Brief Note by Kip Hansen — 6 October 2021
I'm engaged in a group schooling program that features a nice variety of local weather activists and local weather zealots in addition to individuals who're simply curious and involved in enhancing their group’s response to climate and local weather. In the method, I occurred to say in a web based coaching session that Antarctic Ice Mass has been growing, not lowering over the previous couple of many years, correcting a degree made by the trainer.
The course teacher, a local weather activist and educator, took exception to this correction. I used to be, nevertheless, assured in my place, although I had not reviewed the difficulty for years — thus, was a bit uncertain of precisely what sources I used to be relying on. But, I'm not the self-doubting type, so didn't again down. I used to be requested to supply sources for my remark.
As with all issues local weather — information rely on one’s epistemological values.
This is what I used to be capable of report back to the instructors:
Have I discussed that nearly all the pieces about Science subjects is sophisticated and sometimes complicated as nicely?
Antarctic Ice Mass is an instance.
When I mentioned Antarctic Ice Mass has been growing for the reason that flip of the century, I used to be quoting a latest NASA reported on this NASA web site web page: https://www.nasa.gov/feature/goddard/nasa-study-mass-gains-of-antarctic-ice-sheet-greater-than-losses
The examine was printed in 2015. Real science is all the time of the previous, and research like these can take years to do proper, thus they appear “old” however are the truth is usually the most recent research out there.
The examine [ link to original Zwally study ], was reported byNASA right here and quotes the examine lead creator, Jay Zwally, as saying:
“The good news is that Antarctica is not currently contributing to sea level rise, but is taking 0.23 millimeters per year away,” Zwally mentioned. “But this is also bad news. If the 0.27 millimeters per year of sea level rise attributed to Antarctica in the IPCC report is not really coming from Antarctica, there must be some other contribution to sea level rise that is not accounted for.”
The NASA article in regards to the examine [repeating the link] says: “NASA Study: Mass Gains of Antarctic Ice Sheet Greater than Losses”
“According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to [a gain of] 82 billion tons of ice per year between 2003 and 2008.”
Now, right here’s the rub, as they are saying. When one seems at NASA’s Vital Signs internet web page we're handled to this reasonably miserable graph of Antarctic Ice Mass losses:
The 2015 Zwally examine — “the new analysis of satellite data, the Antarctic ice sheet” — exhibits exactly the alternative, GAINS within the re-analysis by Zwally and his workforce as a substitute of the DECLINES proven within the Vital Signs graphic above.
Sorting out these sorts of fundamental knowledge conflicts takes actually weeks of journalistic analysis effort. I've not tackled this situation as of but — however have been conscious of the conflicting data — all from NASA — for a number of years.
It will not be actually doable that each units of knowledge are true and proper.
I actually don’t know. But as a result of NASA publishes opposite knowledge, educators shouldn't be making definitive statements about Antarctic Ice Mass, however reasonably ought to clearly say “Some NASA studies show Antarctica losing Ice Mass and some NASA studies show it gaining Ice Mass.”
I whipped up this alternate graph to point out each units of information on the identical graph — GRACE from NASA Vital Signs and the good points discovered by Zwally et al. (2015):
The graph above makes use of GRACE’s 2002 zero as a typical level — with Zwally’s 1992-2002 knowledge to its left and 2002-2015 to the precise.
I'm conscious that Zwally (2015) was sharply contested by the same old ice mass consensus workforce — however by no means required correction. Zwally is at the moment listed as being with the Cryospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD and the Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD.
Zwally and his workforce have come again in 2021 with this peer-reviewed examine:
Mass stability of the Antarctic ice sheet 1992–2016: reconciling outcomes from GRACE
gravimetry with ICESat, ERS1/2 and Envisat altimetry H. Jay Zwally et al. 29 March 2021 Cambridge University Press
Their newest evaluation seems like this:
One sees the seasonal variation clearly at this scale. Although this newest evaluation exhibits a tiny -12 Gt annual loss, I doubt that it's important given what have to be a reasonably large +/- 1 SD (had it been proven). Even if the -12 Gt per yr was bodily and lasted all 9 years from 2012, the cumulative complete 9 yr loss could be solely 108 GT, a far cry from the NASA Vital Signs GRACE picture’s minus 151 Gt per yr provided to most of the people as an indication of disastrous local weather change.
I'd admire any and all Ice Mass aficionados weighing in on the supply of the disconnect between these two NASA authorized Ice Mass calculations.
UPDATE: Reader John MacDonald identified that “One data item missing is the total ice mass of Antarctic.” The finest guess complete ice mass in Gt from the Wiki is 26.5 million Gt.
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