Visitor geological perspective by David Middleton
It is a type of a spin-off of Rutgers College World Snow Lab and “the Snows of Yesteryear” and A Geological Perspective of the Greenland Ice Sheet. And, sure, there are much more than 5 charts on this publish… And, none of them have been all that simple.
There’s a normal scientific consensus that the Greenland Ice Sheet (GrIS) has been shedding ice mass because the Little Ice Age (LIA). This could come as no shock, because the LIA was fairly seemingly the coldest climatic episode of the Holocene Epoch. Though it does seem that the GrIS could have gained ice mass through the mid-20th century world cooling disaster.
In accordance with Mouginot et al, 2019, the GrIS was gaining a median of +47 ± 21 Gt/y from 1972–1980, then started to lose ice mass after 1980:
-51 ± 17 Gt/y from 1980–1990-41 ± 17 Gt/y from 1990–2000-187 ± 17 Gt/y from 2000–2010-286 ± 20 Gt/y from 2010–2018
The alleged ice mass loss was pushed by:
A pointy lower in floor mass steadiness from 1995-2012A rise in iceberg calving and different ocean-contact discharge
Determine 1. D = iceberg and different ocean contact discharge, SMB = floor mass steadiness (snow accumulation minus ablation), MB = internet mass steadiness. (Van den Broeke, et al.,2017)
The drop in SMB was so extreme, that it could have been unfavourable in 2007 and 2012. Many of the ice mass loss is as a result of calving of icebergs. The “humorous factor” is that, other than a spike in iceberg exercise within the 1990’s, it’s probably not a lot totally different now than it was from 1900 to 1950.
Worldwide Ice Patrol’s Iceberg Counts
Donald L. Murphy
Annually, the Worldwide Ice Patrol (IIP) estimates the variety of icebergs that cross south of 48° N, the latitude south of which icebergs are thought of a menace to North Atlantic mariners. The dataset (Desk 1) extends from 1900, 12 years earlier than the sinking of RMS Titanic, to the current.
For a number of causes, these iceberg counts don’t represent a rigorous, scientific knowledge set and ought to be interpreted with nice care. For instance, IIP’s reconnaissance operations deal with the icebergs closest to the transatlantic delivery routes, and infrequently does IIP conduct a complete survey of the realm south of 48° N. As well as, the strategies of remark have modified radically through the years as new applied sciences turned obtainable to detect and observe icebergs. The earliest knowledge have been obtained from visible observations from early 1900s crusing vessels, whereas the latest info is obtained from visible and radar observations from fashionable ships, plane, and satellites.
There may be hanging year-to-year variability evident within the 112-year document of IIP’s iceberg counts (See Determine 1 under and Desk 1 (a PDF which can open in a brand new window)). The imply variety of icebergs estimated to have handed south of 48° N is 474. The best variety of icebergs (2202) occurred in 1984, whereas twice in IIP’s historical past (1966 and 2006) no icebergs have been estimated to have handed south of 48° N. 5 instances in IIP’s historical past there was a minimum of one iceberg estimated to have handed south of 48° N throughout every of the months of the ice yr: 1915, 1919 by way of 1921, and 1985. April and Might are, by far, the months with essentially the most icebergs coming into the delivery lanes.
US Coast Guard Navigation Middle
Determine 2. Icebergs crossing south of 48° N from 1900-2011 (US Coast Guard)
I used to be capable of finding detailed knowledge on iceberg sightings on the Nationwide Snow and Ice Information Middle web site and prolonged the Coast Guard plot by way of 2019.
Chart Quantity One: Icebergs
Determine three. Icebergs crossing south of 48° N from 1900-2011 (US Coast Guard and NSIDC). Worldwide Ice Patrol. 1995, up to date 2020. Worldwide Ice Patrol (IIP) Iceberg Sightings Database, Model 1. [G00807]. Boulder, Colorado USA. NSIDC: Nationwide Snow and Ice Information Middle. doi: https://doi.org/10.7265/N56Q1V5R. [Accessed 2 Feb 2020].
