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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #950 on: April 21, 2019, 08:38:20 PM »
A decrease in the Agulhas leakage may have been responsible for the decrease in the AMOC in the decade 2006-2015.

https://usclivar.org/research-highlights/agulhas-leakage-not-salinity-linked-atlantic-meridional-circulation-slowdown

Are there any studies regarding an increase in Agulhas leakage in recent times?

The exact timing and impact of climate change on the Agulhas Leakage, AL, and its impact on the slowing of the AMOC, is not well understood, however, due to the increasing Westerly wind velocities (due to both the Antarctic ozone hole and increasing GHG concentrations, the Southern Ocean Subtropical Front is moving Southward; which is resulting in more AL; which per the first linked reference & the attached image should slow the AMOC; which could contribute to ocean 'stratification'.

Gianluca Marino and Rainer Zahn, (2015), "The Agulhas Leakage: the missing link in the interhemispheric climate seesaw?", PAGES MAGAZINE ∙ VOLUME 23 ∙ NO 1 

http://www.pages-igbp.org/download/docs/magazine/2015-1/PAGESmagazine_2015(1)_22-23_Marino.pdf

Extract: "The Agulhas Leakage is a key component of the Atlantic Meridional Overturning Circulation. Unraveling the past patterns of leakage variability and associated heat and salt anomalies into the Atlantic Ocean holds clues for their role in ocean and climate changes."

See also, the second linked reference which discusses the influence of the recent increased Agulhas leakage on tropical Atlantic warming and the response of the AMOC:

Joke F. Lübbecke, Jonathan V. Durgadoo, and Arne Biastoch (2015), "Contribution of increased Agulhas leakage to tropical Atlantic warming", Journal of Climate, doi: http://dx.doi.org/10.1175/JCLI-D-15-0258.1


http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0258.1

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #951 on: April 21, 2019, 08:51:37 PM »
You are a wizard AbruptSLR. Thanks a lot.

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #952 on: April 21, 2019, 09:35:16 PM »
why would a UBI reduce population growth rates ?

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #953 on: April 21, 2019, 10:59:37 PM »
Getting a bit off topic perhaps, but as I understand it. But a major reason that poor people have lots of kids in many parts of the world is for security in their old age, and because there is no guarantee how many will make it past infancy. UBI (especially if accompanied by universal basic health care, including reproductive healthcare, and women's rights, including rights of choice, and to an education...) could go a long way in assuaging the kinds of fears that drive people in such precarious positions from having (or attempting to have) multiple kids.

Generally, most of the countries with the lowest birth rates tend to be those where most people have the most economic security, while most of the countries with the highest birth rates are those where most people are not very economically secure.

But perhaps others have different perspectives, or stats with links?
"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 #954 on: April 22, 2019, 05:25:31 AM »
You are correct, this is offtopic, so i reply here

https://forum.arctic-sea-ice.net/index.php/topic,473.msg196296.html#msg196296

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #955 on: April 22, 2019, 05:35:17 AM »
Here (as in many other western countries) we get higher subsidies with more kids. One kid renders SEK 1,250/month and six kids renders SEK 11,740/month nowadays.
https://upload.wikimedia.org/wikipedia/commons/b/b6/CIA_WFB_TotFertilityRate-GDP-Population_-_Simplified_2016.png

Total fertility rates for Sweden during the last century added below, it didn't take much wealth to drop birth rates here. They were dropping before WW1, GDP per capita doubled between 1876 and 1913. Later/further GDP doubling had much less effect.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #956 on: April 22, 2019, 04:10:37 PM »
The linked reference on terrestrial biosphere CO₂ absorption "… suggests that the increasing trend in carbon uptake rate may not be sustained past the middle of the century and could result in accelerated atmospheric CO2 growth."

Julia K. Green, Sonia I. Seneviratne, Alexis M. Berg, Kirsten L. Findell, Stefan Hagemann, David M. Lawrence & Pierre Gentine (2019), "Large influence of soil moisture on long-term terrestrial carbon uptake", Nature, volume 565, pages476–479 ,https://doi.org/10.1038/s41586-018-0848-x

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

Abstract: "Although the terrestrial biosphere absorbs about 25 per cent of anthropogenic carbon dioxide (CO2) emissions, the rate of land carbon uptake remains highly uncertain, leading to uncertainties in climate projections. Understanding the factors that limit or drive land carbon storage is therefore important for improving climate predictions. One potential limiting factor for land carbon uptake is soil moisture, which can reduce gross primary production through ecosystem water stress, cause vegetation mortality and further exacerbate climate extremes due to land–atmosphere feedbacks. Previous work has explored the impact of soil-moisture availability on past carbon-flux variability. However, the influence of soil-moisture variability and trends on the long-term carbon sink and the mechanisms responsible for associated carbon losses remain uncertain. Here we use the data output from four Earth system models from a series of experiments to analyse the responses of terrestrial net biome productivity to soil-moisture changes, and find that soil-moisture variability and trends induce large CO2 fluxes (about two to three gigatons of carbon per year; comparable with the land carbon sink itself) throughout the twenty-first century. Subseasonal and interannual soil-moisture variability generate CO2 as a result of the nonlinear response of photosynthesis and net ecosystem exchange to soil-water availability and of the increased temperature and vapour pressure deficit caused by land–atmosphere interactions. Soil-moisture variability reduces the present land carbon sink, and its increase and drying trends in several regions are expected to reduce it further. Our results emphasize that the capacity of continents to act as a future carbon sink critically depends on the nonlinear response of carbon fluxes to soil moisture and on land–atmosphere interactions. This suggests that the increasing trend in carbon uptake rate may not be sustained past the middle of the century and could result in accelerated atmospheric CO2 growth."
“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 #957 on: April 22, 2019, 04:12:53 PM »
Getting a bit off topic perhaps, but as I understand it. But a major reason that poor people have lots of kids in many parts of the world is for security in their old age, and because there is no guarantee how many will make it past infancy. UBI (especially if accompanied by universal basic health care, including reproductive healthcare, and women's rights, including rights of choice, and to an education...) could go a long way in assuaging the kinds of fears that drive people in such precarious positions from having (or attempting to have) multiple kids.

Generally, most of the countries with the lowest birth rates tend to be those where most people have the most economic security, while most of the countries with the highest birth rates are those where most people are not very economically secure.

But perhaps others have different perspectives, or stats with links?

Your (& Sleepy's) points are what I meant to imply.  Furthermore, conservatives should support UBI (funded by a carbon tax) because (if structured properly) it could replace welfare.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #958 on: April 22, 2019, 05:20:11 PM »
Happy Earth Day, 2019 :)

Title: "Earth Day 1970 - 2019: No Time To Waste"



“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #959 on: April 22, 2019, 08:00:40 PM »
The linked reference projects an increase in methane emissions from lakes and impoundments equal to 18 to 33% of annual anthropogenic CO₂ emissions by 2100.  This is not good.

Jake J. Beaulieu, Tonya Del Sontro & John A. Downing (2019), "Eutrophication will increase methane emissions from lakes and impoundments during the 21st century", Nature Communications, volume 10, Article number: 1375, https://doi.org/10.1038/s41467-019-09100-5

https://www.nature.com/articles/s41467-019-09100-5

Abstract: "Lakes and impoundments are an important source of methane (CH4), a potent greenhouse gas, to the atmosphere. A recent analysis shows aquatic productivity (i.e., eutrophication) is an important driver of CH4 emissions from lentic waters. Considering that aquatic productivity will increase over the next century due to climate change and a growing human population, a concomitant increase in aquatic CH4 emissions may occur. We simulate the eutrophication of lentic waters under scenarios of future nutrient loading to inland waters and show that enhanced eutrophication of lakes and impoundments will substantially increase CH4 emissions from these systems (+30–90%) over the next century. This increased CH4 emission has an atmospheric impact of 1.7–2.6 Pg C-CO2-eq y−1, which is equivalent to 18–33% of annual CO2 emissions from burning fossil fuels. Thus, it is not only important to limit eutrophication to preserve fragile water supplies, but also to avoid acceleration of climate change."
“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 #960 on: April 22, 2019, 08:37:52 PM »
As discussed previously the Earth's magnetic field is currently changing rapidly and in unexpected ways, so that as the first linked article indicates the consensus science model could not match the changes measured by the ESA's Swarm satellite (see the attached image).  Here I reiterate my previously expressed opinion that this rapid (at least in the past 50-years) change may be related to ice mass losses (see the last two related linked information on the rapid ice mass loss measured over the past 50 years):

Title: "Swarm Helps Pinpoint New Magnetic North for Smartphones"

https://www.esa.int/Our_Activities/Observing_the_Earth/Swarm/Swarm_helps_pinpoint_new_magnetic_north_for_smartphones

Extract: "Driven largely by the churning of fluid in Earth’s core, which generates the magnetic field, the magnetic north pole has always drifted, and geological evidence shows that every few hundred thousand years or so it even flips, so that north becomes south.

Around 50 years ago, the pole was ambling along at around 15 km a year, but now it is sprinting ahead at around 55 km a year. In 2017, it crossed the international date line, leaving the Canadian Arctic and heading towards Siberia.

However, thanks in part to ESA’s Swarm mission, researchers found that the pole is drifting in a way that wasn’t expected. This meant that model was simply too inaccurate for it to remain until the next planned revision. So, an ‘out-of-cycle’ update has just been issued."
&

Title: "GLACIERS LOSE NINE TRILLION TONNES OF ICE IN HALF A CENTURY"

https://m.esa.int/Our_Activities/Observing_the_Earth/Glaciers_lose_nine_trillion_tonnes_of_ice_in_half_a_century

Extract: "When we think of climate change, one of the first things to come to mind is melting polar ice. However, ice loss isn’t just restricted to the polar regions. According to research published today, glaciers around the world have lost well over 9000 gigatonnes (nine trillion tonnes) of ice since 1961, raising sea level by 27 mm."

