Ice Apocalypse - Multiple Meters Sea Level Rise

[Sciguy]

...
Well, if you believe everything the IEA, EIA and the gas producers sell you, yeah.
...

The article and the image clearly show that this new data "... is according to experts at Rystad Energy, “an independent energy consulting services and business intelligence data firm” based in Norway."

Did you even read the article you posted?  It clearly uses the IEA as a source:

Indeed, Rystad’s bullish outlook for U.S. shale is hardly alone. The Paris-based International Energy Agency reported in November that the U.S. will supply 85% of the new oil and 30% of the new gas through 2030. The current bear oil and gas market will not last forever - nothing ever does. Surviving through the pain of lower pricing, the industry has so sharpened its knife that higher prices will offer drastically easier times.

But aside from the IEA, let's look at Rystad's outlook:

Rystad says the U.S. shale industry will continue to mount production even if prices drop. The reality is that oil and gas companies already have. Oil prices have been sliced in half since the triple-digits seen in mid-2014, yet U.S. crude oil production has still jumped over 50% to nearly 13 million b/d. For 2019 alone, the weekly oil rig count has plummeted 25% to 663 rigs as of Friday, yet weekly output has risen another 1.2 million b/d. Natural gas prices have fallen 17% this year and gas rigs are down 34%, yet gas U.S. output has still risen over 10%.

Perhaps in Norway, you don't need money to actually produce things.  In the US though, you do.

https://www.npr.org/2019/11/20/780879474/as-oil-prices-drop-and-money-dries-up-is-the-u-s-shale-boom-going-bust

As Oil Prices Drop And Money Dries Up, Is The U.S. Shale Boom Going Bust?

November 20, 2019

The shale oil boom that catapulted the U.S. into being the world's largest oil producer may be going bust. Oil prices are dropping amid weakening demand, bankruptcies and layoffs are up, and drilling is down — signs of a crisis that's quietly roiling the industry.

https://www.houstonchronicle.com/business/energy/article/U-S-shale-sector-shrinking-to-survive-14833356.php

US shale sector shrinking to survive
Jordan Blum Nov. 14, 2019

The U.S. shale industry is finally learning to live within its financial means, shrinking to survive amid an environment of depressed crude prices and Wall Street animosity toward nearly all things oil and gas.

https://www.stltoday.com/business/columns/david-nicklaus/as-us-nears-energy-independence-its-oil-and-gas-sector/article_81fe27e3-2035-51b8-974b-a757f5747782.html

As US nears energy independence, its oil and gas sector is ailing
Nov 12, 2019

The U.S. is tantalizingly close to energy independence for the first time in 76 years, but the future doesn’t look bright for the firms that got us there.

Bankruptcies are rising in the oil patch, with Texas law firm Haynes and Boone counting filings by 33 producers in the first nine months of this year, up from 28 in all of 2018. Even Chesapeake Energy, a shale-gas pioneer, was forced last week to acknowledge “substantial doubt about our ability to continue as a going concern.”

Big banks reportedly are trying to reduce their exposure to oil and gas loans, and stock-market investors are none too keen on the sector either.

https://www.bizjournals.com/houston/news/2019/11/29/tapped-out-as-investors-ditch-the-energy-industry.html

Tapped out: As investors ditch the energy industry, producers try to keep above ground
 By Chris Mathews  – Reporter, Houston Business Journal
Nov 29, 2019, 2:00am EST

Despite the shale boom oil and gas companies made billions on, investors are shying away from pumping more money into the industry.

https://www.worldoil.com/news/2019/11/22/reduced-access-to-credit-making-life-harder-for-shale-operators

Reduced access to credit making life harder for shale operators
By Kriti Gupta on 11/22/2019

NEW YORK (Bloomberg) - Banks have begun trimming back the credit lines of America’s shale producers, further undercutting a beleaguered industry that’s been struggling to rebuild investor confidence.

Laredo Petroleum Inc. and Oasis Petroleum Inc. are among at least six producers whose ability to secure short-term loans against their oil and natural gas reserves have dropped by 10% or more, according to data in earnings statements and filings. The declines offer the first hint of results from a semi-annual bank review of the industry’s borrowing capacity that generally runs through December.

For the first time since 2016, an industry survey done prior to the review found most respondents expected to see declines. The noose is tightening at a time when producers have seen their market values plunge 21% this year. Meanwhile, at least 15 producers have already filed for bankruptcy during the year.

https://oilprice.com/Energy/Crude-Oil/Is-Big-Oil-Wasting-Its-Time-in-The-US-Shale-Patch.html

s Big Oil Wasting Its Time in The US Shale Patch?
By Nick Cunningham - Nov 19, 2019

Growth in the U.S. shale industry is dramatically slowing down, with cash-strapped drillers slashing spending and scrapping rigs. At the same time, the oil majors are consolidating their position and moving forward with aggressive drilling plans.

The business model for small and medium-sized drillers has been shaky at best, and arguably unworkable since it depends on a steady diet of capital even as constant drilling fails to produce profits. But the story is not over yet. The oil majors have promised to succeed where the rest of the industry has mostly failed, using economies of scale, better technology, and larger contiguous plots of land to cut costs.

But just because the majors are pumping billions of dollars into the ground doesn’t mean that they will succeed either.

In fact, there are some signs that things are not going well for the majors. ExxonMobil recently redefined its strategy in U.S. shale, characterizing its operations as one of long-term value creation instead of the “short-cycle” cash generation, as it previously described its shale venture. Results “will take time, but we’re confident they will bear fruit,” Staale Gjervik, president of XTO Energy, a subsidiary of ExxonMobil, said at a recent industry conference.

The rephrasing may seem trivial, but it amounts to an admission that the oil major’s shale operations are taking longer than previously thought to become a financial success.

[AbruptSLR]

...
Perhaps in Norway, you don't need money to actually produce things.  In the US though, you do.
..

In the US all you need is a company that is willing to loan money for the fracking operation, and enough capital/revenue to make monthly payments on the loan.

[AbruptSLR]

…
Given that we can measure the concentration of methane in the atmosphere and thus calculate the total net emissions (all sources minus all sinks), if two sources were underestimated that implies that another source (or multiple sources) were overestimated or that the sinks were underestimated.
…

The attached NOAA plot of the atmospheric methane concentrations at the South Pole from 2006 to Dec 2, 2019 indicate that the trend line of this methane concentration is accelerating; thus if some methane sources are not changing then other sources are currently accelerating, and may accelerate even more in the future due to global warming.

...

While studies can't point unequivocally to the explosion of fracking in the US over the past decade as a cause for the rise, the timing of the shift from the stabilization period and the growth of fracking may be more than coincidental.

...
I would suggest that increased fracking of natural gas and oil is more likely to be the cause of the recent resumption of methane concentration increases and that reducing and eventually eliminating the use of fossil fuels will lead to a big decrease in the concentrations of methane in the atmosphere.  I've read similar statements from James Hansen but can't find links to them at the moment.

Certainly fracking of natural gas is one source of atmospheric methane; however, the northern wetlands (including the tundra) is another significant source and the attached atmospheric methane concentration graph from Barrow, Alaska (from 2005 to Dec 9, 2019) shows a recent surge in local methane concentrations suggesting a local methane emission source (such as northern wetlands).

[AbruptSLR]

The linked reference provides a convenient summary of consensus climate science's understanding of climate feedbacks and their prospects for evaluation.  However, the reference does not evaluate the risks of a near-term collapse of the WAIS could trigger a cascade of tipping points leading to an abrupt slowdown of the MOC (THC in the reference), due to the potential warming of the tropical ocean's SSTA by 5C.  Instead, the reference categorizes ocean-atmosphere feedbacks as slow but makes the following statement about a possible stability-altering feedback for the MOC (THC):

"However, all projections agree that in the warming climate, increased heating and freshening at the ocean surface in the high latitudes will enhance the stability of the water column at the deep-water formation sites, resulting in positive feedback due to weaker mixing of excess heat downward. An apparent monostable mode of the AMOC in a state-of-the-art ESM may, however, be due to the tropical ocean salinity bias in these models (Liu et al., 2014) so that no final conclusion can be drawn on the possibility of stability-altering feedback, with potentially complex implications for sensitivity-altering feedbacks as well."


