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Messages - AbruptSLR

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1
The relatively rapid eastward shift of warm Tropical Pacific sea surface temperature anomalies, SSTAs, with continued global warming is an indication of relatively high climate sensitivity, and this topic is discussed in the linked reference:

Zixiang Yan et al. (08 Jan 2020), "Eastward shift and extension of ENSO-induced tropical precipitation anomalies under global warming", Science Advances, Vol. 6, no. 2, eaax4177, DOI: 10.1126/sciadv.aax4177

https://advances.sciencemag.org/content/6/2/eaax4177

Abstract
During El Niño events, increased precipitation occurs over the equatorial central eastern Pacific, corresponding to enhanced convective heating that modulates global climate by exciting atmospheric teleconnections. These precipitation anomalies are projected to shift and extend eastward in response to global warming. We show that this predicted change is caused by narrowing of the meridional span of the underlying El Niño–related sea surface temperature (SST) anomalies that leads to intensification of the meridional gradient of the SST anomalies, strengthening boundary-layer moisture convergence over the equatorial eastern Pacific, and enhancing local positive precipitation anomalies. The eastward shift and extension of these anomalies also intensify and extend eastward negative precipitation anomalies over the tropical western North Pacific, by strengthening equatorward advection of low mean moist enthalpy. Changes in El Niño–induced tropical precipitation anomalies suggest that, under global warming, El Niño events decay faster after their peak phase, thus shortening their duration.

2
...
ECS is what happens over the centuries as the climate comes into equilibrium from the forcings.

And it shows that even with the CMIP6 models coming up with higher ECS, the results from those models for TCR are consistent with the CMIP5 models used for AR5.  It looks like consensus science got TCR right.

While it may take centuries to reach full equilibrium for ECS values, the first image (from E3SM) shows that the lion's share of warming from ECS occurs in the first 100-years.  Thus, before deciding what is good news, or not, it is best to look at the direct GMSTA projections such as those shown in the second attached image from a French CMIP6 projections of GMSTA (with a pre-industrial baseline) for the different SSP scenarios; which indicates that by following either SSP5 8.5 or SSP3 7.0, GMSTA could be approaching 2.5C by 2040 (which is not good news):

I remind readers that if ECS is as high as many CMIP6 models project then much of the associated increase in GMSTA will occur this century (see the first image) and that at least one of the French contributions to CMIP6 shows little bias with the observed record (see the second image).

3
The linked reference compares the skill to match observed data for different CMIP archives and of CESM1-LE, and it finds the CMIP6 shows more skill than CMIP5 and that CESM1-LE (as an example of a high-end ESM) also shows more skill than CMIP5.  This may support the concept that the relatively high climate sensitivity values projected by CMIP6 and of current high-end ESM projections should be taken seriously:

Fasullo, J. T.: Evaluating Simulated Climate Patterns from the CMIP Archives Using Satellite and Reanalysis Datasets, Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2020-1, in review, 2020.

https://www.geosci-model-dev-discuss.net/gmd-2020-1/
https://www.geosci-model-dev-discuss.net/gmd-2020-1/gmd-2020-1.pdf

Abstract. An objective approach is presented for scoring coupled climate simulations through an evaluation against satellite and reanalysis datasets during the satellite era (i.e. since 1979). Here, the approach is described and applied to available Coupled Model Intercomparison Project (CMIP) archives and the Community Earth System Model Version 1 Large Ensemble archives, with the goal of benchmarking model performance and its evolution across CMIP generations. The approach adopted is designed to minimize the sensitivity of scores to internal variability, external forcings, and model tuning. Toward this end, models are scored based on pattern correlations of their simulated mean state, seasonal contrasts, and ENSO teleconnections. A broad range of feedback-relevant fields is considered and summarized on various timescales (climatology, seasonal, interannual) and physical realms (energy budget, water cycle, dynamics). Fields are also generally chosen for which observational uncertainty is small compared to model structural differences and error.
Highest mean variable scores across models are reported for well-observed fields such as sea level pressure, precipitable water, and outgoing longwave radiation while the lowest scores are reported for 500 hPa vertical velocity, net surface energy flux, and precipitation minus evaporation. The fidelity of CMIP models is found to vary widely both within and across CMIP generations. Systematic increases in model fidelity across CMIP generations are identified with the greatest improvements in dynamic and energetic fields. Examples include 500 hPa eddy geopotential height and relative humidity, and shortwave cloud forcing. Improvements for ENSO scores are substantially greater than for the annual mean or seasonal contrasts.
Analysis output data generated by this approach is made freely available online for a broad range of model ensembles, including the CMIP archives and various single-model large ensembles. These multi-model archives allow for an exploration of relationships between metrics across a range of simulations while the single-model large ensemble archives enable an estimation of the influence of internal variability on reported scores. The entire output archive, updated regularly, can be accessed at: http://webext.cgd.ucar.edu/Multi-Case/CMAT/index.html chosen for which observational uncertainty is small compared to model structural error. 20 Highest mean variable scores across models are reported for well-observed fields such as sea level pressure, precipitable water, and outgoing longwave radiation while the lowest scores are reported for 500 hPa vertical velocity, net surface energy flux, and precipitation minus evaporation. The fidelity of CMIP models is found to vary widely both within and across CMIP generations. CMATv1 scores report systematic increases in model fidelity across CMIP generations with the greatest improvements in dynamic and energetic fields. Examples include 500 hPa eddy geopotential height and relative humidity, 25 and shortwave cloud forcing. Improvements for ENSO scores are substantially greater than for the annual mean or seasonal contrasts. Analysis output data is made freely available online for a broad range of model ensembles, including the CMIP archives and various single-model large ensembles. These multi-model archives allow for an exploration of relationships between metrics 30 across a range of simulations while the single-model large ensemble archives enable an estimation of the influence of internal variability on CMATV1 scores. The entire CMATv1 archive, updated regularly, can be accessed at: http://webext.cgd.ucar.edu/Multi-Case/CMAT/index.html.

Caption: "Figure 10: Evolution of the distribution of aggregate and selected variable scores across the CMIP archives and the CESM1- LE."

I thought that it would be good to remind readers that CMIP6 generally demonstrate higher skill levels than do earlier CMIP projections.

4
Please note that consensus climate scientists are not promising that decision makers will be given adequate warning before an abrupt change in climate might occur this century; as discussed in the linked article.

Title: "We climate scientists won’t know exactly how the crisis will unfold until it’s too late"

https://theconversation.com/we-climate-scientists-wont-know-exactly-how-the-crisis-will-unfold-until-its-too-late-133400

Extract: "When we hold on to things for too long, change can come about abruptly and even catastrophically. While this will ring true for many from personal experience, similar things can happen at large scales as well. Indeed, the history of Earth’s climate and ecosystems is punctuated by frequent large-scale disruptive events.

When the air warmed and the last ice age was coming to an end, the continent-size glaciers – or ice sheets – stayed around for much longer than the climate would allow. Then parts of them collapsed in spectacular fashion. One such collapse – we still don’t know of which ice sheet – caused at least four metres of sea level rise per century and possibly also the following abrupt transition to a much warmer climate, only to be followed by an equally abrupt flip-flop between warm and cold conditions, before the onset of the stable climate we have enjoyed until recently."

5
The linked article discusses how poorly planned mass planting of trees could do more harm than good:

Title: "Climate change: UK forests 'could do more harm than good'"

https://www.bbc.com/news/science-environment-52200045

Extract: "Mass tree planting in the UK could harm the environment if not planned properly, a report warns."

6
While it is still uncertain how much carbon will be emitted from the degradation of permafrost into the atmosphere, the linked article discusses the fact that such emissions will be irreversible:

Title: "The irreversible emissions of a permafrost ‘tipping point’"

https://www.skepticalscience.com/irreversible-emissions-permafrost-tipping-point.html

Extract: "Tipping points
This article is part of a week-long special series on “tipping points”, where a changing climate could push parts of the Earth system into abrupt or irreversible change

•   Explainer: Nine ‘tipping points’ that could be triggered by climate change
•   Guest post: Could the Atlantic Overturning Circulation ‘shut down’?
•   Guest post: The irreversible emissions of a permafrost ‘tipping point’
•   Guest post: Could climate change and deforestation spark Amazon ‘dieback’?
•   Guest post: How close is the West Antarctic ice sheet to a ‘tipping point’?

Yet, what is irreversible is the escape of the carbon that has been – and is being – emitted. The carbon released from permafrost goes into the atmosphere and stays there, exacerbating global warming."

7
...

But if we keep all else equal then the total sink becomes a bit smaller which means we get there quicker. That probably does not do anything for ECS in itself.

...

Within Earth Systems Models, ESM, there is no parameter for ECS, TCR or other estimates of climate sensitivity; instead there are only the numerous separate positive and negative feedback mechanisms that result in a net change in warming/cooling for a given period of time.  Thus if we get 'there' (as in a warmer world) quicker then that means the climate sensitivity is a small amount higher than previously assumed.

Also, I note that while it is difficult for people to keep track of such small incremental changes; but if the ESMs sum thousands and thousands of such small incremental changes in the coming decades they may very likely push us all over a possible irreversible tipping point, such as a possible MICI-type of collapse of the WAIS in the coming decades.