See also:

M. Zemp et al. (2019), "Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016", Nature, volume 568, pages382–386, https://doi.org/10.1038/s41586-019-1071-0
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #961 on: April 22, 2019, 10:01:12 PM »
As a follow-on to my last post, the linked reference & associated article indicate that Danish researchers have mathematically associated relatively rapid changes in the Earth's magnetic fields to slower changes in the Earth's metallic outer core.  Now the only question is are these changes in the flow of the liquid metal in the outer core strictly random in nature, or are part of the changes associated with ice mass changes and groundwater mass changes around the world most significantly in the past 50 to 70-years (see the attached image from Wikimedia Commons):

Aubert & Finlay (2019), "Geomagnetic jerks and rapid hydromagnetic waves focusing at Earth's core surface", Nature Geoscience, DOI: 10.1038/s41561-019-0355-1

https://www.nature.com/articles/s41561-019-0355-1

Abstract: "Geomagnetic jerks are abrupt changes in the second time derivative—the secular acceleration—of Earth’s magnetic field that punctuate ground observatory records. As their dynamical origin has not yet been established, they represent a major obstacle to the prediction of geomagnetic field behaviour for years to decades ahead. Recent jerks have been linked to short-lived, temporally alternating and equatorially localized pulses of secular acceleration observed in satellite data, associated with rapidly alternating flows at Earth’s core surface. Here we show that these signatures can be reproduced in numerical simulations of the geodynamo that realistically account for the interaction between slow core convection and rapid hydromagnetic waves. In these simulations, jerks are caused by the arrival of localized Alfvén wave packets radiated from sudden buoyancy releases inside the core. As they reach the core surface, the waves focus their energy towards the equatorial plane and along lines of strong magnetic flux, creating sharp interannual changes in core flow and producing geomagnetic jerks through the induced variations in magnetic field acceleration. The ability to numerically reproduce jerks offers a new way to probe the physical properties of Earth’s deep interior."

See also:

Title: "Geomagnetic jerks finally reproduced and explained"

https://phys.org/news/2019-04-geomagnetic-jerks.html

Extract: "The Earth's magnetic field is produced by the circulation of matter within its metallic core, via the energy released when this core cools. Researchers know of two types of movements that cause two types of variations in the magnetic field: those resulting from slow convection movement, which can be measured on the scale of a century, and those resulting from "rapid" hydromagnetic waves, which can be detected on the scale of a few years. They suspected that the latter played a role in the jerks, but the interaction of these waves with slow convection, along with their mechanism of propagation and amplification, had yet to be revealed."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #962 on: April 22, 2019, 10:33:22 PM »
Title: "Geomagnetic jerks finally reproduced and explained"
Strike through added and context was completely ignored.

Well I would like to hear why they are such jerks.  :)  :D  ;D

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #963 on: April 23, 2019, 03:37:05 AM »
The linked reference indicates that ice mass loss has increased sixfold from the 1980s until 2018; this is significantly more than recognized previously by consensus climate science

Jérémie Mouginot, Eric Rignot, Anders A. Bjørk, Michiel van den Broeke, Romain Millan, Mathieu Morlighem, Brice Noël, Bernd Scheuchl, and Michael Wood (April 22, 2019), "Forty-six years of Greenland Ice Sheet mass balance from 1972 to 2018", PNAS, https://doi.org/10.1073/pnas.1904242116

https://www.pnas.org/content/early/2019/04/16/1904242116

Significance

We reconstruct the mass balance of the Greenland Ice Sheet for the past 46 years by comparing glacier ice discharge into the ocean with interior accumulation of snowfall from regional atmospheric climate models over 260 drainage basins. The mass balance started to deviate from its natural range of variability in the 1980s. The mass loss has increased sixfold since the 1980s. Greenland has raised sea level by 13.7 mm since 1972, half during the last 8 years.

Abstract
We reconstruct the mass balance of the Greenland Ice Sheet using a comprehensive survey of thickness, surface elevation, velocity, and surface mass balance (SMB) of 260 glaciers from 1972 to 2018. We calculate mass discharge, D, into the ocean directly for 107 glaciers (85% of D) and indirectly for 110 glaciers (15%) using velocity-scaled reference fluxes. The decadal mass balance switched from a mass gain of +47 ± 21 Gt/y in 1972–1980 to a loss of 51 ± 17 Gt/y in 1980–1990. The mass loss increased from 41 ± 17 Gt/y in 1990–2000, to 187 ± 17 Gt/y in 2000–2010, to 286 ± 20 Gt/y in 2010–2018, or sixfold since the 1980s, or 80 ± 6 Gt/y per decade, on average. The acceleration in mass loss switched from positive in 2000–2010 to negative in 2010–2018 due to a series of cold summers, which illustrates the difficulty of extrapolating short records into longer-term trends. Cumulated since 1972, the largest contributions to global sea level rise are from northwest (4.4 ± 0.2 mm), southeast (3.0 ± 0.3 mm), and central west (2.0 ± 0.2 mm) Greenland, with a total 13.7 ± 1.1 mm for the ice sheet. The mass loss is controlled at 66 ± 8% by glacier dynamics (9.1 mm) and 34 ± 8% by SMB (4.6 mm). Even in years of high SMB, enhanced glacier discharge has remained sufficiently high above equilibrium to maintain an annual mass loss every year since 1998.

Edit, the attached image provides specific numbers for the ice mass loss in Greenland from 1972 to 2018:

Caption: "Cumulative anomalies in SMB (blue), discharge (D, red), and mass (M, purple) in gigatons (gigaton = 10121012 kg) for the time period 1972–2018 for the seven regions of Greenland and the entire ice sheet component: (A) SW, (B) CW, (C) NW, (D) NO, (E) NE, (F) DE, (G) SE, and (H) GIS."

« Last Edit: April 23, 2019, 04:59:03 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #964 on: April 23, 2019, 11:41:42 AM »
some thirty years ago as I was attempting to impress my new girlfriend's family over dinner I introduced them to the idea of poles flipping . In the ensuing conversation at one point I suggested all electric would go out 'just like that .. ' .. in that instant the entire grid in N.I. failed .. said gf was very impressed ..:)  b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #965 on: April 23, 2019, 04:21:13 PM »
It has previously been shown that climate change skeptics (denialists) will acknowledge that climate change is real, if one offers them a technological fix to their pervious misguided ways.  In this regards, I note that the UN's Oceanix City offers just such a technological fix, where say the UN could guarantee residence to climate change skeptics in the coming decades, if they contractually agree to acknowledge climate change and to support climate change action:

Title: "See the United Nations’ Floating, Hurricane-Ready City Concept"

https://futurism.com/the-byte/united-nations-floating-city-concept

Extract: "…  the intergovernmental group unveiled Oceanix City, a concept for one of those floating cities developed as a partnership between architect Bjarke Ingels and Oceanix, a company that specializes in building floating structures  … Unlike countless city concepts before it, Oceanix City might actually come to fruition — thanks to backing by the United Nations Human Settlement Programme (UN-Habitat), the UN’s agency for sustainable urban development."
&

Title: "Oceanix City: This Floating City That Can Resist a Category 5 hurricane Is The City Of Future"



Extract: "Architecture firm BIG has designed a concept for a floating city of 10,000 people that could help populations threatened by extreme weather events and rising sea levels. BIG founder Bjarke Ingels unveiled the scheme yesterday at a round-table discussion on floating cities at the United Nations's New York headquarters. Called Oceanix City, the concept consists of buoyant islands clustered together in groups of six to form villages. These clusters would then be repeated in multiples of six to form a 12-hectare village for 1,650 residents, and then again to form an archipelago home to 10,000 citizens. Oceanix – a company that develops innovate ways to build on water – commissioned BIG to develop the concept, working with MIT's Center for Ocean Engineering and Oceanix. The scheme was unveiled at the First UN High-level Roundtable on Sustainable Floating Cities, which Oceanix co-convened with MIT, the Explorers Club and UN-Habitat, a UN offshoot mandated to work with city development. Oceanix City is intended to provide a habitable, off-shore environment in the event of rising sea levels, which are expected to affect 90 per cent of the world's coastal cities by 2050. Each of the modules would be built on land and then towed to sea, where they would be anchored in place. The miniature islands are also designed to survive a category-five hurricane. Arrangements would be flexible so that the cities could be moved if water levels became too low. BIG intends the buildings atop to be constructed from locally sourced "replenishable" materials such wood and fast-growing bamboo, which also offer " warmth and softness to touch". A number of renewable energy resources, such as wind and water turbines and solar panels are also incorporated. Food production and farming would be integrated and follow a zero-waste policy. "Every island has 3,000 square metres of outdoor agriculture that will also be designed so that it can be enjoyed as free space," said Ingels. Structures populating the modules will be low-level – predicted to rise four to seven stories – in order to keep the centre of gravity. Renderings show that the buildings will taper out towards the top to provide shading and also extra roof space for solar panels. Each mini-village will include a community framework for living, including water baths, markets, spiritual and cultural hubs, but BIG intends the Oceanix City to be adaptable to "any culture, any architecture". Another major benefit of the floating city, according to Oceanix co-founder Marc Collins Chen, is that it is an example of an affordable development, which could offer a solution to displaced societies. "It is our goal to make sure sustainable floating cities are affordable and available to all coastal areas in need," said Chen. "They should not become a privilege of the rich." Oceanix City is intended to be developed in sub-tropical and tropical areas that are most at risk of flooding first, but could soon offer a more attractive living environment. "The idea that we are presenting here is not that we will all be living at sea in the future," said Ingels. "It won't be waterworld." "This is simply another form of human habitat that can be a seed, that essentially can grow with its success as it turns out to be socially and environmentally desirable to chose this lifestyle," he continued. Chen revealed that the team will move forward with producing a prototype of the scheme, with ambitions to launch it on New York's East River. Oceanix City forms part of a surge of interest in floating cities, developed in response to rising sea levels. Examples of projects include colonies of floating houses along Amsterdam's river IJ and an amphibious house in the UK. A number of US cities are exploring other ways to bolster their vulnerable shorelines. Boston and Miami are taking steps to address flooding, while San Francisco and the Bay Area unveiled a design competition asking for ways to protect coastal areas from rising sea levels, as well as earthquakes."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #966 on: April 24, 2019, 07:20:47 AM »
Hmm, what will support those luxury rafts in the future, jellyfish?

