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Author Topic: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)  (Read 93088 times)

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #500 on: January 22, 2019, 12:15:44 AM »
The linked article cites new PNAS findings that ice mass loss from the GIS is accelerating faster than consensus climate science previously assumed:

Title: "Greenland's ice melting faster than scientists previously thought – study"

https://www.theguardian.com/world/2019/jan/21/greenland-ice-melting-faster-than-scientists-previously-thought-study

Extract: "Greenland is melting faster than scientists previously thought, with the pace of ice loss increasing four-fold since 2003, new research has found."
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Klondike Kat

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #501 on: January 22, 2019, 12:49:43 AM »
Yes, the mass loss accelerated from 2003 up until 2012.  However, since then it has decelerated dramatically, to the point where it may actually be gained mass.

http://sciencenordic.com/how-greenland-ice-sheet-fared-2018

https://nsidc.org/greenland-today/

"Exceptional winter snow accumulation and heavy, summer snowfall, drove the net snow input mass to 130 billion tons above the 1981 to 2010 average. This was followed by a near-average melt and runoff period, resulting in a large net mass gain for the ice sheet in 2018 of 150 billion tons. This is the largest net gain from snowfall since 1996, and the highest snowfall since 1972. However, several major glaciers now flow significantly faster than in these earlier years. The net change in mass of the ice sheet overall, including this higher discharge of ice directly into the ocean, is not clear at this point but may be a smaller loss or even a small gain. This is similar to our assessment for 2017, and in sharp contrast to the conditions for the preceding decade."

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #502 on: January 22, 2019, 05:53:32 AM »
Anyone got the doi for the Bevis paper on GIS ? i searched the PNAS site but it didnt appear for 2019

Re: Wolf: I think i agree with Wolf's results on CO2 at high concentrations increasing sensitivity. What I don't trust is the cloud albedo feedback bit.

sidd

Wherestheice

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #503 on: January 22, 2019, 08:13:56 AM »
Anyone got the doi for the Bevis paper on GIS ? i searched the PNAS site but it didnt appear for 2019

Re: Wolf: I think i agree with Wolf's results on CO2 at high concentrations increasing sensitivity. What I don't trust is the cloud albedo feedback bit.

sidd

Wouldn't a warmer planet cause the cloud albedo to lessen, due to there being more water vapor in the atmosphere, causing clouds to have more rain droplets, therefore making them darker. This isn't my field of study, but that makes sense to me
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Phil42

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #504 on: January 22, 2019, 12:50:23 PM »
I always understood the total Greenland (or generally any) ice sheet mass change in a year to mainly be a result of the amount snowfall, melt and calving:
mass change = gain from snowfall - loss from melt - loss through calving
Is this correct?

https://climate.nasa.gov/vital-signs/ice-sheets/

The linked page contains a graph that has data until June 2017 and shows an ongoing downward trend in the Greenland total ice sheet mass.

Yes, the mass loss accelerated from 2003 up until 2012.  However, since then it has decelerated dramatically, to the point where it may actually be gained mass.

http://sciencenordic.com/how-greenland-ice-sheet-fared-2018

https://nsidc.org/greenland-today/

"Exceptional winter snow accumulation and heavy, summer snowfall, drove the net snow input mass to 130 billion tons above the 1981 to 2010 average. This was followed by a near-average melt and runoff period, resulting in a large net mass gain for the ice sheet in 2018 of 150 billion tons. This is the largest net gain from snowfall since 1996, and the highest snowfall since 1972. However, several major glaciers now flow significantly faster than in these earlier years. The net change in mass of the ice sheet overall, including this higher discharge of ice directly into the ocean, is not clear at this point but may be a smaller loss or even a small gain. This is similar to our assessment for 2017, and in sharp contrast to the conditions for the preceding decade."

Do I understand this analysis correctly that this downward trend could have been broken in 2017 and 2018? That would be great news.

Klondike Kat

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #505 on: January 22, 2019, 04:35:34 PM »
I always understood the total Greenland (or generally any) ice sheet mass change in a year to mainly be a result of the amount snowfall, melt and calving:
mass change = gain from snowfall - loss from melt - loss through calving
Is this correct?

https://climate.nasa.gov/vital-signs/ice-sheets/

The linked page contains a graph that has data until June 2017 and shows an ongoing downward trend in the Greenland total ice sheet mass.

Yes, the mass loss accelerated from 2003 up until 2012.  However, since then it has decelerated dramatically, to the point where it may actually be gained mass.

http://sciencenordic.com/how-greenland-ice-sheet-fared-2018

https://nsidc.org/greenland-today/

"Exceptional winter snow accumulation and heavy, summer snowfall, drove the net snow input mass to 130 billion tons above the 1981 to 2010 average. This was followed by a near-average melt and runoff period, resulting in a large net mass gain for the ice sheet in 2018 of 150 billion tons. This is the largest net gain from snowfall since 1996, and the highest snowfall since 1972. However, several major glaciers now flow significantly faster than in these earlier years. The net change in mass of the ice sheet overall, including this higher discharge of ice directly into the ocean, is not clear at this point but may be a smaller loss or even a small gain. This is similar to our assessment for 2017, and in sharp contrast to the conditions for the preceding decade."

Do I understand this analysis correctly that this downward trend could have been broken in 2017 and 2018? That would be great news.

Yes, you are understanding correctly.  Whether this is the start of a new trend or just a temporary reprieve remains to be seen.  So, I would not start celebrating soon.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #506 on: January 22, 2019, 04:41:15 PM »
Anyone got the doi for the Bevis paper on GIS ? i searched the PNAS site but it didnt appear for 2019

Re: Wolf: I think i agree with Wolf's results on CO2 at high concentrations increasing sensitivity. What I don't trust is the cloud albedo feedback bit.

sidd

Michael Bevis el al., "Accelerating changes in ice mass within Greenland, and the ice sheet's sensitivity to atmospheric forcing," PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1806562116
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #507 on: January 22, 2019, 04:47:39 PM »
...
Scanning several papers on the PETM again I see estimates on the rate of emissions and warming vary significantly, so it's hard to have much confidence in any particular estimate, whether it was 10x slower than currently, 100x slower, or maybe even as fast as currently.

...

The linked reference discusses how lessons learned from studying paleo 'hyperthermal' events from the past 300 million years can be used to help calibrate models of our current 'Anthropocene hyperthermal' event.  One such lesson learned is that many key negative feedback mechanisms occur over periods longer than one thousand years, while many key positive forcing mechanisms occur over shorter time frames; thus the observed effective climate sensitivity from paleo-hyperthermal events likely underestimate the effective climate sensitivity for our current 'Anthropogenic hyperthermal' event:

Gavin L. Foster, Pincelli Hull, Daniel J. Lunt, James C. Zachos (3 September 2018), "Placing our current ‘hyperthermal’ in the context of rapid climate change in our geological past", Philosophical Transactions of the Royal Society A, DOI: 10.1098/rsta.2017.0086

http://rsta.royalsocietypublishing.org/content/376/2130/20170086

Extract: "These modern rates of carbon emission likely dwarf the rate seen during the onset of the PETM by a factor of 10 or so. If humanity's fossil fuel use is not tackled rapidly through the development of a low-carbon economy, we face the possibility of emitting as much carbon as was released during the PETM but in a fraction of the time (0.5 versus 50–100 thousand years). The magnitude of atmospheric CO2 change (and hence the magnitude of warming, anoxia and ocean acidification) that occurs following any carbon addition to the Earth system is a function of rate, due to the time scales of a number of key negative feedbacks. Why the Palaeozoic hyperthermals are associated with significantly greater extinction rate is currently not known. However, a consensus is emerging that it is the extreme heat and anoxia that are the likely ‘kill mechanisms’ [50]. Given that the rate of carbon addition during our ‘anthropogenic hyperthermal’ eclipses that of the PETM, at the very least we are likely looking at a potential future with a more severe impact of life on Earth than any climate change event in the last 56 Myr. Exactly how severe, however, remains perhaps one of the most pressing of the ‘unknown unknowns’."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #508 on: January 22, 2019, 04:58:15 PM »


Next, I provide links to Jagniecki et al. (2015) (and an associated article); indicating that early Eocene climatic optimum (EECO) conditions (with an equable climate) may have occurred with atmospheric CO₂ concentrations between 680ppm and 1260ppm (see the attached image); and that under such conditions the effective climate sensitivity (ESS) may have been twice that previously assumed by Royer et al (2012) …

Jagniecki,Elliot A. et al. (2015), "Eocene atmospheric CO2from the nahcolite proxy", Geology, http://dx.doi.org/10.1130/G36886.1

...

There is a reason that equable conditions occurred repeatedly in Earth's past, and the current generation of ESMs have failed to identify those reasons.  For instance, the linked reference confirms that most climate simulations do not capture the greater polar amplification during the Eocene.  As CO2e approaches 560ppm this type of information could become highly relevant to modern times:

David Evans, et al (January 22, 2018), "Eocene greenhouse climate revealed by coupled clumped isotope-Mg/Ca thermometry", PNAS, doi: 10.1073/pnas.1714744115

http://www.pnas.org/content/early/2018/01/12/1714744115.abstract

Significance: "Reconstructing the degree of warming during geological periods of elevated CO2 provides a way of testing our understanding of the Earth system and the accuracy of climate models. We present accurate estimates of tropical sea-surface temperatures (SST) and seawater chemistry during the Eocene (56–34 Ma before present, CO2 >560 ppm). This latter dataset enables us to reinterpret a large amount of existing proxy data. We find that tropical SST are characterized by a modest warming in response to CO2. Coupling these data to a conservative estimate of high-latitude warming demonstrates that most climate simulations do not capture the degree of Eocene polar amplification."

Abstract: "Past greenhouse periods with elevated atmospheric CO2 were characterized by globally warmer sea-surface temperatures (SST). However, the extent to which the high latitudes warmed to a greater degree than the tropics (polar amplification) remains poorly constrained, in particular because there are only a few temperature reconstructions from the tropics. Consequently, the relationship between increased CO2, the degree of tropical warming, and the resulting latitudinal SST gradient is not well known. Here, we present coupled clumped isotope (Δ47)-Mg/Ca measurements of foraminifera from a set of globally distributed sites in the tropics and midlatitudes. Δ47 is insensitive to seawater chemistry and therefore provides a robust constraint on tropical SST. Crucially, coupling these data with Mg/Ca measurements allows the precise reconstruction of Mg/Casw throughout the Eocene, enabling the reinterpretation of all planktonic foraminifera Mg/Ca data. The combined dataset constrains the range in Eocene tropical SST to 30–36 °C (from sites in all basins). We compare these accurate tropical SST to deep-ocean temperatures, serving as a minimum constraint on high-latitude SST. This results in a robust conservative reconstruction of the early Eocene latitudinal gradient, which was reduced by at least 32 ± 10% compared with present day, demonstrating greater polar amplification than captured by most climate models."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #509 on: January 22, 2019, 05:25:38 PM »
The attached image, per sidd, comes from Kidder et al (2004), and shows how (for paleo conditions) equable atmospheric patterns occur and how in an equable atmosphere (hothouse conditions) heat from the tropics is more easily carried through the atmosphere directly to the poles.  Furthermore, it is easier for global warming to flip the NH atmosphere into an equable pattern than the SH; thus if/when the WAIS collapses (say beginning in 2040), this event might conceivable put the NH atmosphere into an equable pattern by say 2100, while leaving the SH atmosphere in its current pattern.