8
The linked reference (& associated article) indicate that flooding during 2019 delayed U.S. Midwest crop planting; which resulted in less carbon uptake.  If climate change trends result in more crop disruptions we can expect similarly reduced CO2 uptake by crops in the future:

Yi Yin, et al. (25 March 2020), "Cropland Carbon Uptake Delayed and Reduced by 2019 Midwest Floods", AGU Advances, https://doi.org/10.1029/2019AV000140

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019AV000140

Abstract
While large‐scale floods directly impact human lives and infrastructures, they also profoundly impact agricultural productivity. New satellite observations of vegetation activity and atmospheric CO2 offer the opportunity to quantify the effects of such extreme events on cropland carbon sequestration. Widespread flooding during spring and early summer 2019 induced conditions that delayed crop planting across the U.S. Midwest. As a result, satellite observations of solar‐induced chlorophyll fluorescence from TROPOspheric Monitoring Instrument and Orbiting Carbon Observatory reveal a 16‐day shift in the seasonal cycle of photosynthesis relative to 2018, along with a 15% lower peak value. We estimate a reduction of 0.21 PgC in cropland gross primary productivity in June and July, partially compensated in August and September (+0.14 PgC). The extension of the 2019 growing season into late September is likely to have benefited from increased water availability and late‐season temperature. Ultimately, this change is predicted to reduce the crop productivity in the Midwest Corn/Soy belt by ~15% compared to 2018. Using an atmospheric transport model, we show that a decline of ~0.1 PgC in the net carbon uptake during June and July is consistent with observed CO2 enhancements of up to 10 ppm in the midday boundary layer from Atmospheric Carbon and Transport‐America aircraft and over 3 ppm in column‐averaged dry‐air mole fractions from Orbiting Carbon Observatory. This study quantifies the impact of floods on cropland productivity and demonstrates the potential of combining solar‐induced chlorophyll fluorescence with atmospheric CO2 observations to monitor regional carbon flux anomalies.

Plain Language Summary
Widespread flooding and inundation across the U.S. Midwest during spring and early summer 2019 forced many farmers to delay crop planting. New satellite observations of vegetation photosynthesis and atmospheric CO2 offer the opportunity to quantify the effects of such events on cropland carbon sequestration. We show that the delayed planting resulted in a shift of 16 days in the seasonal cycle of the crop growth and a ~15% lower peak solar‐induced chlorophyll fluorescence value. We estimate a reduction of 0.21 PgC in the gross primary production during June and July, partially compensated in August and September (+0.14 PgC). The extension of the 2019 growing season into late September is likely to have benefited from increased water availability and late‐season temperature. Ultimately, this change is predicted to reduce the crop production over most of the Midwest Corn/Soy belt by 15%, based on the strong empirical correlation between 2018 growing season SIF and crop yield. The bottom‐up estimated net carbon uptake reduction of ~0.1 PgC in June and July is consistently supported by top‐down inferred CO2 anomalies from both aircraft and satellite observations. We anticipate that such a rapid event detection can benefit agricultural and natural resource management and ecological forecasting efforts.

9
Because if any negative feedback were smaller in reality than in models, then temperature rise in the models would have been larger than observed, unless there was a compensating error. Where is that compensation ?

sidd

sidd,

It sounds to me like you are referring to comparisons of consensus model projections to the observed record.  If so, the observed record is an extremely short period of time, and consensus model are subject to any number of factors that could temporarily mask the impacts of actual trends in climate feedback mechanisms, such as:
a) Boundary conditions of the models and initial start-up conditions,
b) Incorrect modeling of other feedback mechanisms that result in compensating errors (like aerosol feedback mechanisms, or a temporary spurt of growth of vegetation that ends abruptly when increases in GMSTA result in future losses of vegetation that return temporarily sequestered carbon to the atmosphere).
c) The fact that ECS increases with increasing GMSTA, thus looking at the recent past may not be appropriate for simulating the future.

Also, models have so many variables that modelers tweak them as the models run to ensure that they converge towards known parameters; and in this regard, CMIP6 matches many more parameters than does CMIP5; so you may be referring to out of date projections.

Edit: For those who do not know CMIP6 projects a significantly higher range of climate sensitivity values than did CMIP5; and my main criticism of the CMIP6 projections is that they do not adequately consider ice-climate feedback mechanisms (which have not yet become highly nonlinear)

10
Re: if negative feedback mechanisms are less negative than previously assumed then climate sensitivity will be higher than consensus climate scientists previously assumed.

Agreed. But those negative feedbacks also must explain past climate. If they were wrong, the model would not fit past climate. But we know that models do a good job simulating past climate. So there must be a) some other carbon drawdown mechanism or b) carbon emission in the past was smaller than previously assumed.

Which do you think it is ?

sidd

First of all I believe that your assumption the current consensus climate models do a good job of simulating relevant past climate is not correct.  Just search in this thread for either Holsteinian and/or MIS 11 and you will find numerous studies indicating that consensus climate models cannot replicate this highly relevant case.

Second, consensus climate models do not adequately simulate ice-climate feedback mechanisms (especially MICI mechanisms) and thus, in my opinion, cannot reasonably simulate climate risks in the coming decades.

Finally, you gloss over other well documented climate feedback uncertainties such as: a) aerosol-cloud feedbacks, b) cloud feedbacks and c) permafrost degradation.  Thus, how say that you know that if plankton feedbacks are less negative than previously assumed than some other mechanism must be compensating?

11
The UN's WMO (World Meteorological Organization) "Statement on the State of the Global Climate in 2019", confirms that climate change is currently accelerating and that mankind is nowhere near to being on track to stall within the 'well below' 2C target.

Title: "Flagship UN study shows accelerating climate change on land, sea and in the atmosphere"

https://news.un.org/en/story/2020/03/1059061

Extract: "Writing in the foreword to the report, UN chief António Guterres warned that the world is currently “way off track meeting either the 1.5°C or 2°C targets that the Paris Agreement calls for”, referring to the commitment made by the international community in 2015, to keep global average temperatures well below 2°C above pre-industrial levels."

See also:

Title: "WMO Statement on the State of the Global Climate in 2019"

https://reliefweb.int/report/world/wmo-statement-state-global-climate-2019-enarru

Extract: "Multi-agency report highlights increasing signs and impacts of climate change in atmosphere, land and oceans"

12
My point was:

Stipulated that phytoplankton absorb less CO2 that was thought. How does this affect climate sensitivity ?

sidd
sidd,

The linked article explains how consensus science uncertainty about what the true climate sensitivity will be in coming decades is driven by uncertainty about the net combined impact of both positive, and negative, feedback mechanisms.  Thus, if negative feedback mechanisms are less negative than previously assumed then climate sensitivity will be higher than consensus climate scientists previously assumed.

Title: "Explainer: How scientists estimate ‘climate sensitivity’"

https://www.carbonbrief.org/explainer-how-scientists-estimate-climate-sensitivity

Extract: "The wide range of estimates of climate sensitivity is driven by uncertainties in climate feedbacks, including how water vapour, clouds, surface reflectivity and other factors will change as the Earth warms. Climate feedbacks are processes that may amplify (positive feedbacks) or diminish (negative feedbacks) the effect of warming from increased CO2 concentrations or other climate forcings – factors that initially drive changes in the climate."

13
The linked reference indicates that consensus climate scientists have been assuming that phytoplankton absorbed more CO2 from the atmosphere than they actually do, which means that climate sensitivity is higher than previously assumed:

Bolaños, L.M., Karp-Boss, L., Choi, C.J. et al. Small phytoplankton dominate western North Atlantic biomass. ISME J (2020). https://doi.org/10.1038/s41396-020-0636-0

https://www.nature.com/articles/s41396-020-0636-0

Abstract
The North Atlantic phytoplankton spring bloom is the pinnacle in an annual cycle that is driven by physical, chemical, and biological seasonality. Despite its important contributions to the global carbon cycle, transitions in plankton community composition between the winter and spring have been scarcely examined in the North Atlantic. Phytoplankton composition in early winter was compared with latitudinal transects that captured the subsequent spring bloom climax. Amplicon sequence variants (ASVs), imaging flow cytometry, and flow-cytometry provided a synoptic view of phytoplankton diversity. Phytoplankton communities were not uniform across the sites studied, but rather mapped with apparent fidelity onto subpolar- and subtropical-influenced water masses of the North Atlantic. At most stations, cells < 20-µm diameter were the main contributors to phytoplankton biomass. Winter phytoplankton communities were dominated by cyanobacteria and pico-phytoeukaryotes. These transitioned to more diverse and dynamic spring communities in which pico- and nano-phytoeukaryotes, including many prasinophyte algae, dominated. Diatoms, which are often assumed to be the dominant phytoplankton in blooms, were contributors but not the major component of biomass. We show that diverse, small phytoplankton taxa are unexpectedly common in the western North Atlantic and that regional influences play a large role in modulating community transitions during the seasonal progression of blooms.

14
The linked article indicates that the Keystone XL pipeline just received financial support from Alberta's United Conservative government:

Title: "Why Alberta is throwing billions behind the Keystone XL pipeline"

https://www.cbc.ca/news/business/analysis-alberta-invests-in-keystone-1.5516144

Extract: "With the energy sector still reeling from weeks of economic turmoil, Alberta's United Conservative government announced Tuesday it is throwing its financial heft behind the long-delayed Keystone XL pipeline.

The investment of $1.5 billion, plus a $6-billion loan guarantee, aims to accelerate construction of the massive project and was warmly greeted by a sector desperate for some good news.

