this slowdown was largely driven by a negative phase of the Pacific Decadal Oscillation (PDO), with a smaller external contribution from solar variability, and volcanic and anthropogenic aerosols5, 6. The prevailing view is that this negative PDO occurred through internal variability7, 8, 9, 10, 11. However, here we show that coupled models from the Fifth Coupled Model Intercomparison Project robustly simulate a negative PDO in response to anthropogenic aerosols implying a potentially important role for external human influences. The recovery from the eruption of Mount Pinatubo in 1991 also contributed to the slowdown in GMST trends. Our results suggest that a slowdown in GMST trends could have been predicted in advance, and that future reduction of anthropogenic aerosol emissions, particularly from China, would promote a positive PDO and increased GMST trends over the coming years. Furthermore, the overestimation of the magnitude of recent warming by models is substantially reduced by using detection and attribution analysis to rescale their response to external factors, especially cooling following volcanic eruptions. Improved understanding of external influences on climate is therefore crucial to constrain near-term climate predictions.

Here is a carbon brief discussion:  http://www.carbonbrief.org/aerosol-emissions-key-to-the-surface-warming-slowdown-study-says

“Future reductions in aerosol emissions from China – to improve air quality – could promote a positive phase of the PDO and a period of increased trends in global surface temperatures. There are some signs that this could be happening.”

h/t to ATTP:  https://andthentheresphysics.wordpress.com/2016/06/23/aerosol-forcing-and-the-pdo/

[Sleepy]

Reconciled climate response estimates from climate models and the energy budget of Earth.
http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3066.html
Paywalled. A part from the abstract:

We show that there is no evidence that climate models overestimate TCR when their output is processed in the same way as the HadCRUT4 observation-based temperature record. Models suggest that air-temperature warming is 24% greater than observed by HadCRUT4 over 1861–2009 because slower-warming regions are preferentially sampled and water warms less than air.

[AbruptSLR]

The linked reference concludes that SOA concentrations are roughly twice that assumed by current models indicating that the associate masking has been higher than previously assumed, which raises the risk that the effective ECS could increase more rapidly than expected should continued global warming stress sources of SOAs (as projected by numerous models):

Hodzic, A., Kasibhatla, P. S., Jo, D. S., Cappa, C. D., Jimenez, J. L., Madronich, S., and Park, R. J.: Rethinking the global secondary organic aerosol (SOA) budget: stronger production, faster removal, shorter lifetime, Atmos. Chem. Phys., 16, 7917-7941, doi:10.5194/acp-16-7917-2016, 2016.

http://www.atmos-chem-phys.net/16/7917/2016/

Abstract. Recent laboratory studies suggest that secondary organic aerosol (SOA) formation rates are higher than assumed in current models. There is also evidence that SOA removal by dry and wet deposition occurs more efficiently than some current models suggest and that photolysis and heterogeneous oxidation may be important (but currently ignored) SOA sinks. Here, we have updated the global GEOS-Chem model to include this new information on formation (i.e., wall-corrected yields and emissions of semi-volatile and intermediate volatility organic compounds) and on removal processes (photolysis and heterogeneous oxidation). We compare simulated SOA from various model configurations against ground, aircraft and satellite measurements to assess the extent to which these improved representations of SOA formation and removal processes are consistent with observed characteristics of the SOA distribution. The updated model presents a more dynamic picture of the life cycle of atmospheric SOA, with production rates 3.9 times higher and sinks a factor of 3.6 more efficient than in the base model. In particular, the updated model predicts larger SOA concentrations in the boundary layer and lower concentrations in the upper troposphere, leading to better agreement with surface and aircraft measurements of organic aerosol compared to the base model. Our analysis thus suggests that the long-standing discrepancy in model predictions of the vertical SOA distribution can now be resolved, at least in part, by a stronger source and stronger sinks leading to a shorter lifetime. The predicted global SOA burden in the updated model is 0.88 Tg and the corresponding direct radiative effect at top of the atmosphere is −0.33 W m−2, which is comparable to recent model estimates constrained by observations. The updated model predicts a population-weighed global mean surface SOA concentration that is a factor of 2 higher than in the base model, suggesting the need for a reanalysis of the contribution of SOA to PM pollution-related human health effects. The potential importance of our estimates highlights the need for more extensive field and laboratory studies focused on characterizing organic aerosol removal mechanisms and rates.

[AbruptSLR]

As a follow-on to my Reply #1450, I provide the following linked reference on improved modeling of the QBO:

Geller, M.A., T.H. Zhou, D. Shindell, R. Ruedy, I. Aleinov, L. Nazarenko, N. Tausnev, M. Kelley, S. Sun, Y. Cheng, R.D. Field, and G. Faluvegi, 2016: Modeling the QBO — Improvements resulting from higher model vertical resolution. J. Adv. Model. Earth Syst., doi:10.1002/2016MS000699.

http://onlinelibrary.wiley.com/doi/10.1002/2016MS000699/pdf

Abstract: "Using the NASA Goddard Institute for Space Studies (GISS) climate model, it is shown that with proper choice of the gravity wave momentum flux entering the stratosphere and relatively fine vertical layering of at least 500 m in the upper troposphere-lower stratosphere (UTLS), a realistic stratospheric quasi-biennial oscillation (QBO) is modeled with the proper period, amplitude, and structure down to tropopause levels. It is furthermore shown that the specified gravity wave momentum flux controls the QBO period whereas the width of the gravity wave momentum spectrum controls the QBO amplitude. Fine vertical layering is required for the proper downward extension to tropopause levels as this permits wave-mean flow interactions in the UTLS region to be resolved in the model. When vertical resolution is increased from 1000 m to 500 m, the modeled QBO modulation of the tropical tropopause temperatures inceasingly approach that from observations, and the "tape-recorder" of stratospheric water vapor also approaches the observed. The transport characteristics of our GISS models are assessed using age-of-air and N2O diagnostics, and it is shown that some of the deficiencies in model transport that have been noted in previous GISS models are greatly improved for all of our tested model vertical resolutions. More realistic tropical-extratropical transport isolation, commonly referred to as the "tropical pipe," results from the finer vertical model layering required to generate a realistic QBO."

See also:

https://robertscribbler.com/2016/06/28/gigantic-gravity-waves-to-mix-winter-with-summer-wrecked-jet-stream-now-runs-from-pole-to-pole/#comments

[AbruptSLR]

The linked reference indicates that the climate responses (climate sensitivities) projected by advanced climate models generally match observations when apple to apple comparisons are made.  This is a useful finding as advanced climate models generally indicate that climate sensitivity values are towards the high end of the IPCC climate sensitivity range:

Mark Richardson, Kevin Cowtan, Ed Hawkins & Martin B. Stolpe (2016), "Reconciled climate response estimates from climate models and the energy budget of Earth", Nature Climate Change, doi:10.1038/nclimate3066

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3066.html

Abstract: "Climate risks increase with mean global temperature, so knowledge about the amount of future global warming should better inform risk assessments for policymakers. Expected near-term warming is encapsulated by the transient climate response (TCR), formally defined as the warming following 70 years of 1% per year increases in atmospheric CO2 concentration, by which point atmospheric CO2 has doubled. Studies based on Earth’s historical energy budget have typically estimated lower values of TCR than climate models, suggesting that some models could overestimate future warming. However, energy-budget estimates rely on historical temperature records that are geographically incomplete and blend air temperatures over land and sea ice with water temperatures over open oceans. We show that there is no evidence that climate models overestimate TCR when their output is processed in the same way as the HadCRUT4 observation-based temperature record. Models suggest that air-temperature warming is 24% greater than observed by HadCRUT4 over 1861–2009 because slower-warming regions are preferentially sampled and water warms less than air5. Correcting for these biases and accounting for wider uncertainties in radiative forcing based on recent evidence, we infer an observation-based best estimate for TCR of 1.66 °C, with a 5–95% range of 1.0–3.3 °C, consistent with the climate models considered in the IPCC 5th Assessment Report. Climate risks increase with mean global temperature, so knowledge about the amount of future global warming should better inform risk assessments for policymakers. Expected near-term warming is encapsulated by the transient climate response (TCR), formally defined as the warming following 70 years of 1% per year increases in atmospheric CO2 concentration, by which point atmospheric CO2 has doubled. Studies based on Earth’s historical energy budget have typically estimated lower values of TCR than climate models, suggesting that some models could overestimate future warming. However, energy-budget estimates rely on historical temperature records that are geographically incomplete and blend air temperatures over land and sea ice with water temperatures over open oceans. We show that there is no evidence that climate models overestimate TCR when their output is processed in the same way as the HadCRUT4 observation-based temperature record. Models suggest that air-temperature warming is 24% greater than observed by HadCRUT4 over 1861–2009 because slower-warming regions are preferentially sampled and water warms less than air. Correcting for these biases and accounting for wider uncertainties in radiative forcing based on recent evidence, we infer an observation-based best estimate for TCR of 1.66 °C, with a 5–95% range of 1.0–3.3 °C, consistent with the climate models considered in the IPCC 5th Assessment Report."

See:
http://www.climate-lab-book.ac.uk/2016/reconciling-estimates-of-climate-sensitivity/

Extract: "Richardson et al conclude that previous analyses which reported observation-based estimates of TCR toward the low end of the model range did so largely because of inconsistencies between the temperature reconstruction methods in models and observations."

