From NASA JPL:
There are two primary causes of global mean sea level rise – added water from melting ice sheets and glaciers, and the expansion of sea water as it warms. The melting of Antarctica’s ice sheet is currently responsible for 20-25% of global sea level rise.
But how much of a role will it play hundreds of years in the future?
Scientists rely on precise numerical models to answer questions like this one. As the models used in predicting long-term sea level rise improve, so too do the projections derived from them. Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, have discovered a way to make current models more accurate. In doing so, they have also gotten one step closer to understanding what Antarctica’s ice sheet – and the sea level rise that occurs as it melts – will look like centuries from now.
“Unlike most current models, we included solid Earth processes – such as the elastic rebound of the bedrock under the ice, and the impact of changes in sea level very close to the ice sheet,” said JPL’s Eric Larour, first author of the study. “We also examined these models at a much higher resolution than is typically used – we zoomed in on areas of bedrock that were about 1 kilometer instead of the usual 20 kilometers.”
The scientists found that projections for the next 100 years are within 1% of previous projections for that time period; however, further into the future, they observed some significant differences.
“We found that around the year 2250, some of these solid Earth processes started to offset the melting of the ice sheet and the consequent sea level rise,” Larour said. In other words, they actually slowed the melting down.
The team noted that a hundred years even further into the future – by 2350 – this slowdown means that the melting of the ice sheet is likely to contribute 29% less to global sea level rise than previous models indicated.
“One of the main things we learned was that as grounded ice retreats inland, the bedrock under it lifts up elastically,” said Erik Ivins, a co-author of the study. “It’s similar to how a sofa cushion decompresses when you remove your weight from it. This process slows down the retreat of the ice sheet and ultimately the amount of melting.”
Although this sounds like good news, the scientists say it’s important to keep it in perspective. “It’s like a truck traveling downhill that encounters speed bumps in the road,” said Larour. “The truck will slow down a bit but will ultimately continue down the hill” – just as the ice sheet will continue to melt and sea level will continue to rise.
This animation shows projections of ice sheet retreat in Antarctica over 500 years using the previous models (shown in green) and the new models, which take into account solid Earth processes like the elastic rebound of the Earth (shown in red). The new models show that by the year 2350, melting of the ice sheet and its corresponding contribution to sea-level rise will be about 29% less than what previous projections had indicated for this distant time period. Credit: NASA/JPL-Caltech
The breakthrough of this study, he added, was to “reach resolutions high enough to capture as many of these ‘speed bumps’ as possible and determine their effects in Antarctica while also modeling sea level rise over the entire planet.”
The study, titled “Slowdown in Antarctic Mass Loss from Solid Earth and Sea-Level Feedback,” was published today in Science.
More information on the study can be found at:
https://vesl.jpl.nasa.gov/sea-level/slr-uplift
“We found that around the year 2250…
even further into the future – by 2350
Why are they even bothering?
We only have 12 years to save the planet – Washington Post
We have 12 years to act on climate change before the world as we know it is lost. – The Independent
We have 12 years to limit climate change catastrophe, warns UN – The Groaniad
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With just 12 years left to save the planet, here’s @RachelParris on why we CAN’T let the world go floppy!
Looks like a consensus to me.
So what they are saying is that a tiny anthropogenic fraction CO2 ppm of a fraction of total CO2 will overcome this:
https://www.researchgate.net/profile/Martin_Ziegler/publication/51635458_800000_Years_of_Abrupt_Climate_Variability/links/02e7e51a63f144c571000000/800-000-Years-of-Abrupt-Climate-Variability.pdf
Got it.
Aside, from the questions I have about the model specifics, it is worth noting that computer simulations and mathematical/statistical models are important tools in science and engineering. In fact, modern engineering would be impossible without them. This site’s dedication to model bashing has become a major discredit to the important business of climate skepticism.
I retired a few years ago after spending most of my working life in aerospace where, among other things, I worked with developing, testing and using computer models. Admittedly they were for modelling flight operations and logistic processes which are a lot simpler to model than climate.
Even so we thought we were pretty good when our predictions were within 20% of the actual results, and so did our customers.
And I am a climate model basher. Among other things because models with more than two, or at the very most three, parameterized variables are utterly useless. The reason: you can get any result you want by “tuning” your parameters (and within quite reasonable ranges). You are only fooling yourself.
So SLC Dave you defend using climate models with a limited and poor history of accuracy as a viable foundation to base governmental policy on? Really?
Why don’t you read what he actually wrote?
He said nothing of the sort.
What he’s complaining about is something that I have often complained about. Many people here assume that since climate models are worthless, therefore all models are worthless, and nothing could be further from the truth.
Somehow I have3 missed “this site” bashing models used in engineering or for most other purposes other than climate. Wanna show me where “this site” did that?
Once again, would you please read what was written.
I said nothing about “this site” bashing non-climate models.
I’m another who uses models in my work – electronic circuits.
