sea level rise - is Greenland beyond its tipping point?

RISING
SEAS
INSTITUTE
RSI Presents: Expert Discussions
with
Dr. Jason Box, Geological Survey of Denmark and Greenland
Moderated by John Englander at [phone], Rising Seas Institute Recorded June 13, 2024, for RS l's Greenland Fact-Finding Expedition,
per Chatham House rule. Edits by Sharon Gray

[mikeharrington]

Why is so much space devoted to a Greenland "tipping point" when clearly the melting trend of the Greenland ice sheet is, for all intents & purposes, "irreversible" so long as Earth maintains and likely adds to its accumulation of greenhouse gases ?

Isn't such "irreversibility" an indication that we are already "transitioning" to a new state ? Even allowing for ENSO or annual/seasonal variations, we know the trend & the consequences are already bad enough without adding some unknown time-indeterminate Dansgaard–Oeschger event into the equation ?

[wendydelisse]

At 2:29 is heard the key statement, "the models don't deliver the ice [of Greenland to the sea] as quickly as is observed." The question arises of just what did the models under-represent.

My guess is that the important topic of Arctic region sea ice extent was under-represented in the models, as well as the topic of mountaintop ice. Sea ice and mountaintop ice chills warm continental air masses that approach Greenland. Less of that ice means less chilling effect. Early July (July 1 through July 10) snowline elevations have been showing a long term trend of rising north of the Tropic of Cancer, the portion of the world that has applicability to warm air masses that approach Greenland in June or July or August. Also, in all months of the year, Arctic sea ice extent has been in long term decline.

Arctic sea ice during Summer is more fragile on a long term basis than many people know. The big warning came from the year 2007. Arctic sea ice extent on August 5 was at 6.263 million square kilometers, at the time a record low for that date. One month later, the Arctic sea ice extent on September 5 was less than 4 1/2 million square kilometers. There were 3 years that followed, 2012 and 2019 and 2020, in which sea ice extent on August 5 was no higher than on August 5 2007. In all 3 of those years, the pattern repeated of sea ice extent a month later on September 5 being no higher than 4 1/2 million square kilometers.

Another indication of the long term fragility of sea ice is the long term contraction of the +6 degree Celsius sea surface temperature isotherm around the month of August. On Saturday July 27 2024, that +6 degree Celsius isotherm was to the north of the Diomede Islands of the Bering Strait, with the +6 degree isotherm being situated at about 67 1/2 degrees north latitude.

Around the year 2027, when CO2 is about 2 1/2 percent higher than now in the year 2024, the overall Arctic region cryosphere will not have the ability to long term support a continued Greenland ice sheet. What extra CO2 does is to retard heat radiation from the Arctic region in the Winter, therefore resulting in thinner and less extensive sea ice at the beginning of Spring, and therefore less protection of the Greenland ice sheet from warm continental air masses during the Summer. Increased CO2 also elevates early July snowlines north of the Tropic of Cancer on the Northern Hemisphere continents, again decreasing protection of Greenland from warm continental air masses.

Short version: Just a little bit more CO2 will mean that Greenland will not be able to maintain an ice sheet on a geologically lengthy time scale. Pure ice is "metastable" on up to +0.01 degrees Celsius, the "triple point temperature" of water. Above +0.01 degrees Celsius, ice melts into liquid. The Greenland ice sheet has a lot of thermal inertia, but eventually with just a little bit more CO2 in the atmosphere, numerous portions of that ice sheet will progressively reach that +0.01 degree Celsius temperature mark, and flow into the sea. Eventually, the Greenland ice sheet will be too small to fit the definition of ice sheet, and will be demoted to mere glacier status, and in less than 1, 000 years.

[sobolanul]

Sea level rise is a very big problem for coastlines. In my opinion when this will become a real problem, there will be already enough damage and system collapse from extreme heat, drought and storms. As we already see and feel, not so much sea level rise but the other climate change consequences on going at a global scale.