Still, the enormity of the investment will also raise many questions — including, why now?
 
But as with many things in Alberta over the years, the answer can often be found at the intersection of oil, government and politics. Now, the stakes feel higher than ever for an industry with an unsettled future."

15
While the formation of temperate rainforests near the South Pole are not likely to occur in our children's lifetimes; if we do trigger an equable climate (say by the Equatorial Pacific SST increasing by 5oC due to a sufficient slowdown of the MOC and an increase of the CO2-equivant to between 700 ppm & 1,000 ppm), then history could repeat itself (see linked reference), within less than a thousand years (worse case):

Klages, J.P., Salzmann, U., Bickert, T. et al. Temperate rainforests near the South Pole during peak Cretaceous warmth. Nature 580, 81–86 (2020). https://doi.org/10.1038/s41586-020-2148-5

https://www.nature.com/articles/s41586-020-2148-5

Abstract: "The mid-Cretaceous period was one of the warmest intervals of the past 140 million years, driven by atmospheric carbon dioxide levels of around 1,000 parts per million by volume. In the near absence of proximal geological records from south of the Antarctic Circle, it is disputed whether polar ice could exist under such environmental conditions. Here we use a sedimentary sequence recovered from the West Antarctic shelf—the southernmost Cretaceous record reported so far—and show that a temperate lowland rainforest environment existed at a palaeolatitude of about 82° S during the Turonian–Santonian age (92 to 83 million years ago). This record contains an intact 3-metre-long network of in situ fossil roots embedded in a mudstone matrix containing diverse pollen and spores. A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric carbon dioxide concentrations of 1,120–1,680 parts per million by volume and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo under high levels of atmospheric carbon dioxide."

16
By itself, the heat wave recently recorded in East Antarctica means little, but if such heat waves become more frequent in the coming decades, it would not be good news.

Title: "Researchers record 1st-ever heat wave in East Antarctica"

https://theweek.com/speedreads/905968/researchers-record-1stever-heat-wave-east-antarctica

Extract: "This January, East Antarctica — an area that previously seemed to be spared from climate warming — experienced its first recorded heat wave.

The heat wave was recorded at the Casey Research Station between Jan. 23 and 26, marking the area's highest temperature ever at 48.6 degrees Fahrenheit, while minimum temperatures stayed above 32 degrees Fahrenheit, according to research in Global Change Biology.

A rarity in Antarctica, heat waves are known as "three consecutive days with both extreme maximum and minimum temperatures," according to the research."

Edit, see also:

Sharon A. Robinson  Andrew R. Klekociuk  Diana H. King  Marisol Pizarro Rojas  Gustavo E. Zúñiga  Dana M. Bergstrom (30 March 2020), "The 2019/2020 summer of Antarctic heatwaves", Global Change Biology, https://doi.org/10.1111/gcb.15083

https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.15083?af=R

17
The linked reference (& associated article) indicate that recent studies of glacial earthquakes associated with Thwaites Glacier Calving events can help to improve projections of future ice mass loss from this key glacier:

J. Paul Winberry et al. (15 January 2020), "Glacial Earthquakes and Precursory Seismicity Associated With Thwaites Glacier Calving", Geophysical Research Letters, https://doi.org/10.1029/2019GL086178

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL086178

Abstract
We observe two (~MS 3) long‐period (10–30 s) seismic events that originate from the terminus of Thwaites Glacier, Antarctica. Serendipitous acquisition of satellite images confirm that the seismic events were glacial earthquakes generated during the capsizing of icebergs. The glacial earthquakes were preceded by 6 days of discrete high‐frequency seismic events that can be observed at distances exceeding 250 km. The high‐frequency seismicity displays an increasing rate of occurrence, culminating in several hours of sustained tremor coeval with the long‐period events. A series of satellite images collected during this precursory time period show that the high‐frequency events and tremor are the result of accelerating growth of ancillary fractures prior to the culminating calving event. This study indicates that seismic data have the potential to elucidate the processes by which Thwaites Glacier discharges into the ocean, thus improving our ability to constrain future sea level rise.

Plain Language Summary
Thwaites Glacier is one of the largest sources of Antarctic ice mass loss; however, the physics of the processes that control its discharge into the ocean remains incomplete. The long‐term stability of glaciers, such as Thwaites, that discharge directly into the ocean is linked to the rate of calving, the process of iceberg production. Spaceborne observations are crucial to understanding the calving processes; however, the typical repeat time of a satellite imagery is much longer than the typical duration of a calving event (minutes to hours). Increasingly, the seismic signals generated during calving are being used to complement other observations. For larger calving events, seismic energy can be recorded by remote seismic observation (hundreds to thousands of kilometers away from a glacier). While these glacier earthquakes are now regularly used to study calving in Greenland, only a limited number of glacial earthquakes have been observed in Antarctica. We show that Thwaites Glacier has now begun generating glacial earthquakes similar to those observed in Greenland. Additionally, we show that enhanced rates of fracturing can be seismically observed before the event. Our observations open a new avenue for understanding the behavior of Antarctica's leading source of mass loss.

See also:

Title: "Thwaites Glacier in Antarctica is Now Causing Earthquakes"

https://glacierhub.org/2020/03/05/thwaites-glacier-in-antarctica-is-now-causing-earthquakes/

Extract: "Combing through seismograph readings collected in West Antarctica during a large calving event at Thwaites on February 8th 2014, a team of researchers found evidence of two low frequency earthquakes, each about 10-30 seconds long. Their hunch—that the quakes came from the calving—was confirmed when they matched the seismograph readings with satellite images taken on the same day.

They also discovered high frequency blips of seismic activity that chirped on and off in the week preceding the event. Glaciologist and lead author of the study, Paul Winberry, explained to GlacierHub that in these short bursts they were actually “hearing all these little cracks start to propagate.” It was the sound of countless cracks forming and popping apart, heralding the large break about to come.

Thwaites is the only known glacier in Antarctica to exhibit seismic behavior, whereas glaciers in Greenland have been recorded causing earthquakes for some time. This difference can be explained by the fact that the majority of Greenland’s icebergs capsize when they break off into the water. The result is a more boisterous form of calving that produces detectable earthquakes. Why Greenland’s icebergs capsize and Antarctica’s do not has to do with the physical makeup of each landmass’s ice sheets and where they start to float on the water."

18
The linked Nature article discusses an ozone hole that has currently formed over the Arctic, and that this hole is worse than what happened in 1997 and 2011.  While a temporary Arctic ozone hole would not likely have a meaningful impact on climate change; nevertheless, it is discomforting that this event is worse than all previous events, and that if it is prolonged, or if future such events happen more frequently, this might have an impact on Arctic wind patterns; which might then have an impact of Arctic sea ice flow patterns.

Title: "Rare ozone hole opens over Arctic — and it’s big"

https://www.nature.com/articles/d41586-020-00904-w

Extract: "Cold temperatures and a strong polar vortex allowed chemicals to gnaw away at the protective ozone layer in the north.

A vast ozone hole — likely the biggest on record in the north — has opened in the skies above the Arctic. It rivals the better-known Antarctic ozone hole that forms in the southern hemisphere each year.

Record-low ozone levels currently stretch across much of the central Arctic, covering an area about three times the size of Greenland (see ‘Arctic opening’). The hole doesn’t threaten people’s health, and will probably break apart in the coming weeks. But it is an extraordinary atmospheric phenomenon that will go down in the record books.

The Arctic experienced ozone depletion in 1997 and in 2011, but this year’s loss looks on track to surpass those. “We have at least as much loss as in 2011, and there are some indications that it might be more than 2011,” says Gloria Manney, an atmospheric scientist at NorthWest Research Associates in Socorro, New Mexico. She works with a NASA satellite instrument that measures chlorine in the atmosphere, and says there is still quite a bit of chlorine available to deplete ozone in the coming days."

19
While currently 'Big Oil' is not leading the charge into renewable energy; however, their eventual adoption of more renewable energy would speed the transition to more sustainable power infrastructure.  Thus, 'Big Oil's currently wavering investments into sustainable energy is not good news.

Title: "Big Oil's interest in renewable energy investments expected to waver: report"

https://www.nsnews.com/big-oil-s-interest-in-renewable-energy-investments-expected-to-waver-report-1.24108471

Extract: "Budget cutting in response to the twin challenges of COVID-19 demand destruction and low oil prices mean the world's oil and gas industry will likely spend less on renewable energy going forward.

"In a US$60 per barrel oil price environment, most companies were generating strong cash flow and could afford to think about carbon mitigation strategies," said Valentina Kretzschmar, vice-president, corporate analysis, at Wood Mackenzie.

"But now ... all discretionary spend will be under review — that includes additional budget allocated for carbon mitigation. And companies that haven't yet engaged in carbon reduction strategies are likely to put the issue on the back burner.""

20
The linked research '... suggests that substantial reductions or instabilities of the AMOC could also occur in a future warmer climate.'

