Visitor AEUHHH???? by David Middleton
A Terrifying Sea-Stage Prediction Now Appears to be like Far Much less Probably
However specialists warn that our general image of sea-level rise seems far scarier in the present day than it did even 5 years in the past.
JAN four, 2019
One of many scariest situations for near-term, disastrous sea-level rise could also be off the desk for now, in response to a brand new examine previewed at a latest scientific convention.
Two years in the past, the glaciologists Robert DeConto and David Pollard rocked their discipline with a paper arguing that a number of huge glaciers in Antarctica have been way more unstable than beforehand thought. These key glaciers—which embrace Thwaites Glacier and Pine Island Glacier, each within the frigid continent’s west—may enhance world sea ranges by greater than three toes by 2100, the paper warned. Such an increase may destroy the houses of greater than 150 million folks worldwide.
It’s a reassuring constraint positioned on one of the alarming scientific hypotheses superior this decade. The press had described DeConto and Pollard’s authentic work as an “ice apocalypse” spawned by a “doomsday glacier.” Now their worst-case skyrocketing sea-level situation appears extraordinarily unlikely, at the very least inside our personal lifetimes.
But their work—and the work of different sea-level-rise scientists—nonetheless warns of potential disaster for our kids and grandchildren. If each nation meets its present dedication underneath the Paris Settlement, the Earth will heat about 2.7 levels Celsius by the top of the century in contrast with its pre-industrial common. Of their new analysis, DeConto and his colleagues say that there’s a tipping level, someplace between 2 and three levels Celsius of temperature rise, after which the West Antarctic Ice Sheet will slip into speedy and shattering collapse.
The brand new outcomes inform one of many greatest excellent questions—and most fervent debates—regarding how local weather change will reshape our world: How a lot will the seas rise, and how briskly will that upheaval happen? DeConto and a number of other different American glaciologists—together with Richard Alley, a professor at Penn State and a co-author of the brand new analysis—characterize one thing just like the vanguard of that dialogue. They champion an thought known as “marine ice-cliff instability,” or MICI, which maintains that West Antarctic glaciers will ultimately crumble underneath their very own weight. By the center of subsequent century, they warn, this mechanism may ship ocean ranges hovering at a charge of a number of toes per decade. For reference: Alongside the U.S. East Coast, the Atlantic Ocean has risen by solely a couple of foot during the last 12 many years.
Whereas “marine ice-cliff instability” could be clunky, the concept is cinematic.
Different researchers discover this attainable future considerably unbelievable. “We, as European modelers, are barely extra skeptical of the marine-cliff thought,” Frank Pattyn, a glaciologist on the Free College of Brussels, instructed me. “It has not been noticed, not at such a scale.”
There is just one place on the planet the place MICI is unquestionably taking place: Jakobshavn Glacier, on the west coast of Greenland.
Alley, the Penn State glaciologist, addressed the sapphire-colored elephant within the room instantly after taking the dais. As he sees it, it’s simply frequent sense that Antarctic glaciers will develop problematic ice cliffs.
On this situation, he warned, “We won’t have analogues … We’re going to transfer outdoors the instrumental knowledge that we use to calibrate our fashions.”
Then got here the skeptics. Dan Martin, a computational scientist at Lawrence Berkeley Nationwide Lab, argued that his and his colleagues’ work confirmed that ice cliffs may merely be a product of operating a pc mannequin of ice physics at a too-low decision. Eric Larour, a physicist at NASA, offered the chance that the physics of the Earth itself may barely counteract some speedy ice-cliff collapse. Because the ice sitting on West Antarctica melts, the bedrock beneath it’s going to bounce again up.
“When ice melts or thins, you may assume that the Earth [below it] goes to rebound,” he mentioned. That bedrock will rise, lifting the glacier partly out of the water. Such a mechanism may purchase humanity a while, he mentioned, giving us a “23 to 30 yr delay” within the whole collapse of West Antarctica. This impact may maintain off the collapse of West Antarctica till 2250 or 2300, however then the ice sheet would disintegrate as quick as ever.