Models are often optimised to (and do) perform better (i.e. closer to reality) under certain conditions than others. It will do exactly what the model builder wants it to do.
They are very useful but results must always be verified by building the circuits.
Often experience suggests which condition is (and which is not) more likely to yield a helpful result.
And even then if it doesn’t match, shoulders are shrugged and another idea is tried.
In the case of climate models my layman’s impression is that they have been designed with an over-emphasis on the effect of CO2 in order to get some aspects to be closer to reality.
And even then they aren’t very.
And if they don’t match shoulder shrugging won’t fix the effects that the preposterous solutions to the non-issue are (already) having.
Don’t build your climate house on model sand!
SLC Dave
I look at results from Monte Carlo simulations for making some financial decisions.
There are lots of other great uses.
“Antarctica’s ice sheet is currently responsible for 20-25% of global sea level rise.”
Not if Antarctica is currently gaining ice mass as a NASA study suggests. On the other hand there are large lakes beneath the Antarctic ice that must feed groundwater to the ocean. The gold standard of SLR remains Walter Munk (now emeritus) at Scripps: An Enigma, too little, too late, and too linear; meaning we are missing something.
A good candidate for the missing something is groundwater.
“Not if Antarctica is currently gaining ice mass as a NASA study suggests”
Depends is snow accumulation exceeds ice lost at contact with warmer waters.
https://climate.nasa.gov/news/2836/antarcticas-contribution-to-sea-level-rise-was-mitigated-by-snowfall/
“A new NASA-led study has determined that an increase in snowfall accumulation over Antarctica during the 20th century mitigated sea level rise by 0.4 inches. However, Antarctica’s additional ice mass gained from snowfall makes up for just about a third of its current ice loss.
“Our findings don’t mean that Antarctica is growing; it’s still losing mass, even with the extra snowfall,” said Brooke Medley, a glaciologist with NASA Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study, which was published in Nature Climate Change on Dec. 10. “What it means, however, is that without these gains, we would have experienced even more sea level rise in the 20th century.”
Different study.
https://www.nasa.gov/feature/goddard/nasa-study-mass-gains-of-antarctic-ice-sheet-greater-than-losses
They seem to have “unheated” the prior link from October, 2015.
Your Dec. 2018 study deals with snowfall, my prior study with ice mass. The two metrics are related, but not the same. Snowfall over land (rather than back in the ocean) has an immediate effect on sea level. Ice mass is longer term.
Until you understand how everything affects everything, you don’t know nothing.
MarkW
“Until you understand how everything affects everything, you don’t know nothing.”
So because we don’t know everything about some things, what we think we do know about these “some things”…… is wrong? HUH??? That is such a classic BS skeptic tactic.
Simon:
It is “staggering”.
Like mankind has got where we are by knowing everything before we acted.
Staggering indeed.
What’s the point in any study of possible future events then?
Given that we cannot know “everything”.
We don’t know the weather forecast will be correct exactly for us next tuesday.
But we know a hell of a lot more than if there were no weather forecast.
Such that, say, we can make appraisal of contingencies based on probabilities.
It really is sad how pathetic the AGW acolytes have gotten.
Not BS, reality.
Unless you understand ALL of the feedbacks in a system, trying to describe how the system will respond to a perturbation is an exercise in futility.
Either that or a deliberate lie by people who should know better.
Stop the presses on the multi-century forecasts! The science isn’t settled.
These papers are surprising news, contrary to the doomster narrative. I doubt that either will be mentioned in the mainstream press or the liberal websites (that report every doomster paper as gospel). Red emphasis added.
“Non-uniform contribution of internal variability to recent Arctic sea ice loss” by Mark England in Journal of Climate, in press.
“A new 200‐year spatial reconstruction of West Antarctic surface mass balance” by Yetang Wang et al. in JGR Atmospheres, in press.
The National Institute for Standards and Technology could end this contretemps in a week. The entire farcical “issue” of Global Warming/”Climate Change” is all based on ignoring the rules of data that all engineers learn. Calibrate the instruments! All of them, thermometers, satellite altimeters, GRACE satellites, ARGO buoys, right down to the buckets used by the Royal Navy to measure ocean temps starting in 1851.
Guess what: NONE of these have been calibrated, with the possible exception of the United States Historical Climate Network. NONE of the models have been validated. NIST pro’s must be either bemused or disgusted by what they witness, but they remain silent, not wanting to be politicized.
We let them do their jobs, and they are quite good at this, it all goes away quickly. “Climate Scientists” must secretly be terrified by this prospect. The Hockey Stick was publicly flamed by McIntyre, who would be a really good NIST guy. They have lots more McIntyre’s.
Stop the presses! The science isn’t settled.
Both of these papers are contrary to the doomster narrative. I doubt that either will be mentioned in the mainstream press or the liberal websites (that report every doomster paper as gospel). Red emphasis added.
