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    • What CO2 level would cause the Greenland ice sheet to collapse?

      Posted on 23 March 2010 by John Cook

      A matter of concern is the potential instability of the Greenland and Antarctic ice sheets. If the Greenland ice sheet was to completely collapse, it would contribute as much as 7 metres sea level rise. Similarly, the West Antarctic ice sheet would contribute around 6 metres sea level rise. East Antarctica would contribute 70 metres of sea level rise but is less prone to collapse. Consequently, how these ice sheets respond to warming temperatures is a crucial area of research. A new paper (Stone 2010) has been published that estimates that the CO2 level that will lead to collapse of the Greenland ice sheet is between 400 to 560 parts per million (ppm). At our current rate, we should pass 400 ppm within 10 years.

      While there are uncertainties over the specifics of ice sheet behaviour, there are several lines of independent evidence that paint a consistent picture of how ice sheets will respond to global warming. Focusing on Greenland, what do observations tell us has been happening to the Greenland ice sheet? Satellites use gravity data to measure the total mass balance and have found the ice sheet is losing ice mass at an accelerating rate (Velicogna 2009).


      Figure 1: Ice mass changes for the Greenland ice sheet estimated from GRACE satellite measurements. Unfiltered data are blue crosses. Data filtered for the seasonal dependence are shown as red crosses. The best-fitting quadratic trend is shown as a green line(Velicogna 2009).

      How can we know how the Greenland ice sheet will behave over a longer time period? We can determine this by looking at how the ice sheet has responded in the past. Some of the more optimistic emission scenarios from the IPCC predict warming of 1 to 2°C. The last time temperatures were this high were 125,000 years ago. At this time, sea levels were over 6 metres higher than current levels (Kopp 2009). This tells us that the Greenland and Antarctic ice sheets are highly sensitive to sustained, warmer temperatures and that in upcoming centuries, we can expect sea level rise in the range of metres, not centimetres.

      Further light is shed on Greenland ice sheet stability in a new paper The effect of more realistic forcings and boundary conditions on the modelled geometry and sensitivity of the Greenland ice-sheet (Stone 2010). This paper uses updated data on bedrock topography and ice thickness to produce more accurate modelling results of Greenland ice sheetbehaviour. They model how the Greenland ice sheet will respond to three different scenarios with atmospheric CO2 held at 400 ppm, 560 ppm and 1120 ppm. The simulations are run over a 400 year period.

      Although not completely collapsed, the 400 ppm ice-sheet loses ice mass in the north of the island, with a total reduction in ice volume ranging between 20 to 41%. Note - due to the large inertia of the Greenland ice sheet, this mass loss doesn't happen at the moment CO2levels reach 400 ppm but over a period of centuries. Under a 560 ppm climate, the Greenland ice sheet loses between 52 to 87% of its ice volume. If CO2 reaches 1120 ppm, there is almost complete elimination of the Greenland ice sheet with loss between 85 to 92%. The important result from this paper is that there is a critical threshold where the Greenland ice sheet becomes unstable somewhere between 400 and 560 ppm.

      This is a large uncertainty range and one imagines there will be much research in the next few years to reduce the uncertainty. However, the 400 to 560 ppm range is put into perspective when you look at the projected CO2 levels for the various IPCC scenarios. The business as usual scenario has CO2 levels reaching 1000 ppm by 2100. Even the most optimistic scenario tops 500 ppm by 2100.


      Figure 3: Atmospheric CO2 concentrations as observed at Mauna Loa from 1958 to 2008 (black dashed line) and projected under the 6 IPCC emission scenarios (solid coloured lines). (IPCC Data Distribution Centre)

      Of course, Figure 3 displays projected scenarios. What has been happening in the real world? Observed CO2 emissions in recent years have actually been tracking close to or above the worst case scenario.


      Figure 4: Observed global CO2 emissions from fossil fuel burning and cement production compared with IPCC emissions scenarios. The coloured area covers all scenarios used to project climate change by the IPCC (Copenhagen Diagnosis).

      Satellite measurements, paleoclimate data and ice sheet modelling all paint a consistent picture. Global warming is destabilising the Greenland ice sheet which is highly sensitive to sustained warmer temperatures. Our current trajectory with CO2 emissions will likely cause at least several metres sea level rise from the Greenland ice sheet over the next few centuries. Of course, we shouldn't forget that this estimate doesn't include Antarctica - the Antarctic ice sheet is also losing ice at an accelerating rate.

      Comment


      • Duh!
        Tree planting 'has mind-blowing potential' to tackle climate crisis
        Research shows a trillion trees could be planted to capture huge amount of carbon dioxide
        ...
        https://www.theguardian.com/environm...=pocket-newtab

        Last edited by G David Bock; 07 Jul 19, 16:38.

