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Tom_Mazanec

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3700 on: August 27, 2020, 04:38:54 PM »
Any idea when the present hiatus will end, ASLR?
SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3701 on: August 27, 2020, 08:21:49 PM »
The attached image from the linked 2017 article, shows that the last GMSTA faux hiatus occurred during the last negative phase (ending circa 2012) of the Interdecadal Pacific Oscillation (IPO); which is a long-term oscillation of sea-surface temperatures in the Pacific Ocean that can last from 20 to 30 years.  Therefore, as the article indicates we are currently in the surge phase for increasing GMSTA and the next faux hiatus could end circa 2032 to 2042.

Title: "Pacific Ocean shift could see 1.5C limit breached within a decade"

https://www.climatechange.ie/pacific-ocean-shift-could-see-1-5c-limit-breached-within-a-decade-2/

Extract: "The results suggest, on current trends, that warming is likely to reach 1.5C between 2026 and 2031, though it could be even earlier."


If you are interested in details, you could take a look at:

Bo Dong; Aiguo Dai; Mathias Vuille and Oliver Elison Timm (2018), "Asymmetric Modulation of ENSO Teleconnections by the Interdecadal Pacific Oscillation", J. Climate, 31 (18): 7337–7361.
https://doi.org/10.1175/JCLI-D-17-0663.1

https://journals.ametsoc.org/jcli/article/31/18/7337/92229/Asymmetric-Modulation-of-ENSO-Teleconnections-by

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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3702 on: August 27, 2020, 08:40:41 PM »
The linked reference (& non-associated image) provides some idea of consensus climate science's deep uncertainty regarding projected SLR this century.  To me this suggests that consensus climate science has declined to face the full uncertainties associated with: a) climate sensitivity, b) freshwater hosing events and c) MICI mechanism; which indicates that we are likely going to see more surprises in projected SLR in coming decades (say from E3SMv4), as ice-ocean interactions are better understood/modeled:

Andra J. Garner et al. (29 October 2018), "Evolution of 21st Century Sea Level Rise Projections", Earth's Future, https://doi.org/10.1029/2018EF000991

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018EF000991

Abstract
The modern era of scientific global‐mean sea level rise (SLR) projections began in the early 1980s. In subsequent decades, understanding of driving processes has improved, and new methodologies have been developed. Nonetheless, despite more than 70 studies, future SLR remains deeply uncertain. To facilitate understanding of the historical development of SLR projections and contextualize current projections, we have compiled a comprehensive database of 21st century global SLR projections. Although central estimates of 21st century global‐mean SLR have been relatively consistent, the range of projected SLR has varied greatly over time. Among studies providing multiple estimates, the range of upper projections shrank from 1.3–1.8 m during the 1980s to 0.6–0.9 m in 2007, before expanding again to 0.5–2.5 m since 2013. Upper projections of SLR from individual studies are generally higher than upper projections from the Intergovernmental Panel on Climate Change, potentially due to differing percentile bounds or a predisposition of consensus‐based approaches toward relatively conservative outcomes.

Plain Language Summary
In spite of more than 35 years of research, and over 70 individual studies, the upper bound of future global‐mean sea level rise (SLR) remains deeply uncertain. In an effort to improve understanding of the history of the science behind projected SLR, we present and analyze the first comprehensive database of 21st century global‐mean SLR projections. Results show a reduction in the range of SLR projections from the first studies through the mid‐2000s that has since reversed. In addition, results from this work indicate a tendency for Intergovernmental Panel on Climate Change reports to err on the side of least drama—a conservative bias that could potentially impede risk management.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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gerontocrat

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3703 on: August 28, 2020, 07:26:02 PM »
From the Guardian - article includes link to Nature Article (on-line shared only)

https://www.theguardian.com/world/2020/aug/26/antarctica-ice-shelves-risk-fracture-collapse
Antarctica: 60% of ice shelves at risk of fracture, research suggests
Collapse of shelves would accelerate loss of Antarctic ice sheet and increase sea-level rise


Lai and colleagues used machine learning to identify fracture-like features in satellite pictures of Antarctica, before modelling which fractures were vulnerable to hydrofracturing.

They developed a model to predict where fractures could form and found close agreement with the fractures mapped by their machine learning algorithm.

Lai said: “We predicted that the ice-shelves areas that can collapse due to hydrofracture are mostly the crucial part of ice shelves that hold back the upstream flow of ice sheets. Thus the loss of these ice-shelf areas due to hydrofracture can substantially affect the flow of ice sheets into the ocean.

“But predicting how much and how fast the loss of Antarctic ice and sea-level rise will occur due to the hydrofracturing process will require coupling our new fracture model with an ice-sheet and climate model, which is an important next step.”

The researchers hope their fracture model can help create more accurate models of the fate of the ice sheets, which together with climatic modelling will produce more accurate predictions of sea-level rise, which scientists believe could exceed one metre by the century’s end.

"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3704 on: August 28, 2020, 11:30:59 PM »
...

The researchers hope their fracture model can help create more accurate models of the fate of the ice sheets, which together with climatic modelling will produce more accurate predictions of sea-level rise, which scientists believe could exceed one metre by the century’s end.

We shouldn't forget that in the ASE the ice shelves are currently falling apart without hydrofracturing; while both the FRIS and the RIS are projected to change from cold ice shelves to warm ice shelves in coming decades.  In this regard, the first image shows how cool water beneath an ice shelf can stabilize basal crevasses, what warm water can 'burn' through such basal crevasses.  Also, the second image shows how climate change-induced changes in local wind effects on the ocean near the Weddell Sea can direct warm water through the Filchner Trough in order to warm the water beneath the Filchner-Ronne Ice Shelf, FRIS.

Thus, in coming decades, Antarctic ice shelves will be under assault from both the top and bottom.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3705 on: August 30, 2020, 04:38:50 PM »
Both the linked article and the non-associated linked reference confirm that the frequency of intense atmospheric river (AR) events will increase (double) in coming decades with continued global warming.  Furthermore, the attached image cites the threat that such intense AR events have on the near-future melting of snow/ice in both the West Antarctic and Greenland; which, could help to trigger local MICI mechanisms of key marine/marine-terminating glaciers.

Title: "Climate change may lead to bigger atmospheric rivers"

https://climate.nasa.gov/news/2740/climate-change-may-lead-to-bigger-atmospheric-rivers/

Extract: ""The results project that in a scenario where greenhouse gas emissions continue at the current rate, there will be about 10 percent fewer atmospheric rivers globally by the end of the 21st century," said the study's lead author, Duane Waliser, of NASA's Jet Propulsion Laboratory in Pasadena, California. "However, because the findings project that the atmospheric rivers will be, on average, about 25 percent wider and longer, the global frequency of atmospheric river conditions -- like heavy rain and strong winds -- will actually increase by about 50 percent."

The results also show that the frequency of the most intense atmospheric river storms is projected to nearly double."

&

Payne, A.E., Demory, M., Leung, L.R. et al. Responses and impacts of atmospheric rivers to climate change. Nat Rev Earth Environ 1, 143–157 (2020). https://doi.org/10.1038/s43017-020-0030-5

https://www.nature.com/articles/s43017-020-0030-5

Abstract
Atmospheric rivers (ARs) are characterized by intense moisture transport, which, on landfall, produce precipitation which can be both beneficial and destructive. ARs in California, for example, are known to have ended drought conditions but also to have caused substantial socio-economic damage from landslides and flooding linked to extreme precipitation. Understanding how AR characteristics will respond to a warming climate is, therefore, vital to the resilience of communities affected by them, such as the western USA, Europe, East Asia and South Africa. In this Review, we use a theoretical framework to synthesize understanding of the dynamic and thermodynamic responses of ARs to anthropogenic warming and connect them to observed and projected changes and impacts revealed by observations and complex models. Evidence suggests that increased atmospheric moisture (governed by Clausius–Clapeyron scaling) will enhance the intensity of AR-related precipitation — and related hydrological extremes — but with changes that are ultimately linked to topographic barriers. However, due to their dependency on both weather and climate-scale processes, which themselves are often poorly constrained, projections are uncertain. To build confidence and improve resilience, future work must focus efforts on characterizing the multiscale development of ARs and in obtaining observations from understudied regions, including the West Pacific, South Pacific and South Atlantic.

Key points
•   Atmospheric rivers are important components of the meridional transport of atmospheric moisture. They influence the hydroclimate of a number of regions in the mid-latitudes.
•   On land, atmospheric rivers are the source of both beneficial water resources and deleterious hazards (mudslides, floods and, in their absence on longer timescales, droughts).
•   The robust thermodynamic response of atmospheric moisture to climate change means that future atmospheric rivers will contain more moisture, but circulation changes and potential decreases in their precipitation efficiency must be considered in future impact studies.
•   At the global scale, much is still unknown about atmospheric rivers, including basic observations of their development, their interaction with large-scale dynamics and their role in short-duration, high-volume melt events over the Arctic and Antarctic.
•   Future research on the mechanisms driving atmospheric rivers and their life cycles will be a critical advancement for further quantifying their response to climate change.

Extract: "AR intensity is captured by the column-integrated water-vapour transport (IVT) …

 Second, an increase in q results in more latent heat being released as saturated air ascends, …

It is well known that current models do not accurately represent the effects of latent-heat release. Given the projected increases in atmospheric moisture and, therefore, in IVT related to ARs, there is an urgent need to better understand how they interact with large-scale circulation."

