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Messages - AbruptSLR

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1
Not sure if this has passed here:
https://www.nature.com/articles/d41586-020-01484-5?fbclid=IwAR0juyzGRJPR8NrXbrFG16D5CuEzWig2EqG3j69tqFvDjsWurgDpn5GB-10

"Short-term tests validate long-term estimates of climate change
Six-hour weather forecasts have been used to validate estimates of climate change hundreds of years from now. Such tests have great potential — but only if our weather-forecasting and climate-prediction systems are unified. How sensitive is climate to atmospheric carbon dioxide levels? For a doubling of CO2 concentration from pre-industrial levels, some models predict an alarming long-term warming of more than 5 °C. But are these estimates believable? Writing in the Journal of Advances in Modeling Earth Systems, Williams et al. have tested some of the revisions that have been made to one such model by assessing its accuracy for very short-term weather forecasts. The results are not reassuring — they support the estimates... their result provides some of the best current evidence that climate sensitivity could indeed be 5 °C or greater. In short, these results, published in a specialist journal, and probably read by few climate policymakers, carry a far-reaching message: we cannot afford to be complacent. It seems that cloud adjustment to climate change is not going to give us breathing space. Instead, we need to redouble our efforts to cut emissions."

Wiliams et al 2020, Use of Short‐Range Forecasts to Evaluate Fast Physics Processes Relevant for Climate Sensitivity:
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019MS001986

"Abstract
The configuration of the Met Office Unified Model being submitted to CMIP6 has a high climate sensitivity. Previous studies have suggested that the impact of model changes on initial tendencies in numerical weather prediction (NWP) should be used to guide their suitability for inclusion in climate models. In this study we assess, using NWP experiments, the atmospheric model changes which lead to the increased climate sensitivity in the CMIP6 configuration, namely, the replacement of the aerosol scheme with GLOMAP‐mode and the introduction of a scheme for representing the turbulent production of liquid water within mixed‐phase cloud. Overall, the changes included in this latest configuration were found to improve the initial tendencies of the model state variables over the first 6 hr of the forecast, this timescale being before significant dynamical feedbacks are likely to occur. The reduced model drift through the forecast appears to be the result of increased cloud liquid water, leading to enhanced radiative cooling from cloud top and contributing to a stronger shortwave cloud radiative effect. These changes improve the 5‐day forecast in traditional metrics used for numerical weather prediction. This study was conducted after the model was frozen and the climate sensitivity of the model determined; hence, it provides an independent test of the model changes contributing to the higher climate sensitivity. The results, along with the large body process‐orientated evaluation conducted during the model development process, provide reassurance that these changes are improving the physical processes simulated by the model."

2
The rest / Re: Systemic Isolation
« on: April 15, 2020, 12:56:11 AM »
Does Relativity Lie at the Source of Quantum Exoticism?
https://phys.org/news/2020-04-relativity-source-quantum-exoticism.html



Since the arrival of quantum mechanics and the theory of relativity, physicists have lost sleep over the incompatibility of these three concepts (three, since there are two theories of relativity: special and general). It has commonly been accepted that it is the description of quantum mechanics that is the more fundamental and that the theory of relativity that will have to be adjusted to it.

Now, in the article "The Quantum Principle of Relativity," published in the New Journal of Physics, researchers prove that the features of quantum mechanics determining its uniqueness and its non-intuitive exoticism—accepted, what's more, on faith (as axioms)—can be explained within the framework of the special theory of relativity. One only has to decide on a certain rather unorthodox step.

... The special theory of relativity is a coherent structure that allows for three mathematically correct types of solutions: a world of particles moving at subluminal velocities, a world of particles moving at the velocity of light and a world of particles moving at superluminal velocities. This third option has always been rejected as having nothing to do with reality.

"We posed the question: what happens if—for the time being without entering into the physicality or non-physicality of the solutions—we take seriously not part of the special theory of relativity, but all of it, together with the superluminal system? We expected cause-effect paradoxes. Meanwhile, we saw exactly those effects that form the deepest core of quantum mechanics," say Dr. Dragan and Prof. Ekert

... Both theorists have also shown that after taking into account superluminal solutions, the motion of a particle on multiple trajectories simultaneously appears naturally, and a description of the course of events requires the introduction of a sum of combined amplitudes of probability that indicate the existence of superposition of states, a phenomenon thus far associated only with quantum mechanics.

"We noticed, incidentally, the possibility of an interesting interpretation of the role of individual dimensions. In the system that looks superluminal to the observer some space-time dimensions seem to change their physical roles. Only one dimension of superluminal light has a spatial character—the one along which the particle moves. The other three dimensions appear to be time dimensions," says Dr. Dragan.

Past, Present, Future

A characteristic feature of spatial dimensions is that a particle can move in any direction or remain at rest, while in a time dimension it always propagates in one direction (what we call aging in everyday language). So, three time dimensions of the superluminal system with one spatial dimension (1+3) would thus mean that particles inevitably age in three times simultaneously. The ageing process of a particle in a superluminal system (1+3), observed from a subluminal system (3+1), would look as if the particle was moving like a spherical wave, leading to the famous Huygens principle (every point on a wavefront can be treated itself as a source of a new spherical wave) and corpuscular-wave dualism.

For almost a hundred years quantum mechanics has been awaiting a deeper theory to explain the nature of its mysterious phenomena. If the reasoning presented by the physicists from FUW and UO stands the test of time, history would cruelly mock all physicists. The "unknown" theory sought for decades, explaining the uniqueness of quantum mechanics, would be something already known from the very first work on quantum theory.

Open Access: Andrzej Dragan et al, Quantum principle of relativity, New Journal of Physics (2020)
https://iopscience.iop.org/article/10.1088/1367-2630/ab76f7

-----------------------------

Spooky!

3
Antarctica / Re: PIG has calved
« on: March 02, 2020, 09:02:09 PM »
An initial summary analysis of the current status of the PIG/PIIS. This is only an initial analysis that I will subsequently deepen and refine by correcting it whenever necessary.

In the first image: Sentinel1 I detail the main elements:
> The current pinning points: NPP and SPP and the future pinning points once the current ones are lost: FNPP and FSPP.
> The parts of the PIIS currently attached to the PIG: MIS, NEIS and SIS.
> the main tributaries concerning us: SWT, T11, T9 and two minor tributaries T_: one tributary of NEIS and the other of SIS between T11 and T9.
> MIS shear margins: NSM and SSM
> The "Zones of Destruction" of the PIIS: NEZD, SEZD and SWZD
> MIS mini calvings in progress and future SWT-SIS calvings

I also attach an image with the elevations of the Ice Shelf (and thus its thickness), an image of the ice flow velocities with the direction of movement and an image of the bathymetry. The images of the elevations and velocities are more or less recent, but the rapidly changing context requires careful use.

Notes:

NPP: There is a narrow band of NEIS supported by the Ice Rises "Evans Knoll". This band has already been eroded by calving and there is nothing downstream. Furthermore, it will be further eroded by the next mini calving and, in general, by the shearing of the MIS. This pinning point may recede, but not much. Indeed, further upstream the strip widens to the NEIS weakly supplied by a small unnamed tributary (T_), a tributary which cannot constitute a pinning point. We will then see the opening of a Zone of Destruction which will join the NEZD as it moves upstream. Finally, we will reach the future pinning point on the north coast: FNPP.

SPP: already from now on it can be considered that there is no longer anything consistent downstream of this pinning point provided by T11 and anyway the SWZD will be empty soon. It is also necessary to take into account that the more static part of the SIS between T11 and SWT will be dismantled by the SWT push (see below; one can also notice that this part already had points of weakness as one can see by the map of the elevations and by the existence of the SWZD and the rifts which opened recently). Without downstream support, the T11 power supply is not sufficient to withstand the abrasive action of the MIS for a long time. The remaining SWZD will moves upstream and it will join up with the SEZD. Finally, we will reach at the future pinning point on the south coast:
Note that if the FNPP is solid and can retreat while remaining solid, this is not the case on the south side, once the FSPP is lost there will be nothing that can stop, even temporarily, the breakup (see the bathymetric map). 

SWT: this tributary, after losing all contact with the MIS, will in time take an eastern direction, breaking up the part of the SIS that currently still prevents it (see above). Taking into account the fragilities shown in the last months: several calving’s (which I have difficulty explaining at the moment) we can also expect a retreat of the SWT.