Thomas F. Stocker ( 27 Mar 2020), "Surprises for climate stability", Science, Vol. 367, Issue 6485, pp. 1425-1426, DOI: 10.1126/science.abb3569

https://science.sciencemag.org/content/367/6485/1425

Summary
Instabilities in Earth's climate system have intrigued scientists ever since analyses from Greenland ice cores revealed climate variations over the last hundred thousand years (1, 2). Abrupt changes were not singular events but a pervasive feature of the last ice age. Studies pointed to the ocean, specifically the Atlantic Meridional Overturning Circulation (AMOC), as a possible origin of these large swings (3, 4). Their occurrence in the distant past of the last ice age and their absence in the past 8000 years suggested that we are living in times of relative climate stability. On page 1485 of this issue, Galaasen et al. (5) report that over the past 500,000 years, there were disruptions in the formation of the North Atlantic Deep Water mass—an essential driver of the AMOC—during interglacial periods. This suggests that substantial reductions or instabilities of the AMOC could also occur in a future warmer climate.

http://www.sciencemag.org/about/science-licenses-journal-article-reuse

21
The linked article discusses the probability that the modern global socio-economic system is fragile to shocks whether from pandemics, climate change, or other perturbations from the norm:

Title: "Professor Sees Climate Mayhem Lurking Behind Covid-19 Outbreak"

https://www.bloomberg.com/news/articles/2020-03-28/professor-sees-climate-mayhem-lurking-behind-covid-19-outbreak

Extract: "“In modern industrial societies, the fallout from Covid-19 feels like a dress rehearsal for the kind of collapse that climate change threatens,” Bendell said in an interview. “This crisis reveals how fragile our current way of life has become.”

The University of Cumbria social-science professor is well-known among environmentalists for his theory of “deep adaptation.” In a 2018 paper, Bendell said that time was up for gradual measures to combat global warming. Without an abrupt transformation of society, changes in the planet’s climate would bring starvation, destruction, migration, disease and war -- the collapse of civilization -- within a decade."

22
The linked article indicates that many banks are still significantly supporting the fossil fuel industry via loans/finance:

Title: "Study: global banks 'failing miserably' on climate crisis by funneling trillions into fossil fuels"

https://www.theguardian.com/environment/2020/mar/18/global-banks-climate-crisis-finance-fossil-fuels

Extract: "Analysis of 35 leading investment banks shows financing of more than $2.66tn for fossil fuel industries since the Paris agreement"

23
'Banked' CFCs still represent a risk to accelerated climate change; and merit appropriate action:

Lickley, M., Solomon, S., Fletcher, S. et al. Quantifying contributions of chlorofluorocarbon banks to emissions and impacts on the ozone layer and climate. Nat Commun 11, 1380 (2020). https://doi.org/10.1038/s41467-020-15162-7

https://www.nature.com/articles/s41467-020-15162-7

Abstract
Chlorofluorocarbon (CFC) banks from uses such as air conditioners or foams can be emitted after global production stops. Recent reports of unexpected emissions of CFC-11 raise the need to better quantify releases from these banks, and associated impacts on ozone depletion and climate change. Here we develop a Bayesian probabilistic model for CFC-11, 12, and 113 banks and their emissions, incorporating the broadest range of constraints to date. We find that bank sizes of CFC-11 and CFC-12 are larger than recent international scientific assessments suggested, and can account for much of current estimated CFC-11 and 12 emissions (with the exception of increased CFC-11 emissions after 2012). Left unrecovered, these CFC banks could delay Antarctic ozone hole recovery by about six years and contribute 9 billion metric tonnes of equivalent CO2 emission. Derived CFC-113 emissions are subject to uncertainty, but are much larger than expected, raising questions about its sources.

See also:

Title: "Long Phased-Out Refrigeration and Insulation Chemicals Still Widely in Use and Warming the Climate"

https://insideclimatenews.org/news/17032020/cfc-ozone-layer-short-lived-climate-pollutants

Extract: "New study concludes that “banked” CFCs have greenhouse gas impacts equal to all registered U.S. cars and slow the shrinking of the ozone hole."

24
Apparently, the COVID-19 outbreak gave the Trump administration an excuse, last Thursday, to give the U.S. oil & gas industry 'an open license to pollute.'

Title: "Trump’s Move to Suspend Enforcement of Environmental Laws is a Lifeline to the Oil Industry"

https://insideclimatenews.org/news/27032020/coronavirus-covid-19-EPA-API-environmental-enforcement

Extract: "The American Petroleum Institute sought the EPA’s help for companies hurt by COVID-19. One former EPA official called the suspension “an open license to pollute.""

25
The linked reference indicates that climate sensitivity increases with increasing CO2 concentration faster than previously realized due to higher cloud feedback than previously assumed.

Jiang Zhu, Christopher J. Poulsen, Jessica E. Tierney. Simulation of Eocene extreme warmth and high climate sensitivity through cloud feedbacks. Science Advances, 2019; 5 (9): eaax1874 DOI: 10.1126/sciadv.aax1874

https://advances.sciencemag.org/content/5/9/eaax1874

Abstract
The Early Eocene, a period of elevated atmospheric CO2 (>1000 ppmv), is considered an analog for future climate. Previous modeling attempts have been unable to reproduce major features of Eocene climate indicated by proxy data without substantial modification to the model physics. Here, we present simulations using a state-of-the-art climate model forced by proxy-estimated CO2 levels that capture the extreme surface warmth and reduced latitudinal temperature gradient of the Early Eocene and the warming of the Paleocene-Eocene Thermal Maximum. Our simulations exhibit increasing equilibrium climate sensitivity with warming and suggest an Eocene sensitivity of more than 6.6°C, much greater than the present-day value (4.2°C). This higher climate sensitivity is mainly attributable to the shortwave cloud feedback, which is linked primarily to cloud microphysical processes. Our findings highlight the role of small-scale cloud processes in determining large-scale climate changes and suggest a potential increase in climate sensitivity with future warming.

See also:

Title: "Study of ancient climate suggests future warming could accelerate"

https://www.sciencedaily.com/releases/2019/09/190918142035.htm

Extract: ""We were surprised that the climate sensitivity increased as much as it did with increasing carbon dioxide levels," said first author Jiang Zhu, a postdoctoral researcher at the U-M Department of Earth and Environmental Sciences.

"It is a scary finding because it indicates that the temperature response to an increase in carbon dioxide in the future might be larger than the response to the same increase in CO2 now. This is not good news for us.""

26
The linked reference indicates that the MOC is subject to short-term disruptions that could abruptly cause it to slowdown in the future.

Eirik Vinje Galaasen, Ulysses S. Ninnemann, Augustin Kessler, Nil Irvalı, Yair Rosenthal, Jerry Tjiputra, Nathaëlle Bouttes, Didier M. Roche, Helga (kikki) F. Kleiven, David A. Hodell. Interglacial instability of North Atlantic Deep Water ventilation. Science, 2020 DOI: 10.1126/science.aay6381

https://science.sciencemag.org/content/367/6485/1485

Abstract
Disrupting North Atlantic Deep Water (NADW) ventilation is a key concern in climate projections. We use (sub)centennially resolved bottom water δ13C records that span the interglacials of the last 0.5 million years to assess the frequency of and the climatic backgrounds capable of triggering large NADW reductions. Episodes of reduced NADW in the deep Atlantic, similar in magnitude to glacial events, have been relatively common and occasionally long-lasting features of interglacials. NADW reductions were triggered across the range of recent interglacial climate backgrounds, which demonstrates that catastrophic freshwater outburst floods were not a prerequisite for large perturbations. Our results argue that large NADW disruptions are more easily achieved than previously appreciated and that they occurred in past climate conditions similar to those we may soon face.

27
Hopefully, lessons learn from the referenced study of tidal pressures near the grounding zone of the Ross Ice Shelf will be applied to models of the PIIS, and the TEIS, ocean interactions:

Carolyn Branecky Begeman, Slawek Tulaczyk, Laurie Padman, Matt King, Matthew R. Siegfried, Timothy O. Hodson and Helen A. Fricker1(6 March 2020), "Tidal pressurization of the ocean cavity near an Antarctic ice shelf grounding line", JGR Oceans, https://doi.org/10.1029/2019JC015562

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JC015562?af=R

Abstract
Mass loss from the Antarctic Ice Sheet is sensitive to conditions in ice‐shelf grounding zones, the transition between grounded and floating ice. To observe tidal dynamics in the grounding zone, we moored an ocean pressure sensor to Ross Ice Shelf, recording data for 54 days. In this region the ice shelf is brought out of hydrostatic equilibrium by the flexural rigidity of ice, yet we found that tidal pressure variations at a constant geopotential surface were similar within and outside of the grounding zone. This implies that the grounding zone ocean cavity was overpressurized at high tide and underpressurized at low tide by up to 10 kPa with respect to glaciostatic pressure at the ice shelf base. Phase lags between ocean pressure and vertical ice‐shelf motion were tens of minutes for diurnal and semidiurnal tides, an effect that has not been incorporated into ocean models of tidal currents below ice shelves. These tidal pressure variations may affect the production and export of meltwater in the subglacial environment and may increase basal crevasse heights in the grounding zone by several meters, according to linear elastic fracture mechanics. We find anomalously high tidal energy loss at the K1 constituent in the grounding zone and hypothesize that this could be explained by seawater injection into the subglacial environment at high tide or internal tide generation through interactions with topography. These observations lay the foundation for improved representation of the grounding zone and its tidal dynamics in ocean circulation models of sub‐ice‐shelf cavities.