See also:
http://www.carbonbrief.org/scientists-find-common-ground-climate-sensitivity

Extract: "The study raises another interesting point: which global mean temperature is relevant for informing policy? The imperfect record based on observations, or the model record with gaps filled in? On this point, Hawkins says:
“If it is decided that climate targets refer to the latter, then the warming is actually 24% (9-40%) larger than reported by HadCRUT4. And that is a big difference, especially when considering lower global temperature targets.”"

Also see:
https://andthentheresphysics.wordpress.com/2016/06/28/climate-sensitivity-reconciled/

[AbruptSLR]

Climate experts are gradually beginning to acknowledge how much global warming potential is already built into the climate change pipeline; however, I believe that they are still significantly erring on the side of least drama (note in the following linked article focused on recent paleo findings Rolf Schuttenhelm only talks about CO₂ concentrations (currently over 400ppm) and not about CO₂-eq concentrations (currently over 486ppm using a GWP100 of 25 for methane; however, I note that if one assumes that the GWP100 for methane is 35 instead of 25, then NOAA's calculated value for the CO2-eq for 2015 would be 518ppm instead of 485ppm):

http://www.bitsofscience.org/real-global-temperature-trend-paleoclimate-experts-degrees-pipeline-climate-inertia-7160/

Extract: "Mann came up with the following distinction:
“While the canonical (“most likely”) estimate of the “fast feedback” ECS is around 3C, I feel that more recent evidence suggests it might very well be higher than that, between 3C and 4C (say, 3.5C).
The long feedback “Earth System Sensitivity” (ESS) is almost certainly higher, closer to 5C.”

[AbruptSLR]

"If you give me six lines written by the hand of the most honest of men, I will find something in them which will hang him." Cardinal Richelieu

For the quote above, if you substitute "scientist" for "men" and "Denialist Cabal" for "Cardinal Richelieu"; then you will begin to understand why so many climate scientists err on the side of least drama, ESLD.  However, while this is eminently understandable, it is a particularly poor way to manage climate change risk.

[AbruptSLR]

The linked "The Guardian" article discusses the recent Richardson et al (2016) paper (see Reply #1461) and indicates: (a) that if both Kate Marvel's consideration of the efficiencies of various factors contributing to global energy imbalances and non-linear feedback mechanism, were to be considered then climate sensitive is likely higher than that considered by most CMIP5 projections (indicating the CMIP5 projections may well underestimate the influence of masking factors like aerosols, etc.); and (b) using land & ocean temperature departure data to monitor the 2C goal may well be inadvisable.

https://www.theguardian.com/environment/climate-consensus-97-per-cent/2016/jul/05/new-research-climate-may-be-more-sensitive-and-situation-more-dire

Extract: "… in 2013, Kevin Cowtan and Robert Way published a paper finding that climate scientists had been underestimating global surface warming, largely because of a lack of measurements in the rapidly-warming Arctic. Additionally, while climate models simulate surface air temperatures (the temperature of the air a few meters above the Earth’s surface), over the oceans, climate scientists measure sea surface temperatures. It turns out that the water surface isn’t warming quite as fast as the air above it. Thus looking at modeled surface air temperatures versus measured global land-ocean surface temperatures is an apples-to-oranges comparison.
A new study in Nature Climate Change led by Mark Richardson in collaboration with Kevin Cowtan, Ed Hawkins, and Martin Stolpe accounts for these differences to make an apples-to-apples comparison. They find that the use of sea surface temperatures biases the Otto result low by about 9%, and the lack of Arctic observations by another 15%.
…
Previous studies have identified other flaws in the energy budget model approach. Several papers, most recently led by Kate Marvel at NASA, found that Otto’s and similar studies have not accounted for the different efficiencies of various factors that cause global energy imbalances. Other papers have noted that the energy balance model approach assumes that feedbacks amplifying or dampening global warming will stay constant over time, while in reality, some feedbacks kick in later than others. This suggests that energy budget climate sensitivity estimates, based only on today’s feedbacks, will be biased low.
…
When comparing apples to apples, climate models accurately simulate global surface temperature changes, and the evidence for lower climate sensitivity failed to withstand scientific scrutiny and the test of time.
…
We’re also left with the question, when evaluating dangerous global warming, should we consider measured land-ocean temperatures, or faster-warming air temperatures? As Ed Hawkins notes, if we decide climate targets refer to the latter, it puts us about 24% closer to dangerous thresholds. Thus the climate situation may be even more, not less urgent than previously believed."

[AbruptSLR]

In the first linked reference on the efficacy of climate forcings explained by variations in atmospheric boundary layer depth, I want to emphasize the conclusion that "… multiple climate forcings cannot be linearly combined to determine the temperature response."  To me this means that the pdf for ECS has a fat tail (and skewed, and shifted, right) because we do not know how changes to multiple climate forcings will impact GMST without a well calibrated state-of-the-art ESM like ACME.

Richard Davy & Igor Esau (2016), "Differences in the efficacy of climate forcings explained by variations in atmospheric boundary layer depth", Nature Communications, Volume: 7, Article number: 11690, doi:10.1038/ncomms11690


http://www.nature.com/ncomms/2016/160525/ncomms11690/abs/ncomms11690.html

Abstract: "The Earth has warmed in the last century and a large component of that warming has been attributed to increased anthropogenic greenhouse gases. There are also numerous processes that introduce strong, regionalized variations to the overall warming trend. However, the ability of a forcing to change the surface air temperature depends on its spatial and temporal distribution. Here we show that the efficacy of a forcing is determined by the effective heat capacity of the atmosphere, which in cold and dry climates is defined by the depth of the planetary boundary layer. This can vary by an order of magnitude on different temporal and spatial scales, and so we get a strongly amplified temperature response in shallow boundary layers. This must be accounted for to assess the efficacy of a climate forcing, and also implies that multiple climate forcings cannot be linearly combined to determine the temperature response."

From the second linked article on variations in SAT/climate sensitivity with geographical distributions, and I present the attached image of coupled average climate sensitivity spread across Earth’s different latitudes.  This image indicates the extreme variation in ECS with latitude, and indicates that by focusing on GMST departures we run the risk of being surprised by numerous non-linear forcings & feedbacks that could have unexpectedly high impacts on populated areas.

http://www.bitsofscience.org/real-global-temperature-trend-climate-sensitivity-geographical-degrees-global-average-arctic-7141/

Extract: " Real Global Temperature Trend, p23 – Climate sensitivity has large geographical spread: 2-3 degrees global average equals 6+ in the Arctic
Posted on July 2, 2016 by Rolf Schuttenhelm
Why climate change is such a killer? Because disruption is never a linear process. We see that with ecosystem disintegration – where beyond a certain threshold cascading damage sets in – leading to shifts and collapse scenarios that are easy to succumb to, yet almost impossible to predict.

…

NASA GISS shows a 3 degrees geographical spread in climate sensitivity, across latitudes. Notable is the smallest projected temperature rise around -60 degrees latitude at the southern hemisphere, a band of Earth that is dominated by ocean surfaces with very little land masses. Here thermal climate inertia is relatively large, therefore warming is very slow. The highest temperature rise happens at high latitudes at the northern hemisphere (Arctic) followed by an also clearly above-average temperature rise at high southern hemisphere latitudes, around Antarctica."

[AbruptSLR]

The linked reference indicates that fast positive feedbacks from clouds are at least what CMIP5 models assume; while further research is needed to determine whether ECS may be higher than the 3.2C mean value assumed by the CMIP5 ensemble:

Joel R. Norris, Robert J. Allen, Amato T. Evan, Mark D. Zelinka, Christopher W. O’Dell & Stephen A. Klein (2016), "Evidence for climate change in the satellite cloud record", Nature, doi:10.1038/nature18273

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature18273.html

Abstract: "Clouds substantially affect Earth’s energy budget by reflecting solar radiation back to space and by restricting emission of thermal radiation to space. They are perhaps the largest uncertainty in our understanding of climate change, owing to disagreement among climate models and observational datasets over what cloud changes have occurred during recent decades and will occur in response to global warming. This is because observational systems originally designed for monitoring weather have lacked sufficient stability to detect cloud changes reliably over decades unless they have been corrected to remove artefacts. Here we show that several independent, empirically corrected satellite records exhibit large-scale patterns of cloud change between the 1980s and the 2000s that are similar to those produced by model simulations of climate with recent historical external radiative forcing. Observed and simulated cloud change patterns are consistent with poleward retreat of mid-latitude storm tracks, expansion of subtropical dry zones, and increasing height of the highest cloud tops at all latitudes. The primary drivers of these cloud changes appear to be increasing greenhouse gas concentrations and a recovery from volcanic radiative cooling. These results indicate that the cloud changes most consistently predicted by global climate models are currently occurring in nature."


See also:
https://www.washingtonpost.com/news/energy-environment/wp/2016/07/11/the-worlds-clouds-are-in-different-places-than-they-were-30-years-ago/

Extract: "In a new study published in Nature on Monday, scientists say they have for the first time thoroughly documented one of the most profound planetary changes yet to be caused by a warming climate: The distribution of clouds all across the Earth has shifted, they say.
And moreover, it has shifted in such a way — by expanding subtropical dry zones, located between around 20 and 30 degrees latitude in both hemispheres, and by raising cloud tops — as to make global warming  worse.