Caption: "Fig. 2 | Projected changes and impacts in atmospheric rivers.  Summary schematic of the main changes to atmospheric-river (AR) characteristics and impacts under warming. Red and blue symbols reveal increases and decreases, respectively; for frequency, red refers to a poleward movement and blue an equatorward movement of landfall. Light red and blue symbols with ‘?’ indicate uncertainty in the projection. Grey symbols indicate unknown changes. Background shading illustrating AR frequency increases is based on Espinoza et al.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3706 on: August 30, 2020, 05:20:27 PM »
As Greta Thunberg started her first strike against climate change in August 2018, before August 2020 comes to an end, I provide the following relatively recent quote from her:

Some people say that we are not doing enough to fight climate change. But that is not true. Because to “not do enough” you have to do something. And the truth is we are basically not doing anything.” Greta Thunberg Apr 7, 2020
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3707 on: August 31, 2020, 09:59:14 PM »
If AR5 projections on SLR were 'fair and balanced', one would not expect that SLR is currently tracking AR5's worst-case SLR scenario.  However, the linked article, and associated reference, makes it clear that SLR is currently tracking AR5's worst-case SLR scenario; and these documents do not even consider the deep uncertainty associated with possible future MICI-type of behavior:

Title: "Sea level rise from ice sheets track worst-case climate change scenario"

https://phys.org/news/2020-08-sea-ice-sheets-track-worst-case.html

Extract: "Ice sheets in Greenland and Antarctica whose melting rates are rapidly increasing have raised the global sea level by 1.8cm since the 1990s, and are matching the Intergovernmental Panel on Climate Change's worst-case climate warming scenarios."

&

Slater, T., Hogg, A.E. & Mottram, R. Ice-sheet losses track high-end sea-level rise projections. Nat. Clim. Chang. (2020). https://doi.org/10.1038/s41558-020-0893-y

https://www.nature.com/articles/s41558-020-0893-y

Abstract: "Observed ice-sheet losses track the upper range of the IPCC Fifth Assessment Report sea-level predictions, recently driven by ice dynamics in Antarctica and surface melting in Greenland. Ice-sheet models must account for short-term variability in the atmosphere, oceans and climate to accurately predict sea-level rise."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3708 on: September 01, 2020, 06:09:53 PM »
The first attached image shows the model-simulated probability density of annual U.S. hurricane damage, plotted on log damage scale, for the climate of late 20th century and late 21st century. But the second attached image shows just how misleading the first image can be when considering long-tail risk, as the second image shows the product of the damage and the probability graphed against log damage when integrated, the areas under the curves represent that total expected damage; which makes it clear the Hansen's 'storms of my grandchildren' will cause much more damage in the future due to long-tail risk.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3709 on: September 02, 2020, 08:18:14 PM »
Regarding Arctic Amplification (AA), the linked reference concludes that:

"Our results provide new and compelling evidence that AA owes its existence, fundamentally, to fast atmospheric processes."

This indicates that AA's contribution to abrupt climate change would occur quickly (within months) of a perturbation (in my opinion including a significant freshwater hosing event).

Michael Previdi et al. (25 August 2020), "Arctic Amplification: a Rapid Response to Radiative Forcing", Geophysical Research Letters, https://doi.org/10.1029/2020GL089933

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL089933?af=R

Abstract
Arctic amplification (AA) of surface warming is a prominent feature of anthropogenic climate change with important implications for human and natural systems. Despite its importance, the underlying causes of AA are not fully understood. Here, analyzing coupled climate model simulations, we show that AA develops rapidly (within the first few months) following an instantaneous quadrupling of atmospheric CO2. This rapid AA response ‐ which occurs before any significant loss of Arctic sea ice ‐ is produced by a positive lapse rate feedback over the Arctic. Sea ice loss is therefore not needed to produce polar‐amplified warming, although it contributes significantly to this warming after the first few months. Our results provide new and compelling evidence that AA owes its existence, fundamentally, to fast atmospheric processes.

Plain Language Summary
Climate warming is greater in the Arctic than at lower latitudes, a phenomenon known as Arctic Amplification. Despite its importance for humans and ecosystems, the causes of Arctic Amplification are not fully understood. Sea ice loss has long been thought to be a primary cause. However, we show here that Arctic Amplification happens faster than sea ice loss in climate models when atmospheric CO2 is increased. This indicates that atmospheric processes alone are capable of causing Arctic Amplification.

Key Points
•   Arctic Amplification develops rapidly (within a few months) in climate models forced with abrupt CO2 quadrupling
•   This rapid response is produced by a positive lapse rate feedback over the Arctic
•   The response occurs before Arctic sea ice loss becomes significant
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3710 on: September 02, 2020, 08:46:52 PM »
Based on paleo-evidence, the linked reference concludes that:

"Our results demonstrate that even under low-CO2 emission scenarios, surface ocean warming may be expected to exceed model projections and will be accentuated in the higher latitudes."

As increases in SST is critical to climate risk, to me the findings of this reference indicate that current consensus climate model projections are erring on the side of least drama:

McClymont, E. L., Ford, H. L., Ho, S. L., Tindall, J. C., Haywood, A. M., Alonso-Garcia, M., Bailey, I., Berke, M. A., Littler, K., Patterson, M. O., Petrick, B., Peterse, F., Ravelo, A. C., Risebrobakken, B., De Schepper, S., Swann, G. E. A., Thirumalai, K., Tierney, J. E., van der Weijst, C., White, S., Abe-Ouchi, A., Baatsen, M. L. J., Brady, E. C., Chan, W.-L., Chandan, D., Feng, R., Guo, C., von der Heydt, A. S., Hunter, S., Li, X., Lohmann, G., Nisancioglu, K. H., Otto-Bliesner, B. L., Peltier, W. R., Stepanek, C., and Zhang, Z.: Lessons from a high-CO2 world: an ocean view from  ∼ 3 million years ago, Clim. Past, 16, 1599–1615, https://doi.org/10.5194/cp-16-1599-2020, 2020.

https://cp.copernicus.org/articles/16/1599/2020/

Abstract
A range of future climate scenarios are projected for high atmospheric CO2 concentrations, given uncertainties over future human actions as well as potential environmental and climatic feedbacks. The geological record offers an opportunity to understand climate system response to a range of forcings and feedbacks which operate over multiple temporal and spatial scales. Here, we examine a single interglacial during the late Pliocene (KM5c, ca. 3.205±0.01 Ma) when atmospheric CO2 exceeded pre-industrial concentrations, but were similar to today and to the lowest emission scenarios for this century. As orbital forcing and continental configurations were almost identical to today, we are able to focus on equilibrium climate system response to modern and near-future CO2. Using proxy data from 32 sites, we demonstrate that global mean sea-surface temperatures were warmer than pre-industrial values, by ∼2.3 ∘C for the combined proxy data (foraminifera Mg∕Ca and alkenones), or by ∼3.2–3.4 ∘C (alkenones only). Compared to the pre-industrial period, reduced meridional gradients and enhanced warming in the North Atlantic are consistently reconstructed. There is broad agreement between data and models at the global scale, with regional differences reflecting ocean circulation and/or proxy signals. An uneven distribution of proxy data in time and space does, however, add uncertainty to our anomaly calculations. The reconstructed global mean sea-surface temperature anomaly for KM5c is warmer than all but three of the PlioMIP2 model outputs, and the reconstructed North Atlantic data tend to align with the warmest KM5c model values. Our results demonstrate that even under low-CO2 emission scenarios, surface ocean warming may be expected to exceed model projections and will be accentuated in the higher latitudes.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3711 on: September 03, 2020, 04:28:46 PM »
Given that modern climate change is an experiment that can only be conducted once and that consensus climate science contains a significant number of caveats about deep uncertainties (such as significant freshwater hosing, and precipitation, events) decision makers are faced with the question of how certain do we, collectively, need to be in order to take appropriate action?  Consensus climate science (such as AR5) seems to be satisfied that it is sufficient to 'prove' that modern climate change is anthropogenically driven and to have set a target of remaining well below a GMSTA of 2C above a 'pre-industrial' baseline in order for policy makers to take appropriate action and that no further clarification of right-tail climate risk is needed.  That said, I believe that I have provided thousands of peer-reviewed references that demonstrate that there is significant right-tail climate risk, and thus I provide the follow links to website that discuss what 'scientific consensus' is and how it changes with time; with the hope that we can soon collectively realize that ignoring right-tail climate risk in policy making is inappropriate and that a new consensus climate science (such as AR6 or AR7) paradigm needs to be developed ASAP:

Title: "Scientific consensus"

https://en.wikipedia.org/wiki/Scientific_consensus

Extract: "Scientific consensus is the collective judgment, position, and opinion of the community of scientists in a particular field of study. Consensus implies general agreement, though not necessarily unanimity.

Change of consensus over time

Most models of scientific change rely on new data produced by scientific experiment. Karl Popper proposed that since no amount of experiments could ever prove a scientific theory, but a single experiment could disprove one, science should be based on falsification.  Whilst this forms a logical theory for science, it is in a sense "timeless" and does not necessarily reflect a view on how science should progress over time.

Among the most influential challengers of this approach was Thomas Kuhn, who argued instead that experimental data always provide some data which cannot fit completely into a theory, and that falsification alone did not result in scientific change or an undermining of scientific consensus. He proposed that scientific consensus worked in the form of "paradigms", which were interconnected theories and underlying assumptions about the nature of the theory itself which connected various researchers in a given field. Kuhn argued that only after the accumulation of many "significant" anomalies would scientific consensus enter a period of "crisis". At this point, new theories would be sought out, and eventually one paradigm would triumph over the old one – a series of paradigm shifts rather than a linear progression towards truth. Kuhn's model also emphasized more clearly the social and personal aspects of theory change, demonstrating through historical examples that scientific consensus was never truly a matter of pure logic or pure facts.  However, these periods of 'normal' and 'crisis' science are not mutually exclusive. Research shows that these are different modes of practice, more than different historical periods.

Politicization of science

The inherent uncertainty in science, where theories are never proven but can only be disproven (see falsifiability), poses a problem for politicians, policymakers, lawyers, and business professionals. Where scientific or philosophical questions can often languish in uncertainty for decades within their disciplinary settings, policymakers are faced with the problems of making sound decisions based on the currently available data, even if it is likely not a final form of the "truth". The tricky part is discerning what is close enough to "final truth". For example, social action against smoking probably came too long after science was 'pretty consensual'."