Heinze, C., Eyring, V., Friedlingstein, P., Jones, C., Balkanski, Y., Collins, W., Fichefet, T., Gao, S., Hall, A., Ivanova, D., Knorr, W., Knutti, R., Löw, A., Ponater, M., Schultz, M. G., Schulz, M., Siebesma, P., Teixeira, J., Tselioudis, G., and Vancoppenolle, M.: ESD Reviews: Climate feedbacks in the Earth system and prospects for their evaluation, Earth Syst. Dynam., 10, 379–452, https://doi.org/10.5194/esd-10-379-2019, 2019.

https://www.earth-syst-dynam.net/10/379/2019/

Abstract
Earth system models (ESMs) are key tools for providing climate projections under different scenarios of human-induced forcing. ESMs include a large number of additional processes and feedbacks such as biogeochemical cycles that traditional physical climate models do not consider. Yet, some processes such as cloud dynamics and ecosystem functional response still have fairly high uncertainties. In this article, we present an overview of climate feedbacks for Earth system components currently included in state-of-the-art ESMs and discuss the challenges to evaluate and quantify them. Uncertainties in feedback quantification arise from the interdependencies of biogeochemical matter fluxes and physical properties, the spatial and temporal heterogeneity of processes, and the lack of long-term continuous observational data to constrain them. We present an outlook for promising approaches that can help to quantify and to constrain the large number of feedbacks in ESMs in the future. The target group for this article includes generalists with a background in natural sciences and an interest in climate change as well as experts working in interdisciplinary climate research (researchers, lecturers, and students). This study updates and significantly expands upon the last comprehensive overview of climate feedbacks in ESMs, which was produced 15 years ago (NRC, 2003).

[AbruptSLR]

The linked article discusses the just released '2019 Arctic Report Card', and its conclusion that the Arctic permafrost has already become a net emitter of GHGs; which will act as an increasingly positive feedback for global warming:

Title: "The Arctic may have crossed key threshold, emitting billions of tons of carbon into the air, in a long-dreaded climate feedback"

https://www.washingtonpost.com/weather/2019/12/10/arctic-may-have-crossed-key-threshold-emitting-billions-tons-carbon-into-air-long-dreaded-climate-feedback/

See also:

Title: "Arctic Report Card: Record territory for warm temperatures, loss of snow and ice"

https://www.noaa.gov/media-release/arctic-report-card-record-territory-for-warm-temperatures-loss-of-snow-and-ice

&

Title: "Arctic Report Card: Update for 2019"

https://arctic.noaa.gov/Report-Card/Report-Card-2019

[wili]

"uncertainty is not our friend"

Indeed!!

I have a feeling that if his doctors told him "The circulation of blood to your brain may be failing rather quickly" then Hef would jump up and down with joy because the 'may' in the warning expressed some uncertainly !

[Hefaistos]

"uncertainty is not our friend"

Indeed!!

I have a feeling that if his doctors told him "The circulation of blood to your brain may be failing rather quickly" then Hef would jump up and down with joy because the 'may' in the warning expressed some uncertainly !

Here's the graph of those blood vessels attached )

From the same article: "Away from the region of watermass transformation, these southward flowing waters are deep, isolated from atmospheric ventilation, and thus store energy and chemical compounds for hundreds of years. This property of the ocean—storing anomalies at depth—gives the ocean a longer memory than the atmosphere, with the potential to influence climate variability on long timescales."

We know not much about what's hidden down there in that ocean memory of earth's historic climate. Changes to the AMOC both herald and drive climate shifts.
I feel good about the results of this research, that AMOC is not in decline, otoh it's been over its 30 year historical average for the last 5 years.
And again, oceans store more than 99% of earth's thermal energy.

[Lennart van der Linde]

Certainly fracking of natural gas is one source of atmospheric methane; however, the northern wetlands (including the tundra) is another significant source and the attached atmospheric methane concentration graph from Barrow, Alaska (from 2005 to Dec 9, 2019) shows a recent surge in local methane concentrations suggesting a local methane emission source (such as northern wetlands).

At AGU Saunois et al (submitted) think growing methane emissions come entirely from South East Asia and Africa. See these tweets from Zeke Hausfather:
https://twitter.com/hausfath/status/1204549028333023232

And the submitted paper by Saunois et al:
https://www.earth-syst-sci-data-discuss.net/essd-2019-128/

[Lennart van der Linde]

Also see Turner er al 2017, who think the methane sink may have shrunk:
https://www.pnas.org/content/114/21/5367

[kassy]

And again, oceans store more than 99% of earth's thermal energy.

As they always do and still we see all these interesting and sometimes quick changes in the historical record so clearly that cannot be used to argue that future changes can not occur or occur rapidly. 

[Hefaistos]

And again, oceans store more than 99% of earth's thermal energy.

As they always do and still we see all these interesting and sometimes quick changes in the historical record so clearly that cannot be used to argue that future changes can not occur or occur rapidly.

How quick was that, at the quickest?

Given:
i) that renewables already are cheaper than coal for power generation, and soon will be cheaper than natural gas;
ii) that transportation will be based on battery powered vehicles with a ban on new FF cars already in place in 10 years in some countries, and say 20 years in most other OECD countries;
iii) that climate policy is getting ever more active;

I hypothesize that we only need say 30-40 years (1 investment cycles of e.g. power generation installations, or 2 investment cycles for e.g. car production) to get off enough of the fossil fuels to save the world without too much climate change drama.

The brutal forces of the capitalist market mechanism supplemented with more active climate policy incentives will be enough to solve the more burning climate issues.
We don't even need to assume direct CO2 capture/sequestration tech to arrive at such conclusion. I further suppose that this will be the mainstream view of the fortcoming IPCC report (AR6) in 2022.

[Mozi]

You have to be joking.

[Tom_Mazanec]

It may be a quick timeline, but I don't see why it is impossible, and it would save us a lot of climate misery (not all but a lot).

[AbruptSLR]

The  reposted first image illustrates how complicated it is to identify current sources of methane emissions as there are so many different sources, and it also shows that in the observed record permafrost has contributed little to total methane emission.  That said, the reposted second image suggests that in 2019 permafrost degradation has likely increased atmospheric methane concentrations in the Arctic, and the linked articles offers several different reasons to be concerned that this source may currently be accelerating:

Caption for the first image: "Comparison between current day estimates of geological and other methane sources. Geological emissions are based on the bottom-up and top-down estimates discussed in this work (see Fig. 1 and text). Other natural and anthropogenic emissions refer to the average (and range) of bottom-up and top-down estimates reported by Saunois et al. (2016). Note that a downward revision of the geological source requires an upward revision of the same magnitude for the fossil fuel industry (Section 4). DOI: https://doi.org/10.1525/elementa.383.f2"

Cain Silvey, Karla M. Jarecke, Kristine Hopfensperger, Terrance D. Loecke, Amy J. Burgin. Plant Species and Hydrology as Controls on Constructed Wetland Methane Fluxes. Soil Science Society of America Journal, 2019; 0 (0): 0 DOI: 10.2136/sssaj2018.11.0421

https://dl.sciencesocieties.org/publications/sssaj/abstracts/83/3/848

Abstract: "Wetlands are the largest natural source of atmospheric methane (CH4), a potent greenhouse gas. Hydrology and species composition are important controls on wetland CH4 emissions. Few studies target interactive effects on CH4 fluxes, but rather study variables in isolation. Therefore, we asked: How do hydrology and plant species interact to affect CH4 fluxes from wetland soils? We measured CH4 fluxes under stable water tables in mesocosms planted with Asclepias incarnata L. and mesocosms planted with Alisma triviale Pursh. We then tested the interactive effects in saturated and unsaturated restored field locations by measuring CH4 fluxes from the plants and the surrounding soil. In mesocosms, CH4 fluxes from A. incarnata were 8-fold greater than fluxes from control (no plant) or A. triviale mesocosms. Alisma triviale mesocosms had higher CO2 to CH4 ratio (less methanogenic dominance) than control mesocosms but did not differ significantly from A. incarnata mesocosms. In the field, hydrology was the dominant control of CH4 flux; both plant species produced approximately 10-fold more CH4 in saturated plots than in unsaturated plots. Incorporating hydrology and species composition into modeling will better predict CH4 fluxes from wetland soils, which in turn could aid in designing restored wetlands that offset greenhouse gas emissions."

&

Title: "Unexpected culprit: Wetlands as source of methane"

https://www.sciencedaily.com/releases/2019/06/190619085703.htm

Summary: "Wetlands are an important part of the Earth's natural water management system. The complex system of plants, soil, and aquatic life serves as a reservoir that captures and cleans water. However, as cities have expanded, many wetlands were drained for construction. In addition, many areas of land in the Midwest were drained to increase uses for agriculture to feed a growing world."