…

Moving cloud tracks toward the poles enhances warming because at higher latitudes, less solar radiation strikes the Earth — so white clouds are reflecting less of it away from the planet than they would if they were closer to the tropics and the Equator, Norris said. Meanwhile, he continued, higher cloud tops in effect thicken the total column of cloud, and that means more trapping of infrared or heat radiation that would otherwise exit to space.
“We now have a thicker blanket, which is also a warming effect,” Norris said.
Fortunately, these are not new or previously unknown positive feedbacks — they are already contained within the calculations used to derive the climate’s “sensitivity” to greenhouse gases and thus to project how bad warming could get. So this is more a reaffirmation of the existing theory (which was bad enough already) than a discovery of new perils.
However, there are other debates happening right now about other possible cloud changes that would tend to worsen warming beyond current expectations, if they are indeed happening."

Also see:
http://www.npr.org/sections/thetwo-way/2016/07/11/485314321/climate-change-may-already-be-shifting-clouds-toward-the-poles

Extract: "So will other climate researchers buy this new history of clouds? Kevin Trenberth at the National Center for Atmospheric Research in Colorado isn't so sure.
"This is a very good attempt to try and get a handle on this, but I don't think it's the final answer," says Trenberth, who notes that the time frame studied was pretty short and included a period often described as the global warming hiatus, from 1999 to 2013.
Climate researchers still have a lot of work to do when it comes to understanding clouds, says Trenberth, who believes the state of the science is still like that old Joni Mitchell song Both Sides Now, in which she sings, "I really don't know clouds at all.""

See also:
http://www.bloomberg.com/news/articles/2016-07-11/global-cloud-coverage-shifting-in-ominous-sign-of-climate-change

Extract: "“This is an exciting and comprehensive study,” said Kate Marvel, a scientist at NASA’s Goddard Institute for Space Studies. “But other studies have found that these things are happening, and this work provides more evidence of these effects.”
Next up for the study's authors is to untangle further how natural events, such as volcanoes, and greenhouse-led warming contribute to the cloud changes. Ultimately, greater understanding of how clouds behave will help strengthen projections of the rate and trajectory of global warming."

Edit: "See also:

https://robertscribbler.com/2016/07/15/clouds-of-denial-clear-as-rising-storm-tops-middle-latitude-drying-found-to-speed-global-warming/

[jai mitchell]

The linked reference discusses paleodata to indicate that climate sensitivity increased from 3.3 - 5.6 (mean of 4.45k) at the beginning of the PETM up to 3.7 - 6.5 K (mean of 5.1K) near the peak of the PETM; and that if we burn only the easily accessible carbon reserves then GMST could increase by about 10C.  I note these climate sensitivity values are much higher than those inherent in the CMIP5 projections:

Gary Shaffer, Matthew Huber, Roberto Rondanelli & Jens Olaf Pepke Pedersen (23 June 2016), "Deep-time evidence for climate sensitivity increase with warming", Geophysical Research Letters, DOI: 10.1002/2016GL069243

http://onlinelibrary.wiley.com/doi/10.1002/2016GL069243/full

Abstract: "Future global warming from anthropogenic greenhouse gas emissions will depend on climate feedbacks, the effect of which is expressed by climate sensitivity, the warming for a doubling of atmospheric CO2 content. It is not clear how feedbacks, sensitivity and temperature will evolve in our warming world but past warming events may provide insight. Here we employ paleo-reconstructions and new climate-carbon model simulations in a novel framework to explore a wide scenario range for the Paleocene-Eocene Thermal Maximum (PETM) carbon release and global warming event 55.8 million years ago, a possible future warming analogue. We obtain constrained estimates of CO2 and climate sensitivity before and during the PETM and of the PETM carbon input amount and nature. Sensitivity increased from 3.3 - 5.6 to 3.7 - 6.5 K (Kelvin) into the PETM. When taken together with Last Glacial Maximum and modern estimates this result indicates climate sensitivity increase with global warming."

This also reinforces the higher climate sensitivity determined from more recent paleoclimate analysis.  The last 900,000 years are dominated by ice ages with very brief interstadials.  This study shows that the calculated climate sensitivity during these brief warm periods goes off the charts.  This contributed to the 'fat tail' aspect of climate sensitivity with the Paleoclimate data (up to the point of the above referenced deeper time study) was overwhelmingly represented by ice age data (and subsequently low estimates).  (see figure 2. of the study below)

https://www.ethz.ch/content/dam/ethz/special-interest/usys/iac/iac-dam/documents/group/climphys/knutti/publications/rohling12nat.pdf


please note that in this study, they threw out the high values associated with the warm interstadials (see dotted line range on Figure 2. 

[Sigmetnow]

How a single word sparked a four-year saga of climate fact-checking and blog backlash

In May 2012, my colleagues and I had a paper accepted for publication in the Journal of Climate, showing that temperatures recorded in Australasia since 1950 were warmer than at any time in the past 1,000 years.

Following the early online release of the paper, as the manuscript was being prepared for the journal’s print edition, one of our team spotted a typo in the methods section of the manuscript.

While the paper said the study had used “detrended” data – temperature data from which the longer-term trends had been removed – the study had in fact used raw data. When we checked the computer code, the DETREND command said “FALSE” when it should have said “TRUE”.
...

It turned out that someone else had spotted the typo too. Two days after we identified the issue, a commenter on the Climate Audit blog also pointed it out.

The website’s author, Stephen McIntyre, proceeded to claim (incorrectly) that there were “fundamental issues” with the study. It was the start of a concerted smear campaign aimed at discrediting our science.

As well as being discussed by bloggers (sometimes with a deeply offensive and sexist tone), the “flaw” was seized upon by sections of the mainstream media.

Meanwhile, our team received a flurry of hate mail and an onslaught of time-consuming Freedom of Information requests for access to our raw data and years of our emails, in search of ammunition to undermine and discredit our team and results. This is part of a range of tactics used in Australia and overseas in an attempt to intimidate scientists and derail our efforts to do our job.

Bloggers began to accuse us of conspiring to reverse-engineer our results to dramatise the warming in our region. Former geologist and prominent climate change sceptic Bob Carter published an opinion piece in The Australian claiming that the peer-review process is faulty and climate science cannot be trusted....

https://theconversation.com/how-a-single-word-sparked-a-four-year-saga-of-climate-fact-checking-and-blog-backlash-62174

[AbruptSLR]

With continuing global warming the linked research indicates that high latitude forests will likely act as a slightly net negative feedback at the current time:

Edit: Obviously, if/when the high-latitude forest begin to die-off the slight net negative feedback, will likely change into an increasingly positive feedback.

Noah D. Charney, Flurin Babst, Benjamin Poulter, Sydne Record, Valerie M. Trouet, David Frank, Brian J. Enquist & Margaret E. K. Evans (19 July 2016), "Observed forest sensitivity to climate implies large changes in 21st century North American forest growth", Ecology Letters, DOI: 10.1111/ele.12650


http://onlinelibrary.wiley.com/doi/10.1111/ele.12650/abstract

Abstract: "Predicting long-term trends in forest growth requires accurate characterisation of how the relationship between forest productivity and climatic stress varies across climatic regimes. Using a network of over two million tree-ring observations spanning North America and a space-for-time substitution methodology, we forecast climate impacts on future forest growth. We explored differing scenarios of increased water-use efficiency (WUE) due to CO2-fertilisation, which we simulated as increased effective precipitation. In our forecasts: (1) climate change negatively impacted forest growth rates in the interior west and positively impacted forest growth along the western, southeastern and northeastern coasts; (2) shifting climate sensitivities offset positive effects of warming on high-latitude forests, leaving no evidence for continued ‘boreal greening’; and (3) it took a 72% WUE enhancement to compensate for continentally averaged growth declines under RCP 8.5. Our results highlight the importance of locally adapted forest management strategies to handle regional differences in growth responses to climate change."

See also:

http://www.bloomberg.com/news/articles/2016-07-20/trees-can-limit-climate-change-unless-it-kills-them-first

Extract: "… global warming is likelier to limit forests' capacity for absorbing emissions in many parts of the continent, a study released today in the journal Ecology Letters finds. After combining climate projections with the tree records, researchers found no evidence for the boreal greening hypothesis. In fact, they found a risk of a negative feedback loop, as trees in their model reacted poorly to warmer temperatures due to drought and other disturbances. "

[jai mitchell]

warming signal underestimated by 20%

Hi Everyone,

I know off topic - but please point me to the right direction to post this.

https://www.sciencedaily.com/releases/2016/07/160721164201.htm

It's an interesting paper that I've seen the bones of here so many times before but basically the historic record has been skewed by 20% on the downside. It really says the models are spot on! Well to date that is - what feedbacks and unknowns we have to look forward to are why we keep coming here

Have fun boys and girls!

[AbruptSLR]

Scribbler has posted another fine article about the numerous indications that the Earth is likely rather sensitive to radiative forcing:

https://robertscribbler.com/2016/07/22/from-the-arctic-to-africa-to-the-amazon-more-concerning-signs-of-earth-carbon-store-instability/


Extract: "Overall, there’s a decent amount of support for the notion that the Earth System is pretty sensitive to warming, that it tends to respond to even a relatively small amount of initial incoming heat in ways that produce a good deal of extra carbon in the atmosphere. After all, only a small change in the way sunlight hits the Earth is enough to end an ice age and pump an additional 100 parts per million of CO2 out of the Earth’s carbon stores as a result. The added heat forcing provided by the current human fossil-fuel emission is far, far greater than the one that ended the last ice age.