Whereas there was a big enhance within the 5-yr operating common within the 1990’s, since then, it’s been corresponding to 1900-1950. You’ll suppose that with Greenland spitting out Manhattan-sized icebergs on what looks like a weekly foundation and the discharge price supposedly rising by 50% since 1995, it is best to see it within the iceberg rely.
Possibly the “unprecedented” Arctic warming is melting the icebergs earlier than they will get south of 48° N. Properly, the Arctic has a number of very long-term “thermometers”… Ice cores from Greenland. The Greenland temperature reconstruction, most frequently cited by skeptics, is from the GISP2 ice core (Alley, 2000).
Determine four. Central Greenland temperature reconstruction (Alley, 2000).
In my earlier publish, I used to be accused of deceptive individuals with this graph:
Relating to the primary graph: so typically we see the GISP2 knowledge mislabelled and right here is not any exception.
That knowledge sequence ends in 1855, NOT in 1950 as labelled.
This has been made clear on this website so typically, since 2010 in truth, that it’s arduous to consider individuals maintain utilizing it with out figuring out that to be the case.
Why mislead individuals if our argument is so robust?
Anybody with a minimum of a fifth grade studying comprehension can see that the x-axis is labeled “Years Earlier than Current (1950 AD). Anybody with the slightest information of radiometric courting is aware of that the P in BP is 1950. That is additionally the usual for many paleoclimate reconstructions. Until a paper specifies that “current” is any yr apart from 1950, it’s protected to imagine that it’s 1950. The latest yr within the Alley time sequence is 95 BP or 1855.
After all, 1855 was again through the LIA, lengthy earlier than Al Gore invented Gorebal Warming. Fortuitously, there are a number of GISP2 temperature reconstructions that reach as much as 1993 (Kobashi et al., 2008, Kobashi et al., 2011 and Kobashi et al., 2017). Not like Alley, who relied on δ18O depletion as a paleo-thermometer, Kobashi employed “excessive‐precision analyses of δ15N and δ40Ar in trapped air in ice cores”…
The estimated common Greenland snow temperature over the previous 4000 years was −30.7°C with a typical deviation of 1.Zero°C and exhibited an extended‐time period lower of roughly 1.5°C, which is in line with earlier research. The present decadal common floor temperature (2001–2010) on the GISP2 website is −29.9°C.
Kobashi et al., 2011
The GISP2 ice core was drilled on the similar location as Summit Station, Greenland.
Determine 5. Location of Summit Station and Greenland ice core areas. (Yau et al., 2016)
In accordance with Kobashi, the common temperature at Summit Station over the previous four,000 years has been −30.7 °C. The typical temperature since 2008 has been about −30 °C.
Determine 6. Hourly temperatures at Summit Station since 2008 (NOAA/ESRL).
Chart Quantity Two: GISP2 Ice Core
I downloaded the Kobashi et al., 2017 local weather reconstruction from NOAA and plotted it to judge the context of latest local weather change in central Greenalnd. Technically, this might be described as three charts… However, who’s counting?
Determine 7a. GISP2 temperature reconstruction since Youthful Dryas glacial stadial.
Determine 7b. GISP2 temperature reconstruction since 4000 BC. Local weather and historic intervals from Grosjean et al., 2007.
Determine 7c. GISP2 temperature reconstruction since 1900 AD. RMS Titanic, Glacier Woman, The Ice Age Cometh? and Summit Station temperatures included for “scale”… 😉
The inescapable conclusion is that if there ever was a local weather “disaster,” it was through the Little Ice Age… It was FRACKING chilly again then!
What’s that? Central Greenland isn’t the Arctic? No schist Sherlock!
Chart Quantity Three: The Arctic
So, let’s have a look at the latest Arctic temperature reconstruction by McKay & Kaufman, 2014.
Determine 8a. Arctic local weather reconstruction since 1 AD (McKay & Kaufman, 2014).
Determine 8b. Arctic local weather reconstruction since 1900 AD (McKay & Kaufman, 2014).
The inescapable conclusion is that if there ever was a local weather “disaster,” it was through the Little Ice Age… It was FRACKING chilly! And it received fairly chilly once more within the 1970’s!
However, however, what about the entire ice mass loss measured by satellites?
What about it?