&

Strack, M., Hayne, S., Lovitt, J. et al. Petroleum exploration increases methane emissions from northern peatlands. Nat Commun 10, 2804 (2019) doi:10.1038/s41467-019-10762-4

https://www.nature.com/articles/s41467-019-10762-4

Abstract: "Peatlands are globally significant sources of atmospheric methane (CH4). In the northern hemisphere, extensive geologic exploration activities have occurred to map petroleum deposits. In peatlands, these activities result in soil compaction and wetter conditions, changes that are likely to enhance CH4 emissions. To date, this effect has not been quantified. Here we map petroleum exploration disturbances on peatlands in Alberta, Canada, where peatlands and oil deposits are widespread. We then estimate induced CH4 emissions. By our calculations, at least 1900 km2 of peatland have been affected, increasing CH4 emissions by 4.4–5.1 kt CH4 yr−1 above undisturbed conditions. Not currently estimated in Canada’s national reporting of greenhouse gas (GHG) emissions, inclusion would increase current emissions from land use, land use change and forestry by 7–8%. However, uncertainty remains large. Research further investigating effects of petroleum exploration on peatland GHG fluxes will allow appropriate consideration of these emissions in future peatland management."

[AbruptSLR]

It may be a quick timeline, but I don't see why it is impossible, and it would save us a lot of climate misery (not all but a lot).

Certainly, the various Earth Systems that may increase nonlinearly in the next 30 to 40 years will not be anthropomorphically moved by how misery they could save mankind from by holding-off; as they will accelerate in accordance with the laws of physics no matter how much wishful thinking mankind engages in.

[nanning]

What a great metaphore wili

[AbruptSLR]

…
And again, oceans store more than 99% of earth's thermal energy.

The first reference confirms that the oceans absorbs only 93% of the Earth's Energy Imbalance (not 99%); while the second reference and attached image shows that the lion's share of the change in ocean heat content from 1960 to 2015 has ended up in the Southern Ocean; where it is contributing to an expansion of the CDW:

Benoit Meyssignac et al (20 August 2019), "Measuring Global Ocean Heat Content to Estimate the Earth Energy Imbalance", Front. Mar. Sci., https://doi.org/10.3389/fmars.2019.00432

https://www.frontiersin.org/articles/10.3389/fmars.2019.00432/full

Abstract: "The energy radiated by the Earth toward space does not compensate the incoming radiation from the Sun leading to a small positive energy imbalance at the top of the atmosphere (0.4–1 Wm–2). This imbalance is coined Earth’s Energy Imbalance (EEI). It is mostly caused by anthropogenic greenhouse gas emissions and is driving the current warming of the planet. Precise monitoring of EEI is critical to assess the current status of climate change and the future evolution of climate. But the monitoring of EEI is challenging as EEI is two orders of magnitude smaller than the radiation fluxes in and out of the Earth system. Over 93% of the excess energy that is gained by the Earth in response to the positive EEI accumulates into the ocean in the form of heat. This accumulation of heat can be tracked with the ocean observing system such that today, the monitoring of Ocean Heat Content (OHC) and its long-term change provide the most efficient approach to estimate EEI. In this community paper we review the current four state-of-the-art methods to estimate global OHC changes and evaluate their relevance to derive EEI estimates on different time scales. These four methods make use of: (1) direct observations of in situ temperature; (2) satellite-based measurements of the ocean surface net heat fluxes; (3) satellite-based estimates of the thermal expansion of the ocean and (4) ocean reanalyses that assimilate observations from both satellite and in situ instruments. For each method we review the potential and the uncertainty of the method to estimate global OHC changes. We also analyze gaps in the current capability of each method and identify ways of progress for the future to fulfill the requirements of EEI monitoring. Achieving the observation of EEI with sufficient accuracy will depend on merging the remote sensing techniques with in situ measurements of key variables as an integral part of the Ocean Observing System."

&

Lijing Cheng et al. (10 Mar 2017), "Improved estimates of ocean heat content from 1960 to 2015", Science Advances, Vol. 3, no. 3, e1601545, DOI: 10.1126/sciadv.1601545

https://advances.sciencemag.org/content/3/3/e1601545.full

Abstract: "Earth’s energy imbalance (EEI) drives the ongoing global warming and can best be assessed across the historical record (that is, since 1960) from ocean heat content (OHC) changes. An accurate assessment of OHC is a challenge, mainly because of insufficient and irregular data coverage. We provide updated OHC estimates with the goal of minimizing associated sampling error. We performed a subsample test, in which subsets of data during the data-rich Argo era are colocated with locations of earlier ocean observations, to quantify this error. Our results provide a new OHC estimate with an unbiased mean sampling error and with variability on decadal and multidecadal time scales (signal) that can be reliably distinguished from sampling error (noise) with signal-to-noise ratios higher than 3. The inferred integrated EEI is greater than that reported in previous assessments and is consistent with a reconstruction of the radiative imbalance at the top of atmosphere starting in 1985. We found that changes in OHC are relatively small before about 1980; since then, OHC has increased fairly steadily and, since 1990, has increasingly involved deeper layers of the ocean. In addition, OHC changes in six major oceans are reliable on decadal time scales. All ocean basins examined have experienced significant warming since 1998, with the greatest warming in the southern oceans, the tropical/subtropical Pacific Ocean, and the tropical/subtropical Atlantic Ocean. This new look at OHC and EEI changes over time provides greater confidence than previously possible, and the data sets produced are a valuable resource for further study."

Extract: "It is evident that all six ocean basins have experienced significant warming since 1998 but that heat was mainly stored in the southern oceans, the tropical/subtropical Pacific Ocean, and the tropical/subtropical Atlantic Ocean from 1960 to 1998 …"

Partial caption for attached image: "Fig. 5 OHC changes from 1960 to 2015 for different ocean basins. (A) For 0 to 2000 m …"

[AbruptSLR]

The linked reference finds that: "… EffCS is a better predictor than TCR of future transient warming under RCP8.5."  This is likely the case because with strong forcing more feedback mechanisms become nonlinear faster.

Sanderson, B.: Relating Climate Sensitivity Indices to projection uncertainty, Earth Syst. Dynam. Discuss., https://doi.org/10.5194/esd-2019-77, in review, 2019.

https://www.earth-syst-dynam-discuss.net/esd-2019-77/esd-2019-77.pdf
https://www.earth-syst-dynam-discuss.net/esd-2019-77/

Abstract. Can we summarize uncertainties in global response to greenhouse gas forcing with a single number? Here we assess the degree to which traditional metrics are related to future warming indices using an ensemble of simple climate models together with results from CMIP5 and CMIP6. We consider Effective Climate Sensitivity (EffCS), Transient Climate Response at CO2 quadrupling (T140) and a proposed simple metric of temperature change 140 years after a quadrupling of carbon dioxide (A140). In a perfectly equilibrated model, future temperatures under a non-mitigation scenario are almost perfectly described by T140, whereas in a strongly mitigated future, both ECS and T140 are found to be poor predictors of 21st century warming, and future temperatures are better correlated with A140. However, we show that T140 and EffCS calculated in full CMIP simulations are subject to errors arising from control model drift and internal variability. Simulating these factors in the simple model leads to 30 % relative error in the measured value of T140, but only a 10 % error for EffCS. As such, measured values of EffCS can be better correlated with true TCR than measured values of TCR itself. We propose that this could be an explanatory factor in the previously noted surprising result that EffCS is a better predictor than TCR of future transient warming under RCP8.5.

[Tom_Mazanec]

It may be a quick timeline, but I don't see why it is impossible, and it would save us a lot of climate misery (not all but a lot).

Certainly, the various Earth Systems that may increase nonlinearly in the next 30 to 40 years will not be anthropomorphically moved by how misery they could save mankind from by holding-off; as they will accelerate in accordance with the laws of physics no matter how much wishful thinking mankind engages in.

The faster we decarbonize the better off we will be. Even if things get really bad, they could always get even worse.

[gerontocrat]

The faster we decarbonize the better off we will be. Even if things get really bad, they could always get even worse.

I've posted on Arctic Permafrost CO2 emissions at...
https://forum.arctic-sea-ice.net/index.php/topic,2546.msg240382.html#msg240382

Things certainly could get a good deal worse.

[HapHazard]

The faster we decarbonize the better off we will be.

• faster
• decarbonize

In today's global political & economic reality, it is only possible to choose 1 of the above.