This general framework is not comforting ...  :'(  >:(  >:(

twice click to zoom in

Translated with www.DeepL.com/Translator (free version)

4
Antarctica / Re: PIG has calved
« on: March 01, 2020, 09:41:28 PM »
Baking,
The pinning point indicated (corresponding to the contact of tributary 11 with the MIS) for me is not stable   >:(
and the two pininnig points that can be stable for a certain time are further upstream  >:( >:(

To begin with, I'm attaching:
> a map with the tributaries of the PIIS and the line connecting these two pinning points. 
> a map with the speeds of the MIS and SIS, the indication of the tributaries and the line connecting these two pinning points.

As soon as I have time I will post detailed comments and commented images: a Sentinel1 image, a map with the elevations (and thus the thicknessers), another map with the velocities (with directions) and a bathymetric map.

5
Really cool long article:

How boulders in Mongolian mountains reveal the pace of climate change

...

The samples they’ve already studied from trips around the world hint that the shift in climate was not only synchronous in both hemispheres, but also occurred at a much faster rate than many previously suspected. “We had always had this conception that it was a slow process, but as we acquire more data, we developed a clearer picture of how glaciers behaved, and we realized that it was a really sudden event,” said Putnam. “It was so fast that you would have noticed it.”

https://thebulletin.org/2020/02/how-boulders-in-mongolian-mountains-reveal-the-pace-of-climate-change/

Don´t think the science on it is out yet but it should be interesting.
His research with Strand only shows the other regions mentioned in the article.

https://aaroneputnam.weebly.com/publications.html

A cosmogenic 10Be chronology for the local last glacial maximum and termination in the Cordillera Oriental, southern Peruvian Andes: Implications for the tropical role in global climate.

Millennial-scale pulsebeat of glaciation in the Southern Alps of New Zealand.

6
What we already knew

https://www.pnas.org/content/early/2020/02/10/1902469117.short?rss=1

Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica

Fifty years ago, it was speculated that the marine-based West Antarctic Ice Sheet is vulnerable to warming and may have melted in the past. Testing this hypothesis has proved challenging due to the difficulty of developing in situ records of ice sheet and environmental change spanning warm periods. We present a multiproxy record that implies loss of the West Antarctic Ice Sheet during the Last Interglacial (129,000 to 116,000 y ago), associated with ocean warming and the release of greenhouse gas methane from marine sediments. Our ice sheet modeling predicts that Antarctica may have contributed several meters to global sea level at this time, suggesting that this ice sheet lies close to a “tipping point” under projected warming.


7
Zeke Hausfather (Director of Climate and Energy at Breakthrough), has written an article (see the first image) discussing many of the means (logic) that consensus climate science will likely use to reduce the range of ECS recognized by AR6 as compared to that indicated by CMIP6 (see the second image).  Nevertheless, just because consensus climate science will likely be able to achieve in AR6 what Hausfather suggests; this does not mean that Earth Systems will respond in accordance with AR6's recommendations.

Title: "Cold Water on Hot Models"

https://thebreakthrough.org/issues/energy/cold-water-hot-models

Meanwhile Patrick T. Brown posted this figure on twitter, stating:

"Is the higher climate sensitivity in the next generation of climate models credible? Our observationally-constrained ECS of the previous generation falls exactly on the ECS of the next generation. So I would vote yes, it's credible."
https://twitter.com/PatrickTBrown31/status/1227272506240712705

Referring to this paper: https://www.nature.com/articles/nature24672

As of 2017 when that paper was published it was possible to rule out an ECS lower than 2.5K based on observational data. The mean of such constrained models was ~3.8K which is the mean of the CMIP6 models.

8
Scientists Find Far Higher than Expected Rate of Underwater Glacial Melting


Tidewater glaciers, the massive rivers of ice that end in the ocean, may be melting underwater much faster than previously thought, according to a Rutgers co-authored study that used robotic kayaks.

...

“With the kayaks, we found a surprising signal of melting: Layers of concentrated meltwater intruding into the ocean that reveal the critical importance of a process typically neglected when modeling or estimating melt rates,” said lead author Rebecca Jackson, a physical oceanographer and assistant professor in the Department of Marine and Coastal Sciences in the School of Environmental and Biological Sciences at Rutgers University–New Brunswick. Jackson led the study when she was at Oregon State University.

...

Two kinds of underwater melting occur near glaciers. Where freshwater discharge drains at the base of a glacier (from upstream melt on the glacier’s surface), vigorous plumes result in discharge-driven melting. Away from these discharge outlets, the glacier melts directly into the ocean waters in a regime called ambient melting.

The study follows one published last year in the journal Science that measured glacier melt rates by pointing sonar at the LeConte Glacier from a distant ship. The researchers found melt rates far higher than expected but couldn’t explain why. The new study found for the first time that ambient melting is a significant part of the underwater mix.

Paper:


Meltwater Intrusions Reveal Mechanisms for Rapid Submarine Melt at a Tidewater Glacier

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL085335

Abstract
Submarine melting has been implicated as a driver of glacier retreat and sea level rise, but to date melting has been difficult to observe and quantify. As a result, melt rates have been estimated from parameterizations that are largely unconstrained by observations, particularly at the near‐vertical termini of tidewater glaciers. With standard coefficients, these melt parameterizations predict that ambient melting (the melt away from subglacial discharge outlets) is negligible compared to discharge‐driven melting for typical tidewater glaciers. Here, we present new data from LeConte Glacier, Alaska, that challenges this paradigm. Using autonomous kayaks, we observe ambient meltwater intrusions that are ubiquitous within 400 m of the terminus, and we provide the first characterization of their properties, structure, and distribution. Our results suggest that ambient melt rates are substantially higher (×100) than standard theory predicts and that ambient melting is a significant part of the total submarine melt flux. We explore modifications to the prevalent melt parameterization to provide a path forward for improved modeling of ocean‐glacier interactions.

Plain Language Summary
Tidewater glaciers discharge ice into the ocean through iceberg calving and submarine melting. Submarine melting has been implicated as a driver of glacier retreat and sea level rise, but melt rates have been difficult to directly observe and quantify. As a result, melt rates are typically estimated using a theory that has not been tested with observations at any tidewater glaciers. Two types of melting are expected at tidewater glaciers: Where subglacial discharge drains from outlets in the terminus, energetic upwelling plumes rise along the ice face, and theory predicts vigorous melting. Away from discharge outlets, weaker plumes form from ambient melting, and theory predicts that these ambient melt rates are effectively negligible compared to discharge‐driven melting. Here, we present new data from LeConte Glacier, Alaska, that challenges this paradigm. Using autonomous kayaks, we observe intrusions of meltwater—the product of ambient melt plumes—that are only found within 400 m of the terminus, and we provide the first characterization of their properties, structure, and distribution. Their ubiquity suggests that ambient melt rates are substantially higher than standard theory predicts and that ambient melting is a significant—but often neglected—part of the total submarine melt flux.

9
Yes, we're starting to see the 11 year (132 month) running mean bend upwards. While major volcanic eruptions could cool the earth, otherwise it seems unlikely (as the UK MET office has published) that we will not pass 1.5C of warming (at least temporarily) within the next few years.

10
This Caldwell paper is a very good find.

Based on my reading of earlier work from his team, I can see now why E3SM has the highest ECS and TCR since they have been on the cutting edge of tropical cloud constraints.   Looks like they also have better sea ice modeling.  It is a little surprising that the higher resolution didn't increase sensitivity.

11
RCP8.5 is probably closer to a “worst case,” outlier scenario than anything it would be fair to call “business as usual.”
How can that be if we factor in large scale warfare, or inundations tempering with nuke plants, or creating more wetland conditions, in turn creating more greenhouse gases? How is this the new worst case equated to BAU? As far as I know the hothouse climate state is a worst case scenario.

Quote
In the future, the Earth System could potentially follow many trajectories (12, 13), often represented by the large range of global temperature rises simulated by climate models (14). In most analyses, these trajectories are largely driven by the amount of greenhouse gases that human activities have already emitted and will continue to emit into the atmosphere over the rest of this century and beyond—with a presumed quasilinear relationship between cumulative carbon dioxide emissions and global temperature rise (14).