Edit; I'll cross post this one here because I think it's a little gem.

Wise old words.
"Because when the window opens, you have to know what to do."


99 views.
« Last Edit: April 24, 2019, 08:09:11 AM by Sleepy »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #967 on: April 24, 2019, 05:26:35 PM »

Wise old words.
"Because when the window opens, you have to know what to do."

The linked reference concludes that: "… these findings suggest that systems thinking may support the adoption of global warming beliefs and attitudes indirectly by helping to develop an ecological ethic that people should take care of and not abuse the environment.".  However, the 'Systemic Isolation' thread (in 'The rest' folder) contains a lot of discuss addressing how hard it is to get many factions of our current socioeconomic interconnected system to adopt 'systems thinking'.  In this regard, I am concerned that we will cross a cascade of tipping points before we start to act as one world:

Matthew T. Ballew, Matthew H. Goldberg, Seth A. Rosenthal, Abel Gustafson, and Anthony Leiserowitz (April 23, 2019), "Systems thinking as a pathway to global warming beliefs and attitudes through an ecological worldview", PNAS 116 (17) 8214-8219; https://doi.org/10.1073/pnas.1819310116

https://www.pnas.org/content/116/17/8214.short

Significance
Systems thinking is recognized as vital to understanding climate science and addressing climate change. Understanding how systems thinking influences the public’s beliefs and attitudes about climate change has important implications for climate change education and communication. Our findings indicate that across the political spectrum, systems thinking may facilitate an ecological ethic or value system that humans should preserve and protect the natural world rather than exploit it. This, in turn, may strengthen proclimate views and understanding of climate change (e.g., that global warming is happening, is human-caused, etc.). The findings contribute to systems thinking theory and indicate the importance of promoting systems thinking to support proclimate science beliefs, attitudes, and behaviors across political lines.

Abstract
Prior research has found that systems thinking, the tendency to perceive phenomena as interconnected and dynamic, is associated with a general proenvironmental orientation. However, less is known about its relationship with public understanding of climate change and/or whether this relationship varies across people with different political views. Because climate change is a highly politicized issue, it is also important to understand the extent to which systems thinking can foster acceptance of climate science across political lines. Using an online sample of US adults (n = 1,058), we tested the degree to which systems thinking predicts global warming beliefs and attitudes (e.g., believing that global warming is happening, that it is human-caused, etc.), independent of an ecological worldview (i.e., the New Ecological Paradigm). We found that although systems thinking is positively related to global warming beliefs and attitudes, the relationships are almost fully explained by an ecological worldview. Indirect effects of systems thinking are consistently strong across political ideologies and party affiliations, although slightly stronger for conservatives and Republicans than for liberals and Democrats, respectively. We did not find evidence of the converse: Systems thinking does not seem to mediate the relationship between an ecological worldview and global warming beliefs and attitudes. Together, these findings suggest that systems thinking may support the adoption of global warming beliefs and attitudes indirectly by helping to develop an ecological ethic that people should take care of and not abuse the environment.
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― Leon C. Megginson

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My "burning embers"
are not tri-color bar graphs
+3C today

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #969 on: April 25, 2019, 04:08:35 PM »
Consensus climate science (e.g. WGI) has deemphasized communication of climate risk assessments to both decision makers and to the public (see the linked open source reference).  If consensus scientists think that risk assessment is not part of science, then they should either change their way of thinking or find another profession:

Rowan T. Sutton (23 April 2019), "Climate science needs to take risk assessment much more seriously", BAMS, https://doi.org/10.1175/BAMS-D-18-0280.1

https://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-18-0280.1
&
https://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-18-0280.1


Abstract: "For decision makers, climate change is a problem in risk assessment and risk management. It is, therefore, surprising that the needs and lessons of risk assessment have not featured more centrally in the consideration of priorities for physical climate science research, or in the Working Group I contributions to the major Assessment Reports of the Intergovernmental Panel on Climate Change. This article considers the reasons, which include a widespread view that the job of physical climate science is to provide predictions and projections - with a focus on likelihood rather than risk - and that risk assessment is a job for others. This view, it is argued, is incorrect. There is an urgent need for physical climate science to take the needs of risk assessment much more seriously. The challenge of meeting this need has important implications for priorities in climate research, climate modelling and climate assessments."
« Last Edit: April 25, 2019, 05:07:31 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #970 on: April 26, 2019, 03:51:30 PM »
The linked reference clearly states the consensus climate science position (i.e.: "Climate change scientists should instead communicate and engage with policy makers (and the public) on those things that we know with confidence.") that I strongly object to, and which I believe contributes to greater climate change risk.  This consensus climate science position empowered climate skeptics to define what is acceptable to communicate to both policy makers and the public, which is not only bad science but also a very bad idea:

Nafees Meah (2019), "Climate uncertainty and policy making—what do policy makers want to know?", Regional Environmental Change, pp 1–11, DOI: https://doi.org/10.1007/s10113-019-01492-w

https://link.springer.com/article/10.1007%2Fs10113-019-01492-w

Abstract: "In climate change science, the existence of a high degree of uncertainty seems to be the cause of anxiety for many scientists because it appears to undermine the authority of the science. One of the assertions made by the so-called sceptics against the scientific consensus on climate change is that because the science is so uncertain, there is no basis for taking action. The response of the climate change science community has been to develop in-depth analyses of uncertainty of increasing sophistication and complexity. In most areas of policy making, the normal situation is characterised by complexity, ambiguity and uncertainty. Therefore, dealing with uncertainty is not an unusual state of affairs for policy makers. However, the overemphasis given to uncertainty in the climate science discourse by scientists working in the field has been self-defeating as it has led to confusion among the intended recipients of the policy relevant scientific knowledge and allowed room for scepticism to grow. Climate change scientists should instead communicate and engage with policy makers (and the public) on those things that we know with confidence."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #971 on: April 26, 2019, 04:00:31 PM »
The linked reference ignores MICI possible AIS collapse mechanisms; nevertheless, it provides a thoughtful assessment of MISI collapse uncertainties, and finds that following RCP 8.5 will undoubtably at least trigger a MISI collapse of the WAIS:

Bulthuis, K., Arnst, M., Sun, S., and Pattyn, F.: Uncertainty quantification of the multi-centennial response of the Antarctic ice sheet to climate change, The Cryosphere, 13, 1349-1380, https://doi.org/10.5194/tc-13-1349-2019, 2019.

https://www.the-cryosphere.net/13/1349/2019/

Abstract
Ice loss from the Antarctic ice sheet (AIS) is expected to become the major contributor to sea level in the next centuries. Projections of the AIS response to climate change based on numerical ice-sheet models remain challenging due to the complexity of physical processes involved in ice-sheet dynamics, including instability mechanisms that can destabilise marine basins with retrograde slopes. Moreover, uncertainties in ice-sheet models limit the ability to provide accurate sea-level rise projections. Here, we apply probabilistic methods to a hybrid ice-sheet model to investigate the influence of several sources of uncertainty, namely sources of uncertainty in atmospheric forcing, basal sliding, grounding-line flux parameterisation, calving, sub-shelf melting, ice-shelf rheology and bedrock relaxation, on the continental response of the Antarctic ice sheet to climate change over the next millennium. We provide probabilistic projections of sea-level rise and grounding-line retreat, and we carry out stochastic sensitivity analysis to determine the most influential sources of uncertainty. We find that all investigated sources of uncertainty, except bedrock relaxation time, contribute to the uncertainty in the projections. We show that the sensitivity of the projections to uncertainties increases and the contribution of the uncertainty in sub-shelf melting to the uncertainty in the projections becomes more and more dominant as atmospheric and oceanic temperatures rise, with a contribution to the uncertainty in sea-level rise projections that goes from 5 % to 25 % in RCP 2.6 to more than 90 % in RCP 8.5. We show that the significance of the AIS contribution to sea level is controlled by the marine ice-sheet instability (MISI) in marine basins, with the biggest contribution stemming from the more vulnerable West Antarctic ice sheet. We find that, irrespective of parametric uncertainty, the strongly mitigated RCP 2.6 scenario prevents the collapse of the West Antarctic ice sheet, that in both the RCP 4.5 and RCP 6.0 scenarios the occurrence of MISI in marine basins is more sensitive to parametric uncertainty, and that, almost irrespective of parametric uncertainty, RCP 8.5 triggers the collapse of the West Antarctic ice sheet.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #972 on: April 26, 2019, 05:23:59 PM »
The linked reference provides glacial ice data for the Amundsen Sea Embayment focused on the Thwaites Glacier (& ice shelf/tongue) from 1992 until 2017.  It demonstrates that current glacial models for this area underestimate the dynamics of ice mass loss in key marine glaciers (focused on Thwaites):

P. Milillo et al. (2019), "Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica", Sci Adv., 5(1): eaau3433,. doi: 10.1126/sciadv.aau3433

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6353628/

Abstract: "The glaciers flowing into the Amundsen Sea Embayment, West Antarctica, have undergone acceleration and grounding line retreat over the past few decades that may yield an irreversible mass loss. Using a constellation of satellites, we detect the evolution of ice velocity, ice thinning, and grounding line retreat of Thwaites Glacier from 1992 to 2017. The results reveal a complex pattern of retreat and ice melt, with sectors retreating at 0.8 km/year and floating ice melting at 200 m/year, while others retreat at 0.3 km/year with ice melting 10 times slower. We interpret the results in terms of buoyancy/slope-driven seawater intrusion along preferential channels at tidal frequencies leading to more efficient melt in newly formed cavities. Such complexities in ice-ocean interaction are not currently represented in coupled ice sheet/ocean models."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #973 on: April 26, 2019, 06:07:00 PM »
In my opinion the linked article on the worst-case climate change scenario, under represents our true current climate risks.  For example, it does not discuss such risks as the following:

1. As China implements its 'Belt and Road Initiative' (see image), it will likely accelerate Arctic Amplification, both by: a) shifting aerosol emissions from Northern China to Southern/Southeast Asia, which will decrease the associated negative forcing in the Arctic; and b) promote economic development in Siberia, which will promote permafrost degradation.