[AbruptSLR]

While the linked reference is a few years old, it is after AR5, and it indicates that at least CMIP5 models were missing some positive feedbacks (such as possibly ice-climate feedbacks and/or fire related feedbacks) that were active in the Holocene:

Zhengyu Liu, Jiang Zhu, Yair Rosenthal, Xu Zhang, Bette L. Otto-Bliesner, Axel Timmermann, Robin S. Smith, Gerrit Lohmann, Weipeng Zheng, and Oliver Elison Timm (August 11, 2014), "The Holocene temperature conundrum", PNAS, 111 (34) E3501-E3505; https://doi.org/10.1073/pnas.1407229111

https://www.pnas.org/content/111/34/E3501

Significance
Marine and terrestrial proxy records suggest global cooling during the Late Holocene, following the peak warming of the Holocene Thermal Maximum (∼10 to 6 ka) until the rapid warming induced by increasing anthropogenic greenhouses gases. However, the physical mechanism responsible for this global cooling has remained elusive. Here, we show that climate models simulate a robust global annual mean warming in the Holocene, mainly in response to rising CO2 and the retreat of ice sheets. This model-data inconsistency demands a critical reexamination of both proxy data and models.

Abstract
A recent temperature reconstruction of global annual temperature shows Early Holocene warmth followed by a cooling trend through the Middle to Late Holocene [Marcott SA, et al., 2013, Science 339(6124):1198–1201]. This global cooling is puzzling because it is opposite from the expected and simulated global warming trend due to the retreating ice sheets and rising atmospheric greenhouse gases. Our critical reexamination of this contradiction between the reconstructed cooling and the simulated warming points to potentially significant biases in both the seasonality of the proxy reconstruction and the climate sensitivity of current climate models.

[AbruptSLR]

The linked 2015 reference finds that the disintegration of the Thwaites Ice Shelf (both the eastern ice shelf and the ice tongue) is accelerating due to basal melting and warm CDW intrusion beneath the eastern ice shelf since 2000), together with the shear stress between the eastern ice shelf and the residual ice tongue due to differential ice flow rates:

Kim et al (2015), "Disintegration and acceleration of Thwaites Ice Shelf on the Amundsen Sea revealed from remote sensing measurements", GIScience & Remote Sensing, Volume 52, Issue 4, DOI: 10.1080/15481603.2015.1041766

Abstract: "Thwaites Ice Shelf in the Amundsen Sea is one of the biggest ice shelves in West Antarctica and is well known for significant mass changes. In the shear zone between Thwaites Glacier Tongue and its eastern ice shelf, shear stress forced by different flow rates of the ice shelves is causing the ice to break apart. A time series analysis of remote sensing data obtained by Landsat 7 Enhanced Thematic Mapper Plus (ETM+), TerraSAR-X, and airborne synthetic aperture radar (SAR) revealed that the shear zone has extended since 2006 and eventually disintegrated in 2008. We quantified the acceleration of Thwaites Ice Shelf with time by using the feature tracking method. The buttressing loss induced by the extension of the shear zone and progressive disintegration accelerated the flow of Thwaites Glacier Tongue, which in turn increased the shear stress on its eastern ice shelf. We determine causes of disintegration in the newly formed shear zone to be oceanic basal melting and structural weakening induced by Circumpolar Deep Water intrusion beneath the eastern ice shelf since 2000. The structural weakening was examined by using the density distribution of rifts and crevasses on the ice shelf, which were well identified from high-resolution SAR and optical satellite images."

[AbruptSLR]

As the linked reference has many different bathymetries for the ASE, I provide the following information and associated images that clearly shows how the 'Big Ear' cavity at the base of the Thwaites Ice Tongue leads directly into the Byrd Subglacial Basin:

Millan et al. (2017), "Bathymetry of the Amundsen Sea Embayment sector of West Antarctica from Operation IceBridge gravity and other data", Geophysical Research Letters, 44(3), 1360-1368, doi:10.1002/2016GL072071

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016GL072071

Abstract
We employ airborne gravity data from NASA's Operation IceBridge collected in 2009–2014 to infer the bathymetry of sub–ice shelf cavities in front of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica. We use a three‐dimensional inversion constrained by multibeam echo sounding data offshore and bed topography from a mass conservation reconstruction on land. The seamless bed elevation data refine details of the Pine Island sub–ice shelf cavity, a slightly thinner cavity beneath Thwaites, and previously unknown deep (>1200 m) channels beneath the Crosson and Dotson ice shelves that shallow (500 m and 750 m, respectively) near the ice shelf fronts. These sub–ice shelf channels define the natural pathways for warm, circumpolar deep water to reach the glacier grounding lines, melt the ice shelves from below, and constrain the pattern of past and future glacial retreat.

[AbruptSLR]

The linked reference evaluates the implications of more accurately considering a 3-D viscoelastic Earth models as opposed to the less accurate assumption of elastic response on the sea-level fingerprint implications of an abrupt collapse of the WAIS.  Their findings conclude that "… when viscous effects are included, the peak sea-level fall predicted in the vicinity of WAIS during a melt event will increase by ~25% and ~50%, relative to the elastic case, for events of duration 25 years and 100 years, respectively."  This is important w.r.t. global sea level rise as the further the local sea-level drops around West Antarctica, the higher sea level will raise at distance away from West Antarctica.

Carling C. Hay, Harriet C. P. Lau, Natalya Gomez, Jacqueline Austermann, Evelyn Powell, Jerry X. Mitrovica, Konstantin Latychev, and Douglas A. Wiens (2016), "Sea-level fingerprints in a region of complex Earth structure: The case of WAIS", Journal of Climate, DOI: http://dx.doi.org/10.1175/JCLI-D-16-0388.1


http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0388.1


Abstract: "Sea-level fingerprints associated with rapid melting of the West Antarctic Ice Sheet (WAIS) have generally been computed under the assumption of a purely elastic response of the solid Earth. We investigate the impact of viscous effects on these fingerprints by computing gravitationally self-consistent sea-level changes that adopt a 3-D viscoelastic Earth model in the Antarctic region consistent with available geological and geophysical constraints. In West Antarctica, the model is characterized by a thin (~65 km) elastic lithosphere and sub-lithospheric viscosities that span three orders of magnitude, reaching values as low as ~4 × 1018 Pa s beneath WAIS. Our calculations indicate that sea-level predictions in the near field of WAIS will depart significantly from elastic fingerprints in as little as a few decades. For example, when viscous effects are included, the peak sea-level fall predicted in the vicinity of WAIS during a melt event will increase by ~25% and ~50%, relative to the elastic case, for events of duration 25 years and 100 years, respectively. Our results have implications for studies of sea-level change due to both ongoing mass loss from WAIS over the next century and future, large scale collapse of WAIS on century-to-millennial time scales."

[AbruptSLR]

Hopefully, future models of Antarctic Ice Sheets will use the geothermal heat flux information provided by the linked reference:

Yasmina M. Martos, Manuel Catalan, Tom A. Jordan,Alexander Golynsky, Dmitry Golynsky, Graeme Eagles & David G. Vaughan (6 November 2017), "Heat flux distribution of Antarctica unveiled", Geophysical Research Letters, DOI: 10.1002/2017GL075609 

http://onlinelibrary.wiley.com/doi/10.1002/2017GL075609/abstract?utm_content=buffer4cbb3&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

Abstract: "Antarctica is the largest reservoir of ice on Earth. Understanding its ice sheet dynamics is crucial to unraveling past global climate change and making robust climatic and sea level predictions. Of the basic parameters that shape and control ice flow, the most poorly known is geothermal heat flux. Direct observations of heat flux are difficult to obtain in Antarctica, and until now continent-wide heat flux maps have only been derived from low-resolution satellite magnetic and seismological data. We present a high resolution heat flux map and associated uncertainty derived from spectral analysis of the most advanced continental compilation of airborne magnetic data. Small-scale spatial variability and features consistent with known geology are better reproduced than in previous models, between 36% and 50%. Our high-resolution heat-flux map and its uncertainty distribution provide an important new boundary condition to be used in studies on future subglacial hydrology, ice-sheet dynamics and sea-level change."

[AbruptSLR]

For those not too familar with the Pope, Smith and Kohler marine glaciers and their ice shelves: Crosson and Dotson (all in the ASE), I provide the following linked open access reference and associated image:

Lilien, D. A., Joughin, I., Smith, B., and Shean, D. E.: Elevated melt causes varied response of Crosson and Dotson Ice Shelves in West Antarctica, The Cryosphere Discuss., https://doi.org/10.5194/tc-2017-248, in review, 2018.

https://www.the-cryosphere-discuss.net/tc-2017-248/
https://www.the-cryosphere-discuss.net/tc-2017-248/tc-2017-248.pdf

Abstract. Crosson and Dotson Ice Shelves are two of the most rapidly changing outlets in West Antarctica, displaying both significant thinning and grounding-line retreat in recent decades. We used remotely sensed datasets to investigate the processes controlling their changes in speed and grounding-line position over the past 20 years. We combined these observations with inverse modeling of the viscosity of the ice shelves to understand how weakening of the shelves affected this speedup. These ice shelves have lost mass continuously since the 1990s, and we find that this loss is primarily a result of melt beneath Dotson. High melt rates persisted over the period covered by our observations (1996–2014), with the highest rates beneath areas that ungrounded during this time. Grounding line flux exceeded basinwide accumulation by about a factor of two throughout the study period, consistent with earlier studies, resulting in significant loss of grounded as well as floating ice. The near doubling of Crosson's speed in some areas during this time likely is the result of weakening of its margins and retreat of its grounding line. This speedup contrasts with Dotson, which has continued to move slowly despite high, increasing melt rates near its grounding line. Our results indicate that changes to melt rates began before 1996, and suggest that observed increases in melt in the 2000s compounded an ongoing retreat of this system. Advection of a channel along Dotson, as well as the grounding-line position of Kohler Glacier, suggest that Dotson experienced a change in flow around the 1970s, which may be the initial cause of its continuing retreat.