However, here we suggest that biogeophysical feedback processes within the Earth System coupled with direct human degradation of the biosphere may play a more important role than normally assumed, limiting the range of potential future trajectories and potentially eliminating the possibility of the intermediate trajectories.

We argue that there is a significant risk that these internal dynamics, especially strong nonlinearities in feedback processes, could become an important or perhaps, even dominant factor in steering the trajectory that the Earth System actually follows over coming centuries.
https://www.pnas.org/content/115/33/8252

12
For anyone at all familiar with boreal or tropical forests and short rotation tree farms (less than a century between cropping) there is simply no comparison.

The ancient boreal and tropical forests, though dis-similar in many ways, are far more similar to one another in major ways than either is to tree farms. The massive complex assemblies that make up the boreal and tropical forests have multiple distinct life zones from the forest floor up through the middle layers to the high canopies. They are quite simply “cathedral forests’’.

They serve as unique complex bio systems that regulate temperature, moisture, rain, hydrologic cycling, nutrient cycling, and very much more across huge regions. Once destroyed the soils they created are rapidly degraded and destroyed making recovery of the forests extremely difficult.

To naive city dwellers and to those ignorant of these cathedral forests, a dense collection of mono cropped trees undoubtedly looks like a “forest”. It isn’t. It’s a crop. It doesn’t behave in anywhere near the same way, nor serve anywhere near the same functions.

Over short time spans a young growing crop might absorb more carbon per acre, though that seems extremely unlikely. If it does so, it does so with a huge expense in loss of nutrients from the limited soil.The giants of these forests and the complex web of life they support are referred to as the lungs of the world for good reason. They both capture immense quantities of carbon dioxide and generate equally immense volumes of oxygen.

Once cut and lost for a single generations benefit, the underlying souls degrade. As seen in Brazil and elsewhere, these lands are verdant and fertile for a very brief time. Without the restorative value of the forests, the land is rapidly denuded if nutrients. Other uses such as cattle ranching and mono-cropping for food production mine the soil of its precious nutrient load which is then exporting from the area with the crop. Once lost it must be replaced or the environmental value of the land and its abilities to support complex use is lost. Human farming techniques focus on minimum cash cost and maximum value extraction. These practices bring in nitrogen rich fertilizers devoid of nutrients other than potassium, phosphorous and occasionally other minerals like calcium. Micronutrients are lost along with soil with each crop. Soon the land is all but barren.   

The complex multi-tiered forests capture nutrients in many ways that young forests are far less able to. By supporting complex populations, oceanic fish migrate far upstream into the forests. There raptors and large carnivores capture them distributing their nutrient rich bounty far into the forests. Thin first generation small trees are simply unable to support the cool streams and complex ecosystems of the cathedral forests.

Looking at these forests through the monocles of carbon dioxide or finance completely misses and severely discounts their immense values across a thousand other measures. Doing so most particularly misses their climate impacts across huge regions.

Sam

13
Even if we do not stay on RCP 8.5 as long as we continue to emit more CO2 then earth systems  can absorb we will increase the greenhouse effect
A few more years to hit 3C is not a solution it is a delaying tactic to head off action.
I note that those who claim RCP 8.5 is not going to happen never admit neither is 2.5 and most probably 4.5 a possibility.
We do not have a feasible way to draw down CO2 to the extent required. That half the IPCC pathways use unknown technology's to minimize the possible future impact  is a illustration of the lobbyists  capture of the process.

14
Research Reveals Past Rapid Antarctic Ice Loss Due to Ocean Warming
https://phys.org/news/2019-12-reveals-rapid-antarctic-ice-loss.html

New research from the University of Otago has found the sensitive West Antarctic Ice Sheet collapsed during a warming period just over a million years ago when atmospheric carbon dioxide levels were lower than today.

Using biomarkers to reconstruct past ocean temperatures, and through ice sheet computer models, the study published in Quaternary Science Reviews shows that the accepted maximum global warming of 1.5°C under the Paris Agreement could lead to a runaway retreat of the West Antarctic Ice Sheet.

The study found that one million years ago in the ocean surrounding Antarctica, the summer ocean temperature was on average 5°C (±1.2°C) warmer than today.

"Using the data, the ice sheet simulation indicates a complete collapse of the West Antarctic Ice Sheet with additional melting of the East Antarctic Ice Sheet resulting in sustained global sea-level rise of centimetre to decimetres per decade."

The study proposes a two-step model for West Antarctic ice loss which initially involves mild ocean warming forcing ice margin retreat, followed by a rapid warming primarily driven by the extensively modified oceanic and hydrologic system following further ice sheet retreat.



Beltran Catherine et al. Southern Ocean temperature records and ice-sheet models demonstrate rapid Antarctic ice sheet retreat under low atmospheric CO2 during Marine Isotope Stage 31, Quaternary Science Reviews (2019)

Highlights

• Quantification of the Southern Ocean warming during MIS31 using molecular temperature reconstructions at high latitudes.

• Sustained surface Southern Ocean warming & collapse of the sub-Antarctic ocean fronts under low atmospheric CO2 conditions.

• Use of sea surface temperature data to test scenarios for the AIS retreat using coupled ice-sheet/ice-shelf model.

• Two steps WAIS retreat: 1) mild ocean warming forcing ice margin retreat 2) rapid ocean warming as the ice sheet retreats.

We show that the Paris Agreement target temperature of 1.5°C is sufficient to drive runaway retreat of the WAIS.

15
Quote from: Lennart van der Linde link=topic=2205.msg239688#msg239688
Several recent interglacials had even a little less ice than the current interglacial (which by human interference has stopped being an interglacial, or turned into a super-interglacial of at least 50,000-100,000 years).

I myself didn't remember Ganopolski et al 2016 carefully enough:
https://www.nature.com/articles/nature18452

They say:
"our analysis suggests that even in the absence of human perturbations no substantial build-up of ice sheets would occur within the next several thousand years and that the current interglacial would probably last for another 50,000 years. However, moderate anthropogenic cumulative CO2 emissions of 1,000 to 1,500 gigatonnes of carbon will postpone the next glacial inception by at least 100,000 years. Our simulations demonstrate that under natural conditions alone the Earth system would be expected to remain in the present delicately balanced interglacial climate state, steering clear of both large-scale glaciation of the Northern Hemisphere and its complete deglaciation, for an unusually long time."

So a natural super-interglacial has been turned by us into a super-super-interglacial, and maybe we're even tipping the planet into a Hothouse Earth state:
https://www.pnas.org/content/115/33/8252

16
a lot of posters on this forum seem to think that we're doomed and it's too late to do anything.

My impression is that a lot of posters are concerned we're not doing as much as we can, and should, because powerful forces do not think it necessary and/or desirable to do more than we're doing (which has not been much so far).

17
Yes, we need to get off of fossil fuels as soon as possible.  However [...] we're making great progress in doing so [...] Even with the additional carbon being released in the Arctic due to warming, the reduction in CO2 and methane from eliminating those two sources of anthropogenic emissions will result in emissions closer to the RCP 2.6 scenario than the RCP 8.5 scenario.

Lenton et al 2019 say:
"If current national pledges to reduce greenhouse-gas emissions are implemented — and that’s a big ‘if’ — they are likely to result in at least 3 °C of global warming. This is despite the goal of the 2015 Paris agreement to limit warming to well below 2 °C. Some economists, assuming that climate tipping points are of very low probability (even if they would be catastrophic), have suggested that 3 °C warming is optimal from a cost–benefit perspective. However, if tipping points are looking more likely, then the ‘optimal policy’ recommendation of simple cost–benefit climate-economy models aligns with those of the recent IPCC report. In other words, warming must be limited to 1.5 °C. This requires an emergency response [...] Early results from the latest climate models — run for the IPCC’s sixth assessment report, due in 2021 — indicate a much larger climate sensitivity (defined as the temperature response to doubling of atmospheric CO2) than in previous models. Many more results are pending and further investigation is required, but to us, these preliminary results hint that a global tipping point is possible [...] Some scientists counter that the possibility of global tipping remains highly speculative. It is our position that, given its huge impact and irreversible nature, any serious risk assessment must consider the evidence, however limited our understanding might still be. To err on the side of danger is not a responsible option. If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilization. No amount of economic cost–benefit analysis is going to help us. We need to change our approach to the climate problem. In our view, the evidence from tipping points alone suggests that we are in a state of planetary emergency: both the risk and urgency of the situation are acute."