2. The risk of a MICI-type of collapse of the WAIS beginning in the next few decades, which would abruptly increase Earth's energy imbalance for many decades and which would abruptly slow the MOC.

3. With the Earth's population currently at 7.7 billion people, and growing, food production and fossil fuel energy consumption are likely to continue growing for several more decades.

Title: "ARE WE HEADED TOWARD THE WORST-CASE CLIMATE CHANGE SCENARIO?"

https://psmag.com/environment/are-we-headed-toward-the-worst-case-climate-change-scenario?fbclid=IwAR3Kh_A527vsuRrIvYzcMJVXRMgCN1CJLdMOPSkaL6T6eWeOBiuLS6G6SBQ

Extract: "A series of recent studies and reports suggest that, without immediate and drastic action, the worst-case climate scenario will become the rule rather than the exception.

But here's the thing about those long-term climate change concerns: So far, they have a tendency to arrive much earlier than expected."
« Last Edit: April 26, 2019, 06:32:31 PM by AbruptSLR »
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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #974 on: April 26, 2019, 08:21:15 PM »
Larour et al have refined ISSM to 1Km resolution and incorporated self attraction and GIA to calculate SLR over the globe due to AIS. As has been found before, GIA slows down retreat and SLR after 2100.

doi: 10.1126/science.aav7908

open access. read all about it.

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #975 on: April 26, 2019, 09:31:32 PM »
Larour et al have refined ISSM to 1Km resolution and incorporated self attraction and GIA to calculate SLR over the globe due to AIS. As has been found before, GIA slows down retreat and SLR after 2100.

doi: 10.1126/science.aav7908

open access. read all about it.

sidd

Needless to say, ISSM only considers MISI, so if a MICI-type collapse of the WAIS initiates in the next few decades then it may not matter that GIA slows grounding line retreat after 2100.
« Last Edit: April 26, 2019, 10:30:56 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #976 on: April 26, 2019, 10:31:16 PM »
Many consensus climate science scenarios assume much lower rates of primary rainforest loss; hopefully, decision makers can to better then they did in 2018:

Title: "The World Lost a Belgium-sized Area of Primary Rainforests Last Year"

https://blog.globalforestwatch.org/data-and-research/world-lost-belgium-sized-area-of-primary-rainforests-last-year
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #977 on: April 27, 2019, 12:43:51 AM »
It's important to note that the scientific paper that introduced MICI, Pollard, DeConto and Alley, 2016, was done to try to determine how the sea levels could have risen by 17m during the Pliocene era. While MICI may cause the Antarctic ice sheets to collapse more quickly than they would from MISI alone, it's important to understand that the conditions that could initiate MICI are at least a century off in even the worst case business as usual emissions scenarios.

https://www.sciencedirect.com/science/article/pii/S0012821X14007961

Quote
To investigate the impact of the cliff-failure and melt-driven hydrofracture mechanisms, the ice-sheet model is run forward in time, forced by climate representative of past warm periods. Simulations are started from a previous spin-up of modern Antarctica using observed climatology. An instantaneous change to a warmer climate is applied, broadly representative of a warm Pliocene period. The past warm atmospheric climate is obtained from the RegCM3 Regional Climate Model (Pal et al., 2007) applied over Antarctica with some physical adaptations for polar regions, and with 400 ppmv CO2 and an orbit yielding particularly strong austral summers (DeConto et al., 2012). Detailed simulation of ocean warming beneath Antarctic ice shelves is currently not feasible on these time scales, so a simple uniform increment of
+2°C
 is added to modern observed ocean temperatures, broadly consistent with circum-Antarctic warming in Pliocene paleo-oceanic reconstructions (Dowsett et al., 2009). The climate forcings are described in more detail in Supplementary Material Section S.3.

Note that they start the model with a 3C warmer temperature than preindustrial, and a 2C warmer ocean.

Quote
The equivalent eustatic sea level rise reaches 5 m after ∼200 yr and 17 m after ∼3000 yr (Fig. 4, red curve), similar in magnitude to albeit uncertain proxy estimates of past sea-level variations mentioned above. About 3 mesl comes from West Antarctica, and the remaining ∼14mesl  comes from East Antarctic basins. The bigger contribution of EAIS, despite its similar area of collapse to WAIS, is explained by the much greater volumes of ice above flotation in the East Antarctic basins, particularly in the Aurora (Fig. 1c).

Quote
The main aim of adding hydrofracturing and cliff failure was to produce total Antarctic retreat consistent with albeit poorly constrained past sea-level data, and no effort was made to adjust the rate of retreat. The time scale that emerges for West Antarctic collapse (∼3m contribution to global sea-level rise within O(100)  years after a step-function warming) is an order of magnitude faster than previous estimates for the next century, which range from ∼0.1 to 0.6 m by 2100 AD (Pfeffer et al., 2008, Levermann et al., 2014, Joughin et al., 2014). The modeling approaches in Pfeffer et al. and Levermann et al. are very different, and our study is not directly applicable to the future because of our step-function climate change, Pliocene-like climate, and homogeneous ocean warming. But even so, our predicted WAIS retreat rates are much faster than might be expected from the previous work. The main cause is the new mechanisms of hydrofracture and cliff failure.

But to initiate the higher rates of sea level rise, ocean temperatures need to reach 2C above pre-industrial with global temperatures at 3C above pre-industrial.   AbruptSLR, what studies support such a rapid increase in ocean temperatures to allow for initiation of MICI by the 2040s to 2050s as you often claim?

Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #978 on: April 27, 2019, 01:26:24 AM »
This study from 2018 indicates that the West Antarctic Ice sheet wont disintegrate if we can reduce emissions to the RCP 2.6 scenario.

https://www.the-cryosphere-discuss.net/tc-2018-220/tc-2018-220.pdf

Quote
Uncertainty quantification of the multi-centennial response of the
Antarctic Ice Sheet to climate change

Kevin Bulthuis, Maarten Arnst, Sainan Sun, and Frank Pattyn

Abstract. Ice loss from the Antarctic ice sheet (AIS) is expected to become the major contributor to sea-level rise in the next centuries. Projections of the AIS response to climate change based on numerical ice-sheet models remain challenging to establish due to the complexity of physical processes involved in ice-sheet dynamics, including instability mechanisms that can destabilise marine sectors with retrograde slopes. Moreover, uncertainties in ice-sheet models limit the ability to provide accurate sea-level rise 5 projections. Here, we apply probabilistic methods to a hybrid ice-sheet model to investigate the influence of several sources of uncertainty, namely sources of uncertainty in atmospheric forcing, basal sliding, grounding-line flux parameterisation, calving, sub-shelf melting, ice-shelf rheology and bedrock relaxation, on the continental response of the Antarctic ice sheet to climate change over the next millennium. We provide probabilistic projections of sea-level rise and grounding-line retreat and we carry out stochastic sensitivity analyses to determine the most influential sources of uncertainty. We find that all 10 sources of uncertainty, except perhaps the bedrock relaxation times, contribute to the uncertainty in the projections. We show that the sensitivity of the projections to uncertainties increases and the contribution of the uncertainty in sub-shelf melting to the uncertainty in the projections becomes more and more dominant as the scenario gets warmer. We show that the significance of the AIS contribution to sea-level rise is controlled by marine ice-sheet instability (MISI) in marine basins, with the biggest contribution stemming from the more vulnerable West Antarctic ice sheet. We find that, irrespectively of parametric 15 uncertainty, the strongly mitigated RCP 2.6 scenario prevents the collapse of theWest Antarctic ice sheet, that in both RCP 4.5 and RCP 6.0 scenarios the occurrence of MISI in marine basins is more sensitive to parametric uncertainty and that, almost irrespectively of parametric uncertainty, RCP 8.5 triggers the collapse of the West Antarctic ice sheet.

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #979 on: April 27, 2019, 05:22:27 AM »
MICI begins when

a) surface temperatures rise to freezing and above, hydrofracture is a big effect and will destabilize cliffs below 100m above sea level. This was Mercer warning back in 1968 and 78.

b) but even without surface melt cliffs of 100m and above are unstable to MICI. That is the Bassis warning.

The questions are : when do we see surface melt ? when does ocean melt and ice shelf disintegration expose 100m ice cliff ?

either will do.

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #980 on: April 27, 2019, 09:02:55 AM »
As some has noted earlier in this thread, RCP2.6 is no longer attainable.
https://news.agu.org/press-release/new-studies-highlight-challenge-of-meeting-paris-agreement-climate-goals/
A short quote and snipping out the top image from the second study with Peters.
Quote
Stone, with the National Institute of Water and Atmospheric Research, said Peters’ study shows no one country can slip up in the goal to meet climate goals.