Caption: "Figure 1: Overview of study area a) 1996 surface speed overlaid on the mosaic of Antarctica (MOA) (Haran et al., 2013).  Yellow and green lines show grounding line positions in 1996 and 2011 respectively (Rignot et al., 2014). Black lines indicate catchment boundaries of Crosson and Dotson used for flux calculations. b) Surface elevation relative to the EGM2008 geoid from WorldView/GeoEye stereo DEM mosaic (Shean et al., 2016). c) Ice bottom elevation relative to the EGM2008 geoid, which represents bed elevation over grounded ice."

[AbruptSLR]

The linked reference demonstrates that to model significant amounts of ice-climate feedbacks requires a significant degree of nonlinear feedback behavior:

Tigchelaar, M., Timmermann, A., Friedrich, T., Heinemann, M., and Pollard, D.: Nonlinear response of the Antarctic Ice Sheet to late Quaternary sea level and climate forcing, The Cryosphere, 13, 2615–2631, https://doi.org/10.5194/tc-13-2615-2019, 2019.

https://www.the-cryosphere.net/13/2615/2019/

Abstract
Antarctic ice volume has varied substantially during the late Quaternary, with reconstructions suggesting a glacial ice sheet extending to the continental shelf break and interglacial sea level highstands of several meters. Throughout this period, changes in the Antarctic Ice Sheet were driven by changes in atmospheric and oceanic conditions and global sea level; yet, so far modeling studies have not addressed which of these environmental forcings dominate and how they interact in the dynamical ice sheet response. Here, we force an Antarctic Ice Sheet model with global sea level reconstructions and transient, spatially explicit boundary conditions from a 408 ka climate model simulation, not only in concert with each other but, for the first time, also separately. We find that together these forcings drive glacial–interglacial ice volume changes of 12–14 ms.l.e., in line with reconstructions and previous modeling studies. None of the individual drivers – atmospheric temperature and precipitation, ocean temperatures, or sea level – single-handedly explains the full ice sheet response. In fact, the sum of the individual ice volume changes amounts to less than half of the full ice volume response, indicating the existence of strong nonlinearities and forcing synergy. Both sea level and atmospheric forcing are necessary to create full glacial ice sheet growth, whereas the contribution of ocean melt changes is found to be more a function of ice sheet geometry than climatic change. Our results highlight the importance of accurately representing the relative timing of forcings of past ice sheet simulations and underscore the need for developing coupled climate–ice sheet modeling frameworks that properly capture key feedbacks.

[AbruptSLR]

Perhaps the cited attribution studies will be completed in time to impact CMIP7:

Noël, B., van Kampenhout, L., van de Berg, W. J., Lenaerts, J. T. M., Wouters, B., and van den Broeke, M. R.: Brief communication: CESM2 climate forcing (1950–2014) yields realistic Greenland ice sheet surface mass balance, The Cryosphere Discuss., https://doi.org/10.5194/tc-2019-209, in review, 2019.

https://www.the-cryosphere-discuss.net/tc-2019-209/

Abstract. We present a reconstruction of historical (1950–2014) surface mass balance (SMB) of the Greenland ice sheet (GrIS) using a high-resolution regional climate model (RACMO2; ~ 11 km) to dynamically downscale the climate of the Community Earth System Model version 2 (CESM2; ~ 111 km). After further statistical downscaling to 1 km spatial resolution, evaluation using in situ SMB measurements and remotely sensed GrIS mass change shows good agreement, including the recently observed acceleration in surface mass loss (2003–2014). Comparison with an ensemble of eight previously conducted RACMO2 simulations forced by climate reanalysis demonstrates that the current product accurately reproduces the long term average and inter-annual variability of individual SMB components, and captures the recent increase in meltwater runoff that accelerated GrIS mass loss. This means that, for the first time, an Earth System Model (CESM2), without assimilating observations, can be used to reconstruct historical GrIS SMB and the mass loss acceleration that started in the 1990s. This paves the way for attribution studies of future GrIS mass loss projections and contribution to sea level rise.

[Hefaistos]

…
And again, oceans store more than 99% of earth's thermal energy.

The first reference confirms that the oceans absorbs only 93% of the Earth's Energy Imbalance (not 99%);

What we're talking about here, is the ocean as a dynamic system for heat storage. As with all dynamic systems we have state variables and flow variables. The 93% of energy that the ocean absorbs, that you refer to  ASLR, is a FLOW variable.
What I was refering to is the STATE variable, how the total thermal energy on earth is distributed between atmosphere and ocean.
The specific heat capacity of ocean water is around 4000 J/kg/K
The specific heat capacity of air is around 1000 J/kg/K
The mass of the hydrosphere, i.e. mainly the ocean water is 1.4×10²¹ kg
The mass of the atmosphere is 5×10¹⁸ kg

Multiplying out we thus have a ratio of about 4000 to 1 in the state variable (heat capacity).
Conclusion: The ocean stores well above 99% of the 'total energy' on earth. This applies in a steady state situation where heat transfer between ocean and atmosphere are in balance. (I don't claim that we are in a steady state now.)
Or, we can conclude that the time taken to transfer heat in the atmosphere is extremely short compared to the time to transfer heat in the ocean.
Or, we can conclude that the ocean gives the climate system incredible inertia.

https://en.wikipedia.org/wiki/Hydrosphere
https://en.wikipedia.org/wiki/Atmosphere_of_Earth

[nanning]

There are also ocean beds that need to warm with the changing bottom ocean temps. Earth is not just ocean + air. Melting ice takes a lot of energy, providing a cooling effect. There's water in the atmosphere, upper atmosphere heat exchange etc.
To me warming the Earth is much more complex than you picture it. Maybe I misunderstand you.

I agree with your conclusion about inertia. If the ocean stratifies, there will be less ocean inertia and the atmosphere will warm faster.

[Hefaistos]

There are also ocean beds that need to warm with the changing bottom ocean temps. Earth is not just ocean + air. Melting ice takes a lot of energy, providing a cooling effect. There's water in the atmosphere, upper atmosphere heat exchange etc.
To me warming the Earth is much more complex than you picture it. Maybe I misunderstand you.

I agree with your conclusion about inertia. If the ocean stratifies, there will be less ocean inertia and the atmosphere will warm faster.

Nanning, all what you say is of course correct!
I just wanted to point out the more basic relationships in terms of heat storage. 'We' tend to focus a bit too much on what's going on in the atmosphere and 'forget' about the more important role that the Ocean plays in long-term climate change.

[Lennart van der Linde]

'We' tend to focus a bit too much on what's going on in the atmosphere and 'forget' about the more important role that the Ocean plays in long-term climate change.

Hefaistos, I think many on this forum/thread have learned a lot from scientists like Jim Hansen. Have you seen his latest commentary? See:
http://www.columbia.edu/~jeh1/mailings/2019/20191211_Fire.pdf

Do you think he 'forgets' about the more important role of the ocean? Or does he indicate mainstream climate science has maybe even under-estimated the role of the ocean, both in the longer and also the shorter term?

Also see what he says there about the role of the market versus instruments like fee & dividend. Do you agree with him about the urgency of such policies? Or do you believe the market will solve this crisis in time all by itself? And two generations may well be too long to prevent a cascade of tipping points, so how can 'we' minimize this risk?

[kassy]

I just wanted to point out the more basic relationships in terms of heat storage. 'We' tend to focus a bit too much on what's going on in the atmosphere and 'forget' about the more important role that the Ocean plays in long-term climate change.

But that 99% state was probably always true it just does not prevent radical changes on the surface as we know from history.

You cannot use it to feel safe imho.

In post 2210 you state: I hypothesize that we only need say 30-40 years (1 investment cycles of e.g. power generation installations, or 2 investment cycles for e.g. car production) to get off enough of the fossil fuels to save the world without too much climate change drama.