[bobleclair]

A lot of sea coast property was once marshes, they served nature’s purpose, a buffer zone

[-LightningRod-]

it is a quandry to me, how much i want to hear what Mr Jason Boxx has to say, ..
and what i might hear Mr Jason Boxx say, ....
Good luck Everyone, ...
Don't forget to VOTE, ...
VOTE like your/Our lives depend on it

[OldScientist]

JRA55 SAT (2010-2020) shows most of the Canadian Arctic and Greenland cooling with parts of Canada cooling by 3°C and western Greenland cooling by 2.5°C in a decade.
KNMI data (Twentieth Century Reanalysis V2c, 1851-2011, 68°N-80°N, 25°W-60°W, so Greenland) shows the most pronounced warming took place in the 1870s, and when comparing temperature anomalies, highest are in the 1930s and comparison of that period with recent temperature anomalies shows no net warming.
The Greenland Ice Sheet contains about 2.9 million cubic kilometers of ice (NSIDC). Using the formula M=Vd (and assuming density of glacier ice 0.9167 Gt/km³), the mass of GrIS is approximately 2.7 million Gt.
If we use the figure of annual loss of 270 Gt, we get 0.01%, or 10, 000 years, so around 12, 024 AD.
The problem is the average figure of 270 Gt (NASA data 2002-2023, 0.8mm/year sea-level rise, so a non-problem). That average value and the data range used gives no understanding of the changes taking place. Prior to 2000 GrIS was not losing mass. From 2002 to 2012 mass loss accelerated, then from 2012 to the present mass loss trend decelerated (85 Gt, 2021). The changes aren't linear they are sinusoidal and are related to the North Atlantic Oscillation, not the the concentration of CO2 in the atmosphere.

[OldScientist]

Sea level appears to be rising at a small 3mm per year. Atolls in the Pacific nations of the Marshall Islands and Kiribati, as well as the Maldives archipelago in the Indian Ocean, have risen up to 8 percent in size (Ford and Kench, 2020). 89% of the globe’s islands and 100% of large islands have stable or growing coasts (Duvat, 2019). No island larger than 10ha decreased in size.
As regards NOAA tide gauge data, let's look at some examples from around the world. N.B. All sites show a linear Relative Sea Level Trend: Kanmen, China 2.40mm/yr; Sydney, Australia 0.75mm/yr; Ferandina Beach, Florida 2.20mm/yr; Los Angeles, California 1.04mm/yr; Mera, Japan 3.8mm; Cascais, Portugal 1.32mm/yr; Newlyn, UK 1.94mm/yr.
Jevrejeva, et al (2014) estimated 2 mm/year (± 0.3), and Church and White (2006) estimated 1.7mm/year (± 0.3). So that's a total rise of between 126 and 151mm (less than 6 inches) from 2024 to the end of the century.
Or try PSMSL data: Kwajalein (Marshall Islands) 1.95mm/yr; Maldives (Indian Ocean) 3.21mm/yr; Lautoka (Fiji Islands, Pacific Ocean) 3.50mm/yr; Port Elisabeth (South Africa) 2.34mm/yr.
Remember, all linear over many decades, or more than a century.
Anyway, if you prefer satellite data NOAA's trend was +3.0mm/year Global Mean Sea Level (1993-2022), again linear last time I looked for each set of satellite data (but hey, it may have accelerated in the last month).
NASA satellite data (1993-present) for Global Mean Sea Level shows a rise of 3.3mm per year. That's the same as two stacked penny coins.
There is no relationship to the increase in CO2 in the atmosphere. It's going to be decades before even your big toe is submerged.

[darinhitchings]

The notion of Greenland ice melt remaining at 2024 levels is preposterous. It's a violation of the Law of Conservation of Momentum. When tipping points tip, the transient response is an exponential function of time... and yes, little / regional tipping points can definitely tip global ones.

I'm not a scientist, but I have a ph.d. in statistical inference, control theory and systems engineering... And I've been studying these topics intensively, recently.