See also:

Kidder, D. L., & Worsley, T. R. (2010). Phanerozoic Large Igneous Provinces (LIPs), HEATT (Haline Euxinic Acidic Thermal Transgression) episodes, and mass extinctions. Palaeogeography, Palaeoclimatology, Palaeoecology, 295(1-2), 162–191. doi:10.1016/j.palaeo.2010.05.036

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

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #510 on: January 22, 2019, 05:48:31 PM »
Local drivers of amplified Arctic warming

Quote
A new international research study on the cause of Arctic amplification published this week in the journal Nature Climate Change shows that local greenhouse gas concentrations, and Arctic climate feedbacks outweigh other processes. Using complex computer simulations, the scientists were able to disprove previously suggested hypotheses, that emphasized the role of transport of heat from the tropics to the poles as one of the key contributors to the amplified warming in the Arctic.
"Our study clearly shows that local carbon dioxide forcing and polar feedbacks are most effective in Arctic amplification compared to other processes," said corresponding author Malte Stuecker, project leader at the IBS Center for Climate Physics (ICCP) in Busan, South Korea.

Link to Article >> https://phys.org/news/2018-11-local-drivers-amplified-arctic.html

Abstract:


Quote
The surface temperature response to greenhouse gas forcing displays a characteristic pattern of polar-amplified warming1,2,3,4,5, particularly in the Northern Hemisphere. However, the causes of this polar amplification are still debated. Some studies highlight the importance of surface-albedo feedback6,7,8, while others find larger contributions from longwave feedbacks4,9,10, with changes in atmospheric and oceanic heat transport also thought to play a role11,12,13,14,15,16. Here, we determine the causes of polar amplification using climate model simulations in which CO2 forcing is prescribed in distinct geographical regions, with the linear sum of climate responses to regional forcings replicating the response to global forcing. The degree of polar amplification depends strongly on the location of CO2 forcing. In particular, polar amplification is found to be dominated by forcing in the polar regions, specifically through positive local lapse-rate feedback, with ice-albedo and Planck feedbacks playing subsidiary roles. Extra-polar forcing is further shown to be conducive to polar warming, but given that it induces a largely uniform warming pattern through enhanced poleward heat transport, it contributes little to polar amplification. Therefore, understanding polar amplification requires primarily a better insight into local forcing and feedbacks rather than extra-polar processes.

Link to Study >> https://www.nature.com/articles/s41558-018-0339-y

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #511 on: January 22, 2019, 06:40:12 PM »
Local drivers of amplified Arctic warming

Quote
A new international research study on the cause of Arctic amplification published this week in the journal Nature Climate Change shows that local greenhouse gas concentrations, and Arctic climate feedbacks outweigh other processes. Using complex computer simulations, the scientists were able to disprove previously suggested hypotheses, that emphasized the role of transport of heat from the tropics to the poles as one of the key contributors to the amplified warming in the Arctic.
"Our study clearly shows that local carbon dioxide forcing and polar feedbacks are most effective in Arctic amplification compared to other processes," said corresponding author Malte Stuecker, project leader at the IBS Center for Climate Physics (ICCP) in Busan, South Korea.

...

Reposted from Reply #419:

"…

Regarding the future, you need to bear in mind that Stuecker et al (2018) are talking about observed Arctic Amplification, and you need to bear in mind that global warming is only now beginning to have a significant impact on the ENSO cycle (and in a few decades on summer Arctic Sea Ice extent and the associated flip in the ice-albedo feedback), and as cited in Reply #397:

"The linked reference indicates that the warming of the North Pacific subpolar waters is likely the most important feedback for driving enhanced Arctic Amplification with continued global warming, and the attached image demonstrates how the North Pacific subpolar water can be warmed directly by atmospheric telecommunication of energy from the Tropical Pacific.  If show this indicates that the CMIP5 projections likely underestimate ECS, and as ice-climate feedback would likely accelerate warming the Tropical Pacific, it is likely that CMIP6 projections will also underestimate ECS as these models do not consider ice-cliff failures or hydrofracturing:"

Summer Praetorius, Maria Rugenstein, Geeta Persad, Ken Caldeira. Global and Arctic climate sensitivity enhanced by changes in North Pacific heat flux. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-05337-8

https://www.nature.com/articles/s41467-018-05337-8

Thus by 2040 Arctic Amplification will likely be significantly higher that today due to increased water vapor migration from the North Pacific (associated with the increased telecommunication of Tropical Pacific energy due to increased El Nino frequencies), and decreased ice-albedo, as well as the lapse rate feedback cited by Stuecker et al (2018)."
« Last Edit: January 22, 2019, 07:29:37 PM by AbruptSLR »
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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #512 on: January 22, 2019, 09:16:27 PM »
The Bevis paper is interesting. They use GIA as well as a bunch of other observations to estimate GIS mass waste. One  takeaway is that in the twentieth century, atmosphere had not warmed enuf for NAO variation to induce mass waste events thru increased SMB. But this century it is.

"Since 2000, the NAO has worked in concert with global warming to trigger major increases in summertime runoff. Before 2000, the air was too cool for the NAO to do the same. In a decade or two, global warming will be able to drive 2012 levels of runoff with little or no assistance from the NAO. In the shorter term, we can infer that the next time NAO turns strongly negative, SMB will trend strongly negative over west and especially southwest Greenland ..."


They also point out several interesting things. The pause after 2012 was due to NAO :

"Van Angelen et al. (13) concluded that if the sNAO switched back to positive values after 2012, then surface mass balance (SMB) might partially recover. Indeed, not only did the June to August (JJA) and June to September (JJAS) NAO indices turn positive in 2013, but the change in each of these sNAO indices from 2012 to 2013 was the single biggest interannual change recorded since 1950 (Fig. 1 F and G and SI Appendix, Fig. S7). Furthermore, when the sNAO index again turned strongly negative in 2015, significant ice loss was reestablished (Fig. 1 B and E), and the Pause had ended."

Another point they make is that glacier discharge is governed by shallow marine warmth:

"future warming of the shallow ocean is expected to have its largest impact, via DMB (33, 34), in southeast and northwest Greenland"

But the last is not the focus of the paper.

Open access, read all about it:

doi: 10.1073/pnas.1806562116

sidd

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #513 on: January 22, 2019, 09:48:34 PM »
Per the attached image & linked sources, fossil CO₂ emissions in 2018 reached about 37 Billion tons:

Title: "Global Carbon Budget 2018"

http://www.globalcarbonproject.org/global/images/carbonbudget/Infographic_Emissions2018.png

See also:

Le Quéré, C., Andrew, R. M., Friedlingstein, P., Sitch, S., Hauck, J., Pongratz, J., Pickers, P. A., Korsbakken, J. I., Peters, G. P., Canadell, J. G., Arneth, A., Arora, V. K., Barbero, L., Bastos, A., Bopp, L., Chevallier, F., Chini, L. P., Ciais, P., Doney, S. C., Gkritzalis, T., Goll, D. S., Harris, I., Haverd, V., Hoffman, F. M., Hoppema, M., Houghton, R. A., Hurtt, G., Ilyina, T., Jain, A. K., Johannessen, T., Jones, C. D., Kato, E., Keeling, R. F., Goldewijk, K. K., Landschützer, P., Lefèvre, N., Lienert, S., Liu, Z., Lombardozzi, D., Metzl, N., Munro, D. R., Nabel, J. E. M. S., Nakaoka, S.-I., Neill, C., Olsen, A., Ono, T., Patra, P., Peregon, A., Peters, W., Peylin, P., Pfeil, B., Pierrot, D., Poulter, B., Rehder, G., Resplandy, L., Robertson, E., Rocher, M., Rödenbeck, C., Schuster, U., Schwinger, J., Séférian, R., Skjelvan, I., Steinhoff, T., Sutton, A., Tans, P. P., Tian, H., Tilbrook, B., Tubiello, F. N., van der Laan-Luijkx, I. T., van der Werf, G. R., Viovy, N., Walker, A. P., Wiltshire, A. J., Wright, R., Zaehle, S., and Zheng, B.: Global Carbon Budget 2018, Earth Syst. Sci. Data, 10, 2141-2194, https://doi.org/10.5194/essd-10-2141-2018, 2018.

https://www.earth-syst-sci-data.net/10/2141/2018/
&
https://www.earth-syst-sci-data.net/10/2141/2018/essd-10-2141-2018.pdf

Abstract
Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – the “global carbon budget” – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFF) are based on energy statistics and cement production data, while emissions from land use and land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) and terrestrial CO2 sink (SLAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2008–2017), EFF was 9.4±0.5 GtC yr−1, ELUC 1.5±0.7 GtC yr−1, GATM 4.7±0.02 GtC yr−1, SOCEAN 2.4±0.5 GtC yr−1, and SLAND 3.2±0.8 GtC yr−1, with a budget imbalance BIM of 0.5 GtC yr−1 indicating overestimated emissions and/or underestimated sinks. For the year 2017 alone, the growth in EFF was about 1.6 % and emissions increased to 9.9±0.5 GtC yr−1. Also for 2017, ELUC was 1.4±0.7 GtC yr−1, GATM was 4.6±0.2 GtC yr−1, SOCEAN was 2.5±0.5 GtC yr−1, and SLAND was 3.8±0.8 GtC yr−1, with a BIM of 0.3 GtC. The global atmospheric CO2 concentration reached 405.0±0.1 ppm averaged over 2017. For 2018, preliminary data for the first 6–9 months indicate a renewed growth in EFF of +2.7 % (range of 1.8 % to 3.7 %) based on national emission projections for China, the US, the EU, and India and projections of gross domestic product corrected for recent changes in the carbon intensity of the economy for the rest of the world. The analysis presented here shows that the mean and trend in the five components of the global carbon budget are consistently estimated over the period of 1959–2017, but discrepancies of up to 1 GtC yr−1 persist for the representation of semi-decadal variability in CO2 fluxes. A detailed comparison among individual estimates and the introduction of a broad range of observations show (1) no consensus in the mean and trend in land-use change emissions, (2) a persistent low agreement among the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) an apparent underestimation of the CO2 variability by ocean models, originating outside the tropics. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding the global carbon cycle compared with previous publications of this data set (Le Quéré et al., 2018, 2016, 2015a, b, 2014, 2013). All results presented here can be downloaded from https://doi.org/10.18160/GCP-2018.
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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #514 on: January 22, 2019, 10:28:30 PM »
Re: Wolf, cloud albedo

My point is that fig 6 b (which i posted in my original comment on Wolf et al.)  showing a minimum in cloud albedo around temperatures of 320-330 K is based on a coarse atmospheric model that must parametrize cloud processes at finer scale. I am no convinced the parametrizations are reliable.