“It is hard to argue against their conclusion that we need to start seriously considering options such as the deployment of solar geoengineering, with all of the risks that entails, if the world is serious about achieving the Paris Agreement goals,” he said.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #981 on: April 27, 2019, 04:24:35 PM »
I ran the doi       DOI: 10.1126/science.364.6438.322     not posted elsewhere    A search of ozone  and also stratopshere and ozone  no real hits, so
Overworld
    Eli Kintisch
Science  26 Apr 2019:
Vol. 364, Issue 6438, pp. 322-325
DOI: 10.1126/science.364.6438.322

A new NASA mission will probe threats to the ozone layer over the United States.

Nothing proved, but should be a good study (that could have been done years ago if we did not spend so much on the militatry)

oops

https://science.sciencemag.org/content/364/6438/322

I note that they give a dermatologist a paragraph but none to a zooologist or botanist about effects on the other 99.9+ % of species on the planet.

Quote
[Anderson notes he has never used the phrase “alarming reductions,” and he says the satellite data used in the 2013 paper are not sensitive or detailed enough to reveal the relevant mechanisms. But he is worried about the future. “It will be too late,” he fears, if action is delayed until “we actually have measurable decreases in ozone [and] increases in UV radiation [over midlatitudes].” And global warming could speed any losses. Warming has caused moisture in both the lower and upper atmosphere to increase, a trend expected to intensify, and it could mean more powerful thunderstorms pumping that moisture into the stratosphere. In addition, research has shown that although the dominant warming gases, carbon dioxide and methane, warm the lower atmosphere, in the stratosphere they radiate solar energy to space, cooling that part of the sky—which could also favor ozone destruction. The data collected by the DCOTSS project should help determine whether that scenario is already occurring./quote]

 

« Last Edit: April 27, 2019, 06:47:12 PM by longwalks1 »

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #982 on: April 27, 2019, 05:28:54 PM »
Checked the ECMWF SST long range. The red is kinda boring?
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Tor Bejnar

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #983 on: April 27, 2019, 06:25:29 PM »
What is scary is the yellows and browns in the Arctic region during "MJJ" - May, June and July.
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 #984 on: April 28, 2019, 12:14:19 AM »
The gobal population pass 7.7 billion people today April 24, 2019:

Edit: I note that the 'This Year' column provides values from January 1, 2019 to April 24, 2019.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #985 on: April 28, 2019, 01:50:03 AM »
I refer to reply #933.

The third image there categorizes warming (in terms of degrees) by level of impact: dangerous, catastrophic, existential...

My question is, when catastrophic warming is reached, isn't part of the catastrophe that warming of a much higher (existential) level is no longer avoidable?

I am aware that this is highly speculative, but am wondering when runaway global warming occurs. If it very likely occurs somewhere between 2 and 3C, then shouldn't everything above 2C be considered an "existential threat?"

Thanks

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #986 on: April 28, 2019, 06:56:26 AM »
I think you mean the fourth "Categories of Climate Risk.PNG"?

Yes, considering what's in the pipeline, we have already passed 1.5°C and will pass 2°C with ease. We are already aiming for catastrophic warming and 3-4°C.

If the Paris goals were attached to reality we would already be building one large CO₂ removal facility every day along with the power plants to supply the necessary electricity & heat. And we would have to keep at it for decades.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #987 on: April 28, 2019, 07:00:20 AM »
Checked the ECMWF SST long range. The red is kinda boring?
Yes, boring. As the earth is fast plonking towards warmer times an idea would be to use discontinuous scale in visualization. Put a cut in the spot that's the upper limit of normal for 1950-80 and run the 'anthropogenic climate scale' from bright green to hot pink?
Cooling the outside by heat pump.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #988 on: April 28, 2019, 05:06:48 PM »
It's important to note that the scientific paper that introduced MICI, Pollard, DeConto and Alley, 2016, was done to try to determine how the sea levels could have risen by 17m during the Pliocene era. While MICI may cause the Antarctic ice sheets to collapse more quickly than they would from MISI alone, it's important to understand that the conditions that could initiate MICI are at least a century off in even the worst case business as usual emissions scenarios.

https://www.sciencedirect.com/science/article/pii/S0012821X14007961



Note that they start the model with a 3C warmer temperature than preindustrial, and a 2C warmer ocean.

...

But to initiate the higher rates of sea level rise, ocean temperatures need to reach 2C above pre-industrial with global temperatures at 3C above pre-industrial.   AbruptSLR, what studies support such a rapid increase in ocean temperatures to allow for initiation of MICI by the 2040s to 2050s as you often claim?
Ken,

I am going to assume that you are not trolling me, as I know virtually nothing about you, so I will briefly (in two posts) re-post information that I provided earlier in this thread in order to try to clarify both my logic and evidence for a plausible initiation of a MICI-type of collapse of most of the WAIS circa 2040:

First, I note that, Pollard, DeConto & Alley (2018) use their Antarctic Ice Sheet, AIS, model with ice-cliff and hydrofracturing failure mechanisms together with ice mélange back pressures calibrated to that currently observed for the Jakobshavn marine terminating glacier in Greenland (see the first image).  Pollard et al (2018) then assumed the abrupt imposition of warm mid-Pliocene climate conditions (which roughly have a GMSTA above pre-industrial of 2C and ocean water temperatures beneath the ice of key AIS marine glaciers comparable to those found by Bronselaer et al (2018) after 2040, as shown in the second image). 

David Pollard, Robert M. DeConto, Richard B. Alley (13 March 2018), "A continuum model of ice mélange and its role during retreat of the Antarctic Ice Sheet", Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2018-28

https://www.geosci-model-dev-discuss.net/gmd-2018-28/gmd-2018-28.pdf
&

Bronselaer, B. et al. (2018) Change in future climate due to Antarctic meltwater, Nature, doi:s41586-018-0712-z

https://www.nature.com/articles/s41586-018-0712-z
&

Second, based on my interpretation of the third & fourth linked references, I suspect that local ice cliff failures near the base of the Thwaites Ice Tongue (see the third image of a profile through this area) may begin sometime 2025 and 2033, and may be initiated due to influences from Super El Nino events in that timeframe.  The fourth linked reference confirms that the ENSO is directly associated with surface air temperatures across the interior of West Antarctica, and I note that the frequency of extreme El Nino events is projected to double when the global mean surface temp. anom. gets to 1.5C:

Yu, H., Rignot, E., Morlighem, M., & Seroussi, H. (2017). Iceberg calving of Thwaites Glacier, West Antarctica: full-Stokes modeling combined with linear elastic fracture mechanics. The Cryosphere, 11(3), 1283, doi:10.5194/tc-11-1283-2017

https://www.the-cryosphere.net/11/1283/2017/tc-11-1283-2017.pdf
https://www.the-cryosphere.net/11/1283/2017/tc-11-1283-2017-assets.html
&

Kyle R. Clem, James A. Renwick, and James McGregor (2017), "Large-Scale Forcing of the Amundsen Sea Low and its Influence on Sea Ice and West Antarctic Temperature", Journal of Climate, https://doi.org/10.1175/JCLI-D-16-0891.1

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0891.1?utm_content=buffer2e94d&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer
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Finally, the fifth and sixth linked abstracts from the WAIS 2018 workshop clearly indicate that after GMSTA reaches about 2C above pre-industrial, there is significant risk of a major MICI event initiating.

Title: "Climatic Thresholds for WAIS Retreat: Onset of Widespread Ice Shelf Hydrofracturing and Ice Cliff Calving in a Warming World", by Rob DeConto, David Pollard, Knut Christianson, Richard B. Alley & Byron R. Parizek

https://www.waisworkshop.org/sites/waisworkshop.org/files/webform/2018/abstracts/WAIS2018.pdf

Abstract: "The loss or thinning of buttressing ice shelves and accompanying changes in grounding zone stress balance are commonly implicated as the primary trigger for grounding line retreat, such as that observed in Amundsen Sea outlet glaciers today. Ice-shelf thinning is mostly attributed to the presence of warm ocean waters beneath the shelves. However, climate model projections indicate that summer air temperatures could soon exceed the threshold for widespread meltwater production on ice-shelf surfaces. This has serious implications for the future stability of ice shelves, because they are vulnerable to the propagation of water-induced flexural stresses and water-aided crevasse penetration, often referred to as ‘hydrofracturing’. Once initiated, the rate of shelf loss through hydrofracturing can far exceed that caused by sub-surface oceanic melting, and could result in the complete loss of some buttressing ice shelves, with marine-terminating grounding lines suddenly becoming calving ice fronts. In places where those exposed (unbuttressed) ice fronts are thick enough (>900m), deviatoric stresses can exceed the strength of the ice, and the cliff face will fail through brittle processes leading to rapid calving like that seen in analogous settings on Greenland such as Jakobshavn and Helheim. 
 
