As Climate Worsens, a Cascade of Tipping Points Looms

Discussion in 'Environment & Conservation' started by skepticalmike, Dec 15, 2019.

  1. skepticalmike

    skepticalmike Active Member

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    This is about new research presented originally at Nature.com and elaborated on at Yale Environment 360.

    New research warns that the earth may be approaching key tipping points, including the runaway loss of ice sheets, that could fundamentally disrupt the global climate system. A growing concern is a change in ocean circulation, which could alter climate patterns in a profound way (Yale Environment360)

    https://e360.yale.edu/features/as-climate-changes-worsens-a-cascade-of-tipping-points-looms

    https://www.nature.com/articles/d41586-019-03595-0

    IPCC reports from 2001 to 2018 show a trend towards a lowering of the GMT threshold above pre-industrial levels for tipping points to occur.

    [​IMG]


    Even if this research turns out to be wrong that any tipping point thresholds will
    occur at a GMT increase of 2 degrees C. above pre-industrial levels, the GMT
    could be somewhere around 3 degrees C by the end of the 21st century.

    Below is from Nature.com:

    If current national pledges to reduce greenhouse-gas emissions are implemented — and that’s a big ‘if’ — they are likely to result in at least 3 °C of global warming. This is despite the goal of the 2015 Paris agreement to limit warming to well below 2 °C. Some economists, assuming that climate tipping points are of very low probability (even if they would be catastrophic), have suggested that 3 °C warming is optimal from a cost–benefit perspective. However, if tipping points are looking more likely, then the ‘optimal policy’ recommendation of simple cost–benefit climate-economy models4 aligns with those of the recent IPCC report2. In other words, warming must be limited to 1.5 °C. This requires an emergency response.

    The 2 paragraphs below are from the Yale Education 360 article:

    The potential tipping points come in three forms: runaway loss of ice sheets that accelerate sea level rise; forests and other natural carbon stores such as permafrost releasing those stores into the atmosphere as carbon dioxide (CO2), accelerating warming; and the disabling of the ocean circulation system.

    Their biggest fear is for the future of the global ocean circulation system, which moves heat around the world and may dictate global climate. They say melting Greenland ice in a warmer Arctic has driven a key component of ocean circulation to a thousand-year low. Further decline, which would lead to a shift in heat distribution around the planet, could trigger forest collapse in the Amazon; cause near-permanent drought in Africa’s Sahel region; disrupt Asian monsoons; rapidly warm the Southern Ocean, which would cause a surge in global sea levels as the West Antarctic Ice Sheet disintegrates; and potentially shift the planet to a new climate regime they call “hothouse Earth.”

    The Portions below are from the Nature.com article:

    We think that several cryosphere tipping points are dangerously close, but mitigating greenhouse-gas emissions could still slow down the inevitable accumulation of impacts and help us to adapt.

    Research in the past decade has shown that the Amundsen Sea embayment of West Antarctica might have passed a tipping point3: the ‘grounding line’ where ice, ocean and bedrock meet is retreating irreversibly. A model study shows5 that when this sector collapses, it could destabilize the rest of the West Antarctic ice sheet like toppling dominoes — leading to about 3 metres of sea-level rise on a timescale of centuries to millennia. Palaeo-evidence shows that such widespread collapse of the West Antarctic ice sheet has occurred repeatedly in the past.

    The latest data show that part of the East Antarctic ice sheet — the Wilkes Basin — might be similarly unstable3. Modelling work suggests that it could add another 3–4 m to sea level on timescales beyond a century.

    The Greenland ice sheet is melting at an accelerating rate3. It could add a further 7 m to sea level over thousands of years if it passes a particular threshold. Beyond that, as the elevation of the ice sheet lowers, it melts further, exposing the surface to ever-warmer air. Models suggest that the Greenland ice sheet could be doomed at 1.5 °C of warming3, which could happen as soon as 2030.
     