&

Title: "Scientific Change"

https://iep.utm.edu/s-change/

Extract: "If Science Changes, What is Science?
Models of change from science—evolutionary, mechanical, revolutionary—often serve as models of change in science.

This makes it difficult to disentangle the actual history of science from our philosophical expectations about it. … Philosophers, for their part, have argued that details of the history of science matter little to a proper theory of scientific change, and that a distinction can and should be made between how scientific ideas are discovered and how they are justified. Beneath the ranging, messy, and contingent happenings which led to our current scientific outlook, there lies a progressive, systematically evolving activity waiting to be rationally reconstructed."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3712 on: September 03, 2020, 05:16:03 PM »
The linked reference finds that when evaluating the influence of plant physiology with increasing CO2 levels, that TCR (full) has a mean value in CMIP5 & CMIP6 that is about 6.1% higher than the TCR estimated using only radiative forcing (see the attached image & caption) & that this deviation increases with higher values of GMSTA.  Thus consensus science is likely underestimating the risks of global warming in the coming decades:

Claire M. Zarakas et al. (2020), "Plant Physiology Increases the Magnitude and Spread of the Transient Climate Response to CO2 in CMIP6 Earth System Models
J. Climate, 33, (19), 8561–8578, https://doi.org/10.1175/JCLI-D-20-0078.1

https://journals.ametsoc.org/jcli/article/33/19/8561/353455/Plant-Physiology-Increases-the-Magnitude-and

Abstract: "Increasing concentrations of CO2 in the atmosphere influence climate both through CO2’s role as a greenhouse gas and through its impact on plants. Plants respond to atmospheric CO2 concentrations in several ways that can alter surface energy and water fluxes and thus surface climate, including changes in stomatal conductance, water use, and canopy leaf area. These plant physiological responses are already embedded in most Earth system models, and a robust literature demonstrates that they can affect global-scale temperature. However, the physiological contribution to transient warming has yet to be assessed systematically in Earth system models. Here this gap is addressed using carbon cycle simulations from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP) to isolate the radiative and physiological contributions to the transient climate response (TCR), which is defined as the change in globally averaged near-surface air temperature during the 20-yr window centered on the time of CO2 doubling relative to preindustrial CO2 concentrations. In CMIP6 models, the physiological effect contributes 0.12°C (σ: 0.09°C; range: 0.02°–0.29°C) of warming to the TCR, corresponding to 6.1% of the full TCR (σ: 3.8%; range: 1.4%–13.9%). Moreover, variation in the physiological contribution to the TCR across models contributes disproportionately more to the intermodel spread of TCR estimates than it does to the mean. The largest contribution of plant physiology to CO2-forced warming—and the intermodel spread in warming—occurs over land, especially in forested regions."

Caption: "The relationship between TCRRAD (RAD-PI) and TCRFULL (FULL-PI). The gray 1:1 line is where we would expect all models to be if the TCR were entirely caused by the radiative effects of CO2. The added warming from the physiological effect is the vertical distance between the gray 1:1 line and each point. Marker types indicate CMIP phase (CMIP5: circles; CMIP6: triangles) and colors indicate modeling center. Crosses demarcate the CMIP6 (solid) and CMIP5 (dashed) multimodel means, and the width of each cross corresponds to two times the ensemble mean standard deviation in global mean near-surface temperature from the preindustrial control."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3713 on: September 03, 2020, 10:50:42 PM »
While the linked IPCC Chapter 6 from the 2019 Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) is one of the most advanced IPCC assessments of right-tail climate risk; however, I note that it does not consider many risk factors including:

a) The relatively high climate sensitivity values projected by the CMIP6 'Wolf Pack';
b) A likely freshwater hosing event associated with the Beaufort Gyre,
c) The risk MICI-type of failures in the coming decades on the Earth's Energy Imbalance, nor;
d) Many significant pattern effects.

Title: "SPECIAL REPORT: SPECIAL REPORT ON THE OCEAN AND CRYOSPHERE IN A CHANGING CLIMATE - CH06 - Extremes, Abrupt Changes and Managing Risks"

https://www.ipcc.ch/srocc/chapter/chapter-6/

Extract: "This chapter assesses extremes and abrupt or irreversible changes in the ocean and cryosphere in a changing climate, to identify regional hot spots, cascading effects, their impacts on human and natural systems, and sustainable and resilient risk management strategies. It is not comprehensive in terms of the systems assessed and some information on extremes, abrupt and irreversible changes, in particular for the cryosphere, may be found in other chapters."

Caption for the attached image: "Figure 6.1 | Framework used in this chapter (see discussion in Chapter 1). Singular or multiple climate drivers can lead to extreme hazards and associated cascading impacts, which combined with non-climatic drivers affect exposure and vulnerability, leading to compound risks. Extremes discussed are tropical cyclones (TCs) and extratropical cyclones (ETCs) and associated sea surface dynamics (Section 6.3); marine heatwaves (MHWs) (Section 6.4), extreme El Niño and La Niña events (Section 6.5); and extreme oceanic decadal variability (Section 6.6). Examples of abrupt events, irreversibility and tipping points discussed are the Atlantic Meridional Overturning Circulation (AMOC) and subpolar gyre (SPG) system (Section 6.7). Section 6.2 also collects examples of such events from the rest of the Special Report on the Oceans and Cryosphere in a Changing Climate (SROCC) and compiles examples of events whose occurrence or severity has been linked to climate change. Cascading impacts and compound events are discussed in Section 6.8 and three examples are given in Box 6.1. Section 6.9 discusses risk management, climate resilience pathways, transformative governance adaptation and mitigation required to address societal and environmental risks."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3714 on: September 03, 2020, 11:09:40 PM »
The linked 2019 review paper presents a range of relatively recent SLR projections including those associated with DeConto and Pollard (2016).  However, I note that this review paper does not consider such issues as:

1. The relatively high projected climate sensitivities from the CMIP6 'Wolf Pack';
2. Ice-climate feedbacks including freshwater hosing events; nor
3. Significant pattern effects.

Jevrejeva, S., Frederikse, T., Kopp, R.E. et al. Probabilistic Sea Level Projections at the Coast by 2100. Surv Geophys 40, 1673–1696 (2019). https://doi.org/10.1007/s10712-019-09550-y

https://link.springer.com/article/10.1007/s10712-019-09550-y

Abstract: "As sea level is rising along many low-lying and densely populated coastal areas, affected communities are investing resources to assess and manage future socio-economic and ecological risks created by current and future sea level rise. Despite significant progress in the scientific understanding of the physical mechanisms contributing to sea level change, projections beyond 2050 remain highly uncertain. Here, we present recent developments in the probabilistic projections of coastal mean sea level rise by 2100, which provides a summary assessment of the relevant uncertainties. Probabilistic projections can be used directly in some of the decision frameworks adopted by coastal engineers for infrastructure design and land use planning. However, relying on a single probability distribution or a set of distributions based upon a common set of assumptions can understate true uncertainty and potentially misinform users. Here, we put the probabilistic projections published over the last 5 years into context."

Caption: "Fig 3 | Projections of globally mean sea level rise (GMSL, in m) by 2100 under RCP8.5 represented in a cumulative distribution diagram. (Church et al. 2013a; Kopp et al. 2014; Jackson and Jevrejeva, 2016; Kopp et al. 2017; Le Bars et al. 2017). Here, the curve labelled as “Hunter et al. (2013), based on IPCC (Church et al. 2013a)”, is a modification of the median and likely range provided by Church et al. (2013a), following the interpretation of Hunter et al. (2013), which assumes a symmetric Gaussian extrapolation of the IPCC likely range and median values. DP16 is reference to the estimate of contribution from Antarctica ice sheet by DeConto and Pollard (2016), which is used in studies by Kopp et al. (2017) and Le Bars, et al. (2017); JJ16 is reference to Jackson and Jevrejeva, 2016 (including RCP8.5 scenarios, labelled as JJ16 RCP8.5 projection, and the high-end scenario, labelled as JJ16 High-end projection)"
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3715 on: September 04, 2020, 03:24:59 AM »
The linked reference indicates that the reduction of Bering Sea winter sea ice will contribute to accelerating Arctic Amplification with continuing global warming:

Miriam C. Jones et al. (02 Sep 2020), "High sensitivity of Bering Sea winter sea ice to winter insolation and carbon dioxide over the last 5500 years", Science Advances, Vol. 6, no. 36, eaaz9588, DOI: 10.1126/sciadv.aaz9588

https://advances.sciencemag.org/content/6/36/eaaz9588

Abstract
Anomalously low winter sea ice extent and early retreat in CE 2018 and 2019 challenge previous notions that winter sea ice in the Bering Sea has been stable over the instrumental record, although long-term records remain limited. Here, we use a record of peat cellulose oxygen isotopes from St. Matthew Island along with isotope-enabled general circulation model (IsoGSM) simulations to generate a 5500-year record of Bering Sea winter sea ice extent. Results show that over the last 5500 years, sea ice in the Bering Sea decreased in response to increasing winter insolation and atmospheric CO2, suggesting that the North Pacific is highly sensitive to small changes in radiative forcing. We find that CE 2018 sea ice conditions were the lowest of the last 5500 years, and results suggest that sea ice loss may lag changes in CO2 concentrations by several decades.

