Dave Burton,
CNBC and the Potsdam Institute (PIK) report that:
We’re midway to a tipping level that may set off 6 ft of sea degree rise from melting of the Greenland Ice Sheet
PUBLISHED WED, MAR 29 202312:12 PM EDT
By Catherine Clifford
KEY POINTS:
● As soon as individuals have cumulatively emitted roughly 1,000 gigatons of carbon in complete, then the southern a part of the Greenland Ice Sheet will soften finally inflicting the ocean degree to rise by nearly six ft.● As soon as people have cumulatively emitted roughly 2,500 gigatons of carbon in complete, the entire Greenland Ice Sheet will finally soften and the ocean degree rise would rise by 6.9 meters, or 22.6 ft.
● And proper now, now we’re at roughly 500 gigatons of carbon emissions launched.
Right here’s the article:
https://www.cnbc.com/2023/03/29/were-halfway-to-a-tipping-point-for-melting-the-greenland-ice-sheet.html
Right here’s the paper:
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101827
Like most issues from PIK, this “research,” and this CNBC article, are nonsense.
The very best estimates are that since 1850 anthropogenic carbon emissions have totaled about 675 Gt of carbon (a/ok/a PgC) (not 500). Over that very same interval, the quantity of CO2 within the environment has elevated by solely about 135 ppmv CO2 = 287 PgC (gigatonnes carbon). The distinction is the quantity faraway from the environment by pure destructive feedbacks, akin to absorption by the oceans, greening the Earth, and rock weathering.
(Apart: Petagram ≡ gigatonne ≡ Gt, and “PgC” means “petagram of carbon,” so 1 PgC = 1 Gt of carbon (GtC). 1 ppmv CO2 = 7.8024 Gt CO2 = 2.12940 PgC.)
But we’ve solely gotten an estimated 1.02 to 1.27 °C of warming from all that CO2, and it’s been accompanied by negligible acceleration in sea-level tendencies:
https://sealevel.data/MSL_graph.php?id=Honolulu
One other 325 PgC or 500 PgC of emissions would produce even much less further warming than the 675 PgC we’ve already had, and it might have even much less impact on sea-level tendencies.
As a rule of thumb, anytime somebody makes use of a time period like “tipping level” or “runaway” in a sentence about modern local weather change, with out pooh-poohing it, it means they don’t know what they’re speaking about, and so they’re fully clueless about feedbacks.
Imaginary “tipping factors” don’t soften ice, solely temperatures above 0°C can try this. Because of “Arctic Amplification,” Greenland ought to get extra warming than most different locations, however nonetheless no various levels. That a lot warming can be good for the hardy individuals who dwell there, but it surely couldn’t soften the southern a part of the Greenland Ice Sheet, as a result of water has to get above 0°C to soften, and the southern a part of the Greenland Ice Sheet averages a lot colder than that.
What’s extra, we all know that Southern Greenland was significantly hotter, 1000 years in the past, through the Medieval Heat Interval. We all know that as a result of Norse settlers efficiently grew barley there, and the rising season now could be too brief for that, even with fashionable fast-maturing cultivars. Norsemen buried their useless in earth that’s now permafrost, too. But that a lot hotter Greenland local weather nonetheless produced no notable spike in international sea-levels.
That is perhaps as a result of in a warming local weather, there are components which each improve and reduce sea-level tendencies.
On one hand, ice which is close to 0°C can soften, and if it was grounded (relatively than floating) that may elevate sea-level. Additionally, thermal enlargement on the ocean’s floor can improve sea-level rise regionally, although it doesn’t have an effect on sea-level elsewhere. These are issues which elevate sea-level.
Alternatively, hotter temperatures improve snowfall accumulation on glaciers and ice sheets, sequestering water, and thereby decreasing sea-level, in two methods:
● Hotter air carries extra moisture, growing snowfall on glaciers & ice sheets. For every 1°C of warming the moisture-carrying capability of the air will increase by about 7%. That’s why the heaviest blizzards happen when temperatures should not far under freezing.
● Lowered sea-ice protection will increase Lake/Ocean-Impact Snowfall (LOES) downwind, a few of which accumulates on glaciers & ice sheets.
The significance of the LOES is illustrated by the superb story of Glacier Woman, a P-38 warbird which made a compelled touchdown on the Greenland Ice Sheet, not removed from the ocean, throughout WWII. She was buried by snowfall which averaged about 70 ft/12 months! Remarkably, she was nonetheless recovered (in items) from beneath the ice, fifty years later, and is as soon as once more airworthy. (click on to enlarge)
The truth that international warming has not been accompanied by vital sea-level rise acceleration strongly means that the components by which a warming local weather will increase sea-level and the components by which a warming local weather reduces sea-level are related in magnitude, and largely cancel.
Moreover, it’s not “cumulative carbon emissions” which have an effect on temperatures, it’s the focus of CO2 at present within the environment. The authors of this terrible paper appear to assume that CO2 emissions simply accumulate within the environment, however that’s unfaithful. As that atmospheric CO2 focus will increase, the pure destructive feedbacks which take away CO2 from the environment speed up sharply. They’re already eradicating greater than 5 PgC per 12 months from the air, and that removing charge accelerates by 1 PgC/12 months for each roughly 20 to 23 ppmv rise in atmospheric CO2 focus.
For the reason that present CO2 emission charge is just outstripping the pure CO2 removing charge by about 5.3 Gt of carbon per 12 months, meaning the present CO2 emission charge is just enough to extend atmospheric CO2 focus by about 100 to 125 ppmv. Which means mankind may emit CO2 on the present charge without end (or till all of the coal ran out), and the atmospheric CO2 focus would nonetheless by no means attain even 550 ppmv.
A rise from 420 ppmv to 550 ppmv would yield solely 39% of the radiative forcing of 1 “doubling” of CO2. For comparability, we’ve already seen 58% of the radiative forcing of a doubling of CO2 (plus about half that a lot from different GHGs).
The consequences on temperatures have been modest and benign, the results on sea-level have been negligible, and the results of upper CO2 ranges on agriculture and pure ecosystems have been extremely helpful.
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Dave Burton @ncdave4life is the creator of the sealevel.data web page, a member of the CO2 Coalition, and a two-time IPCC Evaluation Report Knowledgeable Reviewer. He lives in Cary, NC.