Plain language summary
One of the challenges for sea level rise prediction is understanding how the Antarctic ice sheets and the Southern Ocean interact. Ocean tides are an important component of this interaction, influencing ice shelf melting and the flow rate of grounded ice toward the coast. We report new observations relevant to this interaction: tidally‐varying ocean pressures where the ice first goes afloat to become an ice shelf. These tidal ocean pressure variations influence tidal currents below the ice shelf, and we propose that they also push seawater beneath the ice inland of the ice shelf and extend fractures at the ice‐shelf base. This study identifies tidal processes that may affect melt and fracture near the inland edge of ice shelves, a highly sensitive zone for ice dynamics.

Key Points
•   We present the first concurrent observations of ocean pressure and ice flexure in the grounding zone of an Antarctic ice shelf
•   Peak ocean pressure in the grounding zone at high tide exceeded glaciostatic pressure and preceded the peak ice shelf tidal deflection
•   These pressure variations may enhance basal crevassing and influence subglacial hydrology near the grounding line

28
The linked reference indicates that the interaction of oceanic induced ice melting and the calving of tidewater glaciers is not linear.  This implies that most consensus climate models of this interaction err on the side of least drama at higher oceanic ice melting rates (such as for the PIG and the Thwaites Glacier):

R. Mercenier, M.P. Lüthi  and A. Vieli (22 March 2020), "How oceanic melt controls tidewater glacier evolution", Geophysical Research Letters, https://doi.org/10.1029/2019GL086769

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL086769

Abstract
The recent rapid retreat of many Arctic outlet glaciers has been attributed to increased oceanic melt, but the relationship between oceanic melt and iceberg calving remains poorly understood. Here, we employ a transient finite‐element model that simulates oceanic melt and ice break‐off at the terminus. The response of an idealized tidewater glacier to various submarine melt rates and seasonal variations is investigated. Our modeling shows that for zero to low oceanic melt, the rate of volume loss at the front is similar or higher than for intermediate oceanic melt rates. Only very high melt rates lead to increasing volume losses. These results highlight the complex interplay between oceanic melt and calving and question the general assumption that increased submarine melt leads to higher calving fluxes and enhanced retreat. Models for tidewater glacier evolution should therefore consider calving and oceanic melt as tightly coupled processes rather than as simple, additive parametrizations.

Key Points
•   The effect of oceanic melt on tidewater glacier evolution is investigated using a transient calving model based on damage evolution
•   Oceanic melt has a complex influence on tidewater glacier evolution and increased melt rates may not necessarily lead to more volume loss
•   The calving and oceanic melt processes are not additive which has implications on the forcing of models for tidewater glacier evolution

29
The linked reference finds 60% more subglacial lakes in the Ellsworth Subglacial Highlands than previously assumed and also finds that the water catchment area for the Thwaites Glacier is much larger than previously assumed (see attached image). Both of these findings imply that current consensus models for the WAIS underestimate the risks for increasing ice mass loss with continued global warming.

Napoleoni, F., Jamieson, S. S. R., Ross, N., Bentley, M. J., Rivera, A., Smith, A. M., Siegert, M. J., Paxman, G. J. G., Gacitúa, G., Uribe, J. A., Zamora, R., Brisbourne, A. M., and Vaughan, D. G.: Subglacial lakes and hydrology across the Ellsworth Subglacial Highlands, West Antarctica, The Cryosphere Discuss., https://doi.org/10.5194/tc-2020-68, in review, 2020.

https://www.the-cryosphere-discuss.net/tc-2020-68/
https://www.the-cryosphere-discuss.net/tc-2020-68/tc-2020-68.pdf

Abstract. Subglacial water plays an important role in ice sheet dynamics and stability. It is often located at the onset of ice streams and has the potential to enhance ice flow downstream by lubricating the ice-bed interface. The most recent subglacial lake inventory of Antarctica mapped nearly 400 lakes, of which ~ 14 % are found in West Antarctica. Despite the potential importance of subglacial water for ice dynamics, there is a lack of detailed subglacial water characterization in West Antarctica. Using radio-echo sounding data, we analyse the ice-bed interface to detect subglacial lakes. We report 37 previously uncharted subglacial lakes and present a systematic analysis of their physical properties. This represents a ~ 60 % increase in subglacial lakes in the region. Additionally, a new digital elevation model of basal topography was built and used to create a detailed hydropotential model of Ellsworth Subglacial Highlands to simulate the subglacial hydrological network. This approach allows us to characterize basal hydrology, subglacial water catchments and connections between them. Furthermore, the simulated subglacial hydrological catchments of Rutford Ice Stream, Pine Island Glacier and Thwaites Glacier do not match precisely with their ice surface catchments.

Extract: "We observe that most of the subglacial water draining towards ASE is routed through the Bentley Subglacial Trench in the upper part of the hydrological catchment and driven through the Byrd Subglacial Basin towards the trunk of Thwaites Glacier. The high topography in the mid PIG catchment (Vaughan et al., 2006) means that the hydrological drainage system does not link to the faster flowing trunk of PIG. Instead, the basal hydrological system is captured by Thwaites. This drainage pattern has two main implications. Firstly, the subglacial hydrological catchments of PIG and Thwaites do not correspond to the ice catchments; they do not coincide either in position or size. Secondly, the hydrological system of TG trunk (Schroeder et al., 2013) may be fed by water sourced in the upper glaciological catchment of PIG, within the ESH. Any change in the water catchment of the TG, at the head of PIG, could therefore have important glaciological consequences for the ice dynamics of Thwaites Glacier and the wider ASE. This is particularly critical since the subglacial water drainage area of TG is bigger than previously thought and recent investigations (e.g., Smith et al., 2017) have demonstrated the presence of active subglacial lakes, in a cascade system-type, beneath the trunk of TG. Any water accumulation/drainage (e.g., chain of active subglacial lakes) in this area may affect the basal friction of the ice and therefore the ice flow velocity."

Partial Caption: "The red line indicates the boundary of the water catchment. The blue lines show the subglacial water drainage and the arrows indicates the general flow direction."


30
The linked reference discusses state of the art work on modeling geothermal heat flow in Antarctica.  The attached summary image makes it clear that the findings are not good news for the stability of key portions of the WAIS:

Burton-Johnson, A., Dziadek, R., and Martin, C.: Geothermal heat flow in Antarctica: current and future directions, The Cryosphere Discuss., https://doi.org/10.5194/tc-2020-59, in review, 2020.

https://www.the-cryosphere-discuss.net/tc-2020-59/
https://www.the-cryosphere-discuss.net/tc-2020-59/tc-2020-59.pdf

Abstract. Antarctic geothermal heat flow (GHF) affects the temperature of the ice sheet, determining its ability to slide and internally deform, as well as the behaviour of the continental crust. However, GHF remains poorly constrained, with few and sparse local, borehole-derived estimates, and large discrepancies in the magnitude and distribution of existing continent-scale estimates from geophysical models. We review the methods to extract GHF, compile borehole and probe-derived estimates from measured temperature profiles, and recommend the following future directions: 1) Obtain more borehole-derived estimates from the subglacial bedrock and englacial temperature profiles. 2) Estimate GHF beneath the interior of the East Antarctic Ice Sheet (the region most sensitive to GHF variation) via long-wavelength microwave emissivity. 3) Estimate GHF from inverse glaciological modelling, constrained by evidence for basal melting. 4) Revise geophysically-derived GHF estimates using a combination of Curie depth, seismic, and thermal isostasy models. 5) Integrate in these geophysical approaches a more accurate model of the structure and distribution of heat production elements within the crust, and considering heterogeneities in the underlying mantle. And 6) continue international interdisciplinary communication and data access.

Caption: "Fig. 16. Difference in heat flow values between the most recent magnetic (Martos et al., 2017) and seismic (An et al., 2015b) heat flow models."

31
The linked reference (& associated article) estimates that previous estimates of methane emissions associated with coal mining are about half of what they actually are, and that abandoned mine methane (AMM) emissions will continue for long after the coal mines are shut-down.  This is not good news:

Kholod, N. et al. (2020) Global methane emissions from coal mining to continue growing even with declining coal production, Journal of Cleaner Production, doi:10.1016/j.jclepro.2020.120489

https://www.sciencedirect.com/science/article/pii/S0959652620305369

Highlights
• This study presents estimates of global coal mine methane emissions through 2100.
• Methane emissions related to coal extraction are higher than reported from previous estimates.
• Coal mines continue emitting methane even if coal production is ceased.
• Evidence-based emission factors are applied to account for increasing mining depth.
• A new methodology for calculating emissions from abandoned mines is proposed.

Abstract
This paper presents projections of global methane emissions from coal mining under different coal extraction scenarios and with increasing mining depth through 2100. The paper proposes an updated methodology for calculating fugitive emissions from coal mining, which accounts for coal extraction method, coal rank, and mining depth and uses evidence-based emissions factors. A detailed assessment shows that coal mining-related methane emissions in 2010 were higher than previous studies show. This study also uses a novel methodology for calculating methane emissions from abandoned coal mines and represents the first estimate of future global methane emissions from those mines. The results show that emissions from the growing population of abandoned mines increase faster than those from active ones. Using coal production data from six integrated assessment models, this study shows that by 2100 methane emissions from active underground mines increase by a factor of 4, while emissions from abandoned mines increase by a factor of 8. Abandoned mine methane emissions continue through the century even with aggressive mitigation actions.

See also:

Title: "Coal mines emit more methane than oil-and-gas sector, study finds"

https://www.carbonbrief.org/coal-mines-emit-more-methane-than-oil-and-gas-sector-study-finds

Extract: "Methane emissions from coal mines could be more than double previous estimates, according to a new study."