Three A long time of Greenland Ice Sheet Change
Posted by ESA Greenland Ice Sheet Local weather Change Initiative.
This week there was important melting over a big space of the Greenland ice sheet. Temperatures even reached over Zero°C for the second time this yr on the very high of the ice sheet 3285m above sea degree at Summit station the place DMI operates a climate station.
The excessive soften charges have been on account of hotter air shifting over the ice sheet, which together with low snowfall over a lot of the ice sheet through the winter interval means fairly massive quantities of soften could be anticipated this yr. A big soften occasion this early is uncommon but it surely’s not unprecedented an analogous occasion occurred in 2012 for instance.
Particular soften occasions of this sort are managed by native climate circumstances within the North Atlantic however when these occasions are averaged over a few years, you get the native background local weather. In a paper printed by scientists in a big European collaboration led by ESA and together with DMI, DTU and GEUS, observations from satellites stretching again to the 1990s, together with many proven right here on the polar portal, have been used to present a well-rounded image of how local weather adjustments in Greenland have been affecting the ice sheet.
We present for instance, that because the early 2000s the ice sheet has change into thinner virtually in all places. For an ice sheet in steadiness with the native local weather we count on to see a small enhance in floor peak yr on yr within the centre and a lower across the edges as extra snow falls than melts at increased elevations and the reverse occurs decrease down. Nonetheless, scientists present that the ice sheet is now getting thinner virtually in all places (blue areas within the high row). “It’s fairly hanging that we see such large adjustments after we evaluate the early 1990s to the previous couple of years” mentioned scientist Sebastian Simonsen from DTU.
The parents at Polar Portal have been sort sufficient to function this picture:
Determine 9. “The higher panel reveals adjustments within the floor elevation of the Greenland ice sheet measured by radar over three totally different time intervals. We then use pc fashions to know what’s driving the adjustments we determine. The center panel reveals the change in floor elevation anticipated simply from floor mass funds (the distinction between snowfall and snowmelt as modelled by the HIRHAM5 regional local weather mannequin additionally used on the polar portal) over the identical time intervals. The decrease panel reveals adjustments in floor elevation calculated utilizing an ice sheet mannequin (PISM) and subsequently together with adjustments in ice sheet elevation on account of ice circulate and to adjustments within the floor mass funds. Whereas the fashions handle to seize the big scale adjustments, there are some areas that they’ve a tough time reproducing, together with a number of the areas with the biggest adjustments.”
I targeted in on the highest panel, elevation adjustments, as a result of I can put these adjustments into geological context.
How does the latest melting evaluate to the remainder of the Holocene? Quick reply: “Identical because it ever was”. Vinther et al., 2009 reconstructed the elevations of 4 ice core websites over the Holocene. There was little or no change in elevation of the 2 inside ice core websites (NGRIP and GRIP), whereas the 2 outboard websites (Camp Century and DYE3) have misplaced 546 and 342 m of ice respectively
Determine 10. Many of the melting because the starting of the Holocene has occurred on the outboard, decrease elevation parts of the GrIS – Identical because it ever was. X-axis is in calendar years AD(BC). Elevation reconstruction knowledge from Vinther et al., 2009. Map from Weißbach et al., 2015.
Vinther’s elevation reconstruction runs from 11,700 to 40 years earlier than the yr 2000. So the latest yr is 1960.
Primarily based on the mass steadiness estimates from Mouginot, there was little or no internet change from 1960 to 1995, the beginning yr for Polar Portal’s elevation change maps. I enlarged the elevation change maps and posted the ice core areas on them.
Determine 11a. Greenland elevation adjustments 1995-1999 and 2001-2005 (Polar Portal).
Determine 11b. Greenland elevation adjustments 2007-2011 and 2013-2017 (Polar Portal).
The dimensions is in meters per yr. Be aware that there was little or no change in ice elevation at these areas. Utilizing my Mark I eyeball, I estimated the annual adjustments in elevation from 1995-2017.
Ice Floor Elevation Change (m/yr)
Utilizing the 2009 elevations offered by Vinther, I calculated the elevations of the 4 areas from 11,700 years in the past as much as 2017.