Here we explore the implications of hydrofacturing and subsequent ice-cliff collapse in a warming climate, by parameterizing these processes in a hybrid ice sheet-shelf model. Model physical parameters controlling sensitivity of surface crevasse penetration to meltwater and ice-cliff calving rate (a function of cliff height above the stress-balance threshold for brittle failure) are based on observations of calving in analogous settings, and model performance relative to observed mass loss and paleo sea-level estimates. Including these processes and exploring a range of atmospheric and ocean climate forcing scenarios, we find the potential for major future WAIS retreat if global mean temperature rises more than ~2ºC above preindustrial. We also find that strict mitigation, with net negative carbon emissions initiated ~2060 substantially reduces the magnitude and rate of long-term WAIS retreat. In simulations following a ‘worst case’ RCP8.5 scenario, the model produces rates of equivalent sea level rise that would be measured in cm per year by the end of this century. Importantly, parameterized Antarctic calving rates at thick ice fronts are not allowed to exceed those observed in Greenland today. This may be an overly conservative assumption, considering the very different spatial scales and physical settings of Antarctic outlet glaciers like Thwaites. Clearly the potential for mechanical/brittle processes to deliver ice to the ocean, in addition to viscous and basal processes, needs to be better constrained through more complete, physically based model representations of calving."
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Title: "Across the Great Divide: The Flow-to-Fracture Transition and the Future of the West Antarctic Ice Sheet", by Richard B. Alley, Byron R. Parizek, Knut Christianson, Robert M. DeConto, David Pollard and Sridhar Anandakrishna

https://www.waisworkshop.org/sites/waisworkshop.org/files/webform/2018/abstracts/Alley_R.pdf

Abstract: "Physical understanding, modeling, and available data indicate that sufficient warming and retreat of Thwaites Glacier, West Antarctica will remove its ice shelf and generate a calving cliff taller than any extant calving fronts, and that beyond some threshold this will generate faster retreat than any now observed. Persistent ice shelves are restricted to cold environments. Ice-shelf removal has been observed in response to atmospheric warming, with an important role for meltwater wedging open crevasses, and in response to oceanic warming, by mechanisms that are not fully characterized. Some marine-terminating glaciers lacking ice shelves “calve” from cliffs that are grounded at sea level or in relatively shallow water, but more-vigorous flows advance until the ice is close to flotation before calving. For these vigorous flows, a calving event shifts the ice front to a position that is slightly too thick to float, and generates a stress imbalance that causes the ice front to flow faster and thin to flotation, followed by another calving event; the rate of retreat thus is controlled by ice flow even though the retreat is achieved by fracture. Taller cliffs generate higher stresses, however, favoring fracture over flow. Deformational processes are often written as power-law functions of stress, with ice deformation increasing as approximately the third power of stress, but subcritical crack growth as roughly the thirtieth power, accelerating to elastic-wave speeds with full failure. Physical understanding, models based on this understanding, and the limited available data agree that, above some threshold height, brittle processes will become rate-limiting, generating faster calving at a rate that is not well known but could be very fast. Subaerial slumping followed by basal-crevasse growth of the unloaded ice is the most-likely path to this rapid calving. This threshold height is probably not too much greater than the tallest modern cliffs, which are roughly 100 m."
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For those who do not understand the implications of Alley et al. (2018)'s comment that ice deformation is a power-function of stress, I attach the fourth image that translates this underlying ice-cliff behavior into terms of calving rate (deformation) per year for various values of marine glacier freeboard (ice face height minus water depth) and relative water depth (which combine determine the primary stresses near the ice cliff face).


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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #989 on: April 28, 2019, 05:35:39 PM »
Now I note that the fact that Pollard, DeConto and Alley (2015 [not 2016 as you cited]), assumed a uniformly warm ocean is irrelevant to what happens beneath the ASE ice shelves and grounding lines, because Bronselar et al. (2018) clearly shows that for modern day conditions the warm CDW will upwell into the ASE, locally creating the warmth of water comparable to mid-Pliocene conditions.

Furthermore, it is conservative for Pollard, DeConto, Alley and others to assume instant local mid-Pliocene conditions (which I say may very well happen circa 2040) because the local ice shelf condition is much worse than assumed by such authors due to decades (since the 1970's) of periodic warm CDW intrusions into the ASE associated with the formation of the Antarctic ozone hole.  The condition of the key ice shelves in the ASE is illustrated by Schroeder et al. (2018), and by the recent retreat of the PIIS calving face to be upstream of the SW Tributary Glacier.

Schroeder et al (2018) indicate that: "… thickness change of the Thwaites Eastern Ice Shelf between 1978 and 2009, revealing the loss of over half of its thickness over the past three decades."  As the Eastern Thwaites Ice Shelf continues to thin, its risk of abrupt collapse increases rapidly in coming decades:

https://www.waisworkshop.org/sites/waisworkshop.org/files/webform/2018/abstracts/SchroederD2018.pdf

Also, the first attached image from Kriegler et al. (2017), shows that SSP5 projects that by 2040 GMSTA will be about 2C above a 1986-2005 baseline.

Kriegler et al (2017), "Fossil-fueled development (SSP5): An energy and resource intensive scenario for the 21st century", Global Environmental Change, Volume 42, Pages 297-315, https://doi.org/10.1016/j.gloenvcha.2016.05.015

https://www.sciencedirect.com/science/article/pii/S0959378016300711

Therefore if Hawkins et al. (2017) is correct and to get from a 1986-2005 baseline to a preindustrial baseline one needs to add an average of 0.675C then the SSP5-Baseline projection for 2040 would be 2C + 0.675C = 2.675C.

I note that Hawkins et al (2017) defines the pre-industrial baseline to be from 1720-1800 for determining GMSTA.

Ed Hawkins et al. (2017), "Estimating Changes in Global Temperature since the Preindustrial Period", BAMS, https://doi.org/10.1175/BAMS-D-16-0007.1

https://journals.ametsoc.org/doi/full/10.1175/BAMS-D-16-0007.1

Abstract: "The United Nations Framework Convention on Climate Change (UNFCCC) process agreed in Paris to limit global surface temperature rise to “well below 2°C above pre-industrial levels.” But what period is preindustrial? Somewhat remarkably, this is not defined within the UNFCCC’s many agreements and protocols. Nor is it defined in the IPCC’s Fifth Assessment Report (AR5) in the evaluation of when particular temperature levels might be reached because no robust definition of the period exists. Here we discuss the important factors to consider when defining a preindustrial period, based on estimates of historical radiative forcings and the availability of climate observations. There is no perfect period, but we suggest that 1720–1800 is the most suitable choice when discussing global temperature limits. We then estimate the change in global average temperature since preindustrial using a range of approaches based on observations, radiative forcings, global climate model simulations, and proxy evidence. Our assessment is that this preindustrial period was likely 0.55°–0.80°C cooler than 1986–2005 and that 2015 was likely the first year in which global average temperature was more than 1°C above preindustrial levels. We provide some recommendations for how this assessment might be improved in the future and suggest that reframing temperature limits with a modern baseline would be inherently less uncertain and more policy relevant."
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Extract: "We have examined estimates of historical radiative forcings to determine which period might be most suitable to be termed preindustrial and used several approaches to estimate a change in global temperature since this preindustrial reference period. The main conclusions are as follows:

1.   The 1720–1800 period is most suitable to be defined as preindustrial in physical terms, although we have incomplete information about the radiative forcings and very few direct observations during this time. However, this definition offers a target period for future analysis and data collection to inform this issue.
2.   The 1850–1900 period is a reasonable pragmatic surrogate for preindustrial global mean temperature. The available evidence suggests it was slightly warmer than 1720–1800 by around 0.05°C, but this is not statistically significant.
3.   We assess a likely range of 0.55°–0.80°C for the change in global average temperature from preindustrial to 1986–2005.
4.   We also consider a likely lower bound on warming from preindustrial to 1986–2005 of 0.60°C, implying that the AR5 estimate of warming was probably too small and that 2015 was the first year to be more than 1°C above preindustrial levels."
&

Finally, per the linked Gavin Schmidt tweeter thread, for a 20yr loess trend line Gavin is predicting that the GMSTA in 2019 will be 1.2+/-0.15C (see the see second attached image) or 1.23C for a 15yr loess trend line (see the extract below).  I note that this prediction is in line with the SSP5-Baseline projection for 2019 shown in the first image:

https://twitter.com/ClimateOfGavin/status/1068336654887337984

Extract: "ENSO forecast for DJF here: https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/ … (I used 1±0.6 (95% CI)). Note there is also some dependence on the smoothing; predictions for 2019 would be 1.23 or 1.17 using a 15yr or 30yr loess smooth....1.2±0.15 ºC above the late 19th C. A warmer yr than 2018 (which will #4), almost certain >1ºC yr, and 1 in 3 chance of a new record."

Edit: Also, I note that Pollard, DeConto & Alley (2018) ice mass loss projections only use hydrofracturing to collapse key ice shelves which are essentially at sea level, thus for a MICI-type of collapse surface temperatures only need to be above freezing (in the Austral Summer) at sea level in order to generate sufficient surface meltwater to cause hydrofracturing of the key WAIS ice shelves.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #990 on: April 29, 2019, 02:15:34 AM »
I would like to remind readers that all current and planned (e.g. E3SMv2) models that simulate glacial ice responses are not sufficiently sophisticated to match both paleo and observed behavior; much of which is highly dependent on: a) initial conditions; b) boundary conditions, c) chaotic reinforcement of fluctuations and d) synergy between adjoining glacial bodies (e.g. the Pine Island  Glacier drainage basin and the Byrd Subglacial Basin) and between glacial bodies, the ocean, the atmosphere and the glacial beds. 

Examples of observed behavior (all previously cited in this thread) that local Antarctic models are currently not getting correct include:

a) The southward migration of mixed CDW; b) the subglacial cavity at the base of the Thwaites Ice Tongue; c) the periodic discharge of subglacial lakes, including those beneath the Thwaites Glacier and d) the dynamic circulation of mixed CDW within the ASE.

Examples of possible future events that are not considered in global or local models include:

a) future changes in local in Antarctic sea ice contentations and of local winds; which may advect more mixed CDW beneath ice shelves such as the FRIS and the RIS; b) future increases in storm activity over the Southern Ocean can increase storm surge, increase rainfall on ice shelves and increase snowfall at higher elvations on marine glaciers which can increase both ice cliff heights and gravitational driving forces; c) future increased El Nino frequencies can drive more CDW into the ASE (including via the ASL) and increase advected heat from the Tropical Pacific to the west coast of the WAIS and d) future ice-climate feedbacks can reinforce cascades of other positive feedback mechanisms that can increase ECS in coming decades.