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #515 on: January 22, 2019, 11:37:04 PM »
Re: Wolf, cloud albedo

My point is that fig 6 b (which i posted in my original comment on Wolf et al.)  showing a minimum in cloud albedo around temperatures of 320-330 K is based on a coarse atmospheric model that must parametrize cloud processes at finer scale. I am no convinced the parametrizations are reliable.

sidd


While your observation seems reasonable, is your point that because Wolf et al (2018) is not perfect:

a. … we can safely ignore their warning?
b. … we should apply the Precautionary Principle and take their warning seriously?
c. … we should redouble our efforts to make better models while also taking precautionary measures?
d. … we should redouble our efforts to make better models while ignoring their warning?

See also:

Title: "Perfect is the enemy of good"

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

Extract: "Aristotle, Confucius, and other classical philosophers propounded the principle of the golden mean which counsels against extremism in general. The Pareto principle or 80–20 rule explains this numerically. For example, it commonly takes 20% of the full time to complete 80% of a task while to complete the last 20% of a task takes 80% of the effort. Achieving absolute perfection may be impossible and so, as increasing effort results in diminishing returns, further activity becomes increasingly inefficient.

Robert Watson-Watt, who developed early warning radar in Britain to counter the rapid growth of the Luftwaffe, propounded a "cult of the imperfect", which he stated as "Give them the third best to go on with; the second best comes too late, the best never comes.""

Edit:

Also, do you think that Team Schmidt is more correct because there are no sharp tipping points in climate science; or do think Team AOC is more correct because the ocean likely already has enough heat content to assure a MISI collapse of the WAIS in the coming centuries and that following a BAU pathway will likely result in sufficient Earth energy imbalance by 2030 to assure a MICI collapse of the WAIS this century?

Title: "Climate scientists refute 12-year deadline to curb global warming"

https://www.axios.com/climate-change-scientists-comment-ocasio-cortez-12-year-deadline-c4ba1f99-bc76-42ac-8b93-e4eaa926938d.html

Extract: "Reality check: "All the time-limited frames are bullshit," Gavin Schmidt, who leads NASA's Goddard Institute for Space Studies in New York, told Axios in an email. "Nothing special happens when the 'carbon budget' runs out or we pass whatever temperature target you care about, instead the costs of emissions steadily rise," he said. The IPCC report, for example, found the impacts worsen considerably beyond 1.5°C of warming.

•   "The thing to push back against is the implicit framing that there is some magic global mean temperature or total emissions that separate 'fine' from 'catastrophic'. There just isn't," Schmidt said.

The bottom line: Even if hard deadlines are scientifically flawed, they can be effective when it comes to activism. The 12-year timeframe, in particular, has been widely adopted by proponents of climate action.

•   "We can quibble about the phraseology, whether it's existential or cataclysmic" impacts that we'll face without taking action in the next 12 years, Ocasio-Cortez spokesman Corbin Trent told Axios. But, he says, the reality is: "We're seeing lots of [climate change-related] problems that are already impacting lives.""
« Last Edit: January 23, 2019, 12:00:46 AM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #516 on: January 23, 2019, 04:42:46 AM »
The linked reference and associated image, indicate that observed Ocean Heat Content, OHC, has increased more rapidly than indicated by AR5.  Hopefully, AR6 will recognize that this trend is not good for mankind's future:

Lijing Cheng, John Abraham, Zeke Hausfather & Kevin E. Trenberth (11 Jan 2019), "How fast are the oceans warming?", Science, Vol. 363, Issue 6423, pp. 128-129, DOI: 10.1126/science.aav7619

They had Zeke Hausfather on The Real News!

Link >>

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #517 on: January 23, 2019, 05:40:49 AM »
Re: Wolf

c) of course

That does not mean i accept Wolf uncritically on cloud albedo minima. Or that i do not look to other sources for variation in sensitivity with CO2 content.

And as far as Schmidt goes i agree with him also when he says that "All time limited frames are bullshit" The world does not end in 12 years or in 2100 or wherever to care to name. And when he says "The thing to push back against is the implicit framing that there is some magic global mean temperature or total emissions that separate 'fine' from 'catastrophic'. There just isn't,"  i agree there also.We see catastrophes today. We will see many, many more in future. How many is within our control.

Lets say we dont meet 12 yr target. The world will not end. Our costs will, of course, skyrocket in terms of blood and treasure and toil and death.

We know too little, but we know enuf to tell us that what we need to do is minimize fossil burn now. Like, immediately.

As for ice sheet collapse, for me that's a given. Now I'm just trying to nail down a timescale, how much time is left to retreat from the coasts. My gut says we should be doing so now. Maritime civil engineering works on more massive scale than ever before will be required merely to maintain ports. Not to speak of huge civil engineering works rehousing the hapless coastal refugees. Or rising storm drainage. Or ...

sidd
« Last Edit: January 23, 2019, 08:03:07 AM by sidd »

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #518 on: January 23, 2019, 04:44:04 PM »
Re: Wolf

c) of course

That does not mean i accept Wolf uncritically on cloud albedo minima. Or that i do not look to other sources for variation in sensitivity with CO2 content.

And as far as Schmidt goes i agree with him also when he says that "All time limited frames are bullshit" The world does not end in 12 years or in 2100 or wherever to care to name. And when he says "The thing to push back against is the implicit framing that there is some magic global mean temperature or total emissions that separate 'fine' from 'catastrophic'. There just isn't,"  i agree there also.We see catastrophes today. We will see many, many more in future. How many is within our control.

Lets say we dont meet 12 yr target. The world will not end. Our costs will, of course, skyrocket in terms of blood and treasure and toil and death.

We know too little, but we know enuf to tell us that what we need to do is minimize fossil burn now. Like, immediately.

As for ice sheet collapse, for me that's a given. Now I'm just trying to nail down a timescale, how much time is left to retreat from the coasts. My gut says we should be doing so now. Maritime civil engineering works on more massive scale than ever before will be required merely to maintain ports. Not to speak of huge civil engineering works rehousing the hapless coastal refugees. Or rising storm drainage. Or ...

sidd

sidd,

Thank you for your usual thoughtful reply, and I also agree with your prior comment that each individual's 'mileage may vary'; nevertheless, I make the following points about Team Schmidt's position:
1. Team Schmidt appears to recognized MISI (as apparently you do also) but not MICI (& you appear to be uncertain about the initiation date and the rate of ice sheet collapse).  In my opinion, David Pollard (with help from DeConto & Alley) has shown that MICI correlates best with the paleo-record than any other correlation used by Team Schmidt in their models.  So it appears to me that consensus science refuses to put their best foot forward and instead put forward confidence levels based only on MISI (which would be much different if they accepted MICI); which means that decision makers will likely make poor decisions about adaptive measures (like your major civil engineering measures) which will likely mean that the world will be worse off due to these poorly advised decisions.  Furthermore, MICI could be both abrupt (on the scale of decades beginning circa 2040+/- 10-years) and irreversible; so to me this gives the 12-year time frame better context than Team Schmidt's characterization of 'bullshit'.

2. If Hansen et al. are correct that the positive ice-climate feedback is composed of numerous sub-feedback mechanisms (including: bipolar seesaw, polar amplification, ENSO-interactions, telecommunications, etc.) each which may contribute individual tipping points to a combined global response.  Indeed, E3SM uses dynamical climate sensitivity to provide the world's most skillful climate projections (in my opinion much more skillful than those by Team Schmidt) to estimate a mean value of 5.3C for ECS (through 2100), which only considered MISI (and not MICI) in its ice-climate feedback.

Thus, I think that consensus climate scientists (like Team Schmidt and the IPCC) would do well to write annual reports addressing all of the strong climate science reported since AR5, that clarifies the 'long-tail' risks facing society; so that both the public and decision makers can better appreciate the consequences of accepting the incomplete confidence levels associated with consensus science climate projections.

ASLR
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #519 on: January 23, 2019, 07:22:50 PM »
With a hat-tip to jai (for the linked reference and image), Persad & Caldeira (2018) show that if (in the coming decades) anthropogenic aerosol emissions shift from such regions as: Western Europe), the USA and China to such areas as: India and its neighbors; then the negative feedback associated for those coming emissions will be less than assumed by 'many scientific and policy discussions'; which will would mean that the associated global warming would likely be higher than assumed by consensus climate science:

Persad & Caldeira (2018), "Divergent global-scale temperature effects from identical aerosols emitted in different regions", Nature Communications, https://doi.org/10.1038/s41467-018-05838-6

https://www.nature.com/articles/s41467-018-05838-6

With another hat-tip to jai Mitchell, the linked reference (& associate linked article) indicate that consensus climate science is underestimating the cooling effect of anthropogenic aerosols, which means that the climate sensitivity values assumed by consensus climate scientists are too low:

Daniel Rosenfeld, Yannian Zhu, Minghuai Wang, Youtong Zheng, Tom Goren, Shaocai Yu. Aerosol-driven droplet concentrations dominate coverage and water of oceanic low level clouds. Science, 2019; eaav0566 DOI: 10.1126/science.aav0566

http://science.sciencemag.org/content/early/2019/01/16/science.aav0566

Abstract: "Lack of reliable estimates of cloud condensation nuclei (CCN) aerosols over oceans has severely limited our ability to quantify their effects on cloud properties and extent of cooling by reflecting solar radiation – a key uncertainty in anthropogenic climate forcing. Here we introduce a methodology for ascribing cloud properties to CCN and isolating the aerosol effects from meteorological effects. Its application showed that, for a given meteorology, CCN explains 3/4 of the variability in clouds radiative cooling effect, mainly through affecting shallow cloud cover and water path. This reveals a much greater sensitivity of cloud radiative forcing to CCN than previously reported, which means too much cooling if incorporated in present climate models. This hints to yet unknown compensating aerosol warming effects, possibly through deep clouds."

See also:

Title: "We need to rethink everything we know about global warming"

https://www.sciencedaily.com/releases/2019/01/190122104611.htm

Extract: "New research shows that the degree to which aerosols cool the earth has been grossly underestimated, necessitating a recalculation of climate change models to more accurately predict the pace of global warming."

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #520 on: January 23, 2019, 09:52:34 PM »
"...the degree to which aerosols cool the earth has been grossly underestimated..."

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

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #521 on: January 23, 2019, 09:57:54 PM »
"...the degree to which aerosols cool the earth has been grossly underestimated..."

That sounds...rather bad!