Let's take the science seriously and recognize the urgency that Lenton et al, ASLR and others describe and justly emphasize as a planetary emergency and existential threat. Downplaying this inconvenient truth may be a natural impulse, but has been done for too long and is nog helping us. Let's face reality and the risks it entails and do what we have to do to minimize those risks, while we still can.

18
Hawkins lists various reasons why there is a discrepancy. Nr 3: "the real world may have a climate sensitivity towards the lower end of the CMIP5 range."
I guess he nailed it there.
If that was true for CMIP5, the CMIP6 models with much higher ECS around or above 5 will have an even tougher fight with reality.

Lewandowsky et al 2018  analyze data up until 2016. If you go back to the figure I attached in Reply #2016 the discrepancy looked less worrying with those data ending in 2016. But when we include 2017 and 2018 in the dataset and compare with the models, we get the impression that actual temperatures follow a lower trajectory, a lower trend, than the models. They write:
"...several biases in the observations and in model projections gave rise to the impression of a divergence between modeled and observed temperature trends. This impression was limited to the period 2011–2013, after which the ongoing debiasing eliminated any appearance of a divergence. During the period 2011–2013, the impression of a divergence could appear to be statistically significant, but only if the selection-bias issue was ignored. "

They might have been correct about selection bias, if it wasn't for a repeat of same in 2017-18. With two more years of data, the divergence seems to become only stronger.

It seems to me you're jumping to conclusions from hypotheses that have not been confirmed or not properly investigated yet. Hawkins lists several hypothetical explanations for the discrepancy between observations and simulations without saying which explanation he thinks is responsible for which part of the discrepancy, if at all. So your guess is as good as any, but needs to be properly investigated first. Lewandowsky et al give some first results from their investigation and do not confirm your guess. Maybe this is because they have not taken the latest years into account yet, but that remains to be seen. If two more years of data would indeed show a significant divergence, then two or more years of data after 2018 may change the picture once again. So it seems a little early to jump to the conclusion that the models are running hot, the more so as ASLR has shown several studies that indicate the ECS may be or may become higher with further warming. Proper risk management would take this possibility into account and demands a little more critical reasoning than you've been showing here so far, if you ask me.

19
Nothing peer reviewed, but prof. Ed Hawkins makes regular updates to evaluate model performance. Models evidently running hot.

http://www.met.reading.ac.uk/~ed/home/index.php
https://www.climate-lab-book.ac.uk/comparing-cmip5-observations/

It may be evident to you, but apparently not to Hawkins himself, and not to peer-reviewed Lewandowsky et al 2018 either.

Hawkins writes on his blog:
"The simulation data uses spatially complete coverage of surface air temperature whereas the observations use a spatially incomplete mix of air temperatures over land and sea surface temperatures over the ocean. It is expected that this factor alone would cause the observations to show smaller trends than the simulations."

He gives some other potential explanations for the apparent divergence as well:
"There are several possible explanations for why the earlier observations are at the lower end of the CMIP5 range. First, there is internal climate variability, which can cause temperatures to temporarily rise faster or slower than expected. Second, the radiative forcings used after 2005 are from the RCPs, rather than as observed. Given that there have been some small volcanic eruptions and a dip in solar activity, this has likely caused some of the apparent discrepancy. Third, the real world may have a climate sensitivity towards the lower end of the CMIP5 range. Next, the exact position of the observations within the CMIP5 range depends slightly on the reference period chosen. Lastly, this is not an apples-with-apples comparison because it is comparing air temperatures everywhere (simulations) with blended and sparse observations of air temperature and sea temperatures. A combination of some of these factors is likely responsible."

Lewandowsky et al 2018  elaborate on this:
https://iopscience.iop.org/article/10.1088/1748-9326/aaf372/meta

"The impression of a divergence early in the 21st century was caused by various biases in model interpretation and in the observations, and was unsupported by robust statistics [...] IPCC Assessment Report (AR5)... stated that '...111 out of 114 realizations show a GMST trend over 1998–2012 that is higher than the entire HadCRUT4 trend ensemble... This difference between simulated and observed trends could be caused by some combination of (a) internal climate variability, (b) missing or incorrect radiative forcing and (c) model response error' (Flato et al 2013, p 769). The consensus view expressed by the IPCC therefore pointed to a divergence between modeled and observed temperature trends, putatively caused by a mix of three factors. Subsequent to the IPCC report, the role of these three factors has become clearer [...] We have established that several biases in the observations and in model projections gave rise to the impression of a divergence between modeled and observed temperature trends. This impression was limited to the period 2011–2013, after which the ongoing debiasing eliminated any appearance of a divergence. During the period 2011–2013, the impression of a divergence could appear to be statistically significant, but only if the selection-bias issue was ignored. We have shown that ignoring of the selection-bias issue can drastically inflate Type-I error rates, which renders the inferences unreliable and in this case erroneous."

See their full paper for further details.
What do you think of their conclusions?

20
The basic concept of LTG is that there are limited resources, and that mankind is depleting those resources in such a way that it triggers more or less uncontrollable dynamic developments regarding environment etc.
This concept is faulty. Resources will get higher relative prices the scarcer they become. But they won't be physically depleted. That was the first big modelling mistake they made.
The second big mistake was to disregard all technical development. This is also connected with the changing relative prices: when an essential resource gets a higher price due to scarcity, it will trigger developments to either replace that resource with substitutes or find ways to improve the extraction or production of the resource [...]
The third modelling mistake was to not include counteractions by TPTB.
That said, I agree with what you say about ecological boundaries. Capitalism needs regulation.

Below a few quotes from Limits to Growth 1972 and the 30-year update Limits to Growth 2004 that seem to contradict your assertions. Paraphrased Meadows et al say:
- dynamics only become uncontrollable if we wait too long to consciously limit material growth
- even when higher prices for scarcer resources lead to technological innovation and substitution in the short run the total supply of resources remains limited in the longer run
- counteractions by TPTB have been modelled in the several scenario's, including a scenario that avoids collapse by consciously limiting further material growth

Meadows et al argue that the longer we postpone implementing policies to limit material growth, the higher the risk of eventual collapse, without being able to predict exactly when this collapse may occur. In (most of) their scenario's this collapse would occur somewhere during this century, mainly depending on the exact ecological and technological limits.

The current climate crisis seems the ultimate illustration of the general accuracy of their analysis, with climate scientists showing we need extremely rapid emission reductions to avoid passing potentially catastrophic climate tipping points, while energy experts argue that such rapid reductions hardly seem possible without (in the short run) shrinking the global economy, or at least the material consumption in the richer economies.

So the crucial question seems to be: how long do we want to keep gambling with the future of our children? Or alternatively: how certain can we be that we're not risking their future by holding on to business-as-usual policies aimed at continued material growth?

21
If you reject the fundamental influence of market forces you always risk repeating the mistake of the Club of Rome report "Limits to growth".

Have you actually read "Limits to Growth"? If so, where exactly did you find the mistake?
As far as I know they didn't reject the fundamental influence of market forces at all, but maybe I missed it.
Even market forces cannot provide unlimited material growth on a finite planet.
Current market forces are already exceeding several planetary ecological boundaries.
The longer this overshoot lasts, the higher the risk of eventual collapse.
Only by governing market forces can we hope to still avoid this collapse, or at least make its impact less destructive.
This is how I understand the Club of Rome's warning of 1972 (updated several times since), which still seems very accurate to me.

22
[Are lower latitudes warming? No, see attached, we have a negative SST trend in Antarctic seas.

Antarctic seas are at higher latitudes, not lower. Lower latitudes are closer to the equator.