I was invited to write a book chapter on tipping points by a group of professors in the U.K. who are writing a book on the history of science. And I'm writing a couple chapters on tipping points and the math prerequisites needed to talk about them.



I'm pleased to hear Prof. Box say he estimates 40 cm of sea level rise by 2050, because that's very close to what I've written, and I arrived at that number independently of anything he has said on YouTube...

That said, the numbers are themselves absolutely catastrophic. And we can forget about the value of most of Earth's largest cities in this equation. They're a noise term. I'm talking about threats to our existence itself.


There are very, very serious implications here which I would bet 100 to 1 you've never thought about before....

I could write a whole dissertation on these topics, and in some sense I almost have because my book chapter is 75 pages plus another 75 pages of figures, 220 citations...

[a.randomjack]

@Jason
I can't see this video in my feed. I had a notification. When I clicked on it, it said this video was private.
Went to your channel's page, saw it and... here i am.
Not the first time I see this kind of throttling lately... ever since those damm wikiwarnings showed up. What do you think regular people think when they read it?
Thank you Prof. Box. I have been following your work for roughly a decade. 🖖 (Peace and prosperity)

[AKrn]

"The poor will be left behind, unfortunately".
Let them eat cake? I know how that story ends.

[michaeldeierhoi]

That was a issue that Jason Box could have waxed on for an hour easily. And this did look like an excerpt from a longer video.

Jason Box has been studying Greenland for over 3 decades so he probably understands it as well as anyone.

He seems to be saying that Greenland has not yet hit a tipping point, but if the warming and consequent melting of the ice pack continues then it will happen in the coming decades. We definitely need to get serious about warming now because the longer we wait the more serious it will get.

[monkeyfist.]

40 cm by 2050 sounds like a lot. I get the feeling like we could get more than that. No sign of slowing down our use of fossil fuels.

[pokemonjodeldodel]

If we look at hidden warming from SO2 we can see a small fracture of the additional warming we already caused since 2020 because boats are now forced to filter this cooling aerosols out. Ice is reacting really slow and considering that CO2 neutral would mean way more additional warming (scientists guessing about 0.4 to 0.8C) even if we can't see it right now I believe Greenlands Ice sheets are lost. Unless we get back to about 350ppm somehow.

[judewarner]

It's amazing how much relevance people on both sides of the argument put in a single season's datapoint. The TREND has ups and downs, but the accumulated data, including previously unrecognised factors, consistently strengthens the climate change case. While weather becomes more variable and old outliers become the new normal, most parts of the developed world have large areas that will be relatively unscathed or even improved. Some aspects, eg. wildfires, even floods, can be controlled by better management and preparedness... good luck with FEMA America!

The developing world, with vast marginal areas that will tip into uninhabitability, will fare worse. Resource wars will erupt, and homeless migrants escaping war, inhospitable climates, and poverty will overwhelm the developed world unless a unified approach is developed, that hopefully does not involve walled countries with machine gun turrets.

[randyrapaport]

The only way to sufficiently cool the planet is massive
thermo nuclear war and you know it Jason.

[martiansoon]

Losing enough altitude is a true tipping element. 1 000m drop means 6C higher temps that leads further melting. Also similar long term melting element comes when ice sheet loses its buttressing ice shelfs. This allows more ice to float to the sea.

Many other elements are not true tipping points, because they varie a lot, mainly due to weather related issues like snowcover, rain patterns or ocean circulation. These can boost/reduce the melting, but with more random patterns.

Currently more elements are rapidly melting the ice.

[pvmagnus]

Folks, It has reached a tipping point. Scientists find it very hard to admit this. Just look at the CO2 concentrations & eCO2 concentrations. We're committed to at least ~100ft of SLR

[pvmagnus]

Just want to clarify, if Greenland keeps melting, Global sea level is 1.5m due ro greenland?

[roberthornack]

Boy, the hopium sure runs deep with this guy!

[Osoyoos-Wine-Tasting]

By 2040 we are all finished - so yeah 2100 floods no problem!