This is rather abstract and it ignores the climate drama we already have.

Long ago the idea was to save the arctic ice and Greenland and Antarctica and prevent permafrost from becoming a source instead of a sink.

So now it is 2019.

Lets say it takes 40 years to hit the emission target. Fine. No drama except:
Arctic ice might very well die in that time frame (see When will the Arctic go ice free)

Antarctica is melting. Even though 99% of the energy is in the oceans some annoying fraction of it is lapping at the glaciers there and that heat is historical heat so even when we will turn things around emission wise it will still continue for years.

Arctic permafrost is a source since at least 2003.

(And we will kill the Amazon in the meantime but the ocean was never gonna save that so lets ignore it).

There is only one mechanism for reversing the ice loss and the damage to the permafrost.
 
We have to reduce CO2e to below the point that triggered those responses.
So below the value of 2003. Probably decades before that.

350 would not be a bad goal. (And since we need to modernize it due to our ever increasingly interesting mix of gasses lets say this is CO2e)

Anything beyond that triggered these responses that will move the world out of our comfort zone

So every year we are running up a rather horrible debt.

And we already have too much climate change drama. It just does not hurt us overall that bad yet. I would not bet on that lasting 40 years.

[nanning]

That's exactly how I see it, but I am not able to put it in such a concise beautiful form. Thanks again. It's getting repetitive

(why 350? I should be 280 I think. To pick up where we left of, although I don't think that is possible within the next 10000 years)

[AbruptSLR]

The first image from the linked article indicates a near 100% chance that the Arctic would have experienced its first ice-free summer by 2050 following RCP 8.5.

Title: "Interactive: When will the Arctic see its first ice-free summer?"

https://interactive.carbonbrief.org/when-will-the-arctic-see-its-first-ice-free-summer/

Extract: "Since satellites first began monitoring the Arctic in 1979, the average area covered by sea ice has shrunk by at least 40%. The average thickness of the ice has fallen by more than half over the same time period."

The second image confirms that in 2019 the global is continuing to follow SSP5 – 8.5; while the third image shows that by following SSP5-Baseline (SSP5 – 8.5) until 2050 radiative forcing due to GHG emissions will be about 5 W/m².  Here, I repost the fourth image to note that by Hansen et al. (2016)'s 5-year doubling ice mass loss scenario, shortly after 2050 ice-climate forcing could add about another 2.2 W/m² of forcing which might temporarily, and abruptly, bring the forcing imbalance to over 7.2 W/m² shortly after 2050.

[Lennart van der Linde]

(why 350? I should be 280 I think. To pick up where we left of, although I don't think that is possible within the next 10000 years)

Jim Hansen says in his latest communication:
http://www.columbia.edu/~jeh1/mailings/2019/20191211_Fire.pdf

'I may have learned more in 2004-2008 than I had in the prior 15 years – about climate science as well as implications for energy policy. Bill McKibben, who was about to form an organization 450.org, asked me to confirm that 450 parts per million (ppm) was an appropriate target for atmospheric CO2 amount. This led to collaboration with some of the best relevant scientists in the world. We concluded that the appropriate target was less than 350 ppm. The optimum target is probably not as low as the preindustrial 280 ppm, in part because of other human-made alterations to Earth, but it is unnecessary to define the final target exactly at this time. The “<350 ppm” target already implies that fossil fuel emissions must be phased out as rapidly as practical.'

[AbruptSLR]

...
Hefaistos, I think many on this forum/thread have learned a lot from scientists like Jim Hansen. Have you seen his latest commentary? See:
http://www.columbia.edu/~jeh1/mailings/2019/20191211_Fire.pdf

Do you think he 'forgets' about the more important role of the ocean? Or does he indicate mainstream climate science has maybe even under-estimated the role of the ocean, both in the longer and also the shorter term?
…

I concur that consensus climate science (including both CMIP5 & CMIP6) are currently underestimating many climate risks associated with the warming oceans, and the linked information provides just a couple of these overlooked risk factors:

Lowell Douglas Stott, Kathleen M. Harazin, Nadine B. Quintana Krupinski. Hydrothermal carbon release to the ocean and atmosphere from the Eastern Equatorial Pacific during the Last Glacial Termination. Environmental Research Letters, 2019; DOI: 10.1088/1748-9326/aafe28

https://iopscience.iop.org/article/10.1088/1748-9326/aafe28

Abstract
Arguably among the most globally impactful climate changes in Earth's past million years are the glacial terminations that punctuated the Pleistocene epoch. With the acquisition and analysis of marine and continental records, including ice cores, it is now clear that the Earth's climate was responding profoundly to changes in greenhouse gases that accompanied those glacial terminations. But the ultimate forcing responsible for the greenhouse gas variability remains elusive. The oceans must play a central role in any hypothesis that attempt to explain the systematic variations in pCO2 because the Ocean is a giant carbon capacitor, regulating carbon entering and leaving the atmosphere. For a long time, geological processes that regulate fluxes of carbon to and from the oceans were thought to operate too slowly to account for any of the systematic variations in atmospheric pCO2 that accompanied glacial cycles during the Pleistocene. Here we investigate the role that Earth's hydrothermal systems had in affecting the flux of carbon to the ocean and ultimately, the atmosphere during the last glacial termination. We document late glacial and deglacial intervals of anomalously old ¹⁴C reservoir ages, large benthic-planktic foraminifera ¹⁴C age differences, and increased deposition of hydrothermal metals in marine sediments from the eastern equatorial Pacific (EEP) that indicate a significant release of hydrothermal fluids entered the ocean at the last glacial termination. The large ¹⁴C anomaly was accompanied by a ~4-fold increase in Zn/Ca in both benthic and planktic foraminifera that reflects an increase in dissolved [Zn] throughout the water column. Foraminiferal B/Ca and Li/Ca results from these sites document deglacial declines in [ ] throughout the water column; these were accompanied by carbonate dissolution at water depths that today lie well above the calcite lysocline. Taken together, these results are strong evidence for an increased flux of hydrothermally-derived carbon through the EEP upwelling system at the last glacial termination that would have exchanged with the atmosphere and affected both Δ¹⁴C and pCO2. These data do not quantify the amount of carbon released to the atmosphere through the EEP upwelling system but indicate that geologic forcing must be incorporated into models that attempt to simulate the cyclic nature of glacial/interglacial climate variability. Importantly, these results underscore the need to put better constraints on the flux of carbon from geologic reservoirs that affect the global carbon budget.

&

Title: "Undersea gases could superheat the planet"

https://www.sciencedaily.com/releases/2019/02/190213090812.htm

Extract: "For today's world, the findings could portend an ominous development. The undersea carbon reservoirs released greenhouse gas to the atmosphere as oceans warmed, the study shows, and today the ocean is heating up again due to humanmade global warming.

If undersea carbon reservoirs are upset again, they would emit a huge new source of greenhouse gases, exacerbating climate change. Temperature increases in the ocean are on pace to reach that tipping point by the end of the century. For example, a big carbon reservoir beneath the western Pacific near Taiwan is already within a few degrees Celsius of destabilizing.

Moreover, the phenomenon is a threat unaccounted for in climate model projections. Undersea carbon dioxide reservoirs are relatively recent discoveries and their characteristics and history are only beginning to be understood.
…
"The grand challenge is we don't have estimates of the size of these or which ones are particularly vulnerable to destabilization," Stott said. "It's something that needs to be determined."

In many cases, the carbon reservoirs are bottled up by their hydrate caps. But those covers are sensitive to temperature changes. As oceans warm, the caps can melt, a development the paper warns would lead to a double wallop for climate change -- a new source of geologic carbon in addition to the humanmade greenhouse gases.

Oceans absorb nearly all the excess energy from the Earth's atmosphere, and as a result they have been warming rapidly in recent decades. Over the past quarter-century, Earth's oceans have retained 60 percent more heat each year than scientists previously had thought, other studies have shown. Throughout the marine water column, ocean heat has increased for the last 50 years. The federal government's Climate Science Special Report projected a global increase in average sea surface temperatures of up to 5 degrees Fahrenheit by the end of the century, given current emissions rates. Temperature gains of that magnitude throughout the ocean could eventually destabilize the geologic hydrate reservoirs, Stott said.

"The last time it happened, climate change was so great it caused the end of the ice age. Once that geologic process begins, we can't turn it off," Stott said.
…
Said Stott: "Discoveries of accumulations of liquid, hydrate and gaseous carbon dioxide in the ocean has not been accounted for because we didn't know these reservoirs existed until recently, and we didn't know they affected global change in a significant way.