        Comment


        • Originally posted by bill shack View Post
          False figures

          Comment


          • Originally posted by G David Bock View Post
            Duh!
            Tree planting 'has mind-blowing potential' to tackle climate crisis

            Research shows a trillion trees could be planted to capture huge amount of carbon dioxide



            ...
            https://www.theguardian.com/environm...=pocket-newtab
            My faith in the scientists behind global warming is so low I suspect the role that agriculture plays has been significantly underestimated. The amount of deforestation that has taken place just in the twentieth century is mind boggling.
            We hunt the hunters

            Comment


            • Originally posted by G David Bock View Post
              Duh!
              Tree planting 'has mind-blowing potential' to tackle climate crisis

              Research shows a trillion trees could be planted to capture huge amount of carbon dioxide



              ...
              https://www.theguardian.com/environm...=pocket-newtab
              there's something that we can agree on.
              The 'scientists integrity ' posts in this forum, and their accompanying blogs are almost always a red herring. climate change science measures 'correlation'. IF the temperatures world wide are rising, and IF the glaciers/icecaps are visibly and measuring melting while Co2 levels in the atmosphere increase, then all the red herrings in the world don't change the correlation.

              Of course, we can return to medieval times, and blame the witches.....
              make your choice...
              The trout who swims against the current gets the most oxygen..

              Comment


              • Originally posted by G David Bock View Post

                Omits the anthropogenic prefix.

                Still awaiting proof that CO2 levels, currently barely above minimum needed to sustain life on this planet is the primary driver of current change/warming. i.e. proof of linkage and causative effect, rather than coincidental ghosting lag shown from some data charts.

                Still awaiting your explanation for the several prior times in past millions of years when temp was higher while CO2 was lower;
                AND
                why you'd rather drive towards that glaciation/Ice Age condition that dominates 90% of climate history.

                Do you understand that climate is never stagnate and that the relatively "mild" and temporary warming of the past 10,000 years is the anomaly and still unexplained?
                As I have pointed out upteen times, g David, If you don't accept correlation as at least a strong symptom of causality, there is little that can be said to convince you.
                The trout who swims against the current gets the most oxygen..

                Comment


                • Originally posted by G David Bock View Post
                  Part Two:
                  As I understand things, Snowshoveler was referring to this;

                  Glacier National Park Quietly Removes Its 'Gone by 2020' Signs ...
                  https://wattsupwiththat.com/.../glacier-national-park-quietly-removes-its-gone-by-202...


                  National Parks Quietly Toss Signs Saying Glaciers ‘Will Be Gone’ By 2020 (They’re Growing)
                  https://www.climatedepot.com/2019/06...heyre-growing/

                  Oh, So That's Why The 'Glaciers Will Be Gone In 2020' Sign Has Been Removed At A National Park
                  https://townhall.com/tipsheet/mattve...-at-a-n2547957

                  Glacier National Park Quietly Ditches Signs Saying Glaciers Will ‘All Be Gone’ By 2020
                  https://www.thegatewaypundit.com/201...-gone-by-2020/

                  The NPS Removes all “Glaciers Gone by 2020” signs at Glacier National Park, Montana after “Larger-than-Average Snowfall over Several Winters”
                  https://electroverse.net/the-nps-rem...veral-winters/

                  Glacier National Park Quietly Removes Its "Gone By 2020" Signs
                  https://www.zerohedge.com/news/2019-...one-2020-signs

                  National park ditches signs saying glaciers will be gone by 2020
                  https://hotair.com/archives/2019/06/...ill-gone-2020/

                  National Parks Toss Signs Warning Of Melting Glaciers After Glaciers Fail To Melt
                  https://www.dailywire.com/news/48287...-emily-zanotti

                  ETC. ;
                  https://www.google.com/search?client...+by+2020+signs

                  Notice that many of the above mention that the glaciers have started to "grow" in recent years ...
                  I read them all, G David, and all I saw is a series of bloggers trying to make a fast buck preaching to the converted. A repeat of the 'laudable puss' doctors of the eighteenth century.. earnestly proclaiming a science that was based on 'speculation'.

                  Your "growing glaciers argument is disproved by the USGS study.

                  Please READ IT.
                  The trout who swims against the current gets the most oxygen..

                  Comment


                  • Originally posted by Daemon of Decay View Post
                    |\\\

                    Which is why it was moved into the politics and environmentalism thread, provided for subjects just like these.
                    rather like the scat and dump sandpit that, hopefully, keeps the rest of the playground somewhat pristine, D of D

                    The trout who swims against the current gets the most oxygen..

                    Comment


                    • Originally posted by marktwain View Post

                      there's something that we can agree on.
                      The 'scientists integrity ' posts in this forum, and their accompanying blogs are almost always a red herring. climate change science measures 'correlation'. IF the temperatures world wide are rising, and IF the glaciers/icecaps are visibly and measuring melting while Co2 levels in the atmosphere increase, then all the red herrings in the world don't change the correlation.

                      Of course, we can return to medieval times, and blame the witches.....
                      make your choice...
                      This is not necessarily true. You are making a cum hoc fallacy. In this you, and most climate scientists are claiming because CO2 is going up and temperatures are going up, that the two are related. It is entirely possible that in a system as complex as a planetary atmosphere, that this isn't the case. I don't think the scientists studying this have a good grasp on how the planetary atmosphere really works.