The authors also note that, for the first time, they developed a methodology for estimating global methane emissions from old mining sites, suggesting a considerable role for abandoned mine methane (AMM), which in the past has been largely ignored. When factoring this in, coal methane emissions in 2020 rise to 114Mt.

“When active mines are closed, it is important to preserve information on the mine and prepare the mine to extract AMM in the future…it is clear that methane from closed mines will be a problem for years to come.”

32
The linked article discusses the possibility that as an economic stimulus measure associated with the novel corona virus outbreak, China's 14th five-year plan may (or may not) promote investments in coal-fire power plants.  All I can say is that I hope that other national leaders around the world do not possibly give in to similar temptations to simulate their economies by returning to their old habits of subsidizing/promoting the use of fossil fuels:

Title: "Analysis: Will China build hundreds of new coal plants in the 2020s?"

https://www.carbonbrief.org/analysis-will-china-build-hundreds-of-new-coal-plants-in-the-2020s

Extract: "China’s 14th five-year plan (FYP), setting out its national goals for 2021-2025, will arguably be one of the world’s most important documents for global efforts to tackle climate change.

The overarching plan for economic and social development in the world’s largest emitter is to be finalised and approved in early 2021, followed by more detailed sectoral targets over the next year. A power sector plan can be expected around winter 2021-22.

Ahead of the FYP’s publication, powerful stakeholders, such as the network operator State Grid and industry body the China Electricity Council, are lobbying for targets that would allow hundreds of new coal-fired power stations to be built. And a recent update to the “traffic light system” for new coal-power construction signaled further relaxation of permitting.
This is all despite significant overcapacity in the sector, with more than half of coal-power firms already loss-making and with typical plants running at less than 50% of their capacity.

As the country grapples with the coronavirus pandemic, however, controls on overcapacity may be vulnerable to the political priority of propping up economic growth. As a result, the restraints on another coal power boom are likely to be financial and economic, rather than regulatory.

Many experts and industry bodies argue for a move away from top-down targets and controls, to investment driven by market forces. However, the spending needed to fuel a new stimulus program can only be mobilized if investment is directed at the behest of the state, rather than the market – as a rule, China does not fund stimulus with on-budget spending, but by directing state-owned enterprises and commercial banks to spend more. In these circumstances, lack of controls on capacity additions runs a high risk of over-investment.

For example, efforts to control overcapacity might be vulnerable to the political priority of boosting investment spending to reach economic targets. An indication of this was the loosening of “traffic lights” for new coal-plant approvals, published by the National Energy Administration in February.

A new wave of coal power in China would pose clear risks for global efforts to limit climate change and could greatly complicate the country’s own energy transition. Yet even if the 14th five-year plan targets another coal boom, it could end up falling short due to economic and financial constraints.

There is a parallel in the 12th five-year plan. This created major overcapacity in the sector, but still fell far short of the target set for coal-power growth. Such an outcome would, however, create significant uncertainty, both for the domestic power industry and the international community."

33
The linked reference, and the associated linked article, indicates that the Denman Glacier in East Antarctica is currently retreating relatively rapidly, and that it could be destabilized if modified CDW keeps causing the grounding line to retreat:

V. Brancato et al. Grounding line retreat of Denman Glacier, East Antarctica, measured with COSMO-SkyMed radar interferometry data, Geophysical Research Letters (2020). DOI: 10.1029/2019GL086291

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL086291

Abstract
Denman Glacier, East Antarctica, holds an ice volume equivalent to a 1.5 m rise in global sea level. Using satellite radar interferometry from the COSMO‐SkyMed constellation, we detect a 5.4±0.3 km grounding line retreat between 1996 and 2017‐2018. A novel reconstruction of the glacier bed topography indicates that the retreat proceeds on the western flank along a previously unknown 5 km wide, 1,800 m deep trough, deepening to 3,400 m below sea level. On the eastern flank, the grounding line is stabilized by a 10 km wide ridge. At tidal frequencies, the grounding line extends over a several kilometer‐wide grounding zone, enabling warm ocean water to melt ice at critical locations for glacier stability. If warm, modified Circumpolar Deep Water reaches the sub‐ice‐shelf cavity and continues to melt ice at a rate exceeding balance conditions, the potential exists for Denman Glacier to retreat irreversibly into the deepest, marine‐based basin in Antarctica.

Plain Language Summary
Using satellite radar data from the Italian COSMO‐SkyMed constellation, we document the grounding line retreat of Denman Glacier, a major glacier in East Antarctica that holds an ice volume equivalent to a 1.5 m global sea level rise. The grounding line is retreating asymmetrically. On the eastern flank, the glacier is protected by a subglacial ridge. On the western flank, we find a deep and steep trough with a bed slope that makes the glacier conducive to rapid retreat. If warm water continues to induce high rates of ice melt near the glacier grounding zone, the potential exists for Denman Glacier to undergo a rapid and irreversible retreat, with major consequences for sea level rise.

Key Points
•   CSK interferometric SAR observations of Denman Glacier, East Antarctica, reveal a 5.4±0.3 km grounding line retreat in the last twenty years
•   Denman Glacier is retreating along a deep trough, with a retrograde bed slope, deepening to 3.4 km below sea level, one of the deepest basins in Antarctica
•   The retrograde glacier bed and likely presence of warm water in the sub‐ice‐shelf cavity makes this region likely prone to marine instability

See also:

Title: "East Antarctica's Denman Glacier has retreated almost 3 miles over last 22 years"

https://phys.org/news/2020-03-east-antarctica-denman-glacier-retreated.html

Extract: "East Antarctica's Denman Glacier has retreated 5 kilometers, nearly 3 miles, in the past 22 years, and researchers at the University of California, Irvine and NASA's Jet Propulsion Laboratory are concerned that the shape of the ground surface beneath the ice sheet could make it even more susceptible to climate-driven collapse.:

34
GRACE and GRACE-FO satellites indicate that Greenland's ice mass loss in the summer of 2019 was twice that of the 2002-2019 average.  When combined with the observed high ice mass loss rates from West Antarctica, that is not good news:

Title: "GRACE, GRACE-FO Satellite Data Track Ice Loss at the Poles"

https://scitechdaily.com/nasa-satellites-track-how-quickly-the-poles-are-melting-greenland-lost-600-billion-tons-of-ice-in-2-months/

Extract: "During the exceptionally warm Arctic summer of 2019, Greenland lost 600 billion tons of ice — enough to raise global sea levels by nearly a tenth of an inch (2.2 millimeters) in just two months, a new study shows.

Led by scientists at NASA’s Jet Propulsion Laboratory and the University of California, Irvine, the study also concludes that Antarctica continues to lose mass, particularly in the Amundsen Sea Embayment and the Antarctic Peninsula on the western part of the continent; however, those losses have been partially offset by gains from increased snowfall in the northeast.

For context, last summer’s losses are more than double Greenland’s 2002-2019 yearly average.
“In Antarctica, the mass loss in the west proceeds unabated, which will lead to an even further increase in sea level rise,” Velicogna said. “But we also observe a mass gain in the Atlantic sector of East Antarctica caused by an uptick in snowfall, which helps mitigate the enormous increase in mass loss that we have seen in the last two decades on other parts of the continent.”"

35
...
The objective of Governments, Central Banks and the Private Sector Oligarchs is to get through the covid-19 ASAP, enter a solid V-shaped recovery and BAU by the end of the year.

This will no doubt include throwing a few squillions of dosh at the fossil fuel industries, legacy auto-makers and aviation etc.  And guess who in the end will have to pay? You, me, the kids,and  their kids.
...

Maybe we should all feel lucky that the novel corona virus doesn't have the multi-billion dollar disinformation campaign budgets that the fossil fuel industry uses each year to delay effective climate action, otherwise, we wouldn't be entering a solid V-shaped recovery.  :P

36
People want wealth and wealthy people use more energy as discussed in the linked reference:

Oswald, Y., Owen, A. & Steinberger, J.K. Large inequality in international and intranational energy footprints between income groups and across consumption categories. Nat Energy 5, 231–239 (2020). https://doi.org/10.1038/s41560-020-0579-8

https://www.nature.com/articles/s41560-020-0579-8

Abstract: "Inequality in energy consumption, both direct and indirect, affects the distribution of benefits that result from energy use. Detailed measures of this inequality are required to ensure an equitable and just energy transition. Here we calculate final energy footprints; that is, the energy embodied in goods and services across income classes in 86 countries, both highly industrialized and developing. We analyse the energy intensity of goods and services used by different income groups, as well as their income elasticity of demand. We find that inequality in the distribution of energy footprints varies across different goods and services. Energy-intensive goods tend to be more elastic, leading to higher energy footprints of high-income individuals. Our results consequently expose large inequality in international energy footprints: the consumption share of the bottom half of the population is less than 20% of final energy footprints, which in turn is less than what the top 5% consume."

37
Paul Ehrlich makes some good points in the linked article about our current, and likely future, global situation:

Title: "Paul R. Ehrlich: A pandemic, planetary reckoning, and a path forward"

https://www.dailyclimate.org/pandemic-population-covid-19-2645545497.html

Extract: "The COVID-19 pandemic is bringing environmental destruction and the deterioration of social and cultural systems into sharp focus. But we can learn from this.