Extract: "Implications for winter sea ice in the Bering Sea and the Arctic
The substantial rate of anthropogenic CO2 inputs into the atmosphere over industrialization suggests that a loss in Bering Sea sea ice extent is accelerating or is already committed to complete sea ice loss as a result of delayed response to anthropogenic forcing. Low winter sea ice anomalies in CE 2018 and CE 2019 indicate future conditions that favor an ice-free Bering Sea. Widespread effects of Bering Sea winter sea ice loss are expected to occur. Ecosystem responses to low sea ice in CE 2018 included altered food webs that led to sea bird die-offs and may represent a harbinger of future low sea ice extent (31). Further intensification of observed North Pacific influence in the Bering Sea leading to a reduction in sea ice can further affect heat transport to the Arctic Ocean basin. Although the Bering Strait throughflow may be relatively small (<1 Sv; 1 Sv = 106 m3 s−1), it can have a disproportionate influence on heatflux into the Arctic Ocean basin, and recent increases have been linked to weakening northerly winds (32), signifying enhanced winds originating from the North Pacific could amplify Arctic Ocean sea ice decline via increasing winds from the south. Simultaneously, the increased frequency and duration of winter cyclones in the Arctic have led to the large reductions in freezing degree days in Arctic Ocean winters (33, 34). A loss of sea ice can also increase coastal erosion and increase land temperatures that result in permafrost thaw (35), further amplifying warming (36)."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3716 on: September 04, 2020, 08:41:00 AM »
For those who are interested, I provide the following video link on ECS and cloud feedback:

Title: "ECS & cloud feedback virtual symposium 4"

https://www.youtube.com/watch?v=ABFwtr1g3z0&feature=youtu.be

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3717 on: September 08, 2020, 03:57:52 AM »
In regard to the findings of the linked reference, Andrew Dessler states: "So energy imbalance is presently +0.87 W/m2/K. How much more does the Earth have to warm to wipe out that imbalance? That connection between energy imbalance and temperature is known as the climate sensitivity.

If climate sensitivity is ~0.75 K/(W/m2) (corresponding to ~3°C for doubled CO2), then that tells us that we need to warm the climate about 1°C *more* to reach energy balance, at which point the Earth will be in energy balance.

Except it won't be. We're still emitting carbon dioxide, so by the time the planet has warmed enough to wipe out the +0.87 W/m2 of energy imbalance that we measure today, we'll have emitted a whole lotta CO2 that will have increased the energy imbalance."

However, if the effective climate sensitivity is higher than that assumed by Dessler, then GMSTA will increase faster than assumed by Dessler:

von Schuckmann, K., Cheng, L., Palmer, M. D., Hansen, J., Tassone, C., Aich, V., Adusumilli, S., Beltrami, H., Boyer, T., Cuesta-Valero, F. J., Desbruyères, D., Domingues, C., García-García, A., Gentine, P., Gilson, J., Gorfer, M., Haimberger, L., Ishii, M., Johnson, G. C., Killick, R., King, B. A., Kirchengast, G., Kolodziejczyk, N., Lyman, J., Marzeion, B., Mayer, M., Monier, M., Monselesan, D. P., Purkey, S., Roemmich, D., Schweiger, A., Seneviratne, S. I., Shepherd, A., Slater, D. A., Steiner, A. K., Straneo, F., Timmermans, M.-L., and Wijffels, S. E.: Heat stored in the Earth system: where does the energy go?, Earth Syst. Sci. Data, 12, 2013–2041, https://doi.org/10.5194/essd-12-2013-2020, 2020.

https://essd.copernicus.org/articles/12/2013/2020/

Abstract
Human-induced atmospheric composition changes cause a radiative imbalance at the top of the atmosphere which is driving global warming. This Earth energy imbalance (EEI) is the most critical number defining the prospects for continued global warming and climate change. Understanding the heat gain of the Earth system – and particularly how much and where the heat is distributed – is fundamental to understanding how this affects warming ocean, atmosphere and land; rising surface temperature; sea level; and loss of grounded and floating ice, which are fundamental concerns for society. This study is a Global Climate Observing System (GCOS) concerted international effort to update the Earth heat inventory and presents an updated assessment of ocean warming estimates as well as new and updated estimates of heat gain in the atmosphere, cryosphere and land over the period 1960–2018. The study obtains a consistent long-term Earth system heat gain over the period 1971–2018, with a total heat gain of 358±37 ZJ, which is equivalent to a global heating rate of 0.47±0.1 W m−2. Over the period 1971–2018 (2010–2018), the majority of heat gain is reported for the global ocean with 89 % (90 %), with 52 % for both periods in the upper 700 m depth, 28 % (30 %) for the 700–2000 m depth layer and 9 % (8 %) below 2000 m depth. Heat gain over land amounts to 6 % (5 %) over these periods, 4 % (3 %) is available for the melting of grounded and floating ice, and 1 % (2 %) is available for atmospheric warming. Our results also show that EEI is not only continuing, but also increasing: the EEI amounts to 0.87±0.12 W m−2 during 2010–2018. Stabilization of climate, the goal of the universally agreed United Nations Framework Convention on Climate Change (UNFCCC) in 1992 and the Paris Agreement in 2015, requires that EEI be reduced to approximately zero to achieve Earth's system quasi-equilibrium. The amount of CO2 in the atmosphere would need to be reduced from 410 to 353 ppm to increase heat radiation to space by 0.87 W m−2, bringing Earth back towards energy balance. This simple number, EEI, is the most fundamental metric that the scientific community and public must be aware of as the measure of how well the world is doing in the task of bringing climate change under control, and we call for an implementation of the EEI into the global stocktake based on best available science. Continued quantification and reduced uncertainties in the Earth heat inventory can be best achieved through the maintenance of the current global climate observing system, its extension into areas of gaps in the sampling, and the establishment of an international framework for concerted multidisciplinary research of the Earth heat inventory as presented in this study. This Earth heat inventory is published at the German Climate Computing Centre (DKRZ, https://www.dkrz.de/, last access: 7 August 2020) under the DOI https://doi.org/10.26050/WDCC/GCOS_EHI_EXP_v2 (von Schuckmann et al., 2020).


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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3718 on: September 08, 2020, 10:42:10 PM »


The linked reference provides more evidence that climate sensitivity is state dependent and increases with increasing values of GMSTA.  That said, the linked reference does not access the multi-decadal influence of significant freshwater hosing events on the effective climate sensitivity in coming decades:

Jiang Zhu and Christopher J. Poulsen (02 September 2020), "On the increase of climate sensitivity and cloud feedback with warming in the Community Atmosphere Models", Geophysical Research Letters, https://doi.org/10.1029/2020GL089143

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL089143

Abstract
Modeling and paleoclimate proxy‐based studies suggest that equilibrium climate sensitivity (ECS) depends on the background climate state, though the reason is not thoroughly understood. Here we study the state dependence of ECS over a large range of global mean surface temperature (GMST) in the Community Atmosphere Model (CAM) versions 4, 5, and 6 by varying atmospheric CO2 concentrations. We find a robust increase of ECS with GMST in all three models, albeit at different rates, which is primarily attributed to strengthening of the shortwave cloud feedback (λcld) at both high and low latitudes. Over high latitudes, increasing GMST leads to a reduction in the cloud ice fraction, weakening the (negative) cloud‐phase feedback due to the phase transition of cloud ice to liquid and thereby strengthening λcld. Over low‐latitude regions, increasing GMST strengthens λcld likely through the nonlinear increase in water vapor, which causes low‐cloud thinning through thermodynamic and radiative processes.

Plain Language Summary
Equilibrium climate sensitivity (ECS) is defined as the equilibrium increase in global mean temperature as a result of a doubling of atmospheric CO2 concentration. The latest assessment by the Intergovernmental Panel on Climate Change reported a likely ECS range of 1.5–4.5°C. Narrowing the ECS range is of paramount importance for prediction of future warming. Earth’s surface has experienced prolonged periods of large magnitude warming in the geological past, which provide important empirical information on ECS. To quantitatively use the paleoclimate information, we need a complete understanding of how ECS may depend on the background climate. In this study, we investigate the physical mechanisms responsible for the state dependence of ECS using three climate models that have distinct model physics. In all three models, we find that ECS grows as the background climate warms, i.e., a warmer climate is more sensitive to external forcing. We attribute the increase of ECS to both high‐ and low‐latitude cloud processes. Over high latitudes, cloud ice fraction decreases with global warming, weakening the potential for mixed‐phase clouds to reflect solar radiation and amplifying surface warming. Over low latitudes, global warming enhances the efficiency of processes that make clouds less opaque, again, amplifying surface warming.

Key Points
•   ECS increases with CO2‐induced global warming in CAM 6, 5, and 4, and is primarily attributed to the strengthening of cloud feedback
•   High‐latitude λcld strengthens with warming due to a decrease of cloud ice fraction and a weakening of the negative cloud‐phase feedback
•   Low‐latitude λcld strengthening is linked to cloud thinning over subsidence regions likely caused by cloud interactions with water vapor
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3719 on: September 09, 2020, 10:05:22 AM »
The linked BBC article discusses new research that more clearly maps pathways (see the image) for modified CDW to beneath the Eastern Thwaites Ice Shelf and the Thwaites Ice Tongue:

Title: "Thwaites: 'Doomsday Glacier' vulnerability seen in new maps"

https://www.bbc.com/news/science-environment-54079587

Extract: "Now, a UK-US team has surveyed the deep seafloor channels in front of the glacier that almost certainly provide the access for warm water to infiltrate and attack Thwaites' underside.

"The connected channels that we've mapped in detail for the first time are the potential pathways for deep-ocean warm water to get in and do damage at that point where the glacier is still grounded on the seabed, where it begins to lift up and float," explained BAS colleague Dr Tom Jordan, "but also to melt the base of the ice shelf, which if you weaken will make the ice further upstream in the glacier flow faster."

At the moment, the eastern side of the ice shelf is hooked on to a large ridge, which gives it stability. But the current melting trend would suggest this situation won't last much longer, says BAS's Dr Robert Larter.

"When the Eastern Ice Shelf becomes unpinned, the ice will spread out and thin, eventually breaking up, as we can see is happening right now on the (central) glacier tongue," he told BBC News. "Even before ice shelf break-up, the unpinning and thinning will reduce the buttressing effect of the ice shelf on the glacier upstream of it, resulting in increased ice flow velocity. This in turn will further accelerate thinning of the glacier and grounding line retreat.""