Anthropogenic aerosol radiative forcing consists of both first indirect effect, FIE, and second indirect effect, SIE.  The linked reference indicates that FIE results in significantly more cooling than previously assumed by consensus climate science:

McCoy, D. T., F. A.-M. Bender, J. K. C. Mohrmann, D. L. Hartmann, R. Wood, and D. P. Grosvenor (2017), The global aerosol-cloud first indirect effect estimated using MODIS, MERRA, and AeroCom, J. Geophys. Res. Atmos., 122, doi:10.1002/2016JD026141.

https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2016JD026141

Abstract: "Aerosol-cloud interactions (ACI) represent a significant source of forcing uncertainty in global climate models (GCMs). Estimates of radiative forcing due to ACI in Fifth Assessment Report range from -0.5 to-2.5Wm-2. A portion of this uncertainty is related to the first indirect, or Twomey, effect whereby aerosols act as nuclei for cloud droplets to condense upon. At constant liquid water content this increases the number of cloud droplets (Nd) and thus increases the cloud albedo. In this study we use remote-sensing estimates of Nd within stratocumulus regions in combination with state-of-the-art aerosol reanalysis from Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA2) to diagnose how aerosols affect Nd. As in previous studies, Nd is related to sulfate mass through a power law relationship. The slope of the log-log relationship between Nd and SO4 in maritime stratocumulus is found to be 0.31, which is similar to the range of 0.2–0.8 from previous in situ studies and remote-sensing studies in the pristine Southern Ocean. Using preindustrial emissions models, the change in Nd between preindustrial and present day is estimated. Nd is inferred to have more than tripled in some regions. Cloud properties from Moderate Resolution Imaging Spectroradiometer (MODIS) are used to estimate the radiative forcing due to this change in Nd. The Twomey effect operating in isolation is estimated to create a radiative forcing of -0.97±0.23Wm-2 relative to the preindustrial era."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #522 on: January 23, 2019, 10:18:53 PM »
A citation for "Team Schmidt" stating anything about ice sheet collapse sans MICI would be nice ...? I find nothing in Dr. Schmidt's statements about this. IN fact, Bassis, Deconto and Pollard published after the deadline for the last IPCC report, so blaming IPCC for not including those results violates causality. If the next IPCC report ignores them, you might have a point. As for your suggestion that IPCC produce yearly reports, have you any idea what it takes to produce one of the AR reports ? Much longer than a year. If all scientists did was lit revieww and reports they would do nothing else.

Further, who is on "Team Schmidt" in the first place ?

I find characterizing people as members of "Teams" is unproductive.

As for my feeling about MICI : ofcourse it is happening, look at Jacobshawn. And I cannot say for sure, but Mercer's famous warning about the midsummer 0C isotherm applies not just to ice shelves, but to grounded ice also. But for now in Antarctica CDW incursion and bottom melt is far more important.

sidd


 

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #523 on: January 23, 2019, 11:19:01 PM »
A citation for "Team Schmidt" stating anything about ice sheet collapse sans MICI would be nice ...? I find nothing in Dr. Schmidt's statements about this. IN fact, Bassis, Deconto and Pollard published after the deadline for the last IPCC report, so blaming IPCC for not including those results violates causality. If the next IPCC report ignores them, you might have a point. As for your suggestion that IPCC produce yearly reports, have you any idea what it takes to produce one of the AR reports ? Much longer than a year. If all scientists did was lit revieww and reports they would do nothing else.

Further, who is on "Team Schmidt" in the first place ?

I find characterizing people as members of "Teams" is unproductive.

As for my feeling about MICI : ofcourse it is happening, look at Jacobshawn. And I cannot say for sure, but Mercer's famous warning about the midsummer 0C isotherm applies not just to ice shelves, but to grounded ice also. But for now in Antarctica CDW incursion and bottom melt is far more important.

sidd

sidd,

First, I used the term 'Team Schmidt' to connect to Schmidt's quotes in the article, but generally I meant contributors to CMIP5.  But as you seem to imply that it violates causality to discuss the limitations (shortcomings) of CMIP5 or AR5, I provide the following link to open access information on ISMIP6 which provides input into CMIP6 (which will figure prominently in AR6), and I note that the first attached image showing ice sheet models used in CMIP6, does not include any models that account for MICI:

Nowicki et al (2016), "Ice Sheet Model Intercomparison Project (ISMIP6) contribution to CMIP6", Geosci. Model Dev., 9, 4521-4545, https://doi.org/10.5194/gmd-9-4521-2016

https://www.geosci-model-dev.net/9/4521/2016/
&
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5911933/

Abstract: "Reducing the uncertainty in the past, present and future contribution of ice sheets to sea-level change requires a coordinated effort between the climate and glaciology communities. The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) is the primary activity within the Coupled Model Intercomparison Project – phase 6 (CMIP6) focusing on the Greenland and Antarctic Ice Sheets. In this paper, we describe the framework for ISMIP6 and its relationship to other activities within CMIP6. The ISMIP6 experimental design relies on CMIP6 climate models and includes, for the first time within CMIP, coupled ice sheet – climate models as well as standalone ice sheet models. To facilitate analysis of the multi-model ensemble and to generate a set of standard climate inputs for standalone ice sheet models, ISMIP6 defines a protocol for all variables related to ice sheets. ISMIP6 will provide a basis for investigating the feedbacks, impacts, and sea-level changes associated with dynamic ice sheets and for quantifying the uncertainty in ice-sheet-sourced global sea-level change."
 
Second, my suggestion was that consensus climate scientist not issue annual Assessment Reports, but rather only to annually discuss the more current estimates of the 'long-tail' risks (e.g. the impact of the greater cooling effects of aerosols on the most likely values of ECS) facing society (such as illustrated by the second and third images for AR5, but updated annually).

ASLR
« Last Edit: January 24, 2019, 04:08:45 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #524 on: January 24, 2019, 12:03:26 AM »
As in my last post I pointed to aerosols as one example of long-tailed risk within the guidance provided by such consensus science documents.  To get a better grip on what this might mean, given that research such as McCoy et al (2017) and Rosenfeld et al (2018), indicate that Fareo (Current aerosol radiative forcing) is likely much more negative than -1.0 Wm-2, I provide Figures 1 & 3 from Mauritsen & Pincus (2017).  Where Figure 1 shows observed values of TCR and ECS used in AR5 (also I provide the third image that shows how observed values of ECS relates to true values of ECS); and Figure 3 shows that for Fareo more negative than -1.0 Wm-2, that observed TCR is higher than assumed by AR5 (see note below), indicating that the Centennial committed warming will be higher than previously estimated:

Thorsten Mauritsen, Robert Pincus. Committed warming inferred from observations. Nature Climate Change, 2017; DOI: 10.1038/NCLIMATE3357

https://www.nature.com/articles/nclimate3357

Also, I note that for:
i) Equilibrium Climate Sensitivity (ECS)
The AR5 assesses ECS as likely to be 1.5°C to 4.5°C. ECS is extremely unlikely to be less than 1°C and very unlikely to be greater than 6°C.

This compares with the Fourth Assessment Report, which assessed ECS as likely to be 2 to 4.5°C.

ii) Transient Climate Response (TCR)
The AR5 assesses TCR as likely to be 1°C to 2.5°C and extremely unlikely to be greater than 3°C. In the Fourth Assessment Report, the assessed range of TCR was very unlikely to be less than 1.0°C and very unlikely to be greater than 3.0°C. The assessed ranges are therefore quoted differently, making direct comparison difficult, but compared with the previous report there has been a decrease in the assessed likelihood that the TCR is over 3.0°C from <10% to <5%.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #525 on: January 24, 2019, 04:19:32 PM »
The linked article (and following linked reference) indicates that the terrestrial biosphere currently absorbs about 25% of all anthropogenic carbon dioxide emissions, but that changes in moisture patterns, together with depletion of nitrogen & phosphorus from the soil, will likely change the terrestrial biosphere from a carbon sink to a carbon source in the second half of this century.  If so, this would likely put Earth on a road toward 'Hothouse' conditions:

Title: "Climate change’s impact on soil moisture could push land past ‘tipping point’"

https://www.carbonbrief.org/climate-changes-impact-on-soil-moisture-could-push-land-past-tipping-point

Extract: "The research, published in Nature, shows that levels of soil moisture – which are impacted by rising temperatures and extreme events such as droughts – can have a “large negative influence” on the land’s ability to store carbon.

It finds that the rate at which land absorbs carbon is likely to increase until the second half of this century as a result of the “CO2 fertilisation effect” – a phenomenon where increased CO2 levels in the atmosphere bolsters the growth and, therefore, carbon uptake of plants.

However, after this point, the fertilisation is expected to “reach a peak”, the lead author tells Carbon Brief. This peak – combined with the negative impact of soil moisture changes – could turn the land “from a carbon sink to a carbon source, greatly accelerating climate change”, she says.

The projected impact of climate change on the land carbon sink is an example of a “tipping point” – a positive feedback mechanism within the Earth’s system that could cause runaway climate change, Green says:

“Unfortunately, many of the climate changes that we are currently witnessing – such as the melting of ice sheets and permafrost – have feedbacks associated with them which can further accelerate global warming. It is very difficult to assess all of the feedbacks that are occurring. I would just stress that we need to start to curb our emissions now.”

However, the models used in study are likely to have “overestimated” the extent to which the CO2 fertilisation effect would boost land carbon uptake, she says. This is because the models do not consider how plant growth could be limited by a lack of essential nutrients, such as nitrogen and phosphorous. She tells Carbon Brief:

“This effect in the models is, in my opinion, strongly over-estimated. Of all the [four] models, only one considers nitrogen limitation – but they do not at all consider phosphorus limitation. This is very important in the tropics, which is where the researchers expect the CO2 fertilisation effect to be the strongest.

“I think if this were corrected, we would see a much stronger effect from soil moisture. The soil moisture feedback would be much stronger.”

This would mean that the rate at which land uptakes carbon could reach a peak before 2060, she notes."

See also:

Green, J. K. et al. (2019) Large influence of soil moisture on long-term terrestrial carbon uptake, Nature, https://doi.org/10.1038/s41586-018-0848-x

https://www.nature.com/articles/s41586-018-0848-x

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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #526 on: January 24, 2019, 05:31:00 PM »
The linked article indicates that the Barents Sea is near a tipping point to become an arm of the Atlantic Ocean possibly within a single decade.  This could be the first of a cascade of tipping points in the coming decades, that may lead the Earth towards 'Hothouse' conditions:

Title: "'Tipping point' risk for Arctic hotspot"

https://www.bbc.com/news/science-environment-46976040

Extract: " The Barents Sea is said to be at a tipping point, changing from an Arctic climate to an Atlantic climate as the water gets warmer.

So it’s now only a matter of time, the researchers say, before this section of the Arctic effectively becomes part of the Atlantic. It could happen in as little as a decade, they warn.

She said the shift was so rapid that the whole Barents Sea could be completely sea ice-free within a few decades - possibly even a decade. Then a new polar frontier region would probably develop further east, in the Kara Sea or Laptev Sea.

Dr Lind explained: “This is probably the first modern example of a rapid climate shift event - a part of the Arctic domain is shifting over to the Atlantic climate regime.

"This sort of shift happened in the Nordic Seas during the last Ice Age – and when it happened it changed very fast.

