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2024-08-22 -Signs, Portents, and the Weather-
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Why climate change models are wrong, according to bombshell study
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| Fancier models than heretofore. |
[Daily Mail, where America gets its news] A new analysis shows the 'worst case scenario' for Antarctica's melting glaciers is much less severe than the United Nation's current estimates.
The UN's prediction that the melting of Antarctica's so-called 'Doomsday' glaciers could alone raise global sea levels two feet before the year 2100 has shaped global climate policy since at least 2016, when the estimate was first introduced.
The model — which the UN Intergovernmental Panel on Climate Change (IPCC) does admit is 'low likelihood' — projects this melt could raise sea levels up 50-ft by 2300.
But three new, more sophisticated climate models, produced with the backing of the National Science Foundation, now call this UN glacier model 'extreme' and 'unlikely.'
More realistic new scenarios, revealed by these new 'ice melt' simulations, predict the glaciers are not likely to break apart in the feared, cascading chain-reaction.
'We're not reporting that the Antarctic is safe and that sea-level rise isn't going to continue,' study co-author and earth sciences professor Mathieu Morlighem, who researches the physics of glacier ice at Dartmouth University, said.
'All of our projections show a rapid retreat of the ice sheet,' he emphasized.
What Morlighem and his co-authors did do was focus their modeling on the polar continent's 'Doomsday Glacier,' the Thwaites Glacier: a 75-mile-wide, heavily monitored plateau of ice whose collapse could swell oceans catastrophically.
What they hoped to test is whether or not the disappearance of massive portions of this glacier's floating outermost edge, its ice shelf, could trigger a the sliding of Antarctica's land-locked ice into the ocean — where it would raise sea levels rapidly.
'High-end projections,' like IPCC's worst case scenario, Morlighem said, 'are important for coastal planning and we want them to be accurate in terms of physics.'
A dramatically high and unlikely scenario, in other words, could lead a city council in Miami to waste taxpayer money on sea walls that are much higher than needed.
'These projections are actually changing people's lives,' Morlighem noted.
His team developed three ice melt models capable of simulating the Thwaites Glacier's retreat at a higher resolution than the IPCC's latest low resolution model.
The new study, published Wednesday in the journal Science Advances, employed a computer model created by Dartmouth in collaboration with NASA's Jet Propulsion Laboratory and the University of California at Irvine.
The model, known as Ice-sheet and Sea-level System Model (ISSM), was capable of handling 75,000 individual elements within its simulation at a resolution of about one mile (1.5 kilometers).
Their two other simulations, were similarly complex.
One, named Úa started with initial conditions consisting of 90,000 elements, and a resolution of 0.62 miles (1 km) near the key points in need of modelling, including where the large pieces of the glacier shelf could 'calve' or break off into the sea.
The last model, called STREAMICE, also had a resolution of 0.62 miles (1 km).
All of these models predicted an instantaneous increase in flow speed of up to 3 km/year right after the initial ice shelf collapse, or a doubling of today’s ice flow speed.
The new study also simulated the rate at which the Doomsday Glacier thinned and the speed at which is would 'calve' portions of the glacier and slide those new icebergs into the sea.
But, ultimately, it found that a lost ice shelf would not lead the remaining glacier to retreat inland, nor trigger a runaway breakdown.
'Ice front retreat requires that the calving rate due to cliff failure exceeds this ice speed,' the team wrote, 'which is rarely the case in our simulations.'
But while these findings undermined the projections of the UN IPCC's models, it did not paint a completely rosy picture of planet Earth's southern-most continent.
Glaciologist Dr Dan Goldberg at the University of Edinburgh, a co-author on the new paper who was once a visiting professor at Dartmouth, noted that the Doomsday Glacier is likely to keep retreating inland in unpredictable ways past this century.
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