Chart Quantity 4…”Identical because it ever was!”
Determine 12a. Elevation of 4 ice core areas 11,700 years in the past to 2017.
Determine 12b. Elevation of 4 ice core areas 1900 to 2017.
“Identical because it ever was…”
However, however, the Greenland ice sheet remains to be shrinking! When all of it melts, sea degree will rise by 7 meters!!!
Chart Quantity 5: The Isopach Map
I often choose to make use of the phrase “graph” as an alternative of “chart”… However charts will be both graphs or maps.
We petroleum geologists are obsessive about calculating volumes of oil and gasoline reservoirs and we spend lots of time making issues known as “isopach maps” and operating “volumetrics“. Fortuitously for me, Eric Gaba – Wikimedia Commons consumer: Sting made an isopach map of the Greenland ice sheet.
Determine 13. Isopach map of Greenland Ice Sheet (Eric Gaba – Wikimedia Commons consumer: Sting) (left) and elevation change map (Polar Portal) (proper).
Virtually the entire latest thinning is within the outboard areas of the ice sheet (“Identical because it ever was”). I downloaded a high-resolution copy of the isopach map and digitized the contours utilizing NeuraMap volumetric evaluation software program. The world and quantity of the isopach map have been inline with estimates in USGS Skilled Paper 1386–A, Desk 2, web page A77.
Space: 1,736,095 km2 Quantity: 2,600,000 km3
I used the 10 m contour because the Zero contour. The world of the Zero m contour was very near the USGS space.
Contours (m)km2Acres three,200 888219,434 three,000 49,38112,202,209 three,000 896.1221,429 2,500 364,16289,986,345 2,000 723,269178,723,576 2,000 5,3951,333,230 2,000 9,1862,269,815 1,500 1,065,247263,228,385 1,000 1,347,485332,970,919 – 1,737,393429,319,196
The amount was a little bit increased than the USGS estimate; however properly throughout the vary of different latest estimates. The USGS cites a 1954 reference for this quantity and in addition cites Bamber et al., 2011, which places the amount at 2,900,000 km3. Bamber has subsequently upped his estimate to 2,960,000 km3.
As will be seen, estimates for the amount of the Greenland ice sheet differ extensively and the strategies of volumetric calculation yield a fairly big selection of outcomes… But fashionable local weather “scientists” can detect Zero.Zero15% annual adjustments in its mass… Go determine!
That is what occurs if I drop the 1,000 m contour by 10 m:
Volumeskm3MethodLose 10 mTrapezoid2,977,60199.90%Pyramid2,950,92699.90%TrapPyra2,958,91599.90%Simpson2,844,332100.00%three/8Rule2,725,668100.00%VerticalSlice2,976,23099.90%Step2,453,89199.90%Average2,841,08099.93%
99.93% of the Greenland ice sheet doesn’t soften and/or calve into the ocean. The USGS paper states that if your entire ice sheet have been to soften, sea degree would rise by 6.5 meters. Within the extremely unlikely situation above, sea degree would rise by a whopping four.Eight mm.
6.5 m * Zero.07% = Zero.00478 m
What occurs if I drop the 1,000 m contour by 100 m?
Volumeskm3MethodLose 100 mTrapezoid2,947,01998.87%Pyramid2,920,46798.87%TrapPyra2,928,33398.87%Simpson2,844,332100.00%three/8Rule2,725,668100.00%VerticalSlice2,945,63698.87%Step2,428,20798.85%Average2,819,95299.18%
That’s simply over 2 inches of sea degree rise.
There you could have it… The insignificance of Greenland’s ice mass loss in 5 simple charts… And lots of not really easy charts and tables.
Alley, R.B. 2000. “The Youthful Dryas chilly interval as seen from central Greenland”. Quaternary Science Opinions 19:213-226.
Alley, R.B.. 2004. “GISP2 Ice Core Temperature and Accumulation Information”.
IGBP PAGES/World Information Middle for Paleoclimatology Information Contribution Collection #2004-013. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.