    Last edited: Dec 15, 2019
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  2. Hoosier8

    Hoosier8 Well-Known Member Past Donor

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    I would think after 3 decades of failed alarmist predictions some would get a clue. Guess not.
     
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  3. gfm7175

    gfm7175 Well-Known Member

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    More Church of Global Warming bullshit...

    Would you like me to demolish the content of your post line by line?
     
  4. skepticalmike

    skepticalmike Active Member

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    Diagram below is from National Geographic, "Climate change driving entire planet to dangerous global tipping point". https://www.nationalgeographic.com/science/2019/11/earth-tipping-point/

    The Atlantic Meridional Overturning Circulation (AMOC) is at a very low risk of shutting down during the 21st century - less than 10%. It is at risk of slowing down between 20% to 50% by 2100.

    From the Guardian: https://www.theguardian.com/environ...-threat-with-2c-global-warming-un-report-says

    Limiting global warming to 1.5C rather than 2C would likely be the difference between the survival of some Great Barrier Reef coral and its complete decline, according to the latest United Nations assessment of climate change science.

    The Intergovernmental Panel on Climate Change special report on the impact of global warming of 1.5C above pre-industrial levels, released in South Korea on Monday, found coral reefs were likely to decline between 70% and 90% if the temperature increased to that level. If global warming reaches 2C, more than 99% of coral reefs were projected to decline.


    [​IMG]
     
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  5. FatBack

    FatBack Well-Known Member

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    We are all going to die horrible deaths unless we give the Gov. the unchecked power to micromanage every aspect of human existence.

    Nothing more than a powergrab. Been hearing the same alarmism for decades.
     
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  6. gfm7175

    gfm7175 Well-Known Member

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    National Geographic is not science.
    Diagrams are not science.

    Define "climate change".
    Define "tipping point".

    So?

    The Guardian is not science.

    It is not possible to measure the temperature of the Earth. We do not have near enough thermometers to perform such a statistical analysis.

    Barrier reefs are fine. Define "climate change". Undefined buzzwords are not science. No theory of science is based on an undefined buzzword.

    The IPCC is not science.
    Define "global warming".
    Define "pre-industrial levels".
    It is not possible to measure the temperature of the Earth. We don't have near enough thermometers to perform such a statistical analysis.

    Reefs are fine. Global temperature cannot be measured.
     
  7. skepticalmike

    skepticalmike Active Member

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    This is an article on the positive feedback contribution from the melting of all Arctic sea ice which may occur sometime in the future. 0.21 watts per square meter of positive feedback has already occurred since
    1979.

    Research Highlight: Loss of Arctic's Reflective Sea Ice Will Advance Global Warming by 25 Years - Scripps Institution of Oceanography

    https://scripps.ucsd.edu/news/resea...e-sea-ice-will-advance-global-warming-25-year

    Losing the remaining Arctic sea ice and its ability to reflect incoming solar energy back to space would be equivalent to adding one trillion tons of CO2 to the atmosphere, on top of the 2.4 trillion tons emitted since the Industrial Age, according to current and former researchers from Scripps Institution of Oceanography at the University of California San Diego.

    At current rates, this roughly equates to 25 years of global CO2 emissions. It would consequently speed up the arrival of a global threshold of warming of 2ºC beyond temperatures the world experienced before the Industrial Revolution. Scientists and analysts, including the authors of an Intergovernmental Panel on Climate Change Special Report released in October 2018, have stated that the planet runs the risk of catastrophic damage ranging from more intense heat waves and coastal flooding to extinction of terrestrial species and threats to food supply if that threshold is passed.

    The results were published June 20 in the journal Geophysical Research Letters. In “Radiative Heating of an Ice-Free Arctic Ocean,” former Scripps graduate student Kristina Pistone, now with the Bay Area Environmental Research Institute based at NASA Ames Research Center, and Scripps climate scientists Ian Eisenman and Veerabhadran Ramanathan used direct satellite observations to assess the impact of a potential ice-free Arctic Ocean. The authors of the study conclude that the loss of sea ice will add a globally-averaged 0.7 watts per square meter (W/m2) of solar heating to the Earth system, 0.21 W/m2 of which has already occurred between 1979 and 2016.