23
Hansen et al 2016:
https://pubs.giss.nasa.gov/abs/ha04710s.html

"Meltwater tends to stabilize the ocean column, inducing amplifying feedbacks that increase subsurface ocean warming and ice shelf melting. Cold meltwater and induced dynamical effects cause ocean surface cooling in the Southern Ocean and North Atlantic, thus increasing Earth's energy imbalance and heat flux into most of the global ocean's surface. Southern Ocean surface cooling, while lower latitudes are warming, increases precipitation on the Southern Ocean, increasing ocean stratification, slowing deepwater formation, and increasing ice sheet mass loss. These feedbacks make ice sheets in contact with the ocean vulnerable to accelerating disintegration. We hypothesize that ice mass loss from the most vulnerable ice, sufficient to raise sea level several meters, is better approximated as exponential than by a more linear response. Doubling times of 10, 20 or 40 years yield multi-meter sea level rise in about 50, 100 or 200 years. Recent ice melt doubling times are near the lower end of the 10-40-year range, but the record is too short to confirm the nature of the response. The feedbacks, including subsurface ocean warming, help explain paleoclimate data and point to a dominant Southern Ocean role in controlling atmospheric CO2, which in turn exercised tight control on global temperature and sea level. The millennial (500-2000-year) timescale of deep-ocean ventilation affects the timescale for natural CO2 change and thus the timescale for paleo-global climate, ice sheet, and sea level changes, but this paleo-millennial timescale should not be misinterpreted as the timescale for ice sheet response to a rapid, large, human-made climate forcing [...] The modeling, paleoclimate evidence, and ongoing observations together imply that 2°C global warming above the preindustrial level could be dangerous. Continued high fossil fuel emissions this century are predicted to yield (1) cooling of the Southern Ocean, especially in the Western Hemisphere; (2) slowing of the Southern Ocean overturning circulation, warming of the ice shelves, and growing ice sheet mass loss; (3) slowdown and eventual shutdown of the Atlantic overturning circulation with cooling of the North Atlantic region; (4) increasingly powerful storms; and (5) nonlinearly growing sea level rise, reaching several meters over a timescale of 50-150 years. These predictions, especially the cooling in the Southern Ocean and North Atlantic with markedly reduced warming or even cooling in Europe, differ fundamentally from existing climate change assessments."

Silvano et al 2018:
https://advances.sciencemag.org/content/4/4/eaap9467

"Strong heat loss and brine release during sea ice formation in coastal polynyas act to cool and salinify waters on the Antarctic continental shelf. Polynya activity thus both limits the ocean heat flux to the Antarctic Ice Sheet and promotes formation of Dense Shelf Water (DSW), the precursor to Antarctic Bottom Water. However, despite the presence of strong polynyas, DSW is not formed on the Sabrina Coast in East Antarctica and in the Amundsen Sea in West Antarctica. Using a simple ocean model driven by observed forcing, we show that freshwater input from basal melt of ice shelves partially offsets the salt flux by sea ice formation in polynyas found in both regions, preventing full-depth convection and formation of DSW. In the absence of deep convection, warm water that reaches the continental shelf in the bottom layer does not lose much heat to the atmosphere and is thus available to drive the rapid basal melt observed at the Totten Ice Shelf on the Sabrina Coast and at the Dotson and Getz ice shelves in the Amundsen Sea. Our results suggest that increased glacial meltwater input in a warming climate will both reduce Antarctic Bottom Water formation and trigger increased mass loss from the Antarctic Ice Sheet, with consequences for the global overturning circulation and sea level rise."

24
1. You misinterpret my posts.  We need to get off of fossil fuels fast. 

What I'm saying is that we're doing that.
...
Your optimism is admirable but I have not seen any data to suggest the world is getting off fossil fuels fast. The only data I have seen suggests that fossil fuel consumption is rising year after year. This is borne out by the inexorable and accelerating climb in CO2 levels as shown by KiwiGriff.

https://www.nationalobserver.com/2019/07/31/opinion/fossil-fuel-burning-leaps-new-record-crushing-clean-energy-and-climate-efforts

Also, you tend to completely ignore facts that make the extreme right tail risks unlikely to occur.  Case in point, renewables have been less expensive than coal for almost two years now.  Investments in new coal plants have plummeted and retirements of coal power plants have accelerated.  Coal use is projected to peak within a few years and then rapidly decrease afterwards.  Even thought that's been pointed out, you seem to think that we'll still be on the RCP 8.5 scenario when there is no other source of greenhouse gas emissions that can make up for the missing coal emissions.
Alas, projections are not facts. And there are plenty of other sources of GHG emissions to replace coal.

25
Quote
In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO2 emissions decline by about 45% from 2010 levels by 2030 (40–60% interquartile range), reaching net zero around 2050
And ........our present reality.

26

Second, per the following article, and associated Rignot et al (2019) reference, if DeConto when back and re-calibrated his model values for the EAIS to match Rignot et al. (2019)'s observed values; he would get significantly higher ice mass loss values at much earlier dates.

Title: "Polar Warning: Even Antarctica’s Coldest Region Is Starting to Melt"

https://e360.yale.edu/features/polar-warning-even-antarctica-coldest-region-is-starting-to-melt

Extract: "In January, Rignot and colleagues published a paper that looked back to 1979. Like the IMBIE study, they found an acceleration in ice loss over the continent as a whole: it went up six times over the four decades of their study. But, more strikingly, they could say that East Antarctica was a big player in that loss: from 2009 to 2017, they concluded, West Antarctica accounted for 63 percent of the continent’s ice loss, and East Antarctica accounted for 20 percent — more than the Antarctic Peninsula’s contribution of 17 percent.

In the face of rapid change and limited data, it is extremely challenging to predict what the Antarctic will do in the future. The models, says Rignot, “all have fundamental flaws. None of them are right.” Their resolution is coarse and they don’t include all the physics; plus they are lacking in critical input data. Very little is known, for example, about water temperatures and the seafloor shape off the coast of much of East Antarctica. That affects things like ocean currents and sea ice buildup, both of which affect glacier flow.

For now, DeConto says, his models show that “the East Antarctic is stable for a few decades, but in the high emissions scenarios it starts to become a player in the late 21st century.” But, he adds, “If I went back and put [Rignot’s] numbers in…” He trails off, waving his hands at the potentially large, unknown increase that would cause."

See also:

Eric Rignot, Jérémie Mouginot, Bernd Scheuchl, Michiel van den Broeke, Melchior J. van Wessem, and Mathieu Morlighem (January 22, 2019), "Four decades of Antarctic Ice Sheet mass balance from 1979–2017", PNAS, 116 (4) 1095-1103; https://doi.org/10.1073/pnas.1812883116

https://www.pnas.org/content/116/4/1095
The Rignot et al paper (and its accompanying spreadsheet separated out melt from the annual mass gain from snowfall of about 1,100GT. They found that in many parts of the EAIS things had changed from annual snowfall in excess of melt, i.e. a net mass gain, to annual snowfall less than melt, .e. a net mass loss.

The GRACE + GRACE-FO data  seems to confirm this, especially in the EIS East of the Ross Ice Shelf (data to September 2019 attached).

27
Here are the projections for RCP 8.5 from DeConto and Pollard 2016:

https://www.geo.umass.edu/climate/papers2/DeConto2016.pdf

Quote
Antarctica contributes 77 cm of GMSL rise by 2100, and continued loss of the Ross and Weddell Sea ice shelves drives WAIS retreat from three sides simultaneously (the Amundsen, Ross, and Weddell seas), all with reverse-sloping beds into the deep ice-sheet interior. As a result, WAIS collapses within 250 years. At the same time, steady retreat into the Wilkes and Aurora basins... adds substantially to the rate of sea-level rise, exceeding 4 cm yr−1 (Fig. 4c) in the next century, which is comparable to maximum rates of sea-level rise during the last deglaciation.

So in the worst case emissions scenario, which is no longer feasible because we aren't going to burn that much coal, the West Antarctic ice shelves collapse after the Larsen C, which collapses in the 2050s. The Wilkes and Aurora basins would contribute to sea level rise next century, after 2100.

And Rob DeConto has publicly backed off of these projections.

https://www.theatlantic.com/science/archive/2019/01/sea-level-rise-may-not-become-catastrophic-until-after-2100/579478/

Quote
In new work, conducted with three other prominent glaciologists, DeConto and Pollard have lowered some of their worst-case projections for the 21st century. Antarctica may only contribute about a foot of sea-level rise by 2100, they now say. This finding, reached after the team improved their own ice model, is much closer to projections made by other glaciologists... Now their worst-case skyrocketing sea-level scenario seems extremely unlikely, at least within our own lifetimes.