Bamber, J. L., J. A. Griggs, R. T. W. L. Hurkmans, J. A. Dowdeswell, S. P. Gogineni, I. Howat, J. Mouginot, J. Paden, S. Palmer, E. Rignot, and D. Steinhag. “A brand new mattress elevation dataset for Greenland”. The Cryosphere, 7, 499–510, 2013 www.the-cryosphere.internet/7/499/2013/ doi:10.5194/tc-7-499-2013.
Grosjean, Martin, Suter, Peter, Trachsel, Mathias & Wanner, Heinz. (2007). “Ice‐borne prehistoric finds within the Swiss Alps replicate Holocene glacier fluctuations”. Journal of Quaternary Science. 22. 203 – 207. 10.1002/jqs.1111.
Kobashi, T., J. P. Severinghaus, and Okay. Kawamura (2008a). “Argon and nitrogen isotopes of trapped air within the GISP2 ice core through the Holocene epoch (Zero–11,600 B.P.): Methodology and implications for gasoline loss processes”. Geochim. Cosmochim. Acta. 72, 4675– 4686, doi:10.1016/j.gca.2008.07.006.
Kobashi, T., Kawamura, Okay., Severinghaus, J. P., Barnola, J.‐M., Nakaegawa, T., Vinther, B. M., Johnsen, S. J., and Field, J. E. ( 2011). “Excessive variability of Greenland floor temperature over the previous 4000 years estimated from trapped air in an ice core”. Geophysical Analysis Letters. 38, L21501, doi:10.1029/2011GL049444.
Kobashi, T., Menviel, L., Jeltsch-Thömmes, A. et al. “Volcanic affect on centennial to millennial Holocene Greenland temperature change”. Scientific Experiences 7, 1441 (2017). https://doi.org/10.1038/s41598-017-01451-7
McKay, N., Kaufman, D. “An prolonged Arctic proxy temperature database for the previous 2,000 years”. Scientific Information 1. 140026 (2014). https://doi.org/10.1038/sdata.2014.26
Mouginot, Jeremie, E. Rignot, Anders Bjørk, Michiel Van den Broeke, Romain Millan, Mathieu Morlighem, Brice Noël, Bernd Scheuchl & Michael Wooden. (2019). “Forty-six years of Greenland Ice Sheet mass steadiness from 1972 to 2018”. Proceedings of the Nationwide Academy of Sciences. 116. 10.1073/pnas.1904242116.
Van den Broeke, M., Field, J., Fettweis, X. et al. “Greenland Ice Sheet Floor Mass Loss: Current Developments in Remark and Modeling”. Present Local weather Change Experiences. (2017) three: 345. https://doi.org/10.1007/s40641-017-0084-Eight
Vinther, B.M., S.L. Buchardt, H.B. Clausen, D. Dahl-Jensen, S.J. Johnsen, D.A. Fisher, R.M. Koerner, D. Raynaud, V. Lipenkov, Okay.Okay. Andersen, T. Blunier, S.O. Rasmussen, J.P. Steffensen, and A.M. Svensson. (2009). “Holocene thinning of the Greenland ice sheet”. Nature. 461. 385-Eight. 10.1038/nature08355.
Weißbach, S., A. Wegner, T. Opel, H. Oerter, B. M. Vinther and S. Kipfstuhl. “Spatial and temporal oxygen isotope variability in northern Greenland – implications for a brand new local weather document over the previous millennium”. Local weather of the Previous. 12, 171–188, 2016 www.clim-past.internet/12/171/2016/ doi:10.5194/cp-12-171-2016.
Williams, R.S., Jr., and Ferrigno, J.G., eds., 2012. “State of the Earth’s cryosphere at first of the 21st century–Glaciers, world snow cowl, floating ice, and permafrost and periglacial environments: U.S. Geological Survey Skilled Paper 1386–A”. 546 p. (Additionally obtainable at https://pubs.usgs.gov/pp/p1386a.) Glaciers.
Yau, Audrey M., Michael L. Bender, Alexander Robinson, Edward J. Brook. “Final interglacial within the GISP2 Greenland ice core”. Proceedings of the Nationwide Academy of Sciences. Aug 2016, 113 (35) 9710-9715; DOI: 10.1073/pnas.1524766113
Exhuming the Glacier Woman