But nothing is more impractical than civilization trying to continue business as usual as it circles the drain.

The current pandemic disaster may end up damping down consumerism and improving the environment – there are reports of the lethal smog usually blanketing some Chinese cities clearing during pandemic lockdowns.

Maybe there's some chance that people are learning lessons.

We can always hope."

38
Many pundits ignore effective radiative forcing when discussing the likely impacts of reactive gases (like methane) and aerosols on GMSTA projections.  Nevertheless, these impacts are real and the linked reference helps to quantify such effective radiative forcings:

Thornhill, G. D., Collins, W. J., Kramer, R. J., Olivié, D., O'Connor, F., Abraham, N. L., Bauer, S. E., Deushi, M., Emmons, L., Forster, P., Horowitz, L., Johnson, B., Keeble, J., Lamarque, J.-F., Michou, M., Mills, M., Mulcahy, J., Myhre, G., Nabat, P., Naik, V., Oshima, N., Schulz, M., Smith, C., Takemura, T., Tilmes, S., Wu, T., Zeng, G., and Zhang, J.: Effective Radiative forcing from emissions of reactive gases and aerosols – a multimodel comparison, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2019-1205, in review, 2020.

https://www.atmos-chem-phys-discuss.net/acp-2019-1205/

Abstract. This paper quantifies the effective radiative forcing from CMIP6 models of the present-day anthropogenic emissions of NOx, CO, VOCs, SO2, NH3, black carbon and primary organic carbon. Effective radiative forcing from pre-industrial to present-day changes in the concentrations of methane, N2O and halocarbons are quantified and attributed to their anthropogenic emissions.

Emissions of reactive species can cause multiple changes in the composition of radiatively active species: tropospheric ozone, stratospheric ozone, secondary inorganic and organic aerosol and methane. We therefore break down the ERFs from each emitted species into the contributions from the composition changes.

The 1850 to 2014 mean ERFs are 1.1 ± 0.07 W m−2 for sulfate, −0.24 ± 0.01 W m−2 for organic carbon (OC), and 0.15 ± 0.04 W m−2 for black carbon (BC), and for the aerosols combined it is −0.95 ± 0.03 W m−2. The means for the reactive gases are 0.69 ± 0.04 W m−2 for methane (CH4), 0.06 ± 0.04 W m−2 for NOx, −0.09 ± 0.03 W m−2 for volatile organic carbons (VOC), 0.16 ± 0.03 W m−2 for ozone (O3), 0.27 W m−2 for nitrous oxide (N2O) and −0.02 ± 0.06 W m−2 for hydrocarbon (HC). Differences in ERFs calculated for the different models reflect differences in the complexity of their aerosol and chemistry schemes, especially in the case of methane where tropospheric chemistry captures increased forcing from ozone production.

39
While the linked reference focuses on how SLR will influence estuarine hydrodynamics in populated areas; I note that the indicated changes in parameters including: tidal range and tidal bores will also serve to reduce the stability of key Antarctic marine glaciers and key Greenland marine terminating glaciers:

Danial Khojasteh et al. (16 March 2020), "Sea level rise and estuarine tidal dynamics: A review", Earth-Science Reviews, 103166, https://doi.org/10.1016/j.earscirev.2020.103166

https://www.sciencedirect.com/science/article/abs/pii/S0012825219307640?dgcid=rss_sd_all

Highlights
• A critical review is provided on how sea level rise (SLR) will influence estuarine hydrodynamics and knowledge gaps are identified.
• Current literature is inconclusive regarding the influences of SLR on estuarine hydrodynamics.
• Hydrodynamic modelling, rather than static approaches, is needed when assessing estuarine responses to SLR.
• Under SLR, the estuarine shape, bathymetry, friction, reflection and tidal resonance influence estuarine hydrodynamic parameters, including tidal range, tidal wave asymmetry, saltwater intrusion, and mixing.
• A conceptual framework is provided to highlight the likely responses of different types of estuaries to SLR.

Abstract
Sea level rise (SLR) poses a hazard to assets, ecosystems, and economies in coastal zones, including over 600 million people worldwide who currently reside near estuaries. SLR implications include more frequent oceanic inundation, shoreline erosion, and the failure of stormwater and drainage infrastructure. To predict and manage these potential impacts, a comprehensive understanding of SLR on estuarine hydrodynamics was assessed via a review of existing theory and available literature. The review highlighted that the most common method of assessing SLR impacts in estuaries has been via simplistic static approaches, such as elevation-based water level projections, that are of limited value as they do not include fundamental hydrodynamic responses to estuarine entrance restriction, geometry, bathymetry, friction, and floodplain connectivity. A much smaller number of studies have conducted hydrodynamic modelling of SLR in estuaries showing that estuarine shape, bathymetry, friction, reflection and resonance have a strong influence on estuarine hydrodynamic parameters such as tidal range and asymmetry, saltwater intrusion, and mixing. The majority of the existing SLR estuarine hydrodynamic literature has focused on the influence of estuarine tidal parameters providing conflicting results in terms of influence of SLR on estuarine tidal dynamics and patterns. For most studies, the saltwater intrusion length of the estuary was shown to increase under SLR, whereas very few studies examined the influence of SLR on estuary entrance condition, friction, reflection, resonance, and mixing. A significant knowledge gap identified was the lack of a generic framework to conceptualise how different estuary types respond to SLR based on shape, bathymetry, and entrance condition. To this aim, several conceptual models are introduced to highlight the role of tidal friction, resonance and tidal wave penetration in estuaries under SLR.

40
The linked reference indicates that most likely future Arctic sea ice losses will increase the frequency of Central Pacific El Nino events; which is particularly bad news for WAIS stability due to the like increase of Equatorial Pacific energy advected to West Antarctica via atmospheric Rossby Waves:

Hyerim Kim et al. (11 March 2020), "Arctic sea ice loss as a potential trigger for Central Pacific El Niño events", Geophysical Research Letters, https://doi.org/10.1029/2020GL087028

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL087028?af=R

Abstract
Little attention has been paid to the influence of Arctic sea ice loss on climate variability in the tropical Pacific. By analyzing observational datasets, we hypothesized that anomalous Arctic sea ice concentration variations have the potential to influence tropical Pacific sea surface temperature (SST) variability via atmosphere‐ocean coupled processes in the eastern subtropical North Pacific. To test this hypothesis, we conducted idealized model experiments with 15 ensembles in which historical SSTs for 1951‐2016 were restored in the Arctic only with different initial conditions. We found that a positive phase of North Pacific Oscillation–like atmospheric circulation, which is modulated by a sea ice reduction in the Pacific Arctic sector, triggers El Niño–like warming in the central tropical Pacific. This implies that connections between the Arctic and the tropics should be considered for further understanding of changes in El Niño and other tropical Pacific climate variability in a changing climate.

41
As my schedule has become busier than previously, I will likely maker fewer posts than recent years.  Thus, I thought I would make a somewhat more philosophical post today by raising the question of what does the Paris Agreement mean when it set a goal of staying 'well below 2C'?

Furthermore, I raise the following sub-topics:

1. As I have previously noted the Paris Agreement probably would not have even adopted the 'well below 2C' goal if it had not been concerned about fat right-tailed risks, which raises the question of what right-screwed PDF did Paris assume and how much has the shape of that PDF changed since 2015?

2. What baseline did Paris assume and what baseline should have it used to measure 2C?

3. Evidently, Paris did not feel comfortable defining what it meant by 'well below' otherwise, it would have used a specific value, or a specific range, like 0.25C to 0.4C below 2C.  Possible reasons that Paris may not have felt comfortable include that 'well below' depends on:
a) Which socio-economic pathway we collectively choose to follow;
b) How much climate variability increases with increasing GMSTA and,
c) How much confidence did Paris have in the AR5 projections w.r.t. variables like: climate sensitivity, ice-climate feedbacks and initial boundary conditions.

4. What confidence range did Paris assume was appropriate when considering issues like:
a) Tipping points,
b) Reversibility and
c) Socio-economic fragility.

5. Much of the current progress in reduction in CO2 emissions has been achieved by substituting coal with natural gas; thus:
a) Do decision makers currently think that collectively we have made more progress in the fight against climate change than we actually have because we are discounting the methane emissions associated with the increased use of natural gas?
b) Will it become more difficult to reduce crude oil and natural gas consumption that it was to reduce coal consumption because of a lack of economically available substitutes?
c) If economic times become harder, will coal consumption increase again in future years?

6. If consensus climate scientists have underestimated the negative feedback associated with anthropogenic aerosol emissions; will future reductions in anthropogenic aerosol emissions drive GMSTA closer to 'well below 2C' even with declining GHG emissions?

42
While the PALeo constraints on SEA level rise (PALSEA) program will not be complete until the end of 2021; it is still worth remembering that the paleo-record contains numerous instances of extremely rapid sea level rise with durations ranging from decades to centuries.  It will be good to learn what PALSEA finally reports after 2021:

Title: "PALSEA - PALeo constraints on SEA level rise"

http://pastglobalchanges.org/science/wg/palsea/intro

Extract: "PALSEA is a continuation of PALSEA1, which operated from 2008 to 2012, and PALSEA2, which operated from 2013-2017.
This third phase of the group runs from 2019-2021.