The assembly arrived at no clear conclusion.
MICI stays a younger thought, first proposed solely six years in the past. It needn’t be rejected just because scientists haven’t arrived at onerous conclusions but, Fricker, the Scripps glaciologist, mentioned.
“It won’t occur,” Fricker mentioned. “But when there’s an opportunity that it may occur, then shouldn’t you contain that in your planning? Should you’re internet hosting a picnic and it would rain, you don’t essentially transfer the entire occasion, however you in all probability do make a Plan B. Should you’re planning a metropolis … you may as properly maintain this behind your thoughts.”
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I considered submitting a letter… However I doubt they’d need to hear what I take into consideration this text. Robinson Meyer is a twenty-something yr previous employees author for The Atlantic with a 2013 B.A. in music.
I really like this bit: “Then got here the skeptics.” Why have been they even invited? I believed they’d all been banished from the AGU. How dare they throw chilly water on a wonderfully good model-derived disaster… /Sarc.
Marine ice cliff instability (MICI) “has not been noticed, not at such a scale,” “may merely be a product of operating a pc mannequin of ice physics at a too-low decision,” ignores put up glacial rebound, couldn’t happen earlier than ” till 2250 or 2300″… But “the concept is cinematic,” “it’s simply frequent sense that Antarctic glaciers will develop problematic ice cliffs” and one thing we must always plan for…
How will you plan for one thing that’s by no means been noticed? Might not ever occur? Gained’t occur for 200-300 years, if it does occur? What’s the purpose in even protecting “this behind your thoughts.” Nobody with this behind their thoughts in the present day will likely be alive in 2250. Their youngsters received’t be alive. Their grandchildren in all probability received’t be alive. In 2250, we will simply let Star Fleet deal with this.
This remark was most reassuring…
“We won’t have analogues … We’re going to transfer outdoors the instrumental knowledge that we use to calibrate our fashions.”
–Richard B. Alley, Penn State College
That can actually be a reduction to local weather modelers, Their fashions will now not should be constrained by actuality… Which received’t be a lot of a change. RCP8.5 is already unconstrained by actuality.
Talking of RCP8.5 and DeConto & Pollard, that’s how all of this received began…
Polar temperatures over the last several million years have, at instances, been slightly warmer than today, yet global imply sea level has been 6–9 metres excessiveer as recently as the Final Interglacial (130,000 to 115,000 years in the past) and possibly higher throughout the Pliocene epoch (about three million years in the past). In each instances the Antarctic ice sheet has been implicated because the primary contributor, hinting at its future vulnercapacity. Here we use a model coupling ice sheet and climate dynamics— including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs—that is calibrated towards Pliocene and Final Interglacial sea-level estimates and applied to future greenhouse fuel emission scenarios. Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated. On this case atmospheric warming will quickly become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.
The “more than a metre of sea-level rise by 2100 and more than 15 metres by 2500″ is predicated on dangerous science fiction (RCP8.5)…
DeConto & Pollard primarily asserted that we’re headed again to the Pliocene over the subsequent few hundred years.
We’ve already skilled almost 1 ºC of warming since pre-industrial time. One other zero.5 to 1.zero ºC between now and the top of the century doesn’t even put us into Eemian local weather territory, a lot much less the Pliocene. Past that, who is aware of what is going to occur? Whereas fossil fuels will dominate the vitality combine for a lot of this century, does anybody actually imagine that higher supply of vitality received’t be added to the combo between 2100 and 2250?
There is just one place on the planet the place MICI is unquestionably taking place: Jakobshavn Glacier, on the west coast of Greenland.
Jakobshavn Glacier shouldn’t be an MICI analogy for Antarctica. It’s not even an analogy for some other glaciers in Greenland.