    The amount of additional heat introduced into the Earth system because of Arctic melt is equivalent to an increase in CO2 concentration from 400 to 456.7 parts per million.

    “Losing the reflective power of Arctic sea ice will lead to warming equivalent to one trillion tons of CO2 and advance the 2ºC threshold by 25 years. Any rational policy would make preventing this a top climate priority for world leaders,” said Ramanathan, a professor of atmospheric and climate sciences at Scripps.


    Here is an article at the New York Times on the accelerating ice loss in Greenland, "one degree of warming in the future will have way more impact than one degree of warming in the last century".

    Greenland’s Melting Ice Nears a ‘Tipping Point,’ Scientists Say
    https://www.nytimes.com/2019/01/21/...&utm_medium=email&utm_source=Revue newsletter

    Greenland’s enormous ice sheet is melting at such an accelerated rate that it may have reached a “tipping point” and could become a major factor in sea-level rise around the world within two decades, scientists said in a study published on Monday.

    The Arctic is warming at twice the average rate of the rest of the planet, and the new research adds to the evidence that the ice loss in Greenland, which lies mainly above the Arctic Circle, is speeding up as the warming increases. The authors found that ice loss in 2012, more than 400 billion tons per year, was nearly four times the rate in 2003. After a lull in 2013-14, losses have resumed.

    The study is the latest in a series of papers published this month suggesting that scientific estimates of the effects of a warming planet have been, if anything, too conservative. Just a week ago, a separate study of ice loss in Antarctica found that the continent is contributing more to rising sea levels than previously thought.

    Another new analysis suggested that the oceans are warming far faster than earlier estimates. Warming oceans are currently the leading cause of sea-level rise, since water expands as it warms.

    Much of the previous research on Greenland’s ice has dealt with the southeast and northeast parts of the island, where large chunks of glacial ice calve into the sea. The new paper focuses on the ice-covered stretches of southwest Greenland, which has few large glaciers and was not generally considered as important a source of ice loss.

    But as the earth warms, the paper concludes, the vast plains of southwestern ice will increasingly melt, with the meltwater flowing to the ocean. Within two decades, it says, the region “will become a major contributor to sea level rise.”

    The study, which appears in the Proceedings of the National Academy of Sciences, used satellite data and ground-based instruments to measure Greenland’s ice loss in the 21st century. It looked closely at what seemed to be a pause in the ice loss for about a year, beginning in 2013, that followed a stretch of greatly accelerated melting.

    The researchers tied the pause in melting to a reversal of the cyclical weather phenomenon known as the North Atlantic Oscillation. Before the pause, the oscillation was in what is known as its negative phase, which is associated with warmer air hitting west Greenland, along with less snowfall and more sunlight, all of which contribute to ice loss. When the cycle shifted into a positive phase in 2013, an “abrupt slowdown” of melting occurred.

    Yet, the slowdown was anything but good news, said Michael Bevis, the lead author of the paper and a professor in the School of Earth Sciences at Ohio State University.

    The North Atlantic Oscillation has occurred throughout the historical record, he noted. But before 2000, overall average temperatures were cool enough that the N.A.O.’s positive and negative cycles did not have much of an effect on rates of melting in Greenland.

    Now, the strong effect that the cooler cycle had on the rate of melting — even if it was helpful in stopping ice loss — is a reason for concern, Dr. Bevis said. If the warm cycles of the N.A.O. are associated with huge losses of ice, and the cool cycles only pause the melting, it suggests a threshold has been reached: As average temperatures rise further, melting will be more sustained, and the cooling cycles will have less of an effect in slowing the ice loss.