“This shows that the Arctic is responding to the one-degree of global warming that we have today by shrinking and losing its outer part to the Atlantic domain. That's alarming.""
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #527 on: January 24, 2019, 05:48:48 PM »
As I introduced ISMIP6 in Reply #523, and noted that it does not introduce MICI collapse mechanisms into the coming CMIP6 projections, I thought that I should provide the following Eyring et al (2016) reference which provides an introduction to CMIP6 including the two attached associated images of CMIP6 endorsed MIPs.  If you are interested in what each MIP does, or does not, address, you can simply Google the name of the MIP that interests you.  Furthermore, while some CMIP6 ESMs are more sophisticated than others, here I will note that I do not believe that any of the will do a sufficiently good enough job at setting initial model conditions to match current Earth System conditions (such as: the slowing of the AMOC/MOC, ice shelf degradation in the ASE, the state of the Barents Sea, the relatively high OHC, the true distribution of anthropogenic aerosol emissions in coming decades, etc.), to properly address our current risk of initiating a cascade of Earth System tipping points in the coming decades. 

Eyring, V., Bony, S., Meehl, G. A., Senior, C. A., Stevens, B., Stouffer, R. J., and Taylor, K. E.: Overview of the Coupled Model Intercomparison Project Phase 6 (CMIP6) experimental design and organization, Geosci. Model Dev., 9, 1937-1958, doi:10.5194/gmd-9-1937-2016, 2016.

https://www.geosci-model-dev.net/9/1937/2016/gmd-9-1937-2016.html

Abstract: " By coordinating the design and distribution of global climate model simulations of the past, current, and future climate, the Coupled Model Intercomparison Project (CMIP) has become one of the foundational elements of climate science. However, the need to address an ever-expanding range of scientific questions arising from more and more research communities has made it necessary to revise the organization of CMIP. After a long and wide community consultation, a new and more federated structure has been put in place. It consists of three major elements: (1) a handful of common experiments, the DECK (Diagnostic, Evaluation and Characterization of Klima) and CMIP historical simulations (1850–near present) that will maintain continuity and help document basic characteristics of models across different phases of CMIP; (2) common standards, coordination, infrastructure, and documentation that will facilitate the distribution of model outputs and the characterization of the model ensemble; and (3) an ensemble of CMIP-Endorsed Model Intercomparison Projects (MIPs) that will be specific to a particular phase of CMIP (now CMIP6) and that will build on the DECK and CMIP historical simulations to address a large range of specific questions and fill the scientific gaps of the previous CMIP phases. The DECK and CMIP historical simulations, together with the use of CMIP data standards, will be the entry cards for models participating in CMIP. Participation in CMIP6-Endorsed MIPs by individual modelling groups will be at their own discretion and will depend on their scientific interests and priorities. With the Grand Science Challenges of the World Climate Research Programme (WCRP) as its scientific backdrop, CMIP6 will address three broad questions:

– How does the Earth system respond to forcing?

– What are the origins and consequences of systematic model biases?

– How can we assess future climate changes given internal climate variability, predictability, and uncertainties in scenarios?

This CMIP6 overview paper presents the background and rationale for the new structure of CMIP, provides a detailed description of the DECK and CMIP6 historical simulations, and includes a brief introduction to the 21 CMIP6-Endorsed MIPs."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #528 on: January 24, 2019, 06:28:38 PM »
The linked article indicates that the Barents Sea is near a tipping point to become an arm of the Atlantic Ocean possibly within a single decade.  This could be the first of a cascade of tipping points in the coming decades, that may lead the Earth towards 'Hothouse' conditions:
The attached graphs show that the Barents Sea is already far more of a open water sea than an icy desert.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #529 on: January 24, 2019, 08:31:12 PM »
At the risk of over simplifying matters, I am concerned that when I mention a cascade of tipping points contributing to the composite ice-climate feedback mechanism that many people may imagine a cascade such as that shown in the first image.  However, due to the mutually reinforcing nature of most of the contributing feedback mechanisms an actual cascade of ice-climate feedback mechanism would look more like the domino wave shown in the second image, with a response amplitude operator looking something like that when moving from right to left, with time, in the third image.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #530 on: January 24, 2019, 11:53:01 PM »
As a brief follow-on to my last post about a potential ice-climate domino-wave feedback mechanism scenario, I provide the following points:

1. Special initial conditions that may contribute to a ice-climate domino wave include:
a) The oceans, and particularly the Southern Ocean, have accumulated unexpectedly high Ocean Heat Contents, OHCs, in recent decades;
b) The Beaufort Gyre has accumulated unexpectedly high amounts of both freshwater and OHC in recent decades;
c) The grounding lines for several key Greenland marine terminating glaciers (like Jakobshavn) have retreated to retrograde zones of the bedslope in recent years;
d) Key ice shelves in the Amundsen Sea Embayment, ASE, have degraded significantly in recent years, and this year the ice shelf in-front of the Southwest Tributary Glacier has disappeared entirely;

2. The following ice-climate feedback mechanisms are all primed to reinforce each other, via:
a) The bipolar seesaw mechanism ice mass loss from Greenland is promoting future ice mass loss from Antarctica;
b) Telecommunication of heat energy from the Tropical Pacific and Atlantic to both polar regions.
c) Increasing MICI.
d) Increasing polar amplification.
e) Continued slowing of the MOC.
f) Telecommunication of heat energy from the Tropical Atlantic to the Pacific Basin.
g) The terrestrial biosphere will degrade with continuing climate change.
h) The permafrost will degrade with continuing climate change.
i) The ocean's ability to absorb carbon will degrade with continuing climate change.
j) Methane hydrates will degrade with continuing climate change.
k) The Hadley atmospheric cell will continue to expand poleward with continued climate change.

3. Assuming:
a) BAU radiative forcing through at least 2030.
b) Anthropogenic radiative forcing is more negative than assumed by AR5 (which implies that ECS is also higher than assumed by AR5).
c) Deforestation (& forest degradation) will continue with continuing climate change.
d) Climate sensitivity increases with continued warming.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #531 on: January 26, 2019, 04:06:39 AM »
I suspect that it is worthwhile to provide more context to the SSP radiative forcing scenarios shown in the first image (with the baselines for the five scenarios shown in heavy solid lines) and to provide this context I provide the second image from the linked reference cited below.

Title: "Well Under 2 Degrees Celsius: Fast Action Policies to Protect People and the Planet from Extreme Climate Change"

http://www.igsd.org/wp-content/uploads/2017/09/Well-Under-2-Degrees-Celsius-Report-2017.pdf

Caption for the second image: "Figure 1: Projected warming for 4 different scenarios from pre-industrial to 2100 as adopted from Xu and Ramanathan (2017). The warming is given in terms of probability distribution instead of a single value, because of uncertainties in climate feedbacks, which could make the warming larger or smaller than the central value shown by the peak probability density value. The three curves on the right side indicated by BL (for baseline), denote projected warming in the absence of climate policies. The BL (CI-80%) is for the scenario for which the energy intensity (the ratio of energy use to economic output) of the economy decreases by 80% compared with its value for 2010. For the BL (CI-50%), the energy intensity decreases by only 50%. These scenarios bound the energy growth scenarios considered by IPCC–WGIII (2014). The right extreme curve, BL (CI-50% & C feedback), includes the carbon cycle feedback due to the warming caused by the BL (CI-50%) case. The carbon cycle feedback adopts IPCC recommended values for the reduction in CO2 uptake by the oceans as a result of the warming; the release of CO2 by melting permafrost; and the release of methane by wetlands.

The green curve adopts the 4 building blocks and the 3 levers proposed in this report. There are four mitigation steps:

1. Improve the energy efficiency and decrease the energy intensity of the economy by as much as 80% from its 2010 value. This step alone will decrease the warming by 0.9ºC (1.6ºF) by 2100.

2. Bend the Carbon emission curve further by switching to renewables before 2030 and achieving carbon neutrality in 3 decades. This step will decrease the warming by 1.5ºC (2.7ºF) by 2100.

3. Bend the Short-Lived Climate Pollutants curve, beginning 2020, following the actions California has demonstrated. This step will decrease the warming by as much as 1.2ºC (2.2ºF) by 2100.

4. In addition, extract as much as 1 trillion tons (about half of what we have emitted so far) from the atmosphere by 2100. This step will decrease the warming by as much as 0.3ºC to 0.6ºC (0.5ºF to 1ºF).

The 50% probable warming for the 4 scenarios are respectively from left to right: 1.4ºC (2.5ºF); 4.1ºC (7.4ºF); 5ºC (9ºF); 5.8ºC (10.4ºF). There is a 5% probability, the warming for the 4 scenarios can exceed respectively (left to right): 2.2ºC (4ºF); 5.9ºC (10.6ºF); 6.8ºC (12.2ºF); 7.7ºC (14ºF).

The risk categories shown at the top largely follow Xu and Ramanathan (2017) with slight modifications. Following IPCC and Xu and Ramanathan (2017), we denote warming in excess of 1.5°C as Dangerous. Following the burning embers diagram of IPCC as updated by Oneill et al. (2017), warming in excess of 3°C is denoted as Catastrophic. We invoke recent literature on health effects of warming >4°C, impacts on mass extinction of warming >5°C and projected collapse of natural systems for warming in excess of 3°C, to denote warming >5°C as exposing the global population to Existential threats."

See also:

Title: "New Climate Risk Classification Created to Account for Potential “Existential” Threats"

https://scripps.ucsd.edu/news/new-climate-risk-classification-created-account-potential-existential-threats

Extract: "“When we say 5 percent-probability high-impact event, people may dismiss it as small but it is equivalent to a one-in-20 chance the plane you are about to board will crash,” said Ramanathan. “We would never get on that plane with a one-in-20 chance of it coming down but we are willing to send our children and grandchildren on that plane.”"

This second image shows an assumed GMSTA probability distribution this century similar to the IPCC's aspirational goal of limiting GMSTA to 1.5C this century on the left-hand side with a green colored curve (labelled 4 blocks + 3 Levers) with a mean GMSTA of 1.4C. The next curve to the right in red (labelled BL Cl-80%) with a mean GMSTA of 4.1C (by 2100) is essentially the baseline for SSP3.  The next curve to the right in solid charcoal (labelled BL Cl-50%) with a mean GMSTA of 5.0C (by 2100) is essentially the baseline for SSP5. The dashed charcoal curve on the right-hand side (labelled BL Cl-50% & Carbon feedbacks) is essentially the PDF for 2100 from putting SSP5 baseline into a consensus science ESM (with a mean GMSTA in 2100 of 5.8C).

However, I emphasis here that consensus science ESMs (like those in CMIP5) contain almost no input from ice-climate feedback mechanisms; which would be like leaving out one to several of the feedback PDFs shown in the third attached image.  Finally, I provide the fourth image where the curve labelled 'Frequency' looks like the green 1.4C PDF in the second image and the curve labelled 'Magnitude' looks like a typical climate change consequence curve with increasing warming, and the curve labelled 'Work' looks like a typical climate change risk curve which illustrates the strong influence of the 'long-tail' of a typical policy climate change PDF (such as for a 1.4C GMSTA).  Now, I emphasis that climate change PDF for BL Cl-50% & Carbon feedbacks curve (or SSP5 baseline) has a very fat long-tail, which means that its climate risks will be very high, and a climate change PDF for SSP5 baseline projected by an ESMs including all of Hansen's ice-climate feedback mechanisms would have extremely high climate change risks by 2100 (probably leading to hothouse conditions).