Skeptical Science has a very good overview of MICI.

https://skepticalscience.com/new-light-antarctica-contribution-slr.html

Quote
DeConto says he is not able to comment on it directly as it is undergoing peer review. However, he has presented some preliminary results at the Fall Meeting of the American Geophysical Union (AGU) in December.

So to recap:
- AbruptSLR continues to confuse the timeframes of the original MICI models published in 2016
- The authors of the original MICI models now state that the 2016 projections were too pessimistic
- Other studies have shown that ice flows instead of fails in a brittle manner, which casts doubt on the mechanism needed for MICI to occur.
- Past sea level rise could have occurred without needing the MICI mechanism
- MICI needs hydrofracturing to occur before MICI can occur and yet there are areas in Antarctica where water flows off the ice sheet rather than penetrating through it to create hydrofractures
- Coal is now more expensive than solar and wind power and coal use is expected to peak next decade, so the emission projections of RCP 8.5 from the 2020s through 2100 aren't possible.

Ken,
Wilkes and Aurora reach their maximum rate of ice loss in the next century, but apparently start to contribute significantly already this century, in my understanding of your quotes of DeConto & Pollard.

And while their new results for 2100 seem to be lower than their earlier results, they also warned that after 2100 the rate of ice loss could be even higher than they found earlier, if I remember correctly. Richard Alley also warns for this possibility in this recent news item:
https://insideclimatenews.org/news/12112019/antarctica-ice-shelf-melt-atmospheric-river-thwaites-glacier-ocean-sea-level-rise?utm_source=facebook&utm_medium=social&fbclid=IwAR0gFMMYkF2K6-PP99Dwonon5CJ-E5TsEmSK5oJSuC4B0Bh-0w9HJjC3Nkw

Quote
Alley noted that some research has suggested that, if global warming pushes West Antarctica's towering ice cliffs to collapse, it could raise sea level more than 3 feet by 2100, surging to 50 feet by 2500, from Antarctic ice melt alone.

"That model is sometimes treated as a worst-case scenario, but in fact the model used a maximum calving rate that has briefly been exceeded in Greenland already, and the possibility exists that even faster calving could occur from higher, wider cliffs that could develop in Antarctica," he said.

Even the most recent international assessment of ice loss relies on models that don't account for some of those ice shelf tipping points, he said. "If we're fortunate, and the ice shelves are retained, then these models may be accurate. If we do lose the ice shelves, the models may project less sea level rise than will occur, perhaps by a lot."

Everyone hopes we'll be lucky, but we can't count on that, so the strongest possible mitigation is urgent and preparing for strong adaptation is urgent as well. RCP8.5 may not be likely, but with people like Trump in power we can't be sure either that it will not come to pass. And also with lower RCP's the risks of rapid and large SLR remain substantial, so it seems reasonable to be very aware of those risks and to not underplay them, as has been done for decades now. It seems to me your posts have a tendency to "err on the side of least drama", like many IPCC reports so far, as argued by Brysse et al and others.

28
Asynchronous Antarctic and Greenland ice-volume contributions to the last interglacial sea-level highstand

    Eelco J. Rohling, Fiona D. Hibbert, Katharine M. Grant, Eirik V. Galaasen, Nil Irvalı, Helga F. Kleiven, Gianluca Marino, Ulysses Ninnemann, Andrew P. Roberts, Yair Rosenthal, Hartmut Schulz, Felicity H. Williams & Jimin Yu

Nature Communications volume 10, Article number: 5040 (2019)
Quote
...
Finally, we infer intra-LIG sea-level rises with event-mean rates of rise of 2.8, 2.3, and 0.6 m c−1. Such high pre-anthropogenic values lend credibility to similar rates inferred from some ice-modelling approaches51. The apparent reality of such extreme pre-anthropogenic rates increases the likelihood of extreme sea-level rise in future centuries.
This research reveals up to 2.8 meters/century sea level rise (without people mucking things up).

Edit:  LIG = The last interglacial

29
Crosspost!

Changes in high-altitude winds over the South Pacific produce long-term effects on the Antarctic

Quote
“The study provides the first evidence of long-term changes in the high-altitude winds of the southern westerly wind belt over the South Pacific,” explains Dr Frank Lamy. “Our findings indicate closer atmospheric ties between the tropics and mid to high latitudes than in other sectors of the Southern Hemisphere, with consequences for global overturning circulation and the storage of atmospheric CO2 in the ocean.”

The team’s findings are also important with regard to understanding current and especially future large-scale climate mechanisms in the comparatively under-researched Southern Hemisphere. One crucial aspect is the coupling of the tropical Pacific with the source of the global climate phenomenon El Niño Southern Oscillation (ENSO) and the West Antarctic. The data shows that the West Antarctic Ice Sheet’s high sensitivity to ENSO in the Pacific sector, which can be seen in satellite observations made over the past few decades, is most likely also significant over much longer time scales. “A change in the high-altitude winds over the South Pacific in response to the increased frequency and intensity of El Niño events that many climate models predict would reduce the stability of the West Antarctic Ice Sheet, while also negatively impacting CO2 storage in the South Pacific,” says Lamy, putting the findings in perspective.

Link >> https://www.awi.de/en/about-us/service/press/press-release/changes-in-high-altitude-winds-over-the-south-pacific-produce-long-term-effects-on-the-antarctic.html

(The study will be published on November 5, 2019 as an open access article in the online portal PNAS

The original title is: Frank Lamy, John C.H. Chiang, Gema Martínez-Méndez, Mieke Thierens, Helge W. Arz, Joyce Bosmans, Dierk  Hebbeln, Fabrice Lambert, Lester Lembke-Jene, Jan-Berend Stuut: Precession modulation of the South Pacific westerly wind belt over the past million years, Proceedings of the National Academy of Sciences of the United States of America (PNAS)  /doi.org/10.1073/pnas.1905847116)

30

Countries that can increase co2 emissions
India - 1.83
Indonesia - 1.94
Vietnam - 2.29

China was at 7.72.... but they make a lot of stuff for the rich countries, I wonder if we removed the CO2 emissions for manufacturing our stuff whether it would be even half that value left over.

Rich countries are looking for ways to do as little as possible at the expense of those who
have not caused the problem and are doing their fair share while growing.

I am not certain the human nature (whether in the first, or third worlds) will allow modern global society to make the adjustments required to avoid a climate catastrophe in the coming decades:

Title: "Delhi air quality: Judges accuse authorities of 'passing the buck'"

https://www.bbc.com/news/world-asia-india-50285343

Extract: "India's top court has accused state governments of "passing the buck" on air pollution and failing to take action to tackle Delhi's toxic smog.

The Supreme Court said authorities were only interested in "gimmicks", rather than concrete measures to combat pollution levels.

Levels of dangerous particles in the air - known as PM2.5 - are at well over 10 times safe limits in the capital."

I agree with you about our inability to react in a way that will reduce the catastrophe that is coming our way.

I also agree that India is basically being stupid in regards to using coal for power. The pollution there is shocking.

My point was more about who needs to do the most work in regards to the actions that need to be taken.
In theory, it is not India or SE Asia.

Oddly, India in particular, need to stop using coal and fossil fuels not to reduce their CO2 emissions, they need to do it to vastly reduce their levels of air pollution.
This means they need to do it for local reasons that are unrelated to global CO2 levels, but rather pollution levels.
To me, this benefit is just one more reason to get rid of fossil fuels. Maybe there is motivation for change in this approach.

As an aside..... India looking to Russia is an indication that the Adani mine in Australia is entering the too hard basket. The Govt is getting rather extreme in their efforts to force the Adani mine to start. For example, making it illegal to protest environmental concerns when it affects mining, imprisoning protest organizers (I am aware or 3 protesters serving 2 years each) and looking to create laws that makes insurance companies and banks unable to refuse their business to fossil fuel companies.
Australia is as corrupt as hell.
It also is why I doubt we fail to do enough to avoid global civilizational collapse within the coming decades.