See also:

New gravity-derived bathymetry for the Thwaites, Crosson, and Dotson ice shelves revealing two ice shelf populations, The Cryosphere (2020). DOI: 10.5194/tc-14-2869-2020

&

Revealing the former bed of Thwaites Glacier using sea-floor bathymetry: implications for warm-water routing and bed controls on ice flow and buttressing, The Cryosphere (2020). doi.org/10.5194/10.5194/tc-14-2883-2020

&

Title: "Deep channels link ocean to Antarctic glacier"

https://phys.org/news/2020-09-deep-channels-link-ocean-antarctic.html

Extract: "Newly discovered deep seabed channels beneath Thwaites Glacier in West Antarctica may be the pathway for warm ocean water to melt the underside of the ice. Data from two research missions, using aircraft and ship, are helping scientists to understand the contribution this huge and remote glacier is likely to make to future global sea level rise."
« Last Edit: September 09, 2020, 10:14:46 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3720 on: September 09, 2020, 05:15:41 PM »
Recent research has found that the oceans have recently been absorbing 10% more CO2 than projected by CMIP models; while the linked reference finds carbon absorbed by the oceans now inhibit future marine CO2 uptake through reductions to the buffering capacity of surface seawater; which amplifies TCR.  This is not good news:

K. B. Rodgers et al. (02 September 2020), "Re‐emergence of anthropogenic carbon into the ocean’s mixed layer strongly amplifies transient climate sensitivity", Geophysical Research Letters, https://doi.org/10.1029/2020GL089275

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL089275?af=R

Abstract
A positive marine chemistry‐climate feedback was originally proposed by Revelle and Suess (1957), whereby the invasion flux of anthropogenic carbon into the ocean serves to inhibit future marine CO2 uptake through reductions to the buffering capacity of surface seawater. Here we use an ocean‐circulation‐carbon‐cycle model to identify an upper limit on the impact of re‐emergence of anthropogenic carbon into the ocean’s mixed layer on the cumulative airborne fraction of CO2 in the atmosphere. We find under an RCP8.5 emissions pathway (with steady circulation) that the cumulative airborne fraction of CO2 has a seven‐fold reduction by 2100 when the CO2 buffering capacity of surface seawater is maintained at pre‐industrial levels. Our results indicate that the effect of re‐emergence of anthropogenic carbon into the mixed layer on the buffering capacity of CO2 amplifies the transient climate sensitivity of the Earth system.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3721 on: September 09, 2020, 05:28:55 PM »
The linked reference indicates that the CMIP6 models imply a high committed global warming if we drastically cut anthropogenic GHG emissions last year; however, we have not done so, so GMSTA will almost certainly raise well above 2C above a pre-industrial baseline, sooner rather than later:

Huntingford, C., Williamson, M.S. & Nijsse, F.J.M.M. CMIP6 climate models imply high committed warming. Climatic Change (2020). https://doi.org/10.1007/s10584-020-02849-5

https://link.springer.com/article/10.1007/s10584-020-02849-5

Abstract: "A question often asked by many, and across different strands of society, is what would happen to global warming levels if atmospheric greenhouse gases (GHGs) are held at their current concentrations. Existing research, e.g. as summarised by Meehl et al. (2007), estimates potentially considerable additional warming resulting from stable present-day atmospheric GHG concentrations. We use the Equilibrium Climate Sensitivity (ECS) values of the latest set of Earth System Models (ESMs) in the CMIP6 ensemble, to estimate equilibrium global warming. Radiative forcing characterises the combined effect of human-induced changes to all GHGs and aerosols in a single metric. We find that based on the ECS values and contemporary radiative forcing, additional warming would be substantial. Approximately half of CMIP6 ESMs project an equilibrium global warming greater than two degrees (compared to pre-industrial times) for the year 2019 radiative forcing. This statistic increases to around 80% for the risk of exceeding the 1.5 °C threshold. Our analysis is specific to what is sometimes referred to as the “constant composition commitment”. For comparison, “net-zero” emissions imply no overall net emissions by humans, which would involve even larger reductions in fossil fuel burning. Achieving net-zero implies that natural land- and ocean-atmosphere exchanges would modulate GHG concentrations and likely including the removal of some atmospheric CO2."
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Bruce Steele

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3722 on: September 09, 2020, 06:07:41 PM »
ASLR, I find the sentence in the abstract KB Rodgers paper kinda confusing.
“We find under an RCP8.5 emissions pathway (with steady circulation) that the cumulative airborne fraction of CO2 has a seven‐fold reduction by 2100 when the CO2 buffering capacity of surface seawater is maintained at pre‐industrial levels.”
The buffer capacity of the oceans is reduced as the pH is pushed into lower numbers by addition of CO2. So the result will be the oceans are less able to uptake CO2 because the buffer is reduced. The alkalinity of the oceans builds over very long term timelines while the CO2 increase is virtually instantaneous. The buffer capacity cannot be rebuilt in timeframes relevant to humans IMO .
 The sentence should be more direct. It should state that under current RCP 8.5 scenarios the ocean carbon sink will be reduced seven fold by 2100 due to a reduction of the buffer capacity of surface waters.

 As the oceans buffer capacity is reduced the CO2 that currently enters the oceans will instead stay in the atmosphere. The ocean will not return to their current ability to absorb one quarter of atmospheric CO2 emissions for tens of thousands of years. The farther we push atmospheric CO2 numbers up the longer it will take earth to recover. Which is why this is an extinction event.
 
 
« Last Edit: September 09, 2020, 06:19:04 PM by Bruce Steele »

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3723 on: September 09, 2020, 06:16:42 PM »
CO2 solubility decreases with increasing water temperature so warmer surface waters lead to less oceanic CO2 uptake. Even if we were able to dump dry lake fulls of sodium bicarbonate into the ocean to neutralize the acidity from added CO2, the warm water would take up less CO2. There's a hysteresis problem.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3724 on: September 09, 2020, 06:17:03 PM »
While to me the linked reference has an ESLD focus; nevertheless, I believe that it provides useful information about uncertainties in GMSTA model projections associated with anthropogenic aerosol radiative forcing/emission scenarios.  For example, the third attached image indicates that we might pass a 1.5C rise in GMSTA (from a pre-industrial baseline) as early as 2022 due uncertainties in anthropogenic aerosol effective radiative forcing.

A H Peace et al. (2020), "Effect of aerosol radiative forcing uncertainty on projected exceedance year of a 1.5 °C global temperature rise", Environmental Research Letters, Volume 15, Number 9, https://doi.org/10.1088/1748-9326/aba20c

https://iopscience.iop.org/article/10.1088/1748-9326/aba20c

Abstract
Anthropogenic aerosol emissions are predicted to decline sharply throughout the 21st century, in line with climate change and air quality mitigation policies, causing a near-term warming of climate that will impact our trajectory towards 1.5 °C above pre-industrial temperatures. However, the persistent uncertainty in aerosol radiative forcing limits our understanding of how much the global mean temperature will respond to near-term reductions in anthropogenic aerosol emissions. We quantify the model and scenario uncertainty in global mean aerosol radiative forcing up to 2050 using statistical emulation of a perturbed parameter ensemble for emission reduction scenarios consistent with three Shared Socioeconomic Pathways. We then use a simple climate model to translate the uncertainty in aerosol radiative forcing into uncertainty in global mean temperature projections, accounting additionally for the potential correlation of aerosol radiative forcing and climate sensitivity. Near-term aerosol radiative forcing uncertainty alone causes an uncertainty window of around 5 years (2034–2039) on the projected year of exceeding a global temperature rise of 1.5 °C above pre-industrial temperatures for a middle of the road emissions scenario (SSP2-RCP4.5). A correlation between aerosol radiative forcing and climate sensitivity would increase the 1.5 °C exceedance window by many years. The results highlight the importance of quantifying aerosol radiative forcing and any relationship with climate sensitivity in climate models in order to reduce uncertainty in temperature projections."

Caption for the first image: "Figure 3. Global mean radiative forcing relative to the year 2000 for anthropogenic aerosol emission (anthropogenic SO2, carbonaceous fossil fuel, carbonaceous biofuel) reductions scaled to match three SSP emission scenarios. The solid line represents the mean of radiative forcing predictions, with the shaded area representing the 95% credible interval that represents the parametric uncertainty within the aerosol-climate model. The dashed line and lighter shaded areas represent where aerosol radiative forcing has been extrapolated.

Caption for the second and third images: "Figure 4. Global mean temperature change relative to 1850–1900 for SSP2-RCP4.5. We prescribe our aerosol radiative forcing (RF) from 2000 for anthropogenic aerosol emissions changes. All other forcings are calculated by FaIR v1.4 from SSP2-RCP4.5 prescribed emissions. The top figure (a) shows the impact of model uncertainty in aerosol radiative forcing from 2000, with the darker shaded line representing our mean radiative forcing value translated to temperature and the shaded region representing the 95% credible interval (CI) for aerosol radiative forcing, with the black dashed like representing observations from HadCRUT4. The bottom figure (b) displays an illustrative range in exceedance year of 1.5 °C if a statistical relationship between uncertainty in aerosol radiative forcing and climate sensitivity is accounted for from 2000, for example if stronger values of our aerosol forcing range are paired with higher values of ECS and TCR, and weaker values of our aerosol forcing range are paired with lower values of ECS and TCR. The range of values selected for ECS and TCR in each projection is displayed in the figure legend."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3725 on: September 09, 2020, 06:35:23 PM »
Fish out of water, The alkalinity of seawater affects the saturation state of aragonite so as pH goes down while alkalinity is reduced the saturation state goes down. Shellfish have a harder time making shells. If on the other hand if CO2 goes up ( pH goes down ) and alkalinity is increased the saturation state can be maintained. Temperature is less important than alkalinity IMO because the timeframe of rebuilding buffer capacity is much longer than timeframes necessary to change surface water temperatures.   