Edit: The second linked article (see above) explains that they characterize climate risks with words like dangerous, catastrophic and existential; and by emotive shading because: "Risk assessments of global temperature rise greater than 5°C have not been undertaken by the IPCC." and "The researchers defined the risk categories based on guidelines established by the Intergovernmental Panel on Climate Change (IPCC) and previous independent studies. “Dangerous” global warming includes consequences such as increased risk of extreme weather and climate events ranging from more intense heat waves, hurricanes, and floods, to prolonged droughts. Planetary warming between 3°C and 5°C could trigger what scientists term “tipping points” such as the collapse of the West Antarctic Ice Sheet and subsequent global sea-level rise, and the dieback of the Amazon rainforest. In human systems, catastrophic climate change is marked by deadly heat waves becoming commonplace, exposing over 7 billion people to heat related mortalities and famine becoming widespread. Furthermore, the changes will be too rapid for most to adapt to, particularly the less affluent, said Ramanathan."
« Last Edit: January 26, 2019, 03:10:41 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #532 on: January 26, 2019, 03:00:48 PM »
For those who still do not understand how tropical oceanic energy, via evaporated water into the atmosphere, is telecommunicated (within weeks to months) poleward, the linked reference adds information about the telecommunication of tropical energy from the Equatorial Pacific to West Antarctica (the image shows a pattern of atmospheric Rossby wave train from the Nino 3 area to West Antarctica), where this energy can contribute to ice mass loss from the WAIS:

Chris S. M. Turney et al. (2017), "Tropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperature reconstruction", Clim. Past, 13, 231-248, https://doi.org/10.5194/cp-13-231-2017

https://www.clim-past.net/13/231/2017/cp-13-231-2017-discussion.html

Abstract: "Occupying about 14% of the world’s surface, the Southern Ocean plays a fundamental role in ocean and atmosphere circulation, carbon cycling and Antarctic ice-sheet dynamics. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine–atmosphere–ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with ocean and atmospheric observations on southwest Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52–54 degrees S). Our annually resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the 1940s, a phenomenon predating the observational record. Climate reanalysis and modelling show a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the Southern Hemisphere during the austral spring and summer. Our results suggest that modern observed high interannual variability was established across the mid-twentieth century, and that the influence of contemporary equatorial Pacific temperatures may now be a permanent feature across the mid- to high latitudes."

Caption for the image: "Figure 6. Rossby wave propagation from the tropical Pacific during the austral spring–summer. Low-to-high-latitude atmospheric teleconnections during the austral spring and summer (October–March). Schematic showing extratropical Pacific–South America (PSA) Rossby wave train (red arrows) associated with low- and high-pressure systems generated by anomalous equatorial upper-level divergence flow (Trenberth et al., 1998); enhanced southerly airflow across the West Antarctic coastline extends into the South Atlantic during anomalously high temperatures in the Nino 3 region (a). Spatial correlations between detrended and deseasonalised Nino 3 sea surface temperature (Rayner et al., 2003) (October–March) and 850 hPa height (b) and zonal wind stress (c) using ERA-Interim (Dee et al., 2011) for the period 1979–2015. Location of key sites are shown. Significance pfield < 0:05."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #533 on: January 26, 2019, 03:18:24 PM »
The linked article discusses how the ENSO cycle impacts on Antarctic Pacific Sector ice shelves.  Thus with the frequency of extreme El Nino events predicted to increase with global warming, we can expect the Antarctic Pacific Sector ice shelves to degrade (due both to enhanced basal ice melting and water accumulation in the firn associated with the projected increased snowfall) more rapidly in the coming decades:

Title: "El Niño causes West Antarctica’s ice shelves to gain height yet lose mass"

https://www.carbonbrief.org/el-nino-causes-west-antarcticas-ice-shelves-gain-height-yet-lose-mass

Extract: "El Niño events are known for bringing floods to South America and contributing to wildfires in Indonesia, but new research reveals they also affect the height and mass of ice shelves in Antarctica.

During an El Niño event, many of the ice shelves around West Antarctica receive more snow on their surface, but also lose more ice from underneath because of warm ocean water.
Overall, the ice shelves actually lose mass during an El Niño, the research finds, making such events an important factor in the year-to-year fluctuations of ice shelf size.
With more “extreme” El Niño events expected as global temperatures rise, West Antarctica’s ice shelves could see larger fluctuations in height and mass, …"

See also:

Paolo et al (2018), "Response of the Pacific-sector Antarctic ice shelves to the El Nino/Southern Oscillation", Nature Geoscience, doi:1038/s41561-017-0033-0

http://www.nature.com/articles/s41561-017-0033-0
&
http://www.nature.com/articles/s41561-017-0033-0.epdf?referrer_access_token=q9RDK3fDMFVTf8SOvsqtDtRgN0jAjWel9jnR3ZoTv0NkbfdogOpJdXh63nd-byA7uSU-nq2NafOwTW6ZvjE8jHg7PHoxQZIwAlcr2Is7Csb5bVcTu9jaWsBXhjsk1URR_BKmbokI_486RX5YhjTwOkunxnod-j-Y8fE1iTOQyxBl7PNIru2LAxGi4Jn2Pll4yazPQeva6laVort7VIHha26oHO8jIC-NxfMr-wUj9zg%3D&tracking_referrer=www.bbc.com

And see:

http://www.bbc.com/news/science-environment-42614412
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #534 on: January 26, 2019, 03:47:56 PM »
In my last post, I provided some evidence that the projected increase in El Nino frequency (with continued warming) will serve to accelerate the collapse of ice shelves in the Antarctic Pacific Sector, and particularly in the Amundsen Sea Embayment, ASE, where the Pine Island, and Thwaites, marine glaciers adjoin.  However, most CMIP5 & CMIP6 models do not fully account for this accelerated loss of key ice shelves, nor to do these models consider the fact that after such key ice shelves are lost, then the accelerated coastal snowfall will increase the gravity force that drives ice cliff failures, to the extent that the 'ice plug' that consensus climate scientist believe would slow the grounding line retreat to the retrograde bedslope in the Thwaites Glacier gateway, may itself be subject to MICI failures rather than just MISI failures.  If so this would accelerate the timeframe for the collapse of the WAIS.

As even Pollard, DeConto and Alley do not consider the gravity forcing of additional snowfall on the gateways of the key ASE marine glaciers; I provide the following linked reference that considers the collapse of the Hudson Strait Ice Stream (within the paleo Laurentide Ice Sheet see the first image), as a rough physical model of the potential collapse of the 'ice plug' in the Thwaites Gateway (i.e. before the grounding line reaches the retrograde bedslope).  The second image shows that immediately after the loss of the ice shelf for the Hudson Strait Ice Steam [see also third image from Alvarez-Solas et al. (2012)], the ice loss surged (even though the water depths are comparable to those in the Thwaites Gateway).  Thus consensus climate scientists may well be surprised at how quickly the 'ice plug' for the Thwaites Gateway degrades:


Ziemen, F. A., Kapsch, M.-L., Klockmann, M., and Mikolajewicz, U.: Heinrich events show two-stage climate response in transient glacial simulations, Clim. Past, 15, 153-168, https://doi.org/10.5194/cp-15-153-2019, 2019.

https://www.clim-past.net/15/153/2019/

Abstract. Heinrich events are among the dominant modes of glacial climate variability. During these events, massive iceberg armadas were released by the Laurentide Ice Sheet and sailed across the Atlantic where they melted and released freshwater, as well as detritus, that formed characteristic layers on the seafloor. Heinrich events are known for cold climates in the North Atlantic region and global climate changes. We study these events in a fully coupled complex ice sheet–climate model with synchronous coupling between ice sheets and oceans. The ice discharges occur as an internal variability of the model with a recurrence period of 5kyr, an event duration of 1–1.5kyr, and a peak discharge rate of about 50mSv, roughly consistent with reconstructions. The climate response shows a two-stage behavior, with freshwater release effects dominating the surge phase and ice sheet elevation effects dominating the post-surge phase. As a direct response to the freshwater discharge during the surge phase, deepwater formation in the North Atlantic decreases and the North Atlantic deepwater cell weakens by 3.5Sv. With the reduced oceanic heat transport, the surface temperatures across the North Atlantic decrease, and the associated reduction in evaporation causes a drying in Europe. The ice discharge lowers the surface elevation in the Hudson Bay area and thus leads to increased precipitation and accelerated ice sheet regrowth in the post-surge phase. Furthermore, the jet stream widens to the north, which contributes to a weakening of the subpolar gyre and a continued cooling over Europe even after the ice discharge. This two-stage behavior can explain previously contradicting model results and understandings of Heinrich events.

Edit: For ease of comparison of the Hudson Strait Ice Stream Gateway profile (third image) to that of the Thwaites Glacier Gateway, I provide the fourth image of a cross-section through the most critical portion of the Thwaites Gateway.
« Last Edit: January 26, 2019, 04:12:46 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #535 on: January 26, 2019, 04:24:05 PM »
For those who still do not understand how tropical oceanic energy, via evaporated water into the atmosphere, is telecommunicated (within weeks to months) poleward.......

Ooooh....me, me, me.....

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #536 on: January 27, 2019, 06:06:08 PM »
For those who want to know more about the International Thwaites Glacier Collaboration's field investigation program, I provide the following linked website and the associated attached image:

Title: "The International Thwaites Glacier Collaboration"

https://thwaitesglacier.org/projects

Extract: "Disintegration of Marine Ice-sheets Using Novel Optimised Simulations
Acronym/nickname
DOMINOS

 Projected rates of sea level rise from the West Antarctic Ice Sheet (and Thwaites Glacier in particular) have large uncertainties due to difficulties in understanding and projecting the calving and dynamic processes that control the ice sheet stability. This uncertainty is magnified by the poorly understood connection between calving processes, ice sheet stability and climate. To address these uncertainties, our proposal seeks to explicitly resolve the processes that could cause retreat and collapse of Thwaites Glacier using a novel ice-dynamics model suite. This model suite includes a discrete element model capable of simulating coupled fracture and ice-flow processes, a 3D full Stokes continuum model, and the continental scale ice-dynamics model BISICLES. Ice dynamics models will be coupled to an ocean forcing model suite including simple plume models, intermediate complexity 2-layer ocean models and fully 3D regional ocean models. This hierarchical approach will use high-fidelity process models to inform and constrain the sequence of lower-order models needed to extrapolate improved understanding to larger scales and has the potential to radically reduce uncertainty of rates of marine ice sheet collapse and associated sea level rise. The large-scale modeling approach will be tested and implemented within the open source BISICLES ice dynamics model and made publicly available to other researchers via a “calving package.”