(I will hunt down the links for the above mentioned statements, I thought I had them saved but didnt do it)

Imprisonments for protesting
This is what they want to do - https://www.theguardian.com/australia-news/2019/oct/03/peter-dutton-accused-dictator-urging-welfare-cuts-protesters
This is what they have done so far -
https://www.theguardian.com/australia-news/2019/oct/24/queensland-parliament-passes-laws-to-crack-down-on-climate-protesters
https://www.abc.net.au/news/2019-10-11/extinction-rebellion-protester-eric-herbert-sentenced-probation/11595318

https://www.canberratimes.com.au/story/6470618/morrison-doesnt-like-it-when-the-quiet-australians-start-to-speak-up/

31
In regard to the Guardian article of the Amazon tipping point.  I have gotten behind  in this thread, busy and one needs to delve and think deeply on this thread. 

From the author cited for her report on papers.  Oct 31 
https://www.piie.com/blogs/realtime-economic-issues-watch/lets-look-evidence-tipping-points-amazon-rainforest

She cites the two primary papers she utilized and critiques the Bolsanaro government regime. 

Her "PIEE" chart is here (bad pun)
https://www.piie.com/research/piie-charts/amazon-deforestation-fast-nearing-tipping-point-when-rainforest-cannot-sustain

Her 7 page review that the Guardian cited is here
https://www.piie.com/sites/default/files/documents/pb19-15.pdf

As always, with admiration to the posts here. 





32
Two more quotes from IPCC SROCC attached:

33
Note that these are the estimates from their 2016 study. They've since indicated that they are considerable over estimates.

There are summaries of many other studies in the chapter, including ones that address the recently discovered cavity under Thwaites Glacier.  They also address the feedbacks from huge increases in meltwater on ocean stratification.

None of the scenarios lead to the catastrophic consequences implied by AbruptSLR's musings.  All of them agree that if we can keep emissions in-line with the RCP 2.6 scenario, the future sea level rise is greatly reduced from the RCP 8.5 emissions scenarios.  Many agree (including DeConto and Pollard) that the WAIS will not collapse under the RCP 2.6 scenario.

As you cite, IPCC SROCC also refers to Kopp et al 2017 (including DeConto & Pollard) which shows a non-negligible risk of pretty fast SLR between 2100-2300 even at RCP2.6 (3m SLR in 2 centuries). See table 1 in Kopp et al attached below. When DeConto & Pollard will have published their lowered estimates for 2100, we may also learn their new estimates for 2200 and 2300, which may be even higher than before, if I've understood their earlier indications of those results correctly. None of these estimates will be as definitive as you seem to present them, which means they still imply risks that should not be ignored, as indicated by the quotes from IPCC SROCC attached below, and as ASLR fortunately does not tire of reminding us, as do experts as for example Dewi Le Bars, when he reflected last February on the implications of two recent papers for the projections by DeConto & Pollard and for ice-climate feedback modelling (as proposed by Hansen et al, amongst others):
https://sites.google.com/site/dewilebars/sea-level-monthly-review/february-2019

On Edwards et al 2019:
'The claim that MICI is "not necessary" to reproduce past sea level high stands is both not really true and not really useful. The uncertainty range about what could have been the contribution of Antarctica to sea level during the Pliocene is 5-20 m and during the Last Interglacial it is 3.6-7.4 m. DeConto and Pollard’s model without MICI can reproduce up to 6 m and 5.5 m respectively for these two period (see Edwards et al. E.D. Fig. 4). So yes it can reproduce the lower part of the ranges. But most of the Pliocene range cannot be reproduced with the no-MICI assumption. What the figure shows is that the model with MICI covers a much bigger par of the possible Antarctic contribution for these periods. And still, even including MICI, the model can only explain a maximum of 12 m contribution for the Pliocene. Which means additional mechanisms would be necessary to cover the whole range of possible Antarctic contribution for that period. The claim that MICI is “not necessary” is also not very useful practically because projections with MICI are used to make high-end sea level scenarios. The important information is then is it possible or not? If it was not possible then it would be good news and decision makers wouldn't need to take it into account. "Not necessary" only has an impact on low-end scenarios, for which MICI would already not be used anyways.'

On Golledge et al 2019:
'Current state of the art (CMIP5 type) climate models do not include ice sheet models so the coupled effects between ice sheets and climate are a blind spot. In these climate models the ice sheets are just white mountains that do not change over time. They might have a snow layer on top of them but no ice. So snow falls on them accumulate a little bit and when it melts it is put in the nearest ocean grid box. If too much accumulates then it is put directly in the ocean to avoid infinite accumulation. What is missing is a model to transform the snow to ice and then transport it back to the sides of the ice sheet or to the ocean under the force of gravity. This is what ice sheet models do. Golledge et al. use the PISM ice sheet model for Greenland and Antarctica and couple them offline to LOVECLIM, an intermediate complexity climate model. Intermediate complexity means lower resolution and simpler physics compared to CMIP5 type climate models. It is the type of models generally used for long paleoclimate simulations.

What they find is that allowing feedbacks between the ice sheets and the climate model leads to strengthen both Antarctic and Greenland mass loss, by 100% and 30% respectively. For Antarctica this is not a surprise, although the magnitude is much bigger than I expected. Freshwater from the melting of ice leads to increase the ocean stratification, because it is is very light. This reduces vertical ocean mixing and as a result the surface of the ocean cools down while the subsurface warms up. Antarctica mostly looses mass from ice shelves basal melt and calving which is strengthened by warmer subsurface ocean temperature. For Greenland, it comes as a surprise to me that the feedback would increase the mass loss, because Greenland mostly looses mass from surface melt and a cooler atmosphere temperature would tend to reduce surface melt. Unfortunately the paper does not explain the mechanisms at play there (or did I miss it?).

There are a few issues with the ice sheet models that reduce my confidence in the projections. For Greenland the model is not able to reproduce the recent fast mass loss acceleration. Therefore the authors artificially impose the mass loss on the model in two ways: (1) decrease the friction between the ice and the bed (basal traction) to have a faster flow between 2000 and 2015 and (2) reduce the snowpack refreezing between 2000 and 2025. Refreezing is important for the mass balance because on ice sheets more than half of the snow that melts in the summer refreezes locally. It never reaches the ocean. Michiel van den Broeke had a similar comments in Trouw (in Dutch). You can force the model to agree with observations but if the model does not have the proper dynamics to explain observations there is no reason it is doing a good job for the future. For Antarctica, the model starts with enormous mass accumulation (1000 Gt/year in 1900) and accumulates mass until the 1980th. This is clearly not possible, such an accumulation would have been seen by tide gauge measurements. In fact as I said in the last review it is expected that Antarctica was slowly loosing mass in the 20th century. Also, the internal variability of grounded ice is so large in the model (Fig. 1a-d) that I do not understand what is going on physically (please let me know if you do).

In conclusion, the paper’s goal is important and it is the first time that two high resolution ice sheet models are coupled to a climate model. This is a big step in the right direction. However, I am not convinced by the results because of the issues mentioned above concerning the ice sheet models. Nevertheless, it is very instructive as it shows the long way that is left for ice sheet models to reach the level at which we can trust their future projections.'

34
Yes but .
The error goes both ways .
You think because the models are not perfect you can discount the result .
Unfortunately there is plenty of evidence  that models underestimate the result of our unfortunate experiment in atmospheric physics.


Still think you should be banned for spreading denial  FUD .
 

35
That Stokes paper referenced in the conversation article is 

doi:10.1038/s41598-019-50343-5

open access. I have commented implications for Amery at

https://forum.arctic-sea-ice.net/index.php/topic,2578.msg232196/topicseen.html#msg232196

That paper references and earlier paper by Alley et al.  (doi: 10.1016/j.rse.2018.03.025 )  who evalued antarctic ice shelf vulnerability to hydrofracture. The measure of vulnerability is the fraction of ice saturated firn. I attach a figure showing that most ice shelves are vulnerable.

sidd

36
earlier today
Quote
"... If the higher CMIP6 ECS estimates hold true as the archive fills out, this will represent a departure from over four decades of research. Higher-sensitivity climates experience a greater probability of long-term temperature pauses and short-term trends, which can translate to more warming hiatuses or periods of fast temperature increase."
very interesting, indeed.  More data for deniers ("pauses") and then ghost-white faces.  :'(

37
Thanks for another nice selection of articles.

Enjoyed the animal ones and i cross posted the CAA glaciers (to What is new in the Arctic) and the Cerrado article.

38
The linked article explains how the current (and relatively rare) sudden stratospheric warming event over Antarctica can push cold air away from the surface ice.
Is the attached graph connected with the SSW? The EU severe weather site shows the area of the SSW moving over the S Pole in the coming days.

