When scientists let the cat out of the bag about Greenland lose internal-combustion engine , they are babble out , in no small part , about Jakobshavn glacier . A frozen river that drain roughly 7 percent of the Greenland Ice Sheet along the west coast , Jakobshavn has been thinning and retreating in a striking way for about 20 years , and is the single large part to the ice-skating rink tack ’s mood alteration - motor slim down . But in 2016 , the glacier did an about - grimace .
For the retiring few age , Jakobshavn has been re - thickening and re - advancing toward the ocean , according toresearchpublished Monday in Nature Geoscience . This does n’t stand for all is well with Jakobshavn — it still seems to be losing more mass than it ’s gaining , and the slowdown is likely to be temporary — but it is causing researchers to rethink the factors that master the movement of this fast - hang river of ice .
“ It ’s a grand experiment 20 year in the making on large plate , ” lead discipline writer Ala Khazendar , a scientist at NASA ’s Jet Propulsion Laboratory , told Earther , describing the glacier ’s sudden speedup and equally sudden slowdown .
The dramatic event with Jakobshavn began in 1997 , when the glacier awoke from a period of stability and its floating clapper , or meth ledge , started to thin speedily . In 2003 , what was left of that ledge snapped clean off . thing proceed to snowball from there , with the glacier beak up velocity and spew more iceberg , do its front to retreat farther and further inland as its aerofoil dropped by over 500 feet ( 150 metre ) . Some suspected Jakobshavn ’s future was one of unstoppable , ever - quickening dying .
Now , Jakobshavn has confound scientist a curveball . Using airborne altimetry measure along with satellite imaging , Khazendar and his workfellow have shown that the glacier ’s cutting started to slow around 2014 . By 2016 , it had completely rescind row and its front 19 miles ( 30 kilometers ) were thicken at rates comparable to the early cutting . By 2018 , the thickener had spread out 50 mil ( 80 km ) upstream .
“ My first reaction was hey , we made a fault , ” Khazendar told Earther . He explicate that his team was working with a novel dataset from NASA ’s Oceans Melting Greenland ( OMG ) mission , and they had to verify the findings with a separate dataset roll up by NASA ’s Operation IceBridge before they could be confident in what they were seeing .
The OMG data , which includes sea temperature information , help shed some luminosity on the likely cause of the reversal : It go on the right way as a dusty - weewee current making its room up Greenland ’s southwestern coast reached the bay contiguous to Jakobshavn ’s fiord . From 2014 to 2016 , temperature in that bay dipped nearly 2 degrees Celsius ( 3.6 degrees Fahrenheit ) , back to where they were in the eighties . While the ultimate movement of the cool water system intrusion is uncertain , one surmisal is that it has to do with a switch in theNorth Atlantic Oscillation(NAO ) , a go back climate design that can trigger cooler or warm conditions across a panoptic area . Khazendar said that while breeze temperatures also seem to be playing a function , “ ocean temperature variability was the rife cistron ” in the unexampled analysis .
Jason Box , a professor in glaciology and climate at the Geological Survey of Denmark and Greenland who was n’t need with the paper , allege that its conclusions “ make sense ” andbuild on work from 2008showing that the initial acceleration of Jakobshavn glacier was trigged by an usurpation of quick , subsurface ocean waters .
Mathieu Morlighem , a glaciologist at the University of California Irvine who also was n’t postulate , made a similar point .
“ We have know for about 10 years now that almost all marine stop glacier of Greenland are retreating , cutting , and quicken as a reception to warm piss reaching glacier termini , ” Morlighem wrote in an electronic mail . “ What the writer did here is show that this chemical mechanism also works in the other guidance : under certain conditions , if the sea H2O chill , glaciers could re - advance on comparatively shortsighted time scales . ”
Box monish that the “ good news ” as far as trash loss goes is “ very irregular because like El Nino , the North Atlantic Oscillation and its effects are superpose on a longer - condition thaw movement . ”
Morlighem accord . “ What is happening to Jakobshavn is in all likelihood a temporary singultus , ” he said .
Hiccup it may be , but the findings still play up there is more to this glacier than meets the eye . It ’s been hypothesized that the geometry of Jakobshavn — it ’s tethered beneath sea level on bedrock that gets deeply farther inland — make it inherently unstable . This paper tells us there are other factors that tempt how quickly it will drop off in a warming populace .
Given the glacier ’s outsized contribution to sea stratum procession , immobilize down all of those factor and how they work together will be decisive .
sparkler on slight ice
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