It is in this understanding and context that we should consider what appears to be an increasing number of Earth System responses to a human-forced warming that has currently exceeded 1 degree Celsius above 1880s averages. It’s easy to envision that these responses would grow in number and intensity as the Earth continues to warm toward 2 C above 19th-century averages."

[AbruptSLR]

Hopefully, AR6 will upgrade their OHC model projections to match the current model findings (see the linked open access reference), as some of the values reported in AR5 erred on the side of least drama:

Cheng, L., Trenberth, K. E., Palmer, M. D., Zhu, J., and Abraham, J. P.: Observed and simulated full-depth ocean heat-content changes for 1970–2005, Ocean Sci., 12, 925-935, doi:10.5194/os-12-925-2016, 2016.

http://www.ocean-sci.net/12/925/2016/

Abstract: "Greenhouse-gas emissions have created a planetary energy imbalance that is primarily manifested by increasing ocean heat content (OHC). Updated observational estimates of full-depth OHC change since 1970 are presented that account for recent advancements in reducing observation errors and biases. The full-depth OHC has increased by 0.74 [0.68, 0.80]  ×  1022 J yr−1 (0.46 Wm−2) and 1.22 [1.16–1.29]  ×  1022 J yr−1 (0.75 Wm−2) for 1970–2005 and 1992–2005, respectively, with a 5 to 95 % confidence interval of the median. The CMIP5 models show large spread in OHC changes, suggesting that some models are not state-of-the-art and require further improvements. However, the ensemble median has excellent agreement with our observational estimate: 0.68 [0.54–0.82]  ×  1022 J yr−1 (0.42 Wm−2) from 1970 to 2005 and 1.25 [1.10–1.41]  ×  1022 J yr−1 (0.77 Wm−2) from 1992 to 2005. These results increase confidence in both the observational and model estimates to quantify and study changes in Earth's energy imbalance over the historical period. We suggest that OHC be a fundamental metric for climate model validation and evaluation, especially for forced changes (decadal timescales)."

Extract: "This study presents new estimates of observed OHC change since 1970 based on improved mapping methods and XBT bias corrections. Our results suggest that previous IPCC AR5 observational estimates of a 0–700m OHC change of ~0.26Wm-2 may be too low, typically by about ~25% compared to our findings here (~0.35Wm-2), supporting the conclusions of Durack et al. (2014) based on somewhat different constraints."

See also:
https://www.theguardian.com/environment/climate-consensus-97-per-cent/2016/jul/27/climate-models-are-accurately-predicting-ocean-and-global-warming

[AbruptSLR]

The linked reference helps to qualify the positive feedback associate with terrestrial carbon uptake with continued warming.  This research indicates that this feedback mechanism is more positive than some climate models previously assumed:

M. Rubino, D. M. Etheridge, C. M. Trudinger, C. E. Allison, P. J. Rayner, I. Enting, R. Mulvaney, L. P. Steele, R. L. Langenfelds, W. T. Sturges, M. A. J. Curran & A. M. Smith (2016), "Low atmospheric CO2 levels during the Little Ice Age due to cooling-induced terrestrial uptake", Nature Geoscience, DOI: 10.1038/ngeo2769


http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2769.html

Abstract: "Low atmospheric carbon dioxide (CO2) concentration during the Little Ice Age has been used to derive the global carbon cycle sensitivity to temperature. Recent evidence confirms earlier indications that the low CO2 was caused by increased terrestrial carbon storage. It remains unknown whether the terrestrial biosphere responded to temperature variations, or there was vegetation re-growth on abandoned farmland. Here we present a global numerical simulation of atmospheric carbonyl sulfide concentrations in the pre-industrial period. Carbonyl sulfide concentration is linked to changes in gross primary production and shows a positive anomaly during the Little Ice Age. We show that a decrease in gross primary production and a larger decrease in ecosystem respiration is the most likely explanation for the decrease in atmospheric CO2 and increase in atmospheric carbonyl sulfide concentrations. Therefore, temperature change, not vegetation re-growth, was the main cause of the increased terrestrial carbon storage. We address the inconsistency between ice-core CO2 records from different sites measuring CO2 and δ13CO2 in ice from Dronning Maud Land (Antarctica). Our interpretation allows us to derive the temperature sensitivity of pre-industrial CO2 fluxes for the terrestrial biosphere (γL = −10 to −90 Pg C K−1), implying a positive climate feedback and providing a benchmark to reduce model uncertainties."

See also:
http://phys.org/news/2016-07-polar-ice-reveals-secrets-carbon-climate.html

Extract: "The paper reveals that the Earth's land biosphere takes up less carbon in a warmer climate.

"Until now it has only been assumed that as the Earth's surface warms the ability of land-based plants to store carbon is reduced. In this study we were able to quantify the relationship," said paper co-author and CSIRO senior scientist Dr David Etheridge.
"Reduced storage of carbon by the biosphere leads to higher atmospheric CO2. This increases the Earth's surface temperature, which leads to even less carbon stored by the biosphere, causing a positive feedback.""

[AbruptSLR]

The linked article points to research that indicates that long after deforesting has stopped trees that were previously cut down continue to gradually decay thus releasing carbon emissions.  Such findings are not included in AR5 projections:

http://www.bloomberg.com/news/articles/2016-07-28/zombie-carbon-emissions-haunt-the-planet

Extract: "After trees are cut down, they gradually decay, releasing carbon, degrading the habitat, and threatening species long after the cutting stops. These lagging emissions have an important impact on the battle against global warming, a study released today in the journal Current Biology finds. Even with the 30 percent reduction in Amazon deforestation, there was only a 10 percent decrease in carbon emissions, the researchers found."

[AbruptSLR]

The linked reference indicates that corrected recent observations indicate that the most likely value of ECS may be as high as 4.6C (see attached plot of the time dependent curve):

Kyle C. Armour  (27 June 2016), "Projection and prediction: Climate sensitivity on the rise", Nature Climate Change, doi:10.1038/nclimate3079

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3079.html

Summary: "Recent observations of Earth's energy budget indicate low climate sensitivity. Research now shows that these estimates should be revised upward, resolving an apparent mismatch with climate models and implying a warmer future."

Edit: A pdf of Armour 2016 can be found at the following link:

http://www.nature.com/articles/nclimate3079.epdf?author_access_token=LNQKgwEONy5YVJSvlubB29RgN0jAjWel9jnR3ZoTv0PPTNF_sOIeFx9myJ_U10XLsj8_p1lqjx0RRDTJbTTc78eupvudlmNtEiNXnWHNhr4crt8ZuOmLA66TNpMu_PUg



See also:
http://variable-variability.blogspot.com/2016/07/climate-sensitivity-energy-balance-models.html

Caption: "Climate sensitivity estimated from observations1 (black), and its revision following Richardson et al. (blue) then following Marvel et al. (green), and in red the revision for the time dependence (Armour). The grey histogram shows climate model values."

Also see:
http://blog.hotwhopper.com/2016/07/explaining-different-results-for.html

[jai mitchell]

This paper shows that all of the climate models hold a striking short-period shift in arctic WINTER sea ice extent from normative to zero in a few years.  This bifurcation impact is a combination of 2 different feedback mechanisms, cloud interactions and albedo interactions.  It provides significant argument that supports a polar cell/Ferrel cell intrusion driven increase in winter temperatures and winter sea ice collapse.  It is possible that we are starting to see the early effects of this which would accelerate the model results by almost 100 years.

http://journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-15-0466.1

On the Potential for Abrupt Arctic Winter Sea Ice Loss
abstract:  The authors examine the transition from a seasonally ice-covered Arctic to an Arctic Ocean that is sea ice free all year round under increasing atmospheric CO2 levels. It is shown that in comprehensive climate models, such loss of Arctic winter sea ice area is faster than the preceding loss of summer sea ice area for the same rate of warming. In two of the models, several million square kilometers of winter sea ice are lost within only one decade. It is shown that neither surface albedo nor cloud feedbacks can explain the rapid winter ice loss in the climate model MPI-ESM by suppressing both feedbacks in the model. The authors argue that the
large sensitivity of winter sea ice area in the models is caused by the asymmetry between melting and freezing: an ice-free summer requires the complete melt of even the thickest sea ice, which is why the perennial ice coverage decreases only gradually as more and more of the thinner ice melts away. In winter, however, sea ice areal coverage remains high as long as sea ice still forms, and then drops to zero wherever the ocean warms sufficiently to no longer form ice during winter. The loss of basinwide Arctic winter sea ice area, however, is still gradual in most models since the threshold mechanism proposed here is reversible and not associated with the existence of multiple steady states. As this occurs in every model analyzed here and is  independent of any specific parameterization, it is likely to be relevant in the real world.

[AbruptSLR]

While I have linked to Rolf Schuttenhelm's article on global warming previously; they are educational so I link again to the following two from July 2, and 5, 2016, respectively:

http://www.bitsofscience.org/real-global-temperature-trend-paleoclimate-warming-in-pipeline-7151/

Extract: "Either the entire world is set to experience dramatic additional warming once we stabilise at the current (400+ ppm) CO2 concentration – or we are still dramatically underestimating the local climate sensitivity of the Arctic – a region that might in that case not warm 2 or 3 times as fast as the global average, but rather about 6 to 8 times. (Perhaps most likely it’s something in between.)

...

Now new research, led by Gary Shaffer of the University of Copenhagen, published in Geophysical Research Letters, shows evidence that the CO2 sensitivity of Earth’s climate system may in fact increase with warming.