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/

39
I added fig 10 from Schroeder to the thwaites discussion thread. I attach here also.

sidd

40
The scientific method is the same regardless the phenomena. However it might be too late to define baseline and departure from baseline for a lot of ecosystems as they are changing rapidly.

41
Unfortunately the changes are faster than we can study them...

42
So Hawkins is redefining preindustrial to be 1720-1800 instead of 1850-1900. So of course it would show greater warming, but the underlying observations havent changed. That doesnt mean that sensitivity has gone up, it just means that we compare with a lower baseline.

One difficulty with Hawkins baseline is that measurements are scarcer the further back you go in time. So i can see why people use 1850-1900.

sidd

But Hawkins is working from a more sensible baseline because we know the the 1850-1900 period already includes human influences:

However, some anthropogenic warming is estimated to have already occurred by 1850 (Hegerl et al. 2007; Schurer et al. 2013; Abram et al. 2016) as greenhouse gas concentrations had started increasing around a century earlier (Fig. 1).

Sensitivity did not change but if you start from the wrong baseline it looks lower...


43
cross post (highlight added):  things are sometimes worse then modeled!
I think sometimes can replaced by usually.

It is just hard to accurately model the whole planet with many missing variables (trouble with clouds and many other things we just had not thought of before).

Once serious trouble in the Arctic was expected in the 2040s and nobody thought much about antarctica. Seemed to gain mass so probably ok for a long time after 2040.

Well that did not turn out to be true on both ends and i really can´t think of an example of a model that predicted things to be way worse.

First we are using a broad brush but we are painting the picture with missing details. So we did not know how warm the cold water coming up near the glaciers was or their topography which is relevant or the way they collapse.

And i think that rate of change is also doing something, maybe especially on land.

There was an interesting discussion in the science subforum about Tietsche et all 2011 and i read that paper then actually looked up the paper on the model they used. Lots of stuff in there. Quite detailed but so much is not in there.

The model mainly does land surface and temperatures and water level.

Every 20 years between 1980 and 2060, three such experiments are started in consecutive years (e.g., 2019,2020, 2021), so that we can analyze five different time slices with a three-member ensemble each.


What the model does not see is all the damage we do in the meantime (which is not that important for the paper i am quoting from but it is more important if you want to predict how much time we have to act.

So in between 1980 and now we have paved over many a grassland for parking lots and build many more roads. Added a couple of cities. Cut away some mangrove forests. Went fracking. Saw bark beetles eat whole forests. Indonesia had some nice fires while they were converting the local jungles to palm tree plantations. Now the Amazon is going to be a cattle ranch and then there is just the Congo left.

Basically you have to vary only some factors. But the models look at what current CO2 etc does in a natural world. It is a bit like the Houston 100 year flood maps. If you update the data you will get a refreshing new picture.

So basically the long term model is mostly run from the initial state while the changes between 1980 and now are quite large even if only looking at extra cities and decline of tropical forests.

Basic line: we are actively eating into all our carbon sinks so we might run out.

44
You didn't read the article. It is about how an increased vapor pressure deficit causes more water to be lost through the leaves, which causes plants to close their stomata to prevent water loss, which in turn reduces the amount of photosynthesis that takes place, so they grow more slowly. Nothing about the amount of water in total available to the plant.

45
The ozone hole has caused upper and middle stratospheric cooling which has contributed to the tightening of winds around Antarctica that led to the upwelling of CDW.

Of course, there are many other variables, but the damage to the ozone layer has cooled the stratosphere at both poles in the months of polar daylight.

46

I think if you really want to know where we are heading with emissions you simply have to follow the money, and investment banks have yet to actually stop funding oil, coal and gas infrastructure, and we have yet to control deforestation and industrial farming. It's not looking good.

That infrastructure has a long lead time to spend the money, 2 years or so, and then usually has a ROI over 10 years and thereafter it makes money. If the money is still flowing towards oil and gas how can we expect emissions to stop growing?

47
Those gravity studies of Antarctic geology are very interesting to me. It appears to me that the WARS is not inactive, but similar to the tectonic situation in the Arctic ocean where there's very slow spreading along ridge segments.

It's impossible to do typical GPS land based tectonic studies there because the ice moves much faster than the rifting. However, the ongoing volcanic activity, while not definitive, is evidence supportive of ongoing activity along the long rift/transform fault system that crosses Antarctica.

Of course, this tectonic situation is relevant to glacial melting, isostatic adjustment and sea level rise. This rift zone will be a potential region of increasing volcanism as glaciers retreat and depressure deep magma reservoirs. Yes, this is a potential positive feedback.

48
How hazardous algae blooms respond to changing oceans conditions may be illustrative of how microbial life responds. Here is an abstract for a webinar by Dave Hutchns that our ocean acidification group ( C-CAN )is sponsoring .
"How ocean acidification works hand-in-hand with warming and other global change stressors to promote toxic Pseudo-nitzschia harmful algal blooms along the West Coast
 
Toxic harmful algal blooms are an increasing problem globally, and the West Coast of the U.S. is no exception. In particular, massive neurotoxic blooms of the domoic acid-producing diatom Pseudo-nitzschia have recently appeared that are larger, more frequent, longer lasting, and much more toxic than any that have been historically recorded.  In recent years, these blooms have caused extensive damage to our Dungeness crab fishery, and they pose an increasing threat to other shellfish and finfish industries. It has become clear that this unprecedented intensification of toxic domoic acid events is very likely linked to ocean environmental change.  For instance, research in my laboratory has shown that ocean acidification can benefit the growth and increase the toxicity of many harmful algal bloom species, including Pseudo-nitzschia. At present day atmospheric CO2 concentrations, obtaining enough dissolved CO2 from the water to support growth can be a problem for Pseudo-nitzschia, which can thus be “carbon dioxide-limited”, and so it may actually directly benefit from higher CO2 levels. There is a definite potential for future CO2 fertilization of more frequent and more intense toxic algal blooms. However, we are now realizing that to understand and predict how ocean acidification will influence harmful algal blooms, we also need to consider a number of other interacting global change impacts. These other direct and indirect human disturbances include sea surface warming, losses of dissolved oxygen, stratification of the surface ocean, and modification of natural nutrient cycles by urban and agricultural pollution. For instance, in addition to ocean acidification, we have also shown that ocean warming strongly promotes domoic acid production by Pseudo-nitzschia.  I will discuss the complex network of interactions between ocean acidification and these many other global change multiple stressors that my lab group is currently working to understand, in order to help predict and perhaps mitigate the tremendously damaging toxic algal blooms that increasingly threaten our coastal fisheries and marine food webs."
 

49
A 2016 paper (Rising atmospheric methane: 2007–2014 growth and isotopic shift   -   summarizedhere) indicated the 2014 'large' increase in atmospheric methane appeared to be largely from tropical wetlands.  I couldn't find a more recent study of methane fingerprinting.

50
Which of course goes alongside this.

https://science.sciencemag.org/content/364/6440/548
Ocean winds blowing harder
Quote
Two frequently asked questions about how climate warming will affect the environment are whether windiness might change and what effects that might have on ocean waves. Young and Ribal analyzed global satellite data over the period from 1985 to 2018 to determine if there are any trends in oceanic wind speed and wave height. They found small increases in both quantities, with the strongest increases in extreme conditions and in the Southern Ocean. These findings are important for understanding air-sea exchange of energy and carbon dioxide and for projecting sea levels during storms.

Science, this issue p. 548
Abstract

In this study, global satellite data were analyzed to determine trends in oceanic wind speed and significant wave height over the 33-year period from 1985 to 2018. The analysis uses an extensive database obtained from 31 satellite missions comprising three types of instruments—altimeters, radiometers, and scatterometers. The analysis shows small increases in mean wind speed and significant wave height over this period, with larger increases in extreme conditions (90th percentiles). The largest increases occur in the Southern Ocean. Confidence in the results is strengthened because the wind speed trends are confirmed by all three satellite systems. An extensive set of sensitivity analyses confirms that both the mean and 90th percentile trends are robust, with only small impacts caused by satellite calibration and sampling patterns.

The higher sea states are  already impacting on west coast erosion rates here in NZ along with the anomalous regional rise in sea level.

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