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3726 on: September 09, 2020, 06:42:46 PM »
ASLR, I find the sentence in the abstract KB Rodgers paper kinda confusing.
“We find under an RCP8.5 emissions pathway (with steady circulation) that the cumulative airborne fraction of CO2 has a seven‐fold reduction by 2100 when the CO2 buffering capacity of surface seawater is maintained at pre‐industrial levels.”
The buffer capacity of the oceans is reduced as the pH is pushed into lower numbers by addition of CO2. So the result will be the oceans are less able to uptake CO2 because the buffer is reduced. The alkalinity of the oceans builds over very long term timelines while the CO2 increase is virtually instantaneous. The buffer capacity cannot be rebuilt in timeframes relevant to humans IMO .
 The sentence should be more direct. It should state that under current RCP 8.5 scenarios the ocean carbon sink will be reduced seven fold by 2100 due to a reduction of the buffer capacity of surface waters.

 As the oceans buffer capacity is reduced the CO2 that currently enters the oceans will instead stay in the atmosphere. The ocean will not return to their current ability to absorb one quarter of atmospheric CO2 emissions for tens of thousands of years. The farther we push atmospheric CO2 numbers up the longer it will take earth to recover. Which is why this is an extinction event.

Bruce, I frequently am confused by the language used by consensus climate scientists, so I went to Sci-hub and input: doi: 10.1029/2020GL089275, which leads me to believe that that sentence in the abstract corresponds to the following sentence from the conclusions (which is different from your interpretation):

"To put this into context, for the case where the Earth system is projected to warm by 3.5°C by the end of the 21st century under a business-as-usual emissions scenario, our results indicate as an upper bound that the 3.5°C warming reflects an amplification by a factor of 7 relative to a 0.5°C warming that would occur in the absence of changes to the buffering capacity of surface seawater."

Extract: "Conclusions

Our CMIP5-class ocean carbon cycle model has demonstrated that the net ocean uptake of anthropogenic carbon (Cant) is strongly sensitive to perturbations in the CO2 buffering capacity of surface ocean waters. This is closely connected to the process of re-emergence of Cant from the ocean interior to the surface mixed layer (the mechanism highlighted by Toyama et al., 2017). For the idealized case we impose of instantaneous subduction of Cant ocean reservoirs with zero re-emergence over the duration of the experiment, the ocean is able to absorb substantially more carbon from the atmosphere than for the case with extensive re-emergence, increasing the ocean carbon inventory by a factor of 2 over the 20th century and reaching a factor of 2.8 by the end of the 21st century.

For the atmospheric carbon reservoir, this corresponds to a significantly reduced cumulative airborne fraction (CAF) for the RE_OFF simulation. The CAF for the perturbed simulation is only 33% of the unperturbed simulation over recent decades, with this decreasing to 15% by the end of the 21st century. As was demonstrated in Eq. 2, this has direct consequences for the Transient Climate Response to Cumulative Emissions (TCRE) within the Earth system. To put this into context, for the case where the Earth system is projected to warm by 3.5°C by the end of the 21st century under a business-as-usual emissions scenario, our results indicate as an upper bound that the 3.5°C warming reflects an amplification by a factor of 7 relative to a 0.5°C warming that would occur in the absence of changes to the buffering capacity of surface seawater. Differences in the simulated buffering capacity of CMIP5 and CMIP6 models may thereby contribute to differences in their inter-model spread in TCRE, due to differences in the renewal timescales of upper ocean waters."

Best,
ASLR

Edit: To me the primary lesson to take from this reference is that TCRE is strongly related to the amount of CO2 absorbed by the oceans and that as: a) the reference uses a CMIP5 vintage model instead of a CMIP6 vintage model and b) as satellite observations indicate that the ocean is absorbing more CO2 than either CMIP5, or CMI6, project; this implies that TCRE is likely higher than currently assumed by consensus climate science (such as by AR5).
« Last Edit: September 09, 2020, 07:29:17 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3727 on: September 09, 2020, 07:16:01 PM »
For those who are interested, I provide the following linked reference that indicates that GHG emissions from future thermokarst lakes in northern permafrost regions represents a meaningful climate risk:

Cristian Estop‐Aragonés et al. (02 September 2020), "Assessing the Potential for Mobilization of Old Soil Carbon after Permafrost Thaw: A Synthesis of 14C Measurements from the Northern Permafrost Region", Global Biogeochemical Cycles, https://doi.org/10.1029/2020GB006672

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GB006672?af=R

Abstract
The magnitude of future emissions of greenhouse gases from the northern permafrost region depend crucially on the mineralization of soil organic carbon (SOC) that has accumulated over millennia in these perennially frozen soils. Many recent studies have used radiocarbon (14C) to quantify the release of this “old” SOC as CO2 or CH4 to the atmosphere or as dissolved and particulate organic carbon (DOC and POC) to surface waters. We compiled ~1,900 14C measurements from 51 sites in the northern permafrost region to assess the vulnerability of thawing SOC in tundra, forest, peatland, lake, and river ecosystems. We found that growing season soil 14C‐CO2 emissions generally had a modern (post‐1950s) signature, but that well‐drained, oxic soils had increased CO2 emissions derived from older sources following recent thaw. The age of CO2 and CH4 emitted from lakes depended primarily on the age and quantity of SOC in sediments and on the mode of emission, and indicated substantial losses of previously‐frozen SOC from actively expanding thermokarst lakes. Increased fluvial export of aged DOC and POC occurred from sites where permafrost thaw caused soil thermal erosion. There was limited evidence supporting release of previously‐frozen SOC as CO2, CH4, and DOC from thawing peatlands with anoxic soils. This synthesis thus suggests widespread but not universal release of permafrost SOC following thaw. We show that different definitions of “old” sources among studies hamper the comparison of vulnerability of permafrost SOC across ecosystems and disturbances. We also highlight opportunities for future 14C studies in the permafrost region.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3728 on: September 09, 2020, 07:51:38 PM »
While I frequently post about climate risks associated with decadal-scale freshwater hosing events (such as an abrupt reversal of the Beaufort Gyre and/or a MICI-type of collapse of the WAIS); the linked reference provides clear evidence that, on average, climate change induced accelerations of hydrological cycles is resulting in an accelerating trend of freshening of the upper zones of seawater.  This particularly represents a climate risk for the freshening of the upper ocean zones of both the North Atlantic and the Southern Ocean, where the relatively fresh surface zones inhibit the release of heat flux from the ocean (to the atmosphere and then to space) because the relatively warm water advected to these regions of the high latitude ocean from the topics by the MOC are inhibited from reaching the surface by the relatively low density of the relatively fresh surface waters in these key high latitude regions.  This results in the accumulation of ocean heat in the North Atlantic that is then advected into the Arctic Ocean and in the Southern Ocean, where in both high latitude regions this increasing ocean heat content increases climate instability.

Lijing Cheng et al. (2020), "Improved estimates of changes in upper ocean salinity and the hydrological cycle", J. Climate, 1–74, https://doi.org/10.1175/JCLI-D-20-0366.1

https://journals.ametsoc.org/jcli/article/doi/10.1175/JCLI-D-20-0366.1/354497/Improved-estimates-of-changes-in-upper-ocean?searchresult=1

Abstract
Ocean salinity records the hydrological cycle and its changes, but data scarcity and the large changes in sampling make the reconstructions of long-term salinity changes challenging. Here, we present a new observational estimate of changes in ocean salinity since 1960 from the surface to 2000 m. We overcome some of the inconsistencies present in existing salinity reconstructions by using an interpolation technique that uses information on the spatio-temporal co-variability of salinity taken from model simulations. The interpolation technique is comprehensively evaluated using recent Argo-dominated observations through subsample tests. The new product strengthens previous findings that ocean surface and subsurface salinity contrasts have increased, i.e., the existing salinity pattern has amplified. We quantify this contrast by assessing the difference between the salinity in regions of high and low salinity averaged over the top 2000 m, a metric we refer to as SC2000. The increase in SC2000 is highly distinguishable from the sampling error and less affected by inter-annual variability and sampling error than if this metric was computed just for the surface. SC2000 increased by 0.5±0.3% from 1960 to 1990 and by 1.0±0.1% from 1991 to 2017 (1.6±0.2% for 1960-2017), indicating an acceleration of the pattern amplification in recent decades. Combining this estimate with model simulations, we show that the change in SC2000 since 1960 emerges clearly as an anthropogenic signal from the natural variability. Based on the salinity-contrast metric and model simulations, we find a water cycle amplification of 2.1±3.9% K-1 since 1960, with the larger error than salinity metric mainly being due to model uncertainty.

“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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FishOutofWater

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3729 on: September 09, 2020, 07:59:47 PM »
Yes, Bruce, I'm a geochemist and I've been aware for many years of the role of rock weathering and chemical buffering on global paleoclimates. Natural rock weathering is a slow process. A recent study showed that it may be practical to speed it up by using rock flour from crushed basalt as a soil amendment. This possibility has been known for a long time but the economics were not well known.

RoxTheGeologist

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3730 on: September 09, 2020, 08:24:39 PM »
Yes, Bruce, I'm a geochemist and I've been aware for many years of the role of rock weathering and chemical buffering on global paleoclimates. Natural rock weathering is a slow process. A recent study showed that it may be practical to speed it up by using rock flour from crushed basalt as a soil amendment. This possibility has been known for a long time but the economics were not well known.

The thought is that it simply takes too much energy to crush rock in the first place. I believe total global weathering is around 0.1 GT per year, a drop in the ocean compared to the other parts of the carbon cycle.

I have a proposal on the table to work with a local construction company; they own quarries and rock flour is an issue for them. I'm looking at ways they can utilize it to soak up CO2 and produce bicarbonate and aqueous silicates.