The Thwaites Glacier Collaboration is about more than just 5-years of field work (beginning January 2019) of just that one glacier, but essentially the stability of all adjoining ice basins.  As the researcher recently off-loaded 600 tonnes of supplies on the Stange Ice Shelf, I provide the first image from the first linked (open access) reference which cites research on four decades of marine glacier grounding line retreat in the Bellingshausen margin.  This region contributes significantly to the instability of the WAIS:

Frazer D.W. Christie, Robert G. Bingham, Noel Gourmelen, Simon F.B. Tett & Atsuhiro Muto (22 May 2016), "Four-decade record of pervasive grounding line retreat along the Bellingshausen margin of West Antarctica", Geophysical Research Letters, DOI: 10.1002/2016GL068972


http://onlinelibrary.wiley.com/doi/10.1002/2016GL068972/abstract

Abstract: "Changes to the grounding line, where grounded ice starts to float, can be used as a remotely-sensed measure of ice-sheet susceptibility to ocean-forced dynamic thinning. Constraining this susceptibility is vital for predicting Antarctica's contribution to rising sea levels. We use Landsat imagery to monitor grounding line movement over four decades along the Bellingshausen margin of West Antarctica, an area little monitored despite potential for future ice losses. We show that ~65% of the grounding line retreated from 1990-2015, with pervasive and accelerating retreat in regions of fast ice flow and/or thinning ice shelves. Venable Ice Shelf confounds expectations in that despite extensive thinning, its grounding line has undergone negligible retreat. We present evidence that the ice shelf is currently pinned to a sub-ice topographic high which, if breached, could facilitate ice retreat into a significant inland basin, analogous to nearby Pine Island Glacier."

See also:
http://www.climatecentral.org/news/overlooked-area-antarctica-major-ice-loss-20408
Extract: "During a 2009-2010 field mission, Bingham looked to shed more light on the region by scanning the ground below one of the fastest-moving Bellingshausen glaciers, the Ferrigno Ice Stream. He found a huge canyon underneath that is likely funneling warm ocean water under the ice.
“This only served to highlight to me that there is so much about the Bellingshausen Sea sector of West Antarctica that has gone unmonitored while most of the world's eyes (glaciologically speaking) were looking beyond to Pine Island Glacier,” Bingham said.
To get a better picture of the overall ice loss in the area, Bingham and his Ph.D. student Frazer Christie, analyzed hundreds of satellite images of the area going back to 1975 and tracked the position of the grounding line along 1,240 miles of coast.
They found that 65 percent of the coastline had seen grounding line retreat since 1990, while only 7 percent had seen an advance. The total amount of ice lost over the last 40 years is about 390 square miles, an area about the size of Dallas.
The results “show that this whole coastline has been in a state of retreat since records began in the early 1970s,” Bingham said. That contrasts with previous thinking that only certain glaciers, like the Ferrigno Ice Stream, were seeing significant ice loss while the rest were fairly stable.
“The study illustrates that Antarctica is not immune to changes and that some of what we are seeing today started decades ago,” Eric Rignot, a NASA glaciologist who was not involved with the work, said in an email.
One notable oddity was the Venable Ice Shelf, which has thinned, but hasn’t retreated much. The researchers think it is pinned to a ridge on the seafloor that is keeping it stable for now. Scientists think the same was true of Pine Island Glacier — for a while.
Exactly what the pervasive ice loss in the Bellingshausen Sea area means for future global sea level rise isn’t entirely clear, in part because of the paucity of data from the area. Bingham says that researchers need a better idea of the topography underlying the ice so they can better model how it will change in the future."

The second attached image shows the ice mass loss per the Grace Satellite into 2017, which confirms that ice mass loss from marine glaciers around the Bellingshausen Sea margin is proceeding at a rate only somewhat slower than from the ASE:

Jonathan L Bamber et al 2018 Environ. Res. Lett. 13 063008

https://iopscience.iop.org/article/10.1088/1748-9326/aac2f0/pdf

Abstract: "Since 1992, there has been a revolution in our ability to quantify the land ice contribution to sea level rise using a variety of satellite missions and technologies. Each mission has provided unique, but sometimes conflicting, insights into the mass trends of land ice. Over the last decade, over fifty estimates of land ice trends have been published, providing a confusing and often inconsistent picture. The IPCC Fifth Assessment Report (AR5) attempted to synthesise estimates published up to early 2013. Since then, considerable advances have been made in understanding the origin of the inconsistencies, reducing uncertainties in estimates and extending time series. We assess and synthesise results published, primarily, since the AR5, to produce a consistent estimate of land ice mass trends during the satellite era (1992–2016).We combine observations from multiple missions and approaches including sea level budget analyses. Our resulting synthesis is both consistent and rigorous, drawing on (i) the published literature, (ii) expert assessment of that literature, and (iii) a new analysis of Arctic glacier and ice cap trends combined with statistical modelling.

We present annual and pentad (five-year mean) time series for the East, West Antarctic and Greenland Ice Sheets and glaciers separately and combined. When averaged over pentads, covering the entire period considered, we obtain a monotonic trend in mass contribution to the oceans, increasing from 0.31±0.35mm of sea level equivalent for 1992–1996to 1.85±0.13 for 2012–2016. Our integrated land ice trend is lower than many estimates of GRACE-derived ocean mass change for the same periods. This is due, in part, to a smaller estimate for glacier and ice cap mass trends compared to previous assessments. We discuss this, and other likely reasons, for the difference between GRACE ocean mass and land ice trends."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #537 on: January 27, 2019, 06:08:33 PM »
For those who still do not understand how tropical oceanic energy, via evaporated water into the atmosphere, is telecommunicated (within weeks to months) poleward.......

Ooooh....me, me, me.....

SH,

Feel free to ask questions, as everyone knows that long-tail climate change is a complex and somewhat confusing topic.

ASLR
« Last Edit: January 27, 2019, 06:37:39 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #538 on: January 27, 2019, 07:49:47 PM »
For those who still do not understand how tropical oceanic energy, via evaporated water into the atmosphere, is telecommunicated (within weeks to months) poleward.......

Ooooh....me, me, me.....

SH,

Feel free to ask questions, as everyone knows that long-tail climate change is a complex and somewhat confusing topic.

ASLR

ASLR,

I rarely comment on these types of threads but want you to know I visit them daily. I suspect there are many others who do the same.

Thank you.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #539 on: January 27, 2019, 08:59:37 PM »
ASLR,

I just want to "join" Shared Humanity in saying that your contributions in this thread are very valuable and necessary. I thank you for your daily effort of informing us about the latest results of peer-reviewed science.

Stephan

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #540 on: January 27, 2019, 09:31:37 PM »
Echoing the previous 2 comments, at risk of creating a "too long" off-topic comment chain.

These are the type of threads & information I come here for. I love it, thanks.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #541 on: January 27, 2019, 11:09:12 PM »
SH, Stephan, HapHazard,

Thank you for the thoughtful words.  So in the way of general education, I note that Pollard & DeConto (2016) estimates that Totten Glacier is the most susceptible for of the Antarctic Ice Sheet, AIS, to collapse after the WAIS glaciers, so I note that the linked reference helps to quantify the recent ice mass loss of the Totten and Moscow University Glaciers:

Yara Mohajerani et al. (25 July 2018), "Mass Loss of Totten and Moscow University Glaciers, East Antarctica, Using Regionally Optimized GRACE Mascons", Geophysical Research Letters, https://doi.org/10.1029/2018GL078173

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL078173

Abstract: "Totten and Moscow University glaciers, in the marine‐based sector of East Antarctica, contain enough ice to raise sea level by 5 m. Obtaining precise measurements of their mass balance is challenging owing to large area of the basins and the small mass balance signal compared to West Antarctic glaciers. Here we employ a locally optimized processing of Gravity Recovery and Climate Experiment (GRACE) harmonics to evaluate their mass balance at the sub‐basin scale and compare the results with mass budget method (MBM) estimates using regional atmospheric climate model version 2.3 (RACMO2.3) or Modèle Atmosphérique Régional version 3.6.4 (MAR3.6.4). The sub‐basin mass loss estimate for April 2002 to November 2015 is 14.8 ± 4.3 Gt/yr, which is weakly affected by glacial isostatic adjustment uncertainties (±1.4 Gt/yr). This result agrees with MBM/RACMO2.3 (15.8 ± 2.0 Gt/yr), whereas MBM/MAR3.6.4 underestimates the loss (6.6 ± 1.6 Gt/yr). For the entire drainage, the mass loss for April 2002 to August 2016 is 18.5 ± 6.6 Gt/yr, or 15 ± 4% of its ice flux. These results provide unequivocal evidence for mass loss in this East Antarctic sector."

Edit:  In the attached image from DeConto & Pollard (2016), the 'T' stands for Totten.  Also, note that the timescale on the image assumes a consensus science climate model, thus it is possible (probable) that the indicated dates are conservative.
« Last Edit: January 28, 2019, 04:36:34 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #542 on: January 28, 2019, 04:29:33 PM »
As an indication of how concerned climate scientists are about the stability of the WAIS (and the Antarctic Peninsula), I provide the following two linked news articles from the British Antarctic Survey website"

Title: "Scientists drill to record depths in West Antarctica", 24 January, 2019 Press releases

https://www.bas.ac.uk/media-post/scientists-drill-to-record-depths-in-west-antarctica/

Extract: "A team of scientists and engineers has for the first time successfully drilled over two kilometres through the ice sheet in West Antarctica using hot water. This research will help understand how the region will respond to a warming climate.

The 11-person team has been working on the Rutford Ice Stream for the last 12 weeks in freezing temperatures at low as minus 30 degrees Celsius. On Tuesday 8 January, following a 63 hour continuous round-the-clock drilling operation, the team broke through to the sediment 2152 metres below the surface.

The team has now drilled two holes (with the second completed on 22 January) and plan to be working on the ice until mid-February 2018. Further work will now continue at a second site a few kilometres away."

See also:

Title: "BEAMISH: Bed Access, Monitoring and Ice Sheet History"

https://www.bas.ac.uk/project/bed-access-monitoring-and-ice-sheet-history-beamish/

Extract: "BEAMISH: Basal conditions on Rutford Ice Stream: Bed Access, Monitoring and Ice Sheet History"
&

Title: "International research expedition heads to West Antarctica

https://www.bas.ac.uk/media-post/international-research-expedition-heads-to-west-antarctica/

Extract: "An international team of scientists is travelling to the Amundsen Sea – one of the most vulnerable sectors of the Antarctic Ice Sheet – to answer vital scientific questions about the history of the West Antarctic Ice Sheet (WAIS).

As part of the International Ocean Discovery Program (IODP), researchers will spend 8 weeks working on board the JOIDES Resolution – a scientific drill ship. During the research cruise, the multinational team aim to recover sediment cores from the seabed on the fringes of the continent. These will be the first drill cores deeper than 35 metres obtained in the region, with target depths ranging from 700 to 1200 metres."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #543 on: January 28, 2019, 05:37:55 PM »
The linked reference (and following article) indicate that the AMOC has slowed by about 15% since the mid-20th century and is at its slowest rate in at least 1,500 years and may be partially due to both anthropogenic global warming and freshwater input into the North Atlantic for ice melt.  This confirms a key part of the ice-climate feedback mechanism, and will lead to continued warming of SST in tropical regions in both the Atlantic and Pacific oceans:

Benoit Thibodeau et al. (2018), "Last Century Warming Over the Canadian Atlantic Shelves Linked to Weak Atlantic Meridional Overturning Circulation", Geophysical Research Letters, https://doi.org/10.1029/2018GL080083

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL080083

Abstract
The Atlantic meridional overturning circulation (AMOC) is a key component of the global climate system. Recent studies suggested a twentieth‐century weakening of the AMOC of unprecedented amplitude (~15%) over the last millennium. Here we present a record of δ18O in benthic foraminifera from sediment cores retrieved from the Laurentian Channel and demonstrate that the δ18O trend is linked to the strength of the AMOC. In this 100‐year record, the AMOC signal decreased steadily to reach its minimum value in the late 1970s, where the weakest AMOC signal then remains constant until 2000. We also present a longer δ18O record of 1,500 years and highlight the uniqueness of the last century δ18O trend. Moreover, the Little Ice Age period is characterized by statistically heavier δ18O, suggesting a relatively weak AMOC. Implications for understanding the mechanisms driving the intensity of AMOC under global warming and high‐latitude freshwater input are discussed.