During the PETM, when temperatures rose by 5-8 degrees in about 10,000 years Earth’s CO2 climate sensitivity rose from 3.3–5.6 to 3.7–6.5 – values that are much higher than today’s most cited numbers (IPCC’s range = 1.5/2-4.5 degrees – most experts say ‘close to or just over 3 degrees’)

This new understanding is important because it implies we may need to look for climate comparisons that are close to today’s average global temperatures – to find the best paleoclimate assessments of climate sensitivity."

See also:

http://www.bitsofscience.org/real-global-temperature-trend-paleoclimate-experts-degrees-pipeline-climate-inertia-7160/

[AbruptSLR]

This paper shows that all of the climate models hold a striking short-period shift in arctic WINTER sea ice extent from normative to zero in a few years.  This bifurcation impact is a combination of 2 different feedback mechanisms, cloud interactions and albedo interactions.  It provides significant argument that supports a polar cell/Ferrel cell intrusion driven increase in winter temperatures and winter sea ice collapse.  It is possible that we are starting to see the early effects of this which would accelerate the model results by almost 100 years.

I have to admit that the probability of increasing Arctic climate sensitivity is a serious concern in the coming decades.

[AbruptSLR]

This paper shows that all of the climate models hold a striking short-period shift in arctic WINTER sea ice extent from normative to zero in a few years.  This bifurcation impact is a combination of 2 different feedback mechanisms, cloud interactions and albedo interactions.  It provides significant argument that supports a polar cell/Ferrel cell intrusion driven increase in winter temperatures and winter sea ice collapse.  It is possible that we are starting to see the early effects of this which would accelerate the model results by almost 100 years.

I have to admit that the probability of increasing Arctic climate sensitivity is a serious concern in the coming decades.

To state the obvious, per the first two attached plots, respectively, & the following linked data; both the AMO & the PDO are positive at the moment as confirmed by the third attached plot of the nullschooll SSTA for July 30 2016.  A few years of continued synchronization of abnormally warm SSTA's for both the North Atlantic & the North Pacific, could promote an accelerated degradation of Arctic sea ice extent/area in the coming years:


http://www.esrl.noaa.gov/psd/data/correlation/amon.us.data

 2015    0.006    0.010   -0.115   -0.058    0.058    0.043    0.146    0.192    0.314    0.338    0.200    0.243
 2016    0.245    0.169    0.202    0.191    0.358    0.423   


https://climatedataguide.ucar.edu/climate-data/atlantic-multi-decadal-oscillation-amo

Extract: "The Atlantic Multi-decadal Oscillation (AMO) has been identified as a coherent mode of natural variability occurring in the North Atlantic Ocean with an estimated period of 60-80 years. It is based upon the average anomalies of sea surface temperatures (SST) in the North Atlantic basin, typically over 0-80N."


http://research.jisao.washington.edu/pdo/PDO.latest

2015 2.45 2.30 2.00 1.44 1.20 1.54 1.84 1.56 1.94 1.47 0.86 1.01
2016 1.53 1.75 2.40 2.62 2.35 2.03

http://www.atmos.washington.edu/~mantua/REPORTS/PDO/PDO_cs.htm

Extract: "Two main characteristics distinguish the PDO from ENSO. First, typical PDO "events" have shown remarkable persistence relative to that attributed to ENSO events - in this century, major PDO eras have persisted for 20 to 30 years (Mantua et al. 1997, Minobe 1997). Second, the climatic fingerprints of the PDO are most visible in the North Pacific/North American sector, while secondary signatures exist in the tropics - the opposite is true for ENSO. Several independent studies find evidence for just two full PDO cycles in the past century (e.g. Mantua et al. 1997, Minobe 1997): cool PDO regimes prevailed from 1890-1924 and again from 1947-1976, while warm PDO regimes dominated from 1925-1946 and from 1977 through (at least) the mid-1990's. Recent changes in Pacific climate suggest a possible reversal to cool PDO conditions in 1998, …"

[AbruptSLR]

As the linked PNAS reference is behind a paywall, I am not sure what it concludes

Dennis Hartmann (August 1 2016), "Tropical anvil clouds and climate sensitivity", PNAS, doi: 10.1073/pnas.1610455113

http://www.pnas.org/content/early/2016/07/29/1610455113.extract

Extract: "The surface temperature of Earth is being increased by human activities, principally by the release of greenhouse gases. Future warming will depend upon the rate at which greenhouse gases are released and the sensitivity of Earth’s surface temperature to those increased greenhouse gases. An often used metric of the sensitivity of Earth’s climate is the equilibrium climate sensitivity, the amount of global average surface warming that is the steady, long-term response to a doubling of carbon dioxide. The equilibrium climate sensitivity remains uncertain by about a factor of two, despite decades of study using evidence from basic theory, instrumental observations, paleoclimatic data, and global climate models. Global climate models indicate that a large contributor to uncertainty in climate sensitivity is the strength of cloud feedbacks. Cloud feedback is a response of cloud structure or amount to warming, which then alters the energy balance of Earth, which causes an additional change of surface temperature. An advance was made in the most recent report of the Intergovernmental Panel on Climate Change, which concluded that cloud feedback is likely positive, meaning that the response of clouds to climate change acts to increase the magnitude of the surface temperature change. This consensus is based in part on the development of basic physical understanding of why high clouds get higher and low clouds decrease their area coverage in a warmed climate. In PNAS, Bony et al. propose a basic thermodynamic mechanism that may cause the temperature profile to become more stable in the upper troposphere when the Earth warms. They expect this stabilization to cause anvil cloud area to decrease in a warmed climate, although they conclude that the effect of this anvil area reduction on cloud feedback is uncertain.

..."

[AbruptSLR]

The linked references indicate how poorly AR5 addresses the potential impact of contrails.  Such conventional thinking assumes that in 2005 the average radiative forcing from contrails was  0.012 W/m2 (watts per square meter); however, the first linked reference finds that in 2006 it was actually 0.056 W/m2 .  While the second linked reference uses the old (incorrect) estimate to calculate that by 2050 this forcing will increase seven times from 0.012 to 0.087 W/m2 for a four-fold increase in airline miles flown by 2050.  If we were to apply the factor of seven times to the correct value of 0.056 we would get 0.392 W/m2 of associated positive radiative forcing by 2050.

The add to this confusion the second article indicates that aviation sulfate aerosols emitted can act as negative forcing; however, as airlines are current making great strides in reducing these emissions, it is not clear to me what the net radiative forcing from contrails and aviation aerosol emissions will be in the coming decades:

Lisa Bock &Ulrike Burkhardt (2 August 2016), "Reassessing properties and radiative forcing of contrail cirrus using a climate model", Journal of Geophysical Research Atmospheres, DOI: 10.1002/2016JD025112


http://onlinelibrary.wiley.com/doi/10.1002/2016JD025112/abstract

Abstract: "Contrail cirrus is the largest known component contributing to the radiative forcing associated with aviation. Despite major advances simulating contrail cirrus, their microphysical and optical properties and the associated radiative forcing remain largely uncertain. We use a contrail cirrus parameterization in a global climate model which was extended to include a microphysical two-moment scheme. This allows a more realistic representation of microphysical processes, such as deposition and sedimentation, and therefore of the microphysical and optical properties of contrail cirrus.

The simulated contrail microphysical and optical properties agree well with in situ and satellite observations. As compared to estimates using an older version of the contrail cirrus scheme, the optical depth of contrail cirrus is significantly higher, particularly in regions with high air traffic density, due to high ice crystal number concentrations on the main flight routes. Nevertheless, the estimated radiative forcing for the year 2002 supports our earlier results. The global radiative forcing of contrail cirrus for the year 2006 is estimated to be 56mW/m2. A large uncertainty of the radiative forcing estimate appears to be connected with the, on average, very small ice crystal radii simulated in the main air traffic areas, which make the application of a radiative transfer parameterization based on geometric optics questionable."


Chen, C.-C. and Gettelman, A.: Simulated 2050 aviation radiative forcing from contrails and aerosols, Atmos. Chem. Phys., 16, 7317-7333, doi:10.5194/acp-16-7317-2016, 2016.

http://www.atmos-chem-phys.net/16/7317/2016/
http://www.atmos-chem-phys.net/16/7317/2016/acp-16-7317-2016.pdf

Abstract: "The radiative forcing from aviation-induced cloudiness is investigated by using the Community Atmosphere Model Version 5 (CAM5) in the present (2006) and the future (through 2050). Global flight distance is projected to increase by a factor of 4 between 2006 and 2050. However, simulated contrail cirrus radiative forcing in 2050 can reach 87 mW m−2, an increase by a factor of 7 from 2006, and thus does not scale linearly with fuel emission mass. This is due to non-uniform regional increase in air traffic and different sensitivities for contrail radiative forcing in different regions.

CAM5 simulations indicate that negative radiative forcing induced by the indirect effect of aviation sulfate aerosols on liquid clouds in 2050 can be as large as −160 mW m−2, an increase by a factor of 4 from 2006. As a result, the net 2050 radiative forcing of contrail cirrus and aviation aerosols may have a cooling effect on the planet. Aviation sulfate aerosols emitted at cruise altitude can be transported down to the lower troposphere, increasing the aerosol concentration, thus increasing the cloud drop number concentration and persistence of low-level clouds. Aviation black carbon aerosols produce a negligible net forcing globally in 2006 and 2050 in this model study.