One further complication is it's granitic, without the high number of cations one finds in more mafic rocks. The resulting absorption of CO2 is at a ratio of around 1:3. Even at $200 a ton for CO2 in California it is expensive to move the rock anywhere. A 20 ton truck costs around $500 per 100 miles.




Bruce Steele

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3731 on: September 09, 2020, 08:40:00 PM »
FishOutOfWater, I have enjoyed reading your articles in grist. And ASLR here.
Alkalinity and acidification are difficult to understand for most of the rest of us. For those wanting
more info.

http://www.veoliawatertech.com/crownsolutions/ressources/documents/2/21951,Water-pp393-394.pdf

The processes that transfer antC and carbonates to depth are largely biological. Because acidification of seawater reduces carbonate availability of seawater it can compromise the carbonate sink. Although I can’t find the Toyama et al 2017 paper ASLR references I assume the processes bringing DIC into the surface mixed layer are physical. Seawater can only uptake atmospheric CO2 if the gas differential between the atmosphere and seawater favors uptake. If physical processes bring DIC back into the surface mixed layer it reduces the efficacy of the biological and carbonate sinks because it reverses the differential created by biological processes.
 

morganism

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3732 on: September 09, 2020, 08:58:32 PM »
Rox, can you just truck it to an undammed river and dump it in to flow to the sea?

wili

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3733 on: September 09, 2020, 08:59:20 PM »
Rox wrote: "...too much energy to crush rock..."

If the rock could be economically distributed to areas that have occasional overabundance of renewable energy (Pacific NW...), could the rock blocks be pulverized when such excess is available?

And wouldn't transport by water (where available) be much cheaper in terms of both $$ and energy?

« Last Edit: September 09, 2020, 09:35:25 PM by wili »
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Bruce Steele

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3734 on: September 09, 2020, 09:14:54 PM »
Rivers naturally carry different amounts of alkalinity. It would be possible to modify the riverine alkalinity carried to sea but the easiest way to do it would be to use hydronic mining of a mountain. There are carbonates and gold sometimes associated so if you gave someone a subsidy to hydronic mine a mountain with the expressed intent to wash as much carbonates downstream as possible you might get enough gold to pay for it.

https://www.sciencedirect.com/science/article/abs/pii/0009254181901042

You gotta admit it’s “out of the box”

gerontocrat

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3735 on: September 09, 2020, 10:06:01 PM »
No time to read this this evening, so here are the links

https://tc.copernicus.org/articles/14/2869/2020/
New gravity-derived bathymetry for the Thwaites, Crosson, and Dotson ice shelves revealing two ice shelf populations


and a press release that includes the animation below

https://www.bas.ac.uk/media-post/deep-channels-link-ocean-to-antarctic-glacier/
Deep channels link ocean to Antarctic glacier



"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3736 on: September 09, 2020, 10:13:06 PM »
The papers discussed in the BBC article on Thwaites are

doi: 10.5194/tc-14-2883-2020

and

doi: 10.5194/tc-14-2869-2020

Open access. Both very good. I quote from the second:

"the ice front in the centre of Thwaites Glacier is directly and easily accessible to mCDW through a channel over 800 m deep beneath the Thwaites Eastern Ice Shelf and Thwaites Glacier tongue (Millan et al., 2017; Tinto and Bell, 2011) (Fig. 2a). This trough is separated from an adjacent > 1000 m deep trough by a ridge that is in places < 150 m deep where the Eastern Ice Shelf and Thwaites Glacier tongue were pinned. However, 700 to 800 m deep channels cut the ridge, linking the two troughs and potentially facilitating lateral circulation beneath the ice shelves."

"The Crosson Ice Shelf is underlain by bathymetry 300 to 500 m deep, shallower than the typical core of the mCDW (Assmann et al., 2013). A 700–1000 m deep channel is present flanking Bear Island (Figs. 2b and 3c), but its width of just 10 km suggests that the flux of mCDW may be lower via this route. However, in some years the upper boundary of the mCDW can sit around 400–600 m deep (Dutrieux et al., 2014; Jenkins et al., 2018), shallower than much of the bathymetry beneath the Crosson Ice Shelf, meaning mCDW could still access the inner Crosson cavity."

"The Dotson Ice Shelf is underlain by a broad cavity > 800 m deep and is separated from the currently rapidly changing grounding line of the western branch of the Kohler Glacier by a sill 700–800 m deep (Fig. 3d). This sill may partially shield this grounding line from oceanographically driven change, as the bulk of the inflowing mCDW is mapped at a depth of ∼ 800 m at the Dotson ice shelf margin (Miles et al., 2016)."

I attach Fig 2.

sidd

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3737 on: September 09, 2020, 10:29:08 PM »
FishOutOfWater, I have enjoyed reading your articles in grist. And ASLR here.
Alkalinity and acidification are difficult to understand for most of the rest of us. For those wanting
more info.

http://www.veoliawatertech.com/crownsolutions/ressources/documents/2/21951,Water-pp393-394.pdf

The processes that transfer antC and carbonates to depth are largely biological. Because acidification of seawater reduces carbonate availability of seawater it can compromise the carbonate sink. Although I can’t find the Toyama et al 2017 paper ASLR references I assume the processes bringing DIC into the surface mixed layer are physical. Seawater can only uptake atmospheric CO2 if the gas differential between the atmosphere and seawater favors uptake. If physical processes bring DIC back into the surface mixed layer it reduces the efficacy of the biological and carbonate sinks because it reverses the differential created by biological processes.

The references from the Geophysical Research Letters article provide the following information regarding Toyama et al 2017:

"Toyama, K., K.B. Rodgers, B. Blanke, D. Iudicone, M. Ishii, O. Aumont, J.L. Sarmiento: Large Reemergence of Anthropogenic Carbon into the Ocean’s Surface Mixed Layer Sustained by the Ocean’s Overturning Circulation, 30, 8515-8631, 2017."

Edit, see also:

Katsuya Toyama, Keith B. Rodgers, Bruno Blanke, Daniele Iudicone, Masao Ishii, Olivier Aumont, Jorge Louis Sarmiento (2017), "Large reemergence of anthropogenic carbon into the ocean's surface mixed layer sustained by the ocean's overturning circulation", Journal of Climate, Volume 30, No. 21, pp 8515-8631, https://doi.org/10.1175/JCLI-D-16-0725.1

https://journals.ametsoc.org/jcli/article/30/21/8615/95517/Large-Reemergence-of-Anthropogenic-Carbon-into-the

Abstract
We evaluate the output from a widely used ocean carbon cycle model to identify the subduction and obduction (reemergence) rates of anthropogenic carbon (Cant) for climatological conditions during the World Ocean Circulation Experiment (WOCE) era in 1995 using a new set of Lagrangian diagnostic tools. The principal scientific value of the Lagrangian diagnostics is in providing a new means to connect Cant reemergence pathways to the relatively rapid renewal time scales of mode waters through the overturning circulation. Our main finding is that for this model with 2.04 PgC yr-1 of uptake of Cant via gas exchange, the subduction and obduction rates across the base of the mixed layer (MLbase) are 4.96 and 4.50 PgC yr-1, respectively, which are twice as large as the gas exchange at the surface. Given that there is net accumulation of 0.17 PgC yr-1 in the mixed layer itself, this implies the residual downward Cant transport of 1.40 PgC yr-1 across the MLbase is associated with diffusion. Importantly, the net patterns for subduction and obduction transports of Cant mirror the large-scale patterns for transport of water volume, thereby illustrating the processes controlling Cant uptake. Although the net transfer across the MLbase by compensating subduction and obduction is relatively smaller than the diffusion, the localized pattern of Cant subduction and obduction implies significant regional impacts. The median time scale for reemergence of obducting particles is short (< 10 yr), indicating that reemergence should contribute to limiting future carbon uptake through its contribution to perturbing the Revelle factor for surface waters.
« Last Edit: September 09, 2020, 10:49:51 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3738 on: September 09, 2020, 11:33:30 PM »
The linked reference, and associated article, indicate that with regard forests serving as a carbon sink, that:

"Extant Earth system model projections of global forest carbon sink persistence are likely too optimistic, increasing the need to curb greenhouse gas emissions."

Also, this implies that planting trees to try to fight atmospheric CO2 concentrates will be less effective than previously assumed by consensus climate scientists:

Brienen, R.J.W., Caldwell, L., Duchesne, L. et al. Forest carbon sink neutralized by pervasive growth-lifespan trade-offs. Nat Commun 11, 4241 (2020). https://doi.org/10.1038/s41467-020-17966-z

https://www.nature.com/articles/s41467-020-17966-z

Abstract: "Land vegetation is currently taking up large amounts of atmospheric CO2, possibly due to tree growth stimulation. Extant models predict that this growth stimulation will continue to cause a net carbon uptake this century. However, there are indications that increased growth rates may shorten trees′ lifespan and thus recent increases in forest carbon stocks may be transient due to lagged increases in mortality. Here we show that growth-lifespan trade-offs are indeed near universal, occurring across almost all species and climates. This trade-off is directly linked to faster growth reducing tree lifespan, and not due to covariance with climate or environment. Thus, current tree growth stimulation will, inevitably, result in a lagged increase in canopy tree mortality, as is indeed widely observed, and eventually neutralise carbon gains due to growth stimulation. Results from a strongly data-based forest simulator confirm these expectations. Extant Earth system model projections of global forest carbon sink persistence are likely too optimistic, increasing the need to curb greenhouse gas emissions."

See also:

Title: "Too Much CO2 Has an Unnerving Effect on The World's Trees, New Study Finds"

https://www.sciencealert.com/too-much-co2-makes-trees-live-fast-and-die-young-says-study

Extract: "Commenting on the study, David Lee, professor of atmospheric science at England's Manchester Metropolitan University, said Earth system climate models currently predict the carbon storage of forests to continue or increase.

"This study shows the opposite, that increased CO2 compromises forests as a carbon sink," he said.