    “If a relatively minor cycle can cause massive melting,” he said, “it means you’ve reached a point of amazing sensitivity” to warmer temperatures, which could represent “the tipping point.”

    And so, he said, “One degree of warming in the future will have way more impact than one degree of warming in the last century.”

    The new research dovetails with other recent papers on the accelerating melting. Last month a team of researchers published a paper in Nature that used satellite observations, analysis of ice cores and models to show that losses from the Greenland ice sheet have reached their fastest rate in at least 350 years.
     
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  8. tecoyah

    tecoyah Well-Known Member Past Donor

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    Several "Tipping Points" have already been reached and there is no going back.
     
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  9. Hoosier8

    Hoosier8 Well-Known Member Past Donor

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    After 3 decades of failed hysterical doom and gloom predictions one would think these alarmists would get a clue.
     
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  10. skepticalmike

    skepticalmike Active Member

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    This is from the Proceedings of the National Academy of Sciences (PNAS) of the U.S. The mass loss from Antarctica has been accelerating in recent decades while the snowfall accumulation has remained
    roughly constant.

    https://www.pnas.org/content/116/4/1095
    Four decades of Antarctic Ice Sheet mass balance from 1979–2017

    We use updated drainage inventory, ice thickness, and ice velocity data to calculate the grounding line ice discharge of 176 basins draining the Antarctic Ice Sheet from 1979 to 2017. We compare the results with a surface mass balance model to deduce the ice sheet mass balance. The total mass loss increased from 40 ± 9 Gt/y in 1979–1990 to 50 ± 14 Gt/y in 1989–2000, 166 ± 18 Gt/y in 1999–2009, and 252 ± 26 Gt/y in 2009–2017. In 2009–2017, the mass loss was dominated by the Amundsen/Bellingshausen Sea sectors, in West Antarctica (159 ± 8 Gt/y), Wilkes Land, in East Antarctica (51 ± 13 Gt/y), and West and Northeast Peninsula (42 ± 5 Gt/y). The contribution to sea-level rise from Antarctica averaged 3.6 ± 0.5 mm per decade with a cumulative 14.0 ± 2.0 mm since 1979, including 6.9 ± 0.6 mm from West Antarctica, 4.4 ± 0.9 mm from East Antarctica, and 2.5 ± 0.4 mm from the Peninsula (i.e., East Antarctica is a major participant in the mass loss). During the entire period, the mass loss concentrated in areas closest to warm, salty, subsurface, circumpolar deep water (CDW), that is, consistent with enhanced polar westerlies pushing CDW toward Antarctica to melt its floating ice shelves, destabilize the glaciers, and raise sea level.

    [​IMG]

    Time series of cumulative anomalies in SMB (blue), ice discharge (D, red), and total mass (M, purple) with error bars in billions of tons for (A) West Antarctica, (B) East Antarctica; (C) Antarctic Peninsula), and (D) Antarctica, with mean mass loss in billions of tons per year and an acceleration in billions of tons per year per decade for the time period 1979 to 2017. The balance discharge is SMB1979−2008" role="presentation" style="-webkit-font-smoothing: antialiased; box-sizing: border-box; display: inline; line-height: 1.4em; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">SMB1979−2008SMB1979−2008. Note that the total mass change, M = SMB − D, does not depend on SMB1979−2008" role="presentation" style="-webkit-font-smoothing: antialiased; box-sizing: border-box; display: inline; line-height: 1.4em; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">

    Recent observations have shown that the ice sheet is losing mass along the periphery due the enhanced flow of its glaciers, at a rate that has been increasing over time, while there is no long-term trend change in snowfall accumulation in the interior [i.e., Antarctica contributes to sea-level rise (SLR) principally via changes in ice dynamics] (57). Various techniques have been used to estimate ice sheet mass balance, including (i) the component method, which compares accumulation of snowfall over the interior basins with ice discharge by glaciers across the grounding line (where ice becomes afloat in ocean waters and detaches from the bed) at a high resolution (100 m to 1 km); (ii) the altimetry method, which measures elevation changes over the entire ice sheet and converts them into mass changes by assuming a density of change at intermediate resolution (1 to 10 km); and (iii) the gravity method, which measures directly the relative change in mass on a monthly basis, within centimeters per year, albeit at low resolution (333 km). The techniques have been compared (810) to yield reconciled numbers for ice-sheet-wide assessments for the time periods 1992–2011 and 1992–2017, except for East Antarctica, where uncertainties remain.
     