Examples of anthropogenic radiative forcing that are not fully considered by the SSP scenarios include:

a) A relocation of aerosol sources away from the Arctic could abruptly accelerate Arctic Amplification which could result in a rapid reduction of Arctic Sea Ice Extent that could trigger an associated albedo flip; b) a drive for sustainable energy without reducing fossil fuel production could support a rapid increase in the use of refrigeration and air conditioning in the Third World without reducing GHG emissions; c) SSP5 assumes population peaks around 8 billion while we are already at 7.7 billion people and the associate demand for meat is growing faster than the population growth; and d) a drive to push BECCS could devastate bio-diversity which could result in a rapid reduction of thenatural terrestial CO2 sink.

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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #991 on: April 29, 2019, 02:26:47 AM »
As a follow-on to my last post, the following linked references future illustrate paleo cases that climate models find difficult to match:

The first linked Ivanovic et al. (2018) reference indicates that paleo-signals from meltwater pulse events in the NH override any such paleo-signals from SH meltwater pulse events.  Thus it is difficult to find evidence of a meltwater pulse event in the paleo-record from a meltwater pulse event associate with an abrupt MICI collapse of the WAIS.

R. F. Ivanovic et al. (04 June 2018), "Climatic Effect of Antarctic Meltwater Overwhelmed by Concurrent Northern Hemispheric Melt", Geophysical Research Letters 45, Issue 11
https://doi.org/10.1029/2018GL077623

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL077623

Abstract
Records indicate that 14,500 years ago, sea level rose by 12–22 m in under 340 years. However, the source of the sea level rise remains contentious, partly due to the competing climatic impact of different hemispheric contributions. Antarctic meltwater could indirectly strengthen the Atlantic Meridional Overturning Circulation (AMOC), causing northern warming, whereas Northern Hemisphere ice sheet meltwater has the opposite effect. This story has recently become more intriguing, due to increasing evidence for sea level contributions from both hemispheres. Using a coupled climate model with freshwater forcing, we demonstrate that the climatic influence of southern‐sourced meltwater is overridden by northern sources even when the Antarctic flux is double the North American contribution. This is because the Southern Ocean is quickly resalinized by Antarctic Circumpolar water. These results imply that the pattern of surface climate changes caused by ice sheet melting cannot be used to fingerprint the hemispheric source of the meltwater.

Plain Language Summary
The fastest major sea level rise ever recorded took place 14,500 years ago, when sea level rose by 12–22 m in under 340 years. The extra water came from melting ice sheets, which stretched across North America and northern Europe as well as Greenland and Antarctica. We ran a climate model to test the impact of different meltwater contributions from Antarctica and the Northern Hemisphere ice sheets (North America, Greenland, and Eurasia). Our simulations demonstrate that northern meltwater has a much stronger and longer lasting effect on ocean circulation and climate than Southern Hemisphere melt. Consequently, northern melting overrides the impact of southern melting even when the flux of water from North America is only half the magnitude of the Antarctic flux. This means that past climate records cannot be used to identify the contribution of meltwater from different ice sheets: the northern signal can override the southern signal.
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The second linked reference [Erhardt et al. (2019)] indicates that Dansgaard-Oeschger warming effects can be trigger by decadal-scale atmospheric circulation changes including changes in precipitation (such as increased rainfall in Arctic and Antarctic areas):

Erhardt, T., Capron, E., Rasmussen, S. O., Schüpbach, S., Bigler, M., Adolphi, F., and Fischer, H.: Decadal-scale progression of the onset of Dansgaard–Oeschger warming events, Clim. Past, 15, 811-825, https://doi.org/10.5194/cp-15-811-2019, 2019.

https://www.clim-past.net/15/811/2019/

Abstract
During the last glacial period, proxy records throughout the Northern Hemisphere document a succession of rapid millennial-scale warming events, called Dansgaard–Oeschger (DO) events. A range of different mechanisms has been proposed that can produce similar warming in model experiments; however, the progression and ultimate trigger of the events are still unknown. Because of their fast nature, the progression is challenging to reconstruct from paleoclimate data due to the limited temporal resolution achievable in many archives and cross-dating uncertainties between records. Here, we use new high-resolution multi-proxy records of sea-salt (derived from sea spray and sea ice over the North Atlantic) and terrestrial (derived from the central Asian deserts) aerosol concentrations over the period 10–60 ka from the North Greenland Ice Core Project (NGRIP) and North Greenland Eemian Ice Drilling (NEEM) ice cores in conjunction with local precipitation and temperature proxies from the NGRIP ice core to investigate the progression of environmental changes at the onset of the warming events at annual to multi-annual resolution. Our results show on average a small lead of the changes in both local precipitation and terrestrial dust aerosol concentrations over the change in sea-salt aerosol concentrations and local temperature of approximately one decade. This suggests that, connected to the reinvigoration of the Atlantic meridional overturning circulation and the warming in the North Atlantic, both synoptic and hemispheric atmospheric circulation changes at the onset of the DO warming, affecting both the moisture transport to Greenland and the Asian monsoon systems. Taken at face value, this suggests that a collapse of the sea-ice cover may not have been the initial trigger for the DO warming.
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The third linked reference [Coletti et al. (2015)] elaborates on the fact that even the most advanced modern analysis of the MIS 11c event cannot yet full account for the exceptionally high Arctic Amplification which may have been associated with a paleo-collapse of the WAIS.

Coletti, A. J., DeConto, R. M., Brigham-Grette, J., and Melles, M.: A GCM comparison of Pleistocene super-interglacial periods in relation to Lake El'gygytgyn, NE Arctic Russia, Clim. Past, 11, 979-989, doi:10.5194/cp-11-979-2015, 2015.

http://www.clim-past.net/11/979/2015/cp-11-979-2015.pdf
http://www.clim-past.net/11/979/2015/cp-11-979-2015.html

Abstract: "Until now, the lack of time-continuous, terrestrial paleoenvironmental data from the Pleistocene Arctic has made model simulations of past interglacials difficult to assess. Here, we compare climate simulations of four warm interglacials at Marine Isotope Stages (MISs) 1 (9 ka), 5e (127 ka), 11c (409 ka) and 31 (1072 ka) with new proxy climate data recovered from Lake El'gygytgyn, NE Russia. Climate reconstructions of the mean temperature of the warmest month (MTWM) indicate conditions up to 0.4, 2.1, 0.5 and 3.1 °C warmer than today during MIS 1, 5e, 11c and 31, respectively. While the climate model captures much of the observed warming during each interglacial, largely in response to boreal summer (JJA) orbital forcing, the extraordinary warmth of MIS 11c compared to the other interglacials in the Lake El'gygytgyn temperature proxy reconstructions remains difficult to explain. To deconvolve the contribution of multiple influences on interglacial warming at Lake El'gygytgyn, we isolated the influence of vegetation, sea ice and circum-Arctic land ice feedbacks on the modeled climate of the Beringian interior. Simulations accounting for climate–vegetation–land-surface feedbacks during all four interglacials show expanding boreal forest cover with increasing summer insolation intensity. A deglaciated Greenland is shown to have a minimal effect on northeast Asian temperature during the warmth of stages 11c and 31 (Melles et al., 2012). A prescribed enhancement of oceanic heat transport into the Arctic Ocean does have some effect on Lake El'gygytgyn's regional climate, but the exceptional warmth of MIS 11c remains enigmatic compared to the modest orbital and greenhouse gas forcing during that interglacial."

Extract: "The timing of significant warming in the circum-Arctic can be linked to major deglaciation events in Antarctica, demonstrating possible interhemispheric linkages between the Arctic and Antarctic climate on glacial–interglacial timescales, which have yet to be explained."
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Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #992 on: April 29, 2019, 06:15:48 PM »
As some has noted earlier in this thread, RCP2.6 is no longer attainable.
https://news.agu.org/press-release/new-studies-highlight-challenge-of-meeting-paris-agreement-climate-goals/
A short quote and snipping out the top image from the second study with Peters.
Quote
Stone, with the National Institute of Water and Atmospheric Research, said Peters’ study shows no one country can slip up in the goal to meet climate goals.

“It is hard to argue against their conclusion that we need to start seriously considering options such as the deployment of solar geoengineering, with all of the risks that entails, if the world is serious about achieving the Paris Agreement goals,” he said.

Note that the two studies referenced in that article relate to old information.  One is about Paris commitments made in 2015 and the other is about changes in carbon intensity of energy production from 1990 to 2016.  Two important trends in our favor have occurred since then.

One is that the renewables are now cheaper than operating coal (and will soon be cheaper than operating natural gas) in many countries, including the US and the EU.  That means that it will be rare for new coal plants to be built and in many instances it will be cheaper to shut down an operating coal plant and replace it with wind or solar.

The other is that the cost trends for battery electric vehicles (BEV) are on pace to make them cheaper than internal combustion engine (ICE) by 2020.  It's difficult to assume that new ICEs will be sold in the 2030s and that there will be infrastructure (such as gas stations or repair shops) to serve operating ICEs in the future.

So basically, we could achieve much lower carbon emissions by the 2030s and get to 5% of current emissions by 2050.  There was a study published earlier this that indicates the current fossil fuel infrastructure can be replaced by non-carbon emitting sources at the end of it's useful life and we could still be within the 1.5 C emissions limit.

https://www.nature.com/articles/s41467-018-07999-w

Quote

Current fossil fuel infrastructure does not yet commit us to 1.5 °C warming
Christopher J. Smith, Piers M. Forster, Myles Allen, Jan Fuglestvedt, Richard J. Millar, Joeri Rogelj & Kirsten Zickfeld

Nature Communications volume 10, Article number: 101 (2019)  |  Download Citation

Abstract

Committed warming describes how much future warming can be expected from historical emissions due to inertia in the climate system. It is usually defined in terms of the level of warming above the present for an abrupt halt of emissions. Owing to socioeconomic constraints, this situation is unlikely, so we focus on the committed warming from present-day fossil fuel assets. Here we show that if carbon-intensive infrastructure is phased out at the end of its design lifetime from the end of 2018, there is a 64% chance that peak global mean temperature rise remains below 1.5 °C. Delaying mitigation until 2030 considerably reduces the likelihood that 1.5 °C would be attainable even if the rate of fossil fuel retirement was accelerated. Although the challenges laid out by the Paris Agreement are daunting, we indicate 1.5 °C remains possible and is attainable with ambitious and immediate emission reduction across all sectors.