Jakobshavn Glacier Calving Entrance Recession from 1850 to 2006
Visualizations by Cindy Starr Launched on January 5, 2007
Jakobshavn Isbrae is situated on the west coast of Greenland at Latitude 69 N. The ice entrance, the place the glacier calves into the ocean, receded greater than 40 km between 1850 and 2006. Between 1850 and 1964 the ice entrance retreated at a gradual charge of about zero.three km/yr, after which it occupied roughly the identical location till 2001, when the ice entrance started to recede once more, however way more quickly at about three km/yr. After 2004, the glacier started retreating up its two primary tributaries: one to the north, and a extra speedy one to the southeast.
These adjustments are essential for a lot of causes. As extra ice strikes from glaciers on land into the ocean, it causes an increase in sea degree. Jakobshavn Isbrae is Greenland’s largest outlet glacier, draining 6.5 p.c of Greenland’s ice sheet space. The ice stream’s speed-up and near-doubling of the ice circulation from land into the ocean has elevated the speed of sea degree rise by about .06 millimeters (about .002 inches) per yr, or roughly four p.c of the 20th century charge of sea degree enhance.
The calving traces have been overlaid on a 2001 Landsat picture.
This text was up to date in July 2007 with a brand new picture…
The glacier had certainly retreated from 2001-2006 after almost 40 years of little motion. Nevertheless, the entire retreat has occurred on the “floating ice tongue”…
Jakobshavn Isbrae – Greenland Glacier Has At all times Modified With The Local weather
By Information Employees | July 16th 2011
New analysis on Jakobshavn Isbrae, a tongue of ice extending out to sea from Greenland’s west coast, exhibits that giant, marine-calving glaciers don’t simply shrink quickly in response to world warming, additionally they develop at a exceptional tempo during times of worldwide cooling. *Glaciers change.
Jakobshavn Isbrae has been the main target of intense scientific curiosity as a result of it is likely one of the world’s fastest-flowing glaciers, releasing huge portions of Greenland’s ice into the ocean. It’s believed that adjustments within the charge at which icebergs calve off from the glacier may affect world sea degree rise. The decline of Jakobshavn Isbrae between 1850 and 2010 has been documented, largely just lately by aerial images and satellite tv for pc images.
“We all know that Jakobshavn Isbrae has retreated at this unimaginable charge lately, and our examine means that it superior that quick, additionally,” mentioned Jason Briner, the affiliate professor of geology on the College of Buffalo, who led the analysis. “Our outcomes assist rising proof that calving glaciers are notably delicate to local weather change.”
“Our outcomes assist rising proof that calving glaciers are notably delicate to local weather change.” Greenland’s local weather is all the time altering… At all times has and all the time will change… And the local weather adjustments noticed over the previous couple of many years will not be unprecedented. The Greenland ice sheet is not any extra disappearing this yr than it was final yr and it’s bodily not possible for the ice sheet to “collapse” into the ocean.
Each [fill-in-the-blank]-sized iceberg to calve off Greenland or Antarctica triggers the identical alarmist nonsense and glacial junk science journalism. Glaciers are rivers of ice. They circulation downhill. Downhill is mostly towards the ocean, the place they calve icebergs. Elevated calving of icebergs is indicative of extra ice accumulation, not melting. Previous glacial levels and stadials are related to a rise in dropstones in marine sediment cores as a result of icebergs calve extra incessantly when the supply of ice is increasing.
From 1850 by 2006, Jakobshavn Isbrae’s floating ice tongue has calved into the ocean. Previous to 1850, glaciers had largely been advancing because the finish of the Holocene Climatic Optimum, a interval often known as “Neoglaciation.” Whereas the retreat of Jakobshavn Isbrae’s floating ice tongue was punctuated with a protracted hiatus related to the mid-20th century cooling interval, this course of started on the finish of Neoglaciation. The top of Neoglaciation was a “good factor”…
DeConto, Robert & Pollard, David. (2016). Contribution of Antarctica to previous and future sea-level rise. Nature. 531. 591-597. 10.1038/nature17145.
Zachos, J. C., Pagani, M., Sloan, L. C., Thomas, E. & Billups, Okay. Tendencies, rhythms, and aberrations in world local weather 65 Ma to current. Science 292, 686–-693 (2001).