"This study shows that we've been missing a critical component of the marine carbon budget. It shows these geologic reservoirs can release large amounts of carbon from the oceans. Our paper makes the case that this process has happened before and it could happen again.""

See also:

Olivier Sulpis, Bernard P. Boudreau, Alfonso Mucci, Chris Jenkins, David S. Trossman, Brian K. Arbic, Robert M. Key. Current CaCO3 dissolution at the seafloor caused by anthropogenic CO2. Proceedings of the National Academy of Sciences, 2018; 201804250 DOI: 10.1073/pnas.1804250115

https://www.pnas.org/content/115/46/11700

Significance
The geological record contains numerous examples of “greenhouse periods” and ocean acidification episodes, where the spreading of corrosive (CO2-enriched) bottom waters enhances the dissolution of CaCO3 minerals delivered to the seafloor or contained within deep-sea sediments. The dissolution of sedimentary CaCO3 neutralizes excess CO2, thus preventing runaway acidification, and acts as a negative-feedback mechanism in regulating atmospheric CO2 levels over timescales of centuries to millennia. We report an observation-based indication and quantification of significant CaCO3 dissolution at the seafloor caused by man-made CO2. This dissolution is already occurring at various locations in the deep ocean, particularly in the northern Atlantic and near the Southern Ocean, where the bottom waters are young and rich in anthropogenic CO2.

[AbruptSLR]

There are also ocean beds that need to warm with the changing bottom ocean temps.
…

Don't forget the influence of geothermal heat flux from the seafloor on the MOC and the risk of possible future abrupt climate changes:

Title: "Overview: Seafloor Eruptions and Ocean Warming"

https://rclutz.wordpress.com/2016/10/05/overview-seafloor-eruptions-and-ocean-warming/

Extract: "Without geothermal heat fluxes, the temperatures of the abyssal ocean would be up to 0.5 C lower than observed, deep stratification would be reinforced by about 25%, and the strength of the abyssal circulation would decrease by between 25% and 50%, substantially altering the ability of the deep ocean to transport and store not only heat but also carbon and other climatically important tracers (Adcroft et al., 2001, Hofmann and Morales Maqueda, 2009, Mashayek et al., 2013). It has been hypothesised that interactions between the ocean circulation and geothermal heating are responsible for abrupt climatic changes during the last glacial cycle (Adkins et al, 2005)."

[nanning]

Thanks very much Lennart and AbruptSLR. For all your great posts here.

"Undersea gases could superheat the planet"
That's a biggie.

[AbruptSLR]

...
What we're talking about here, is the ocean as a dynamic system for heat storage. As with all dynamic systems we have state variables and flow variables. The 93% of energy that the ocean absorbs, that you refer to  ASLR, is a FLOW variable.
What I was refering to is the STATE variable, how the total thermal energy on earth is distributed between atmosphere and ocean.
…

The attached image shows the annual distribution of thermal energy assumed by AR4, which did not change significantly w.r.t. the ocean's share in AR5.

[AbruptSLR]

What are the chances that the world will reach 'peak meat' by 2030?

Title: "World must reach 'peak meat' by 2030 to meet climate change targets, scientists warn"

https://www.cnn.com/2019/12/12/world/peak-meat-2030-lancet-intl-scli-scn/index.html

Extract: "The world needs to reach "peak meat" within the next 10 years to combat the effects of climate change, scientists have warned.

In a letter to The Lancet Planetary Health Journal, they said all but the poorest countries needed to set a time frame for livestock production to stop growing, since the meat and dairy sector is responsible for such a large proportion of emissions.

The scientists called on governments to identify the largest emissions sources or land-occupiers in the livestock sector and set reduction targets to help fight the risk of global temperatures rising by more than the "safe" limit of 1.5-2 degrees Celsius above pre-industrial levels."

Edit, see also:

Title: "Emissions – Impossible"

https://www.iatp.org/emissions-impossible

Extract: "Emissions intensity targets count emissions per kilogram of meat or milk, but they do nothing to curtail overall growth in company emissions, sales, processing volumes, revenues, or profits. While intensity may be kept in check or even reduced, total emissions will continue to rise in tandem with production. It is easy to see why corporations focus on reducing intensity rather than reducing total emissions."

[AbruptSLR]

The linked reference and associate articles about the new BedMachine Antarctica findings indicate that the Ross Ice Shelf (RIS) is less stable than previously thought, and that there are no pinning points to stop the Thwaites Glacier grounding line from retreating into the BSB, and that the Recovery and Support Force glaciers are more susceptible to retreat than previously thought:

Morlighem, M., Rignot, E., Binder, T. et al. Deep glacial troughs and stabilizing ridges unveiled beneath the margins of the Antarctic ice sheet. Nat. Geosci. (2019) doi:10.1038/s41561-019-0510-8

https://www.nature.com/articles/s41561-019-0510-8

Abstract: "The Antarctic ice sheet has been losing mass over past decades through the accelerated flow of its glaciers, conditioned by ocean temperature and bed topography. Glaciers retreating along retrograde slopes (that is, the bed elevation drops in the inland direction) are potentially unstable, while subglacial ridges slow down the glacial retreat. Despite major advances in the mapping of subglacial bed topography, significant sectors of Antarctica remain poorly resolved and critical spatial details are missing. Here we present a novel, high-resolution and physically based description of Antarctic bed topography using mass conservation. Our results reveal previously unknown basal features with major implications for glacier response to climate change. For example, glaciers flowing across the Transantarctic Mountains are protected by broad, stabilizing ridges. Conversely, in the marine basin of Wilkes Land, East Antarctica, we find retrograde slopes along Ninnis and Denman glaciers, with stabilizing slopes beneath Moscow University, Totten and Lambert glacier system, despite corrections in bed elevation of up to 1 km for the latter. This transformative description of bed topography redefines the high- and lower-risk sectors for rapid sea level rise from Antarctica; it will also significantly impact model projections of sea level rise from Antarctica in the coming centuries."

See also:

Title: "Team releases high-precision map of Antarctic ice sheet bed topography"

https://phys.org/news/2019-12-team-high-precision-antarctic-ice-sheet.html


Extract: "A University of California, Irvine-led team of glaciologists has unveiled the most accurate portrait yet of the contours of the land beneath Antarctica's ice sheet—and, by doing so, has helped identify which regions of the continent are going to be more, or less, vulnerable to future climate warming.
…
Among the most striking results of the BedMachine project are the discovery of stabilizing ridges that protect the ice flowing across the Transantarctic Mountains; a bed geometry that increases the risk of rapid ice melting in the Thwaites and Pine Island glaciers sector of West Antarctica; a bed under the Recovery and Support Force glaciers that is hundreds of meters deeper than previously thought, making those ice sheets more susceptible to retreat; and the world's deepest land canyon below Denman Glacier in East Antarctica."

&

Title: "BedMachine Antarctica"

https://sites.uci.edu/morlighem/bedmachine-antarctica/

Edit, see also:

Title: "MEaSUREs BedMachine Antarctica, Version 1"

https://nsidc.org/data/nsidc-0756

[AbruptSLR]

The linked reference, & associated article, indicate that an observed increase in methane from East African wetlands may account for up to one third of the increase in observed atmospheric methane concentrations in the period from 2010 to 2016:

Lunt, M. F., Palmer, P. I., Feng, L., Taylor, C. M., Boesch, H., and Parker, R. J.: An increase in methane emissions from tropical Africa between 2010 and 2016 inferred from satellite data, Atmos. Chem. Phys., 19, 14721–14740, https://doi.org/10.5194/acp-19-14721-2019, 2019.