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  11. roorooroo

    roorooroo Well-Known Member Past Donor

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    Are you doing anything personally to prepare for the Armageddon which is approaching? If you would be so kind, please let me in on your efforts so I too can also be prepared for the inevitable. I mean, if you are truly concerned about what is happening, then you have surely been getting prepared, right?
     
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  12. AFM

    AFM Well-Known Member Past Donor

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    The Greenland ice sheet will be gone in 50 years. That’s hilarious. How thick is the ice sheet ??? What is the mechanism by which the ice sheet will melt ???

    Do you ever ask yourself basic questions ???
     
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  13. AFM

    AFM Well-Known Member Past Donor

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    Which tipping points are those ???
     
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  14. Bowerbird

    Bowerbird Well-Known Member

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    Translation

    “Panic panic panic government bad!!!”

    Doesn’t address the science
     
  15. Bowerbird

    Bowerbird Well-Known Member

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    Didn’t you read the OP?

    Hey! You could always do something novel and actually read an IPCC report or two
     
  16. Bowerbird

    Bowerbird Well-Known Member

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    Edited
    Meh! Not worth it
     
    Last edited: Dec 18, 2019
  17. Hoosier8

    Hoosier8 Well-Known Member Past Donor

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    Don't worry, the Greenland Ice Sheet will not disappear during this 2.5 million year long ice age. We are in an ice age you know.
     
    Last edited: Dec 18, 2019
  18. Bowerbird

    Bowerbird Well-Known Member

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    Summary of denialist posts so far

    “I don’t think so”
    “Government bad”
    “I haven’t read it but I know it is wrong”
    “I haven’t read it but I will keep asking you to do more research that I won’t read whilst asserting it is wrong and demanding more research”
    “It’s not science”( this is the most hilarious because it invariably comes from someone who does not use citations to support any claims)
     
  19. Hoosier8

    Hoosier8 Well-Known Member Past Donor

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    You still don't realize what this is based on.
     
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  20. AFM

    AFM Well-Known Member Past Donor

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    So you have nothing.
     
  21. jay runner

    jay runner Well-Known Member

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    Sky gonna fall, sky gonna fall.
     
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  22. AFM

    AFM Well-Known Member Past Donor

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    How thick is the Greenland ice sheet ??

    How long will it take for the Greenland ice sheet to melt with a consensus climate sensitivity to CO2 of 3 degrees Centigrade ??
     
  23. jay runner

    jay runner Well-Known Member

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    Why would there be anything wrong with the Greenland ice sheet melting completely? That would be a completely natural event, whatever the ramifications might be.
     
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  24. skepticalmike

    skepticalmike Active Member

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    The article states that models suggest that Greenland could be doomed with 1.5 degrees of warming. That doesn't mean that all of Greenland will melt down in 50 years., that is when destabilization could occur.

    One of the articles mentioned a 1000 year time frame for all of Greenland to melt at 2.0 degrees C. GMT above pre-industrial levels and several hundred years if the GMT rise to 3.0 degrees C. above

    pre-industrial levels. The risk of destabilization would be low at the 1.5 degree C. GMT level and gradually rise with increasing GMT.
     
  25. Hoosier8

    Hoosier8 Well-Known Member Past Donor

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    "The models". In science there is a saying, "all models are wrong". Even worse, the hysteria is based on the worst case/least likely model RCP8.5 that observed science is not following.
     
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