Uncertainties in the methodology and the modeling are significant and discussed in detail. Nevertheless, the projected percentage increase in contrail radiative forcing is important for future aviation impacts. In addition, the role of aviation aerosols in the cloud nucleation processes can greatly influence on the simulated radiative forcing from aircraft-induced cloudiness and even change its sign. Future research to confirm these results is necessary."


See also:
https://en.wikipedia.org/wiki/Contrail

Extract: "Contrails, by affecting the Earth's radiation balance, act as a radiative forcing. Studies have found that contrails trap outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) at a greater rate than they reflect incoming solar radiation (negative radiative forcing). NASA conducted a great deal of detailed research on atmospheric and climatological effects of contrails, including effects on ozone, ice crystal formation, and particle composition, during the Atmospheric Effects of Aviation Project (AEAP). Global radiative forcing has been calculated from the reanalysis data, climatological models and radiative transfer codes. It is estimated to amount to 0.012 W/m2 (watts per square meter) for 2005, with an uncertainty range of 0.005 to 0.026 W/m2, and with a low level of scientific understanding. Therefore, the overall net effect of contrails is positive, i.e. a warming effect. However, the effect varies daily and annually, and overall the magnitude of the forcing is not well known: globally (for 1992 air traffic conditions), values range from 3.5 mW/m2 to 17 mW/m2. Other studies have determined that night flights are mostly responsible for the warming effect: while accounting for only 25% of daily air traffic, they contribute 60 to 80% of contrail radiative forcing. Similarly, winter flights account for only 22% of annual air traffic, but contribute half of the annual mean radiative forcing."

[AbruptSLR]

Denialist scientists are finding fewer and fewer arguments that they can use to create uncertainty about Anthropogenic Global Warming:

S. Lovejoy, L. del Rio Amador, R. Hébert & I. de Lima (29 July 2016), "Giant natural fluctuation models and anthropogenic warming", Geophysical Research Letters, DOI: 10.1002/2016GL070428


http://onlinelibrary.wiley.com/doi/10.1002/2016GL070428/abstract

Abstract: "Explanations for the industrial epoch warming are polarized around the hypotheses of anthropogenic warming (AW) and Giant Natural Fluctuations (GNF's). While climate sceptics have systematically attacked AW, up until now they have only invoked GNF's. This has now changed with the publication by D. Keenan of a sample of 1000 series from stochastic processes purporting to emulate the global annual temperature since 1880. While Keenan's objective was to criticize the IPCC's trend uncertainty analysis (their assumption that residuals are only weakly correlated), for the first time it is possible to compare a stochastic GNF model with real data. Using Haar fluctuations, probability distributions and other techniques of time series analysis, we show that his model has unrealistically strong low frequency variability so that even mild extrapolations imply ice ages every ≈ 1000 years. The GNF model can easily be scientifically rejected."

[AbruptSLR]

In the linked article on various consequences of permafrost thawing, Scribbler tries very hard to humanize the message that: "… we should be very trepedacious about the now-thawing permafrost — embedded as it is with zombie anthrax — as well as the various and multiple other surprises human-forced climate change continues to serve up".  So while I complement Scribbler on his excellent article; let me briefly comment on a few of the "surprises" that the thawing permafrost will likely "serve up", including:

(a) A significant fraction of the carbon released from the permafrost this century will be in the form of methane, which over a 20-year period has a GWP 105 times that of carbon dioxide;

(b) Microbes currently hibernating in the permafrost since the last interglacial warming period are already genetically optimized to feed on the unthawed organics; which will likely accelerate carbon emission rates beyond that cited by Scribbler within a few decades; and

(c) Synergy with other Arctic positive feedback mechanisms (like and albedo flip) will likely increase Arctic Amplification beyond that assumed by Scribbler:

https://robertscribbler.com/2016/08/03/permafrost-thaw-generates-anthrax-outbreak-wrecks-roads-generates-carbon-spewing-peat-primed-to-burn-in-the-heat-of-human-warming/

Extract: "In total, it’s estimated that around 160 billion tons of this carbon could hit the atmosphere by 2100. That would be like adding nearly two billion tons to the carbon emission from fossil-fuel burning every year. All told, such an emission would be enough to increase atmospheric CO2 concentrations by around 35-75 ppm (depending on the state of carbon sinks), if it all emitted as CO2.  The extra carbon in the air would then trap more heat, generating a self-reinforcing cycle that we call an amplifying feedback.

The frozen land therefore releases disease as it thaws, it crumbles infrastructure, and as it dries and melts and wettens and burns it releases still more heat-trapping gasses. All reasons why we should be very trepedacious about the now-thawing permafrost — embedded as it is with zombie anthrax — as well as the various and multiple other surprises human-forced climate change continues to serve up."

[AbruptSLR]

The linked reference concludes that based on satellite observations: "… the low-cloud optical depth feedback at middle and high latitudes is likely too negative in climate models."  This implies that the CMIP5 models are likely underestimating ECS:

C. R. Terai, S. A. Klein & M. D. Zelinka (4 August 2016), "Constraining the low-cloud optical depth feedback at middle and high latitudes using satellite observations", Journal of Geophysical Research Atmospheres, DOI: 10.1002/2016JD025233


http://onlinelibrary.wiley.com/doi/10.1002/2016JD025233/abstract

Abstract: "The increase in cloud optical depth with warming at middle and high latitudes is a robust cloud feedback response found across all climate models. This study builds on results that suggest the optical depth response to temperature is timescale invariant for low-level clouds. The timescale invariance allows one to use satellite observations to constrain the models' optical depth feedbacks. Three passive-sensor satellite retrievals are compared against simulations from eight models from the Atmosphere Model Intercomparison Project (AMIP) of the 5th Coupled Model Intercomparison Project (CMIP5).
This study confirms that the low-cloud optical depth response is timescale invariant in the AMIP simulations, generally at latitudes higher than 40°. Compared to satellite estimates, most models overestimate the increase in optical depth with warming at the monthly and interannual timescales. Many models also do not capture the increase in optical depth with estimated inversion strength that is found in all three satellite observations and in previous studies. The discrepancy between models and satellites exists in both hemispheres and in most months of the year. A simple replacement of the models' optical depth sensitivities with the satellites' sensitivities reduces the negative shortwave cloud feedback by at least 50 % in the 40° – 70°S latitude band and by at least 65 % in the 40° – 70°N latitude band. Based on this analysis of satellite observations, we conclude that the low-cloud optical depth feedback at middle and high latitudes is likely too negative in climate models."

[AbruptSLR]

The linked reference uses satellite data to confirm that globally ice clouds result in a significant net positive feedback for climate change:

Yulan Hong, Guosheng Liu and J.-L. F. Li (3 August 2016), "Assessing the Radiative Effects of Global Ice Clouds Based on CloudSat and CALIPSO Measurements", Journal of Climate, DOI: http://dx.doi.org/10.1175/JCLI-D-15-0799.1


http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0799.1

Abstract: "Although it is well-established that cirrus warms the Earth, the radiative effect of the entire spectrum of ice clouds is not well understood. In this study, the role of all ice clouds in the Earth’s radiation budget is investigated by performing radiative transfer modeling using ice cloud properties retrieved from CloudSat and CALIPSO measurements as inputs. Results show that, for the 2008 period, the warming effect (~21.8 ± 5.4 W m-2) induced by ice clouds due to trapping longwave radiation exceeds their cooling effect (~-16.7 ± 1.7 W m-2) caused by shortwave reflection, resulting in a net warming effect (~5.1 ± 3.8 W m-2) globally on the earth-atmosphere system. The net warming is over 15 W m-2 in the tropical deep convective regions, whereas cooling occurs in the midlatitudes, which is less than 10 W m-2 in magnitude. Seasonal variations of ice cloud radiative effects are evident in the midlatitudes where the net effect changes from warming during winter to cooling during summer, whereas warming occurs all year round in the tropics. Ice cloud optical depth (τ) is shown to be an important factor in determining the sign and magnitude of the net radiative effect. Ice clouds with τ < 4.6 display a warming effect with the largest contributions from those with τ ~ 1.0. In addition, ice clouds cause vertically differential heating and cooling of the atmosphere, particularly with strong heating in the upper troposphere over the tropics. At Earth’s surface, ice clouds produce a cooling effect no matter how small the τ value is."

[AbruptSLR]

The linked reference indicates that from 1700 (and/or from 1860) to 2005 the effective radiative forcing from biogeophysical effects (i.e. land use albedo changes) have been more negative than previously realized in climate change models.  This implies that current climate models have been underestimating the positive feedback from other feedback mechanisms (such as from clouds):

Andrews, T., Betts, R.A., Booth, B.B.B., Jones, C.D. & Jones, G.S. (2016), "Effective radiative forcing from historical land use change", Clim Dyn, pp 1–17, doi:10.1007/s00382-016-3280-7

http://link.springer.com/article/10.1007%2Fs00382-016-3280-7

Abstract: "The effective radiative forcing (ERF) from the biogeophysical effects of historical land use change is quantified using the atmospheric component of the Met Office Hadley Centre Earth System model HadGEM2-ES. The global ERF at 2005 relative to 1860 (1700) is −0.4 (−0.5) Wm−2, making it the fourth most important anthropogenic driver of climate change over the historical period (1860–2005) in this model and larger than most other published values. The land use ERF is found to be dominated by increases in the land surface albedo, particularly in North America and Eurasia, and occurs most strongly in the northern hemisphere winter and spring when the effect of unmasking underlying snow, as well as increasing the amount of snow, is at its largest. Increased bare soil fraction enhances the seasonal cycle of atmospheric dust and further enhances the ERF. Clouds are shown to substantially mask the radiative effect of changes in the underlying surface albedo. Coupled atmosphere–ocean simulations forced only with time-varying historical land use change shows substantial global cooling (dT = −0.35 K by 2005) and the climate resistance (ERF/dT = 1.2 Wm−2 K−1) is consistent with the response of the model to increases in CO2 alone. The regional variation in land surface temperature change, in both fixed-SST and coupled atmosphere–ocean simulations, is found to be well correlated with the spatial pattern of the forced change in surface albedo. The forcing-response concept is found to work well for historical land use forcing—at least in our model and when the forcing is quantified by ERF. Our results suggest that land-use changes over the past century may represent a more important driver of historical climate change then previously recognised and an underappreciated source of uncertainty in global forcings and temperature trends over the historical period."