https://www.atmos-chem-phys.net/19/14721/2019/

Abstract
Emissions of methane (CH4) from tropical ecosystems, and how they respond to changes in climate, represent one of the biggest uncertainties associated with the global CH4 budget. Historically, this has been due to the dearth of pan-tropical in situ measurements, which is particularly acute in Africa. By virtue of their superior spatial coverage, satellite observations of atmospheric CH4 columns can help to narrow down some of the uncertainties in the tropical CH4 emission budget. We use proxy column retrievals of atmospheric CH4 (XCH4) from the Japanese Greenhouse gases Observing Satellite (GOSAT) and the nested version of the GEOS-Chem atmospheric chemistry and transport model (0.5 ∘ ×0.625 ∘  0.5∘×0.625∘) to infer emissions from tropical Africa between 2010 and 2016. Proxy retrievals of XCH4 are less sensitive to scattering due to clouds and aerosol than full physics retrievals, but the method assumes that the global distribution of carbon dioxide (CO2) is known. We explore the sensitivity of inferred a posteriori emissions to this source of systematic error by using two different XCH4 data products that are determined using different model CO2 fields. We infer monthly emissions from GOSAT XCH4 data using a hierarchical Bayesian framework, allowing us to report seasonal cycles and trends in annual mean values. We find mean tropical African emissions between 2010 and 2016 range from 76 (74–78) to 80 (78–82) Tg yr−1, depending on the proxy XCH4 data used, with larger differences in Northern Hemisphere Africa than Southern Hemisphere Africa. We find a robust positive linear trend in tropical African CH4 emissions for our 7-year study period, with values of 1.5 (1.1–1.9) Tg yr−1 or 2.1 (1.7–2.5) Tg yr−1, depending on the CO2 data product used in the proxy retrieval. This linear emissions trend accounts for around a third of the global emissions growth rate during this period. A substantial portion of this increase is due to a short-term increase in emissions of 3 Tg yr−1 between 2011 and 2015 from the Sudd in South Sudan. Using satellite land surface temperature anomalies and altimetry data, we find this increase in CH4 emissions is consistent with an increase in wetland extent due to increased inflow from the White Nile, although the data indicate that the Sudd was anomalously dry at the start of our inversion period. We find a strong seasonality in emissions across Northern Hemisphere Africa, with the timing of the seasonal emissions peak coincident with the seasonal peak in ground water storage. In contrast, we find that a posteriori CH4 emissions from the wetland area of the Congo Basin are approximately constant throughout the year, consistent with less temporal variability in wetland extent, and significantly smaller than a priori estimates.

&

Title: "Climate change: Methane pulse detected from South Sudan wetlands"

https://www.bbc.com/news/science-environment-50708544

Extract: " Researchers, led from Edinburgh University, UK, say their studies point to a big jump in emissions coming from just the wetlands of South Sudan.

Satellite data indicates the region received a large surge of water from East African lakes, including Victoria.

This would have boosted CH4 from the wetlands, accounting for a significant part of the rise in global methane.

Perhaps even up to a third of the growth seen in the period 2010-2016, when considered with East Africa as a whole."

[AbruptSLR]

I note that in two hours from now you can use the following link to watch the AGU Session on "Climate Sensitivity and Feedbacks: Advances and New Paradigms I" for free:

Title: "AGU GO"

https://www.agu.org/Fall-Meeting/Pages/AGU-GO

12 December 2019:

o   A44B - Climate Sensitivity and Feedbacks: Advances and New Paradigms I
04:00 PM - 06:00 PM | Moscone West, 3004, L3,

Edit: At some point in the future readers can use the link to access a video of the session when it is eventually up-loaded to YouTube.

[AbruptSLR]

The linked article discusses a recently discovered subglacial river beneath the GIS that flows almost 1,000 miles and then exists at Petermann Fjord on the north coast of Greenland.  While the discharge of this river appears to be episodic, I cannot imagine that this is good news for the long-term stability of Petermann Glacier:

Title: "A Dark River Nearly 1,000 Miles Long May Be Flowing Beneath Greenland's Ice"

https://www.livescience.com/hidden-subglacial-river-greenland.html

Extract: "Far below the frozen cover of the Greenland ice sheet sprawls miles of bedrock — and extending through that bedrock for close to 1,000 miles (1,600 kilometers) is a valley that may contain a subterranean river, transporting water from central Greenland to the northern coast.
…
"Eventually if you get it deep enough — minus 500 meters [1,640 feet] — the water is now flowing the entire length along the valley and then exiting at Petermann Fjord," creating a pathway that measures up to 1,600 kilometers (1,000 miles) long Chambers said.

Because this river would be running in darkness for hundreds of miles under the ice, the researchers named it "the Dark River," they wrote in a summary of their research. The Dark River likely doesn't have a very strong or constant flow, because glacier melt disperses over a large area, Chambers said. The river could occasionally be quite powerful "but only at certain times," when large reservoirs of meltwater build up and then release into the valley, he added."

[AbruptSLR]

The link below leads to a PowerPoint presentation entitled: "Investigating the climate sensitivity difference between CESM1 and CESM2 in 4XCO2 and SOM runs"; which discusses possible reasons why CESM1 has a mean ECS value of 4.1C while CESM2 has a mean ECS value of 5.3C, and which indicates that the influence of the atmosphere is only part of the reason:

http://www.cesm.ucar.edu/events/wg-meetings/2019/presentations/AMWGChemWAWG/hannay.pdf

[Hefaistos]

'We' tend to focus a bit too much on what's going on in the atmosphere and 'forget' about the more important role that the Ocean plays in long-term climate change.

Hefaistos, I think many on this forum/thread have learned a lot from scientists like Jim Hansen. Have you seen his latest commentary? See:
http://www.columbia.edu/~jeh1/mailings/2019/20191211_Fire.pdf

Do you think he 'forgets' about the more important role of the ocean? Or does he indicate mainstream climate science has maybe even under-estimated the role of the ocean, both in the longer and also the shorter term?

Lennart, thanks for referring that paper by Hansen. It's a long, personal rant, but an interesting read!
Hansen's model(s), that he has published in several papers since 2005, is in my opinion not accepted science. The latest paper is: "Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 C global warming could be dangerous" (open source)

He speculates that exponentially increasing ice losses primarily from the Antarctic will cause the AMOC/SMOC to shut down within a few decades, which will trigger more large-scale climate changes. But this is just a modelling excercise, based on incomplete theories, and totally insufficient data, especially from the ever important Southern Ocean. The ocean array data on AMOC show that it is strengthening, not weakening. We know very little about those very long term processes in the ocean. And we aren't yet able to adequately model deep convection in the tropics, where most of energy transfer takes place. Etc.etc., just to point out that we shouldn't get panic because of some computer simulations that is essentially GIGO.

Also see what he says there about the role of the market versus instruments like fee & dividend. Do you agree with him about the urgency of such policies? Or do you believe the market will solve this crisis in time all by itself? And two generations may well be too long to prevent a cascade of tipping points, so how can 'we' minimize this risk?

I agree about the urgency of climate policies to avoid the 'tipping points'. But I think that:
i. The capitalist market forces already strongly favouring renewables due to pure price competitiveness; and
ii. The kind of aggressive climate policies now implemented by the EU and some other OECD countries;

will be quite sufficient to avoid those tipping points in reasonable time, say 40 years. I think we already left the exponential growth of CO2, and that we are now in linear growth. In as little as 5-10 years I hypothesize that we will see flat CO2 growth.

On EU policies: Nearly every major aspect of the European economy is to be re-evaluated in light of the imperatives of the climate and ecological emergency, according to sweeping new plans set out by the European Commission.

"As well as bidding to lead the world on climate action, with a proposed target of net-zero carbon by 2050 and halving emissions by 2030, the EU will delve far more deeply into the root problems that contribute to carbon emissions and pollution."

One example is here in Sweden, where carbon emissions are in decline for several years now, and where climate policies are getting ever more aggressive. E.g. a ban on sale of new ICE cars from 2030.

https://www.theguardian.com/environment/2019/dec/11/european-green-deal-will-change-economy-to-solve-climate-crisis-says-eu

[Hefaistos]

I just wanted to point out the more basic relationships in terms of heat storage. 'We' tend to focus a bit too much on what's going on in the atmosphere and 'forget' about the more important role that the Ocean plays in long-term climate change.

But that 99% state was probably always true it just does not prevent radical changes on the surface as we know from history.

You cannot use it to feel safe imho.

In post 2210 you state: I hypothesize that we only need say 30-40 years (1 investment cycles of e.g. power generation installations, or 2 investment cycles for e.g. car production) to get off enough of the fossil fuels to save the world without too much climate change drama.

This is rather abstract and it ignores the climate drama we already have.
---
Lets say it takes 40 years to hit the emission target. Fine. No drama except:
Arctic ice might very well die in that time frame (see When will the Arctic go ice free)

Maybe in the summer time. Which will be reversible. I strongly disagree that we will 'ever' get an equable climate.

...
There is only one mechanism for reversing the ice loss and the damage to the permafrost.
 
We have to reduce CO2e to below the point that triggered those responses.
So below the value of 2003. Probably decades before that.

350 would not be a bad goal. (And since we need to modernize it due to our ever increasingly interesting mix of gasses lets say this is CO2e)

Anything beyond that triggered these responses that will move the world out of our comfort zone

...

I agree about 350 as a good goal.
I think we're getting out of CO2 growth pretty soon (5-10 years), and we will see a stable decline starting well before 2050.

[kassy]

I have to see it first before i believe it (reports from Madrid are not very hopeful).

Nanning: why 350? I should be 280 I think. To pick up where we left of, although I don't think that is possible within the next 10000 years

If you scroll up you see i did say 350 CO2e which sort of works out around that value.