                      We were told that if we got rid of CFC's back in the 80's that by today the hole in the ozone layer over the South Pole would be gone. It's still there, and depending on who you ask, it possibly always will be to some degree.

                      The IPCC has made so many wrong predictions it hurts.

                      The point I'm making is that there are other potential causes of climate change beyond CO2. The fixation on one potential cause and one potential solution is myopic at best and ignorant at worst.

                      Comment


                      • Originally posted by G David Bock View Post
                        Part Two:
                        As I understand things, Snowshoveler was referring to this;

                        Glacier National Park Quietly Removes Its 'Gone by 2020' Signs ...
                        https://wattsupwiththat.com/.../glacier-national-park-quietly-removes-its-gone-by-202...


                        National Parks Quietly Toss Signs Saying Glaciers ‘Will Be Gone’ By 2020 (They’re Growing)
                        https://www.climatedepot.com/2019/06...heyre-growing/

                        Oh, So That's Why The 'Glaciers Will Be Gone In 2020' Sign Has Been Removed At A National Park
                        https://townhall.com/tipsheet/mattve...-at-a-n2547957

                        Glacier National Park Quietly Ditches Signs Saying Glaciers Will ‘All Be Gone’ By 2020
                        https://www.thegatewaypundit.com/201...-gone-by-2020/

                        The NPS Removes all “Glaciers Gone by 2020” signs at Glacier National Park, Montana after “Larger-than-Average Snowfall over Several Winters”
                        https://electroverse.net/the-nps-rem...veral-winters/

                        Glacier National Park Quietly Removes Its "Gone By 2020" Signs
                        https://www.zerohedge.com/news/2019-...one-2020-signs

                        National park ditches signs saying glaciers will be gone by 2020
                        https://hotair.com/archives/2019/06/...ill-gone-2020/

                        National Parks Toss Signs Warning Of Melting Glaciers After Glaciers Fail To Melt
                        https://www.dailywire.com/news/48287...-emily-zanotti

                        ETC. ;
                        https://www.google.com/search?client...+by+2020+signs

                        Notice that many of the above mention that the glaciers have started to "grow" in recent years ...
                        G David, in the 1920's scientists pointing out the correlations between the dangers of radium in face paints, cosmetics, nAil polish and of course, the 'wonder tonic of Radithor ' were castigated by the ballyhoo press of the day.

                        Until the bone necrosis rates and the horror photos came in.....

                        We have been here nbefore.


                        BTW, stay away form Radithor…

                        and ,the glaciers in Glacier NATIONAL PARK CONTINUE TO SHRINK. I've BEEN THERE, And have hiked the continental divide with their wonderfull field staff.
                        Last edited by marktwain; 07 Jul 19, 08:31.
                        The trout who swims against the current gets the most oxygen..

                        Comment


                        • Originally posted by marktwain View Post

                          there's something that we can agree on.
                          The 'scientists integrity ' posts in this forum, and their accompanying blogs are almost always a red herring. climate change science measures 'correlation'. IF the temperatures world wide are rising, and IF the glaciers/icecaps are visibly and measuring melting while Co2 levels in the atmosphere increase, then all the red herrings in the world don't change the correlation.

                          Of course, we can return to medieval times, and blame the witches.....
                          make your choice...
                          Science doesn't measure correlation. One of the cardinal axioms of science is that correlation is not causation.
                          We hunt the hunters

                          Comment


                          • Originally posted by marktwain View Post

                            I read them all, G David, and all I saw is a series of bloggers trying to make a fast buck preaching to the converted. A repeat of the 'laudable puss' doctors of the eighteenth century.. earnestly proclaiming a science that was based on 'speculation'.

                            Your "growing glaciers argument is disproved by the USGS study.

                            Please READ IT.
                            Why should we believe any word from the USGS, especially as this is an anti Trump government institution .

                            Comment


                            • Originally posted by wolfhnd View Post

                              Science doesn't measure correlation. One of the cardinal axioms of science is that correlation is not causation.
                              With all due respect- wrong.
                              Science finds REASONS for correlation. It's why we no longer have formaldehyde in children's milk. for example. the Correlation between deaths and formaldehyde became too obvious.
                              The trout who swims against the current gets the most oxygen..

                              Comment


                              • Originally posted by The Doctor View Post
                                The Political Environmentalism Thread

                                Since bureaucrats are incapable of doing anything useful, this should be no surprise...
                                New study translated: public servants are more likely to become eco-activists

                                For example, for NASA GISS administrator, James Hansen, aka patient zero, seen below being arrested at a climate protest ...


                                UGA research reveals public servants individually motivated to help environment

                                Athens, Ga. – New University of Georgia research shows that while on the job, public servants contribute not just to mandated sustainability but also to discretionary…

                                [...]

                                http://wattsupwiththat.com/2014/12/0...eco-activists/
                                I miss the doc's ability to reason from the specific to the general in no time flat.,,,,,,,,
                                where IS the ol rooster, anyway??
                                The trout who swims against the current gets the most oxygen..

                                Comment

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