[AbruptSLR]

The worldwide increasing use of air conditioning represents a positive feedback that is underestimated in IPCC estimates:

https://www.washingtonpost.com/news/energy-environment/wp/2016/05/31/the-world-is-about-to-install-700-million-air-conditioners-heres-what-that-means-for-the-climate/?utm_term=.433fa8d55a89

Extract: "As summer temperatures finally settle in, many in the United States take it for granted that they can dial down the thermostat: Americans use 5 percent of all of their electricity cooling homes and buildings. In many other countries, however — including countries in much hotter climates — air conditioning is still a relative rarity. But as these countries boom in wealth and population, and extend electricity to more people even as the climate warms, the projections are clear: They are going to install mind-boggling amounts of air conditioning, not just for comfort but as a health necessity."

See also:
http://eetd.lbl.gov/sites/all/files/lbnl-1003671_0.pdf

[AbruptSLR]

While there are already several posts, in the forum, about the risks of GHG emission from climate change induced burning of peatlands; the linked NY Times article reminds us all of the considerable risks associated with such emission that are not considered by AR5:

http://www.nytimes.com/2016/08/09/science/climate-change-carbon-bogs-peat.html?_r=0

Extract: "There are an estimated 1.6 million square miles of peatlands, or about 3 percent of the earth’s land surface, mostly in northern latitudes in Canada, Alaska, Europe and Russia.
…
Like forests, peatlands are threatened by climate change. Warming temperatures can dry out bogs, making them more susceptible to fires, and to deeper, more intense burning. A peat fire, which can smolder like a cigarette for months, can release a lot of carbon.
“It’s carbon that has accumulated over several thousands of years,” said Mike Waddington, a McMaster professor who has been researching peat in Alberta and elsewhere for more than two decades. “If it were to be released, the global CO2 concentration would be much higher.”"

[AbruptSLR]

The linked reference indicates that new research (from PlioMIP2) demonstrates that the climate sensitivity for the Pliocene was higher than previously believed (from PlioMIP1):

Kamae, Y., Yoshida, K., and Ueda, H.: Sensitivity of Pliocene climate simulations in MRI-CGCM2.3 to respective boundary conditions, Clim. Past, 12, 1619-1634, doi:10.5194/cp-12-1619-2016, 2016.

http://www.clim-past.net/12/1619/2016/

http://www.clim-past.net/12/1619/2016/cp-12-1619-2016.pdf

Abstract. Accumulations of global proxy data are essential steps for improving reliability of climate model simulations for the Pliocene warming climate. In the Pliocene Model Intercomparison Project phase 2 (PlioMIP2), a part project of the Paleoclimate Modelling Intercomparison Project phase 4, boundary forcing data have been updated from the PlioMIP phase 1 due to recent advances in understanding of oceanic, terrestrial and cryospheric aspects of the Pliocene palaeoenvironment. In this study, sensitivities of Pliocene climate simulations to the newly archived boundary conditions are evaluated by a set of simulations using an atmosphere–ocean coupled general circulation model, MRI-CGCM2.3. The simulated Pliocene climate is warmer than pre-industrial conditions for 2.4 °C in global mean, corresponding to 0.6 °C warmer than the PlioMIP1 simulation by the identical climate model. Revised orography, lakes, and shrunk ice sheets compared with the PlioMIP1 lead to local and remote influences including snow and sea ice albedo feedback, and poleward heat transport due to the atmosphere and ocean that result in additional warming over middle and high latitudes. The amplified higher-latitude warming is supported qualitatively by the proxy evidences, but is still underestimated quantitatively. Physical processes responsible for the global and regional climate changes should be further addressed in future studies under systematic intermodel and data–model comparison frameworks.

[AbruptSLR]

Scientists have known about Mt Pinatubo two and a half decades now, but as the linked reference indicates only now are they realizing that the 1991 Mt. Pinatubo eruption suppressed subsequent sea level rise.  However, this effect was not considered by Large Ensemble (LE) climate models (see attached plots) and thus we can expect the rate of SLR to accelerate (faster than recent observations and faster than AR5 projected) in the near-term as the Mt. Pinatubo effect dissipates:

Fasullo, J.T., Nerem, R.S. & Hamlington, B. (August 10, 2016), "Is the detection of accelerated sea level rise imminent?", Scientific Reports 6, No. 31245, doi: 10.1038/srep31245.

http://www.nature.com/articles/srep31245

See also:

http://www.wired.co.uk/article/climate-change-sea-level-rise

Extract: "Recent reports that suggest sea levels aren't rising as fast as expected – and may even be dropping – could be inaccurate, according to new research.

Experts from the National Center for Atmospheric Research (NCAR) have discovered that the 1991 eruption of Mount Pinatubo in the Philippines could have masked the true reading, and this could have dire consequences for the future.

Satellite observations, which began in 1993, show that the rate of sea level rise has held fairly steady at about 3 millimeters per year. However, these records began soon after the eruption, which temporarily cooled the planet, causing sea levels to drop.

The new study finds that the lower starting point effectively distorts the calculation of sea level rise acceleration for the last couple of decades. It also lends support to projections that show the rate of sea level rise escalating over time as the climate warms.

"When we used climate model runs designed to remove the effect of the Pinatubo eruption, we saw the rate of sea level rise accelerating in our simulations," said NCAR scientist John Fasullo, who led the study. "Now that the impacts of Pinatubo have faded, this acceleration should become evident in the satellite measurements in the coming decade, barring another major volcanic eruption.""

[AbruptSLR]

We need to fight lukewarmers (neoskeptics), both public and scientific, by not allowing them to focus on the best case scenarios, but rather we need to evaluate the full range of risks (and consequences) including the fat-tail of the pdf:

Paul C. Stern, John H. Perkins, Richard E. Sparks & Robert A. Knox (12 Aug 2016), "The challenge of climate-change neoskepticism", Science, Vol. 353, Issue 6300, pp. 653-654, DOI: 10.1126/science.aaf6675

http://science.sciencemag.org/content/353/6300/653

Summary: "Opponents of policies to limit anthropogenic climate change (ACC) have offered a changing set of arguments—denying or questioning ACC's existence, magnitude, and rate of progress, the risks it presents, the integrity of climate scientists, and the value of mitigation efforts. Similar arguments have characterized environmental risk debates concerning arsenical insecticides in the late 1800s, phosphates in detergents in the 1960s, and the pesticide DDT in the 1960s and '70s. Typically, defenders of business as usual first question the scientific evidence that risks exist; then, they question the magnitude of the risks and assert that reducing them has more costs than benefits. A parallel rhetorical shift away from outright skepticism led us to identify “neoskepticism” as a new incarnation of opposition to major efforts to limit ACC. This shift heightens the need for science to inform decision making under uncertainty and to improve communication and education."

See also:
Wendel, J. (2016), Climate scientists’ new hurdle: Overcoming climate change apathy, Eos, 97, doi:10.1029/2016EO057547. Published on 11 August 2016.

https://eos.org/articles/climate-scientists-new-hurdle-overcoming-climate-change-apathy

Extract: "Climate Scientists' New Hurdle: Overcoming Climate Change Apathy
It's not just about deniers anymore. Scientists now have to convince a new group: those who believe humans have altered the climate but don't think anything can or should change.
…
Neoskeptics aren’t just random venting bloggers; policy makers and even respected scientists are joining in. They may argue that climate scientists “overblow” the risks or insist that because scientists are still hammering out the details on climate change’s effects on the globe, immediate mitigation is too costly.
How can scientists and educators, many of whom have their hands full combating outright deniers of human-caused climate change, address neoskeptics? It’s all about communicating risk, argue Stern and his colleagues.
…
Unfortunately, in climate science, “there’s been a long history that says that scientific uncertainty is a reason for not taking action,” Stern said. Such delay of action feeds back to fuel neoskepticism.
…
“The basic error these ‘lukewarmers’ make is in always taking as gospel the lowest estimate of a plausible range. They are simply allowing their biases to eliminate real uncertainty—and this is merely confirmation bias, not ‘rational optimism,’” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies.
The consequences of neoskeptical thinking are to greatly downplay risk, Schmidt explained. “It would be like only insuring one room of your home because that was the minimum damage you project, ignoring completely that the maximum damage could be much worse.”"

[Sleepy]

ASLR, what a coincidence, I was just reading that article in EOS and went in here to moan a bit and found your post.

It refers to Bjørn Lomborg as a "respected scientist". Not only that, when I got to the comments, that was already pointed out by Mashey yesterday and they have not yet edited the article.