And as I mentioned above, many fossil fuel power plants (especially coal plants and natural gas peakers) will be replaced by renewables before the end of their useful life, because renewable energy is now cheaper than those plants.

So RCP 2.6 is still feasible.  In 2018, the IPCC published a study indicating that it's still possible to limit warming to 1.5C (although 2C is easier).

https://www.ipcc.ch/sr15/chapter/summary-for-policy-makers/

Quote
C.1. In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO2 emissions decline by about 45% from 2010 levels by 2030 (40–60% interquartile range), reaching net zero around 2050 (2045–2055 interquartile range). For limiting global warming to below 2°C CO2 emissions are projected to decline by about 25% by 2030 in most pathways (10–30% interquartile range) and reach net zero around 2070 (2065–2080 interquartile range). Non-CO2 emissions in pathways that limit global warming to 1.5°C show deep reductions that are similar to those in pathways limiting warming to 2°C. (high confidence) (Figure SPM.3a) {2.1, 2.3, Table 2.4}

C.1.1. CO2 emissions reductions that limit global warming to 1.5°C with no or limited overshoot can involve different portfolios of mitigation measures, striking different balances between lowering energy and resource intensity, rate of decarbonization, and the reliance on carbon dioxide removal. Different portfolios face different implementation challenges and potential synergies and trade-offs with sustainable development. (high confidence). (Figure SPM.3b) {2.3.2, 2.3.4, 2.4, 2.5.3}

C.1.2. Modelled pathways that limit global warming to 1.5°C with no or limited overshoot involve deep reductions in emissions of methane and black carbon (35% or more of both by 2050 relative to 2010). These pathways also reduce most of the cooling aerosols, which partially offsets mitigation effects for two to three decades. Non-CO2 emissions12 can be reduced as a result of broad mitigation measures in the energy sector. In addition, targeted non-CO2 mitigation measures can reduce nitrous oxide and methane from agriculture, methane from the waste sector, some sources of black carbon, and hydrofluorocarbons. High bioenergy demand can increase emissions of nitrous oxide in some 1.5°C pathways, highlighting the importance of appropriate management approaches. Improved air quality resulting from projected reductions in many non-CO2 emissions provide direct and immediate population health benefits in all 1.5°C model pathways. (high confidence) (Figure SPM.3a) {2.2.1, 2.3.3, 2.4.4, 2.5.3, 4.3.6, 5.4.2}

Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #993 on: April 29, 2019, 06:25:59 PM »
Ken,

I am going to assume that you are not trolling me, as I know virtually nothing about you, so I will briefly (in two posts) re-post information that I provided earlier in this thread in order to try to clarify both my logic and evidence for a plausible initiation of a MICI-type of collapse of most of the WAIS circa 2040:


Abrupt SLR,

I'm not trolling you.  As I posted above, I believe that we can still keep the global temperature increase to less than 2C (and maybe even 1.5C, although we'll probably end up closer to 2C). 

The UNFCC in 1992 set the 2C limit because above 3C is believed to be the temperature at which threshold events occur.  The world has been up to 3C warmer during interglacials and CO2 and methane levels were much lower that today, which indicates that there weren't massive releases from the Arctic permafrost or methane clathrates.  So limiting the temperature increase to 2C avoids worst case scenarios.

The IPCC makes it clear that at 1.5C there are many bad impacts (worse droughts, worse floods, worse tropical storms, etc...) and they get worse the warmer you go.  The jury is still out on sea level rise though, which is why I asked you about the 2040 to 2050 initiation of rapid sea level rise.

Thanks for posting the studies in response to my questions.  I'll look them up and read them.  It's helpful to go beyond the abstracts and see how they modeled the events to reach their conclusions, as often they assume some starting point the in the future that will take decades or centuries to be reached (if they occur).

wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #994 on: April 29, 2019, 07:18:29 PM »
Ken,

While I appreciate your perspective, it seems to be out of step with reality.

The first image below was recently tweeted by Greta Thunberg showing that pathways required to limit warming to 1.5C (see below). All realistic pathways rely on negative emissions, which will either require massive reforestation (which means limiting and reversing urban sprawl and other development), or carbon capture technology powered by non-emitting energy sources we currently do not have.

The second set of three images comes from Glen Peters, Research Director at the Centre for International Climate Research. It shows the required emissions reductions for 2C, or to meet the Paris agreement. It shows what is required by the rest of the world if India, China, the Euro zone and the US achieve emissions reductions consistent with Paris.

Caption: a) Global warming under 2 °C with a 75% probability, with negligible development of engineered sinks and land use change (LUC); (b) global warming under 2 °C with a 66% probability and negligible development in engineered sinks and LUC; and (c) global warming under 2 °C with a 75% probability, and with scalable development in engineered sinks and LUC.)

Please note three things, which Glen Peters also recognizes: 1) As far as we know, passing 2C of warming will make it very difficult to avoid catastrophic climate change; 2) The image assumes 2017 as a turnaround date. This did not happen (nor is it expected to happen this year), making the required reductions even more significant; 3) It is likely that the emissions pathways laid out are optimistic, since they rely on IPCC projections which have been proven to understate the risks; and it has recently been confirmed that emissions from the tar sands are up to 64% higher than reported (see https://www.cbc.ca/news/technology/oilsands-carbon-emissions-study-1.5106809?__vfz=medium%3Dsharebar). If this is the case in Canada we can expect that emissions are also higher than reported elsewhere in the world, meaning that we have already emitted more (and potentially much more) than assumed by these pathways.

Last month a "massive analysis" came out stating all of the above in a different way:

"The massive analysis shows that meeting the 2C target is exceptionally difficult in all but the most optimistic climate scenarios. One pathway is to immediately and aggressively pursue carbon-neutral energy production by 2030 and hope that the atmosphere's sensitivity to carbon emissions is relatively low, according to the study. If climate sensitivity is not low, the window to a tolerable future narrows and in some scenarios, may already be closed.

... If the climate sensitivity is greater than 3 Kelvin (median of assumed distribution), the pathway to a tolerable future is likely already closed."

Subsequent to this massive analysis, the preliminary results from the new generation of climate models -- which will inform the next IPCC report -- began to be released.

"Early results suggest ECS values from some of the new CMIP6 climate models are higher than previous estimates, with early numbers being reported between 2.8C and 5.8C. This compares with the previous coupled model intercomparison project (CMIP5), which reported values between 2.1C to 4.7C. The IPCC’s fifth assessment report (AR5) assessed ECS to be “likely” in the range 1.5C to 4.5C and “very unlikely” greater than 6C. (These terms are defined using the IPCC methodology.)"

https://www.carbonbrief.org/guest-post-why-results-from-the-next-generation-of-climate-models-matter

The median given by AR5 was 3C (or 3K). The difference with the new models is represented graphically below in the third image.

As we are now seeing the new models are giving a value of ECS ranging from 2.8C to 5.8C, with a median of 4.3C.

So what is to be gained by assuming the lower risk scenarios, when, should you be wrong -- as I would suggest the overwhelming amount of evidence now indicates -- we expose ourselves to a tremendous amount of risk?

This seems to me the underlying message of ASLR's posts.

« Last Edit: April 29, 2019, 08:00:20 PM by wdmn »

b_lumenkraft

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #995 on: April 29, 2019, 07:22:35 PM »
Ken,

While I appreciate your perspective, it seems to be out of step with reality.

i was about to write something along the same lines. Thanks Wdmn for writing it and'll just add a '+1'.

Stephan

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #996 on: April 29, 2019, 09:13:01 PM »
I looked at the bedrock map tealight recently published here in the "What's new in Antarctica?" thread.
I looked at the connection between the Antarctic Peninsula (AP) and the ridge that forms the Transantarctic Mountains (TAM). If you put all the ice away there is a big gap between AP and TAM (white circle in the map). To the northeast is Weddell Sea, to the Northwest it is the WAIS and the PIG, followed by the Amundsen Sea. So once there should be a free flow of ocean waters between Weddell Sea and Amundsen Sea which probably puts all ocean currents in that area upside down. Is there any historical evidence that this area had ever been open? And what would that mean to the stability of the WAIS (if it still exists in parts at that stage)? Is there any danger of MISI or other mechanisms of that circled area caused by / coming from Weddell Sea?
It is too late just to be concerned about Climate Change

Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #997 on: April 29, 2019, 10:11:45 PM »
I'm surprised by the tone of the responses I get when I post a scientific study that contradicts the contention that we're all doomed to perish in a climate catastrophe.  And I'm curious about some of the responses I see on this website when posting positive articles about renewable energy or advocating for cracking down on fossil fuel emissions.

Do you think it doesn't matter?  That there's no point in advocating for change?

Should we just be placing bets on when the first blue ocean event in the Arctic Ocean will occur or the first evidence of widespread MICI in the WAIS?


sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #998 on: April 29, 2019, 10:19:57 PM »
"Is there any historical evidence that this area [Weddel - Amundsen - Ross ] had ever been open? "

Yes. There is paleo evidence of this, but i have not presently the time to find the reference.

sidd

sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #999 on: April 29, 2019, 10:21:20 PM »
"tone of the responses"

Well we have our catastrophists and we have our pollyannas . Judicious use of the ignore buttons might help the thin skinned.

sidd