Sea-level rise due to polar ice-sheet retreat in a warming world is one of the most important, and uncertain aspects associated with future climate change. The geologic record, features major, and sometimes rapid, changes in ice sheets and sea level that offers an excellent opportunity to assess the rates, magnitudes, and processes involved in ice-sheet and sea-level change, as well as their connection to climate forcings."

See also:

Title: "Ocean Circulation and Carbon Cycling"

http://pastglobalchanges.org/products/pages-magazine/12916

Edit: Also, I note that the image is from 2015 when GMSTA was about 0.9C but it is now officially over 1.1C.

43
I think the goal is to offer 3 scenarios of policy changes.
...

If it is not clear in the cartoon, the figure with the hat is the decision maker and the figures without hats are consensus climate scientists.

44
Consequences / Re: COVID-19
« on: March 13, 2020, 02:09:32 PM »
The attached image from Vox showing the ratio of COVID-19 test kits vs the population of key countries, shows how ill prepared the Trump Administration is to address this epidemic in the U.S.A.

Edit, see also:

Title: "Why the U.S. is so far behind on coronavirus testing"

https://www.axios.com/coronavirus-testing-labs-delay-a3868ece-a2e5-4ed2-8822-44d20c73774d.html

Extract: "Some of the nation’s best academic laboratories wanted to begin developing their own coronavirus diagnostic tests early last month, but were blocked by federal rules about test development.

Why it matters: The U.S. is woefully behind in mass deployment of tests to detect coronavirus, determine its spread and isolate hot spots. Once given the go-ahead to develop tests under more relaxed terms, some of these labs were able to get tests up and running in a matter of days.
...
The bottom line: As of yesterday, the U.S. has the capacity to test about 22,000 people a day, although it's unclear how many people are actually being tested. South Korea — which has a significantly smaller population — is testing nearly 20,000 people a day, the BBC reports."

45
The linked article discusses a new government-industries guide for UK pension funds as to how they might assess up-coming climate change risk, and they recommend including an analysis of at least one scenario assuming a "no transition, pathway to 4+oC":

Title: "UK pension trustees presented with guide to climate-related risks"

https://www.ipe.com/news/uk-pension-trustees-presented-with-guide-to-climate-related-risks/10044243.article

Extract: "The Pensions Climate Risk Industry Group (PCRIG), as it was named, described the guide, as “structured sequentially based on the way a pension trustee board might typically approach decision-making”.

It recommends scenario analysis as “a helpful technique for trustees to assess their scheme’s resilience to different future outcomes”. Three scenarios are recommended: an orderly transition to a 2⁰C or lower scenario; an abrupt transition to a 2⁰C or lower scenario, and a “no transition, pathway to 4+⁰C scenario”.

46
Paleontologists discover solid evidence of formerly elusive abrupt sea-level jump

...

https://www.sciencedaily.com/releases/2020/03/200310094223.htm

For those who do not like to click on links, I provide the following reference that presents findings that kassy discussed.  Also, I note that much of the abrupt sea level rise contributions for the Meltwater pulses during the transition to the Holocene came from marine glaciers situated in various portions of the current Antarctic continental shelf.

Skye Yunshu Tian, Moriaki Yasuhara, Yuanyuan Hong, Huai-Hsuan M. Huang, Hokuto Iwatani, Wing-Tung Ruby Chiu, Briony Mamo, Hisayo Okahashi, Tine L. Rasmussen. Deglacial–Holocene Svalbard paleoceanography and evidence of meltwater pulse 1B. Quaternary Science Reviews, 2020; 233: 106237 DOI: 10.1016/j.quascirev.2020.106237

https://www.sciencedirect.com/science/article/abs/pii/S0277379119309485?via%3Dihub

Abstract
Better understanding of deglacial meltwater pulses (MWPs) is imperative for future predictions of human-induced warming and abrupt sea-level change because of their potential for catastrophic damage. However, our knowledge of the second largest meltwater pulse MWP-1B that occurred shortly after the start of the Holocene interglacial remains very limited. Here, we studied fossil ostracods as paleoenvironmental indicators of water depth, salinity, and temperature in two marine sediment cores from Storfjorden, Svalbard margin (the Arctic Ocean), to investigate near-field (i.e. areas located beneath continental ice sheets at the Last Glacial Maximum) evidence of MWP-1B. The depositional environment changed from a cold bathyal environment to a warmer bathyal environment at ∼11,300 yr BP indicating incursion of warm Atlantic water into the Nordic seas, and eventually to a cold neritic environment by ∼11,000 yr BP because of melting of the Svalbard-Barents Sea ice sheet and resultant isostatic rebound. This process corresponds to rapid relative sea-level fall of 40–80 m of MWP-1B from ∼11,300 to 11,000 yr BP.

47
To those who follow this thread, the linked article and associated reference come a no surprise:

Title: "Six-fold jump in polar ice loss lifts global oceans"

https://phys.org/news/2020-03-six-fold-polar-ice-loss-global.html

Extract: "Greenland and Antarctica are shedding six times more ice than during the 1990s, driving sea level rise that could see annual flooding by 2100 in regions home today to some 400 million people, scientists have warned."

See also:

Shepherd, A., Ivins, E., Rignot, E. et al. Mass balance of the Greenland Ice Sheet from 1992 to 2018. Nature 579, 233–239 (2020). https://doi.org/10.1038/s41586-019-1855-2

https://www.nature.com/articles/s41586-019-1855-2

Abstract: "The Greenland Ice Sheet has been a major contributor to global sea-level rise in recent decades, and it is expected to continue to be so3. Although increases in glacier flow and surface melting have been driven by oceanic and atmospheric warming, the magnitude and trajectory of the ice sheet’s mass imbalance remain uncertain. Here we compare and combine 26 individual satellite measurements of changes in the ice sheet’s volume, flow and gravitational potential to produce a reconciled estimate of its mass balance. The ice sheet was close to a state of balance in the 1990s, but annual losses have risen since then, peaking at 345 ± 66 billion tonnes per year in 2011. In all, Greenland lost 3,902 ± 342 billion tonnes of ice between 1992 and 2018, causing the mean sea level to rise by 10.8 ± 0.9 millimetres. Using three regional climate models, we show that the reduced surface mass balance has driven 1,964 ± 565 billion tonnes (50.3 per cent) of the ice loss owing to increased meltwater runoff. The remaining 1,938 ± 541 billion tonnes (49.7 per cent) of ice loss was due to increased glacier dynamical imbalance, which rose from 46 ± 37 billion tonnes per year in the 1990s to 87 ± 25 billion tonnes per year since then. The total rate of ice loss slowed to 222 ± 30 billion tonnes per year between 2013 and 2017, on average, as atmospheric circulation favoured cooler conditions and ocean temperatures fell at the terminus of Jakobshavn Isbræ. Cumulative ice losses from Greenland as a whole have been close to the rates predicted by the Intergovernmental Panel on Climate Change for their high-end climate warming scenario17, which forecast an additional 70 to 130 millimetres of global sea-level rise by 2100 compared with their central estimate."

48
For those who want to read more about the International Thwaites Glacier Collaboration (ITGC) five-year program, I provide the following link to a relevant article:

Title: "Investigating Thwaites: the riskiest glacier on Earth"

http://geographical.co.uk/nature/polar/item/3606-investigating-thwaites-the-riskiest-glacier-on-earth

Extract: "Dubbed the riskiest glacier on Earth, an ongoing project to learn more about Thwaites is vital to ensure the accuracy of sea-level rise predictions"

49
The linked article and WMO State of the Global Climate in 2019 report card indicates that climate change continued advance in 2019:

Title: "We've Officially Passed The Threshold of 1.1 Degree Celsius Warming"

https://www.sciencealert.com/the-last-five-years-were-the-warmest-ever-recorded-again

Extract: "Global average temperatures in 2019 were 1.1 degrees Celsius above pre-industrial levels. Only 2016 was hotter, but that year came at the end of an extreme El Niño, which typically has a warming influence on global temperatures."

See also:

Title: "WMO Statement on the State of the Global Climate in 2019"

https://library.wmo.int/index.php?lvl=notice_display&id=21700#.XmkbKHOSmUk
https://library.wmo.int/doc_num.php?explnum_id=10211

Caption: "Figure 14. Annual (blue) and cumulative (red) mass balance of reference glaciers with more than 30 years of ongoing glaciological measurements. Global mass balance is based on an average for 19 regions to minimize bias towards well-sampled regions. Annual mass changes are expressed in meter water equivalent (m w.e.) which corresponds to tonnes per square meter (1 000 kg m-2) (Source: World Glacier Monitoring Service (WGMS, 2020, updated)."

50
The analysis at the linked website find that whether considering only long-lived GHG emissions or both long and short-lived GHG emissions from food; it is a good idea to become a vegetarian:

Title: "The carbon footprint of foods: are differences explained by the impacts of methane?"

https://ourworldindata.org/carbon-footprint-food-methane

Extract: "This data suggests that the most effective way to reduce the climate impact of your diet is to eat less meat overall, especially red meat and dairy

In this post I want to investigate whether these conclusions depend on the particular metric we rely on to quantify greenhouse gas (GHG) emissions. It could be argued that red meat and dairy have a much higher footprint because its emissions are dominated by methane – a greenhouse gas that is much more potent but has a shorter lifetime in the atmosphere than carbon dioxide. Methane emissions have so far driven a significant amount of warming – with estimates ranging from around 23% to 40% of the total – to date."

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