[AbruptSLR]

The linked reference indicates that current models underestimate the soil organic carbon (SOC) stock in fertile areas (calibrated against Swedish forest soils); which indicates that AR5 projections underestimate the risks of future CO₂ emissions from such SOC stock, with continued global warming:

Ťupek, B., Ortiz, C. A., Hashimoto, S., Stendahl, J., Dahlgren, J., Karltun, E., and Lehtonen, A.: Underestimation of boreal soil carbon stocks by mathematical soil carbon models linked to soil nutrient status, Biogeosciences, 13, 4439-4459, doi:10.5194/bg-13-4439-2016, 2016.

http://www.biogeosciences.net/13/4439/2016/

Abstract. Inaccurate estimate of the largest terrestrial carbon pool, soil organic carbon (SOC) stock, is the major source of uncertainty in simulating feedback of climate warming on ecosystem–atmosphere carbon dioxide exchange by process-based ecosystem and soil carbon models. Although the models need to simplify complex environmental processes of soil carbon sequestration, in a large mosaic of environments a missing key driver could lead to a modeling bias in predictions of SOC stock change.

We aimed to evaluate SOC stock estimates of process-based models (Yasso07, Q, and CENTURY soil sub-model v4) against a massive Swedish forest soil inventory data set (3230 samples) organized by a recursive partitioning method into distinct soil groups with underlying SOC stock development linked to physicochemical conditions.

For two-thirds of measurements all models predicted accurate SOC stock levels regardless of the detail of input data, e.g., whether they ignored or included soil properties. However, in fertile sites with high N deposition, high cation exchange capacity, or moderately increased soil water content, Yasso07 and Q models underestimated SOC stocks. In comparison to Yasso07 and Q, accounting for the site-specific soil characteristics (e. g. clay content and topsoil mineral N) by CENTURY improved SOC stock estimates for sites with high clay content, but not for sites with high N deposition.

Our analysis suggested that the soils with poorly predicted SOC stocks, as characterized by the high nutrient status and well-sorted parent material, indeed have had other predominant drivers of SOC stabilization lacking in the models, presumably the mycorrhizal organic uptake and organo-mineral stabilization processes. Our results imply that the role of soil nutrient status as regulator of organic matter mineralization has to be re-evaluated, since correct SOC stocks are decisive for predicting future SOC change and soil CO2 efflux.

[AbruptSLR]

The linked Union of Concerned Scientists article indicates that the "domino effect" of early Springs  will likely increase the impacts of Anthropogenic climate change beyond that previously considered by AR5:

http://www.ucsusa.org/global_warming/science_and_impacts/impacts/springs-domino-effect.html#.V7CzBpgrKUk

Extract: ""You build the infrastructure to take advantage of timing, but now systems are no longer optimized for the new reality. You have to invest in new systems and more energy-intensive systems for drinking water, for agriculture. This results in more irrigation and more pumping, more energy use, and more investment in infrastructure."

Another domino effect of an early spring is an increase in large forest fires. According to research published by Westerling and colleagues, rising temperatures combined with early snowmelt are contributing to large forest fires in areas that have infrequently experienced natural fires, and in high elevation Rocky Mountain forests where fire has been largely unaffected by other human activities.

...

"Anthropogenic [human-caused] climate change is occurring at a much faster rate than species have evolved to handle," Westerling says, "so it's a very complex combination of human effects that are putting a lot of stress on the species. It will be interesting to see which ones flourish and which ones don't."

It's all in the timing."

[Sigmetnow]

Michael Mann on the different ethics between climate scientists and deniers.  Brief video.
https://twitter.com/mtscientists/status/764871894591954944

[Sigmetnow]

Uncertainty Can't Be an Excuse for Climate Inaction, Researchers Argue
Writers warn that waiting for absolute certainty in climate models spells doom for a warming planet.

In a new essay, researchers dismantle a common form of climate skepticism: defending inaction on climate change by citing lingering uncertainties in climate models and in other scientific evidence of the mounting crisis.

This tactic of using uncertainty as an excuse to stall policy action on global warming is often politically motivated and driven by self-interest, say the essay's authors, led by a senior scholar at the National Academies of Sciences, Engineering and Medicine. The authors use the label "neoskeptics" to describe people or companies that have shifted the uncertainty debate in this way.

The best way for climate experts to respond, they say, is to focus more on areas of science that expose the true costs of inaction. They cite a growing body of peer-reviewed work in the disciplines of decision science and risk management.

"Although neoskeptics claim to accept the reality" that humans are changing the climate, "their inference that inaction is justified seriously under-emphasizes some well-established characteristics of [man-made climate change] that are important for informing choices," the authors wrote.

These characteristics are: "that the risks of extreme and damaging outcomes are continually increasing, so that waiting for certainty has increasing costs; that inertia in the system may result in its crossing major tipping points without timely warning; and that there is value to insuring against worse cases, especially when they are likely to be worse than those of the past."

https://insideclimatenews.org/news/11082016/uncertainty-excuse-climate-change-inaction-researchers-argue

[AbruptSLR]

Uncertainty Can't Be an Excuse for Climate Inaction, Researchers Argue
Writers warn that waiting for absolute certainty in climate models spells doom for a warming planet.

See also Reply #1491

[Sigmetnow]

"Marine Heatwaves", like The Blob, have decimated major mangrove and kelp forest areas near Australia.

How marine heatwaves are causing unprecedented climate chaos

He says his study suggested it was made about 16% more likely as a result of climate change – but he warns that while he’s confident that the results show it was made significantly more likely by climate change, he’s not very confident with the precise figure. “I would feel comfortable with the sign of the effect, not necessarily with number.”

But generally, Di Lorenzo says, looking at what is happening, he thinks climate change is increasing both the frequency and severity of marine heatwaves. So much so, he wonders if climate models are wrong, and underestimating the fluctuations in temperature that will occur as the globe warms.

“The real system – if you look at the observations, and this is a paper I will publish very soon – the increase in variance is much much stronger than what models are predicting,” he says. “Maybe our models are too conservative.”

https://www.theguardian.com/science/2016/aug/15/the-blob-how-marine-heatwaves-are-causing-unprecedented-climate-chaos

[AbruptSLR]

The linked reference demonstrates that  for the past 90,000 years Arctic sea ice cover has retreated abruptly with increasing global warming.  Hopefully, climate models can be better calibrated using such findings in order to better project what is already happening in the Arctic:

Ulrike Hoff et al (2016 Jul 26) “Sea ice and millennial-scale climate variability in the Nordic seas 90 kyr ago to present”, Nature Communications, doi: 10.1038/ncomms12247

http://www.nature.com/ncomms/2016/160726/ncomms12247/full/ncomms12247.html

Abstract: “In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial-scale climatic events (Dansgaard/Oeschger events) using the sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species in a record from the southeast Norwegian Sea. We demonstrate that expansion and retreat of sea ice varies consistently in pace with the rapid climate changes 90 kyr ago to present. Sea ice retreats abruptly at the start of warm interstadials, but spreads rapidly during cooling phases of the interstadials and becomes near perennial and perennial during cold stadials and Heinrich events, respectively. Low-salinity surface water and the sea ice edge spreads to the Greenland-Scotland Ridge, and during the largest Heinrich events, probably far into the Atlantic Ocean.”

See also:

http://phys.org/news/2016-08-sea-ice-strongly-linked-climate.html

Extract: ""Understanding the influence of sea ice on climate changes and ocean currents of the past, helps us understand future development in the ever warming climate." Rasmussen says."

[AbruptSLR]

While I applaud proposals to amend the Montreal Protocol to phase down the production and consumption of HFCs; the linked EIA article indicates that there is a "huge risk" that "both developed and developing countries spiral into a race to the bottom" possibly/probably allowing the accumulation of large banks of HFCs in the next 10 (ala China) to 15 years (ala India), before any such amendment takes effect.  Further as such HFCs already contribute one gigatonne of CO₂-e per year to the atmosphere, any further accumulation of additional banks of HFCs significantly accelerates the timing of the potential/probable global socio-economic collapse (possible from 2060 to 2050).  Furthermore, I note that such potentially large future CO2-e contributions from HFC emissions are not included in the RCP scenarios:

https://eia-international.org/major-climate-commitment-closer-to-adoption-in-2016

Extract: "“Already, the HFCs used in refrigerators, air-conditioners, inhalers and other items are emitting an entire gigatonne of carbon dioxide-equivalent pollution into the atmosphere annually. Now, if that sounds like a lot my friends, it’s because it is. It’s the equivalent to emissions from nearly 300 coal-fired power plants every single year” – John F Kerry in his speech during the 3rd Extraordinary Meeting of Parties to the Montreal Protocol, July 22, 2016, Vienna
…
India stuck to its previously submitted amendment proposal of a freeze date in 2031 which will allow unrestrained HFC growth for 15 years from now. Other major developing countries including China, Brazil and Indonesia proposed to freeze HFC consumption close to 2025. A late freeze and a baseline set far into the future mean that developing countries lose opportunities for their industries to leapfrog dead-end technologies and allow a massive phase-in of climate damaging chemicals.
…
If developed parties do not inject ambition into their own reduction schedules there is a huge risk that overall ambition will be compromised, as both developed and developing countries spiral into a race to the bottom.
An ambitious agreement on HFCs is a must in Kigali if we want to retain the possibility of remaining within safe temperature limits on our planet."