Plain Language Summary
Oceanic circulation in the North Atlantic transports huge amounts of water, heat, salt, carbon, and nutrients around the globe. As such, changes in the strength of oceanic currents can yield profound changes in both North American and European climate, in addition to affecting the African and Indian summer monsoon rainfall. In this study, we used geochemical evidence to highlight a slowdown in the North Atlantic Ocean circulation over the last century. This change appears to be unique over the last 1,500 years and could be related to global warming and freshwater input from ice sheet melt. Based on our data, we also suggest that the period often called “The Little Ice Age” was characterized by a slowdown, of less amplitude than the modern weakening, in the North Atlantic Ocean circulation. Thus, our results contribute to ongoing investigations of the state of the circulation in the North Atlantic by providing a robust reconstruction of its variability over the last 1,500 years.

See also:

Title: "What the 2018 climate assessments say about the Gulf Stream System slowdown"

http://www.realclimate.org/index.php/archives/2019/01/what-the-2018-climate-assessments-say-about-the-gulf-stream-system-slowdown/#more-22250

Extract: "In December also a new study – too late to be included in the assessments – was published by Thibodeau et al in Geophysical Research Letters, which further supports an unprecedented AMOC weakening during the past decades. The authors write:

In this study, we used geochemical evidence to highlight a slowdown in the North Atlantic Ocean circulation over the last century. This change appears to be unique over the last 1,500 years and could be related to global warming and freshwater input from ice sheet melt."

First of all, while we don’t have regular direct measurements of the AMOC going back throughout the 20th Century, indirect evidence for an AMOC slowdown is not new. Dima and Lohmann already concluded in 2010 that “the conveyor has been slowing down over the last seven decades” (where ‘conveyor’ refers to the AMOC).

Strangely, this finding was not discussed at all in the fifth IPCC report published in 2013. Therefore, the IPCC now finding that an ongoing slowdown is “more likely than not” is progress, yet still a very cautious statement. Likewise the statement about the “limited evidence” for the slowdown being human-caused is also very cautious. Why do I find this overly cautious?

In fact, the strength of this pattern and the conclusion that it corresponds to a 15% AMOC slowdown just matches the median slowdown found in the historic climate runs of the CMIP5 climate models – in other words, it is exactly what the models predict as a response to human-caused climate change. In addition, there are several independent data sets that show this slowdown to be unprecedented for at least a millennium."
« Last Edit: January 28, 2019, 08:56:06 PM by AbruptSLR »
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uniquorn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #544 on: January 29, 2019, 07:24:28 PM »
AbruptSLR, as someone familiar with scientific papers and articles, could you point me in the direction of 3 or 4 free to view papers that might indicate why the Lincoln Sea/Nares is so late to freeze during recent years?
Sorry to be off topic.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #545 on: January 29, 2019, 10:40:30 PM »
Sometimes, it seems to me that it must be convenient (as in the context of: 'An Inconvenient Truth') to espouse consensus climate science, as, for instance, it allows one to:
1. Assume any radiative pathway from SSP1 to SSP5-baseline, without estimating a most likely pathway.
2. Assume that merely advising society to stay 'well below' a GMSTA of 2C, while being as close to 1.5C as practicable, is sufficient warning to society about climate risk; without adequately discussing long-tail climate risks.
3. Assume the use of TCR, instead of ECS, when calculating our collective carbon budget, because society has been sufficiently warning about climate risk to assume climate change will be capped quickly.

In this regards, I noted the per the linked reference the rise in China's methane emissions (largely from increased coal mining) from 2010 to 2015, alone accounted for roughly one quarter of the global increase in methane emissions during this period; which indicates that China's associated policy measures to control methane emissions in this period were ineffective.  Thus it appears likely that carbon emissions will remain close to the BAU pathway for at least the next fifteen, to twenty, years; by which time the WAIS may be experiencing the initial phases of MICI collapse:

Miller, S. M., Michalak, A. M., Detmers, R. G., Hasekamp, O. P., Bruhwiler, L. M. P., & Schwietzke, S. (2019). China’s coal mine methane regulations have not curbed growing emissions. Nature Communications, 10(1). doi:10.1038/s41467-018-07891-7

https://www.nature.com/articles/s41467-018-07891-7

Abstract: "Anthropogenic methane emissions from China are likely greater than in any other country in the world. The largest fraction of China’s anthropogenic emissions is attributable to coal mining, but these emissions may be changing; China enacted a suite of regulations for coal mine methane (CMM) drainage and utilization that came into full effect in 2010. Here, we use methane observations from the GOSAT satellite to evaluate recent trends in total anthropogenic and natural emissions from Asia with a particular focus on China. We find that emissions from China rose by 1.1±0.4TgCH4 yr−1 from 2010 to 2015, culminating in total anthropogenic and natural emissions of 61.5±2.7TgCH4 in 2015. The observed trend is consistent with pre-2010 trends and is largely attributable to coal mining. These results indicate that China’s CMM regulations have had no discernible impact on the continued increase in Chinese methane emissions."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #546 on: January 29, 2019, 11:05:56 PM »
AbruptSLR, as someone familiar with scientific papers and articles, could you point me in the direction of 3 or 4 free to view papers that might indicate why the Lincoln Sea/Nares is so late to freeze during recent years?
Sorry to be off topic.

uniquorn,

I really do not know why in recent years the Nares sea ice has been so late to freeze, but the following three references might (or might not) provide clues.  You can get the first reference from; Science Hub:

https://sci-hub.tw/

1)  Moore & McNeil (2018), "The Early Collapse of the 2017 Lincoln Sea Ice Arch in Response to Anomalous Sea Ice and Wind Forcing", Geophysical Research Letters, https://doi.org/10.1029/2018GL078428

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078428


2) Korosov et al. (2018), "A new tracking algorithm for sea ice age distribution estimation", The Cryosphere, 12, 2073–2085, https://doi.org/10.5194/tc-12-2073-2018

https://www.the-cryosphere.net/12/2073/2018/tc-12-2073-2018.pdf


3) Sea Ice Prediction Network: "2018: June Report"

https://www.arcus.org/sipn/sea-ice-outlook/2018/june

Extract: "Nares Strait 2018
Summary of contribution from Preben Gudmandsen, Professor emeritus, National Space Institute, Technical University of Denmark


After more than two months of anomalous winter, the “Ice Bridge” (a blocking of further sea ice motion due to the forming of an east-west arch in the sea ice due to internal ice physics) formed again in the southwestern corner of the Kane Basin on 1 March 2018. This resulted in a complete stop of ice drift to the south, and a gradually decreasing compression of ice in the northern part of the Nares Strait between Greenland and Ellesmere Island to the west."

Best,
ASLR
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #547 on: January 29, 2019, 11:13:59 PM »
Thanks. That will keep me busy for a while :)

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #548 on: January 30, 2019, 12:32:58 AM »
Quote
papers that might indicate why the Lincoln Sea/Nares is so late to freeze during recent years
These two article may offer some clues:
Nares Strait hydrography and salinity field from a 3‐year moored array
B. Rabe, A. Münchow, H. L. Johnson and H. Melling
First published: 17 July 2010  https://doi.org/10.1029/2009JC005966
extract from Abstract:
Quote
...
Data show warm salty water on the Greenland side and cold fresher water on the Ellesmere Island side, especially in the top layers. There was a clear difference in hydrographic structure between times when sea ice was drifting and when it was land fast. Ice was drifting in late summer, fall, and early winter with a strong surface‐intensified geostrophic flow in the middle of the strait. Ice was land fast in late winter, spring, and early summer, when there was a subsurface core of strong geostrophic flow adjacent to the western side of the strait. Salinity variations of about 2 psu in time and space reflect a variable freshwater outflow from the Arctic Ocean. One particularly strong pulse occurred at the end of July 2005. For several days, steeply sloping isohalines indicated strong geostrophic flow down the middle of the strait coinciding with an amplified ice export from the Arctic due to strong southward winds.

Water, Heat, and Salt Transports through Nares Strait, Ellesmere Island
H. Eric Sadler
Published on the web 14 April 2011 - Journal of the Fisheries Research Board of Canada

Abstract
Quote
Data obtained in Nares Strait are used to provide estimates of the transports of water, heat, and salt between the polar ocean and northern Baffin Bay. The annual volume export of water through Nares Strait is 2.1 × 104 km3 ± 30%, which is equivalent to a mean flow of 0.67 × 106 m3∙s−1 and which is about 15% of the total outflow of water from the polar ocean. The annual net heat input into the polar ocean due to the outflow of cold water and ice is found to be 15 × 1019 J ± 50% assuming a reference temperature of −0.1 C. This volume is about 7% of the total advective heat transport into the polar ocean. The mean annual export of salt from the polar ocean is 6.7 × 1014 kg ± 30% or about 6% of the total export. The total transports through the whole Canadian archipelago are estimated and it is shown that they are appreciable fractions of the total exchanges between the polar ocean and the world ocean.
Arctic ice is healthy for children and other living things.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #549 on: January 30, 2019, 03:33:24 PM »
This may be of some use

Quote
August 2011. Regions with predominant FYI show larger heat input than those with predominating MYI, but the absolute flux is also controlled by surface solar irradiance. Including fluxes through open water, the effect of sea‐ice concentration (Figure S4) becomes most obvious, particularly in the marginal ice zones, and fluxes within the sea‐ice extent reach more than 5 W m−2 (Figure S6). Mean heat flux through the sea ice over the entire Arctic was 0.68 W m−2(mean transmittance: 0.08) in August 2011. Including open water within the sea‐ice extent it was 12.3 W m−2 (mean transmittance: 0.40)



https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL053738#support-information-section

Changes in Arctic sea ice result in increasing light transmittance and absorption

Our results show that transmittance through first‐year ice (FYI, 0.11) was almost three times larger than through multi‐year ice (MYI, 0.04), and that this is mostly caused by the larger melt‐pond coverage of FYI (42 vs. 23%). Also energy absorption was 50% larger in FYI than in MYI. Thus, a continuation of the observed sea‐ice changes will increase the amount of light penetrating into the Arctic Ocean, enhancing sea‐ice melt and affecting sea‐ice and upper‐ocean ecosystems.
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