“Non-uniform contribution of internal variability to recent Arctic sea ice loss” by Mark England in Journal of Climate, in press.
“A new 200‐year spatial reconstruction of West Antarctic surface mass balance” by Yetang Wang et al. in JGR Atmospheres, in press.
I have a very precise, accurate, highest resolution model that says you are a witch!
Must be more truer than ever!
I mean… It’s a MODEL!
I would think that a truck hitting speed bumps while traveling down an incline would soon lose stability, and run off the road.
Other than the above thought, my assessment of future conditions is that the current Warm Period will give way to cooling either side of 2200. These guys are nuts to think that the climate system will never cool again.
Are they providing precise numbers with a highly uncertain uncertainty?
I am glad they made the effort and that a 1 km resolution gave a different projection from the 20 km resolution. We learned something useful about models.
Catch-22 for all you melting glacier alarmists: the faster a glacier runs out into the water and calves huge icebergs, the more ice that will have to be melted by the warm ocean waters. Thus, the thermal expansion will be partly checked by more ice. Furthermore, that cooler water means more CO2 will be absorbed by the ocean’s water, and HEAT WILL NO LONGER BE TRAPPED AT THE SAME RATE! [1] Ergo, sea level will not rise as much as they fear.
Ba-BAM! In your face, alarmists.
[1] – the author of this comment personally rejects the notion that CO2 in the atmosphere “traps heat” and that small shifts in atmospheric CO2 concentrations drive major climate shifts on planet Earth.
I have just purchased a block of land with a beautiful vies on the North Face of Mt Everest so I no longer need to worry about these impending sea level rises.
As this paper come from the Jet Propulsion Laboratory does this mean it is a load of hot air?
It appears you ignored the effect of magma intrusion from sub aerial volcanoes on sea level?
This must be around 2.8 x10^12 cubic metres pa, if population is roughly 100,000 over 1Km high, in their main/established phase of 28×10^6 m^3 pa average emissions. Less if we low ball this established estimate to 50,000, close to the population of Pacific Atols we can see above the surface, never mind the rest that didn’t make it the average 10,000 oceanic feet – just for scaling cred. The estimate I use for active oceanic volcano population is the University of Oregon’s, their average emission volume of 28×10^6m^3 p is from Scott White’s paper. This is certainly in the right order/space, on the facts we have measured, so know.
Crucially the low ball 50,000 population arithmetic delivers a surface displacement upwards of 3 or 4 mm pa over 362×10^12m^2 ocean surface area, less depending on how much the 7Km wafer thin oceanic crust is depressed by the added weight of the sea floor, pulled into the visco elastic upper mantle by gravity, hence the 10-30 KBar pressure under it.
Just saying. Following the agenda of others as to causes while also ignoring significant real effects can create unsupportable beliefs ;-). Favouring what you think is causing the effect at the expense of what you consider insignificant, or exclude arbitrarily, rather than allowing all possible effects to be separately assessed by the experimenter is Cargo Cult Science 101, as applied in climate science. Doing the arithmetic objectively quickly quantifies this significant effect, left totally ignored, or falsely denied as “insignificant” without the evidence of arithmetic. No it isn’t. Details here if you are interested, in Table 3, all input data and maths is transparent in the text.
Call me sceptical … but no denier of the provable facts.
So corrections of fact with references and arithmetic are very welcome.
I may be wrong, It’s easy to fool yourelf. But I believe sub aerial volcanoes havesome significance for our problem.
PS I do realise the sea floor is being subducted into the mantle so that basalt and limestone deposits are continuously recycled out of new volcanoes as CO2 and water vapour in the radioactively heated furnace beneath. But the volume involved in the necessary planetary crack filling is a few ten’s of 10Km^3 pa, far less than the sub aerial magma emission of 2,800km^3 from volcanoes that penetrate the faults in tectonic slabs. (74,000km of divergent plate boundaries, x 0.00007m pa average x 7km deep = 36Km^3 ……….. and yup, I ignored flood basalts from the join). This is not even in my number, because it is filling a gap. The number I calculate is for the estimated population of sub aerial volcanoes alone.
KK, no need for “high speed” till “They were high enough that my ’63 Jag E-Type would drag its undercarriage on them”.
Just don’t go at an right angle across them so the tires go BUMM BUMM
but on some 20 degrees deviant so the tires go BADUMM BADUMM.
spares suspension and shock absorbers and results in sovereign gliding.
Re. speed bumps. In the early 1950 tees my brother and I rode a BSA
650 cc twin bike over most of Australia. Back then outside of the Towns
and Cities it was all dirt roads. We used to say that at night little green
men came out and dug all the pot holes and the bumps, which naturally
occurred.
We found that if we kept our speed at 60 mph it was not too bad, the bike
would ride from the top of one bump to the top of the next one, and the
suspension took it ok. Of course cornering could be interesting.
Oh happy days.
MJE VK5ELL