That suggests the idea that "fossil-fuel based emissions can be 'offset' by planting trees (or avoiding deforestation) really does not stand up to scientific scrutiny", he added."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

1rover1

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3739 on: September 10, 2020, 02:13:53 AM »
I agree over the long haul that forests have little affect on long term carbon.  In my forestry classes in University 30 years ago, as they explained the carbon cycle, professional foresters. were dubunking the concept of  forests as a carbon storage solution.   If you were to put a dome over a forest, over the life cycle of that forest, the net carbon input vs output is 0.  Yes, trees store carbon as they grow, in the form of wood, and leaves, and roots, and animal biomass.  As that biomass ages and dies, and decays, the leaves and trees and bark and wood, and animal carbon, is all consumed by insects, fungus, micro-organisms and fire, that carbon they consume is then released again, back into the atmosphere.   You can generate some medium term storage of the carbon by harvesting the forest, and storing the products as lumber and paper and stacking things up in libraries, but that too, eventually, will break down and be released as carbon again. The only long term land storage of carbon in a forest is in the peat bogs, which can also burn and decay on occasion.  But farming peat and long term conversion of peat to coals and other fossil fuels for long term storage is a separate discussion from forestry.   

RoxTheGeologist

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3740 on: September 10, 2020, 04:35:52 PM »

At best trees store carbon, at worst they convert carbon dioxide to methane. With increased cycling of carbon and higher decay rates with increasing humidity and temperature, I would expect the latter to become more important; particularly as warm water contains less dissolved gasses.

RoxTheGeologist

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3741 on: September 10, 2020, 04:38:45 PM »

On the CO2 conversion - sadly, the amount of fuel used in a quarry generates enough CO2 to react with all the rock flour. It can be a local solution (haha). It just has to be cost-effective and fit within CARBs regulations to generate the required credits.

ms

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3742 on: September 10, 2020, 07:50:35 PM »

On the CO2 conversion - sadly, the amount of fuel used in a quarry generates enough CO2 to react with all the rock flour. It can be a local solution (haha). It just has to be cost-effective and fit within CARBs regulations to generate the required credits.

Rock dust is grinded for free by Greenland glaiciers. Transport could be expensive though.
This link tells about research in using the rock dust for multiple puropses.
https://sciencenordic.com/denmark-forskerzonen-greenland-science-special/can-greenlandic-mud-help-feed-the-world/1454254

wili

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3743 on: September 10, 2020, 09:44:03 PM »
Electric mining machines charged with renewables? Transported by (mostly) wind powered ships?

What am I missing?
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

mitch

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3744 on: September 10, 2020, 11:16:16 PM »
Terrestrial storage of carbon does not depend so much on the forest trees but on forest soil--roughly 3 times as much carbon in the soil as in the biomass. Soil carbon is old, roughly 5000 years.  This is why oxidation of organic carbon in soils can be an issue in climate change. 
http://www.fao.org/about/meetings/soil-organic-carbon-symposium/key-messages/en/

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3745 on: September 11, 2020, 01:11:23 AM »
The linked reference, and associated article, evaluate past changes in climate state; which is important to understand in order to better assess the risk that we may collectively transition in to a 'Hothouse' climate state (see the attached image) in the coming century.

Thomas Westerhold et al. (11 Sep 2020), "An astronomically dated record of Earth’s climate and its predictability over the last 66 million years", Science, Vol. 369, Issue 6509, pp. 1383-1387, DOI: 10.1126/science.aba6853

https://science.sciencemag.org/content/369/6509/1383

The states of past climate
Deep-sea benthic foraminifera preserve an essential record of Earth's past climate in their oxygen- and carbon-isotope compositions. However, this record lacks sufficient temporal resolution and/or age control in some places to determine which climate forcing and feedback mechanisms were most important. Westerhold et al. present a highly resolved and well-dated record of benthic carbon and oxygen isotopes for the past 66 million years. Their reconstruction and analysis show that Earth's climate can be grouped into discrete states separated by transitions related to changing greenhouse gas levels and the growth of polar ice sheets. Each climate state is paced by orbital cycles but responds to variations in radiative forcing in a state-dependent manner.
Science, this issue p. 1383

Abstract
Much of our understanding of Earth’s past climate comes from the measurement of oxygen and carbon isotope variations in deep-sea benthic foraminifera. Yet, long intervals in existing records lack the temporal resolution and age control needed to thoroughly categorize climate states of the Cenozoic era and to study their dynamics. Here, we present a new, highly resolved, astronomically dated, continuous composite of benthic foraminifer isotope records developed in our laboratories. Four climate states—Hothouse, Warmhouse, Coolhouse, Icehouse—are identified on the basis of their distinctive response to astronomical forcing depending on greenhouse gas concentrations and polar ice sheet volume. Statistical analysis of the nonlinear behavior encoded in our record reveals the key role that polar ice volume plays in the predictability of Cenozoic climate dynamics.

See also:

Title: "Earth barreling toward 'Hothouse' state not seen in 50 million years, epic new climate record shows"

https://www.livescience.com/oldest-climate-record-ever-cenozoic-era.html

Extract: " The new paper, which comprises decades of deep-ocean drilling missions into a single record, details Earth's climate swings across the entire Cenozoic era — the 66 million-year period that began with the death of the dinosaurs and extends to the present epoch of human-induced climate change. The results show how Earth transitioned through four distinct climate states — dubbed the Warmhouse, Hothouse, Coolhouse and Icehouse states — in response to changes in the planet's orbit, greenhouse gas levels and the extent of polar ice sheets.

When the team overlaid orbital data with their isotopic climate data, they saw that orbital variations created distinct but relatively small-scale changes to the global climate. Crucially, each big jump between climate states was tied to a massive shift in greenhouse gas levels, the researchers said.

For example, about 10 million years after the dinosaur extinction, Earth jumped from a warmhouse state to a hothouse state. This event, known as the Paleocene-Eocene Thermal Maximum, saw temperatures up to 60 degrees Fahrenheit (16 degrees Celsius) above modern levels, Zachos said, and was driven by a massive release of carbon into the atmosphere, thought to be the result of huge volcanic eruptions in the North Atlantic. Similarly, as carbon dioxide disappeared from the atmosphere over the next 20 million years, ice sheets started to form in Antarctica and the planet entered a coolhouse phase, with surface temperatures averaging about 40 F (4 C) above modern levels."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3746 on: September 11, 2020, 01:23:47 AM »
If it is not clear to some readers, large Antarctic sea ice extents, and/or relatively fresh surface seawaters, help to inhibit the radiation of heat into the atmosphere (& then long-wave radiation into space) from relatively warm water delivered to the Southern Ocean by the MOC.  Thus, the fact that in 2020 Antarctica will have record high sea ice extents (see the attached image created by Gerontocrat) implies that the Southern Ocean is continuing to build-up record high ocean heat content; which is currently helping to destabilize key Antarctic marine glaciers like Thwaites Glacier.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3747 on: September 11, 2020, 07:58:26 AM »
That Westerhold paper is very nice. ( doi: 10.1126/science.aba6853 ) I have not the time now, but i think i have to read this carefully comparing to the Kidder-Worsley papers i have posted about before.

I attach fig 2 C) and D) which illustrates climate wander thru hot,warm,cool,ice house states. LGM is Last Glacial Maximum, mMCT is mid Miocene Climate Transition (13.9 MYr), MCO is Miocene Climate Optimum (17-14MYr), EOT Eocene-Oligocene Transition (34MYr), K/Pg is Cretaceous/Paleogene boundary (66MYr), EECO is Early Eocene Climate Optimum (47MYr)

sidd


Hefaistos

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3748 on: September 11, 2020, 08:26:07 AM »
If it is not clear to some readers, large Antarctic sea ice extents, and/or relatively fresh surface seawaters, help to inhibit the radiation of heat into the atmosphere (& then long-wave radiation into space) from relatively warm water delivered to the Southern Ocean by the MOC.  Thus, the fact that in 2020 Antarctica will have record high sea ice extents (see the attached image created by Gerontocrat) implies that the Southern Ocean is continuing to build-up record high ocean heat content; which is currently helping to destabilize key Antarctic marine glaciers like Thwaites Glacier.

This is difficult to understand!
Maximum sea ice around Antarctica implies record ocean heat?

What parts of Antarctica have the most sea ice?

Do you have some data source that there is record ocean heat around Antarctica? The sea surface temperature data seem to show the opposite.

40 year temperature trend in Antarctica is slightly negative, -0.0230C per year.
40 year temperature trend in SH midlatitudes (30S - 60S) is very slightly positive, +0.0070C per year.
40 year temperature trend in the Southern Ocean (50S - 70S) is negative.

« Last Edit: September 11, 2020, 08:31:08 AM by Hefaistos »

KiwiGriff

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE
« Reply #3749 on: September 11, 2020, 08:42:27 AM »
Quote
Do you have some data source that there is record ocean heat around Antarctica? The sea surface temperature data seem to show the opposite.

40 year temperature trend in Antarctica is slightly negative, -0.0230C per year.
40 year temperature trend in SH midlatitudes (30S - 60S) is very slightly positive, +0.0070C per year.
What the fuck have any of these to do with ocean heat content ?
https://tos.org/oceanography/article/southern-ocean-warming


OBSERVED TEMPERATURE TRENDS
Comparing temperature measurements obtained at the end of the twentieth century or early in the twenty-first century with temperature records of previous decades is unambiguous: the Southern Ocean within and north of the Antarctic Circumpolar Current has warmed at all depths in the upper 2,000 m at a more rapid rate than the globally averaged ocean warming (Figure 4a,b; Gille, 2008 ; Böning et al., 2008; Giglio and Johnson, 2017). This long-term trend agrees with warming observed during the last decade, when profiling floats greatly improved spatial sampling (e.g., Giglio and Johnson, 2017). The water masses north and within the Antarctic Circumpolar Current have warmed at a rate of 0.1°–0.2°C per decade in the upper 1 km (Figures 1 and 4).
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