Meltwater Pulse 1A

Guest “trying not to nitpick” by David Middleton

An Ancient Meltwater Pulse Raised Sea Levels by 18 Meters
Meltwater pulse 1A, a period of rapid sea level rise after the last deglaciation, was powered by melting ice from North America and Scandinavia, according to new research.

By Tim Hornyak  24 hours ago

The period of time when sea levels shot up at the end of the last glacial period, roughly 14,600 years ago, is known as meltwater pulse 1A (MWP-1A). Ever since this pulse was identified from coral records in 1989, the origins of the meltwater have been the subject of debate. Some researchers have hypothesized that Antarctica was the major source of the meltwater, whereas other scientists have suggested that it came from the Northern Hemisphere.

A new study in Nature Communications has concluded that melting ice sheets in North America, followed by Scandinavia, were the dominant drivers of MWP-1A and that the world’s mean sea level rise was 17.9 meters over 500 years.

[…]

Eos

The Climatariat has been desperately trying to blame Meltwater Pulse 1A on Antarctic marine ice cliff instability (MICI) ever since they first identified it in 1989, right after Al Gore invented Global Warming. Their poster child for this phenomena was Greenland’s Jakobshavn Isbrae glacier, which suddenly stopped cooperating in 2016. In their typical style, the Climatariat quickly changed the Chicken Little cackle from “Run Away! The glaciers are shrinking!” to “Run Away! The glaciers are growing!”

The paper, Lin et al., 2021, supports the obvious explanation of Meltwater Pulse 1A.

Figure 1. Late Pleistocene to Early Holocene deglaciation. (Illinois State Museum)

The full text of the paper is available and worth reading. The Eos article on the other hand…

Meltwater pulse 1A, a period of rapid sea level rise after the last deglaciation…

Eos

Meltwater Pulse 1A (MWP 1A) occurred rather early on during the last deglaciation, not afterwards.

Figure 2. Global seal level rise during Holocene Transgression. MWP 1A occurred ~14.6 kya. Note the error bar is ±12 meters.
(Siddall et al., 2003)

Then there was the obligatory and gratuitous…

Insights on Climate Change Today
Yusuke Yokoyama, a professor at the University of Tokyo’s Atmosphere and Ocean Research Institute who was not involved in the study, said the new research is a possible answer to the question of meltwater sources for MWP-1A, but that the debate is far from over.

Eos

The “not involved in the study” professor’s main beef was with the choice of the radiometric dating method… However, at no point did any contributor to the article provide any “insights on climate change today” because there are none.

References

Hornyak, T. (2021), An ancient meltwater pulse raised sea levels by 18 meters, Eos, 102, https://doi.org/10.1029/2021EO159031. Published on 02 June 2021.

Lin, Y., Hibbert, F.D., Whitehouse, P.L. et al. A reconciled solution of Meltwater Pulse 1A sources using sea-level fingerprinting. Nat Commun 12, 2015 (2021). https://doi.org/10.1038/s41467-021-21990-y

Siddall M, Rohling EJ, Almogi-Labin A, Hemleben C, Meischner D, Scmelzer I, Smeed DA (2003). “Sea-level fluctuations during the last glacial cycle”. Nature 423:853–858

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John Tillman
June 3, 2021 10:10 am

Abstract
The most rapid global sea-level rise event of the last deglaciation, Meltwater Pulse 1A (MWP-1A), occurred ∼14,650 years ago. Considerable uncertainty regarding the sources of meltwater limits understanding of the relationship between MWP-1A and the concurrent fast-changing climate. Here we present a data-driven inversion approach, using a glacio-isostatic adjustment model to invert for the sources of MWP-1A via sea-level constraints from six geographically distributed sites. The results suggest contributions from Antarctica, 1.3 m (0–5.9 m; 95% probability), Scandinavia, 4.6 m (3.2–6.4 m) and North America, 12.0 m (5.6–15.4 m), giving a global mean sea-level rise of 17.9 m (15.7–20.2 m) in 500 years. Only a North American dominant scenario successfully predicts the observed sea-level change across our six sites and an Antarctic dominant scenario is firmly refuted by Scottish isolation basin records. Our sea-level based results therefore reconcile with field-based ice-sheet reconstructions.

https://www.nature.com/articles/s41467-021-21990-y

Last edited 12 days ago by John Tillman
Ron Long
June 3, 2021 10:22 am

Good posting, David. This meltwater event also produced the spectacular Channeled Scablands, mostly in Eastern Washington state. This event, actually a series of really strong floods, was initiated by ice dams near Missoula, Montana, being episodically breached by lake build-up behind the ice dam. For a view of the phenomena go to Google Earth ™ at 423800 E and 5229000 N, elev. 580 m (WGS 84, UTM meters). The CAGW crowd has no idea about natural earth processes.

John Tillman
Reply to  David Middleton
June 3, 2021 10:48 am

Latest thinking is that the Missoula floods occurred repeatedly from around 15 to 13 Ka (dunno if calender or radiocarbon). Average duration of the ice-dammed lake is estimated at 55 years.

Very little of MWP1A came from the Rockies via the Columbia.

However it now appears that the meltwater flood which triggered the Younger Dryas cold snap, c. 12.9 calender Ka, entered the Arctic Ocean down the Mackenzie River drainage, with outflow from both the Cordilleran and Laurentide Ice Sheets. Previously it was thought that the water came from the St. Lawrence, but in any case not down the Mississippi.

John Tillman
Reply to  MarkW
June 3, 2021 11:40 am

There’s no reason to suppose that the cause of the YD differed from those of the Older and Oldest Dryas. Or similar cold snaps like the 8.2 Ka Event and during prior deglaciations, such as before the Eemian.

The Hiawatha Crater, if it indeed be an impact crater, is far older than the YD, and the second putative crater appears older still, as your NASA link says.

https://www.geosociety.org/GSA/News/pr/2020/20-16.aspx

The Hiawatha feature dates from the Pliocene, as shown by charcoal around three million years old.

Last edited 12 days ago by John Tillman
Pipo
Reply to  John Tillman
June 3, 2021 6:34 pm

Randall Carlson is one of the foremost experts on YD.

He and his work help explain, or at least can throw out some of the nonsense theories being thrown around by Académia regarding the melting of the Ice Sheets

John Tillman
Reply to  Pipo
June 4, 2021 6:32 am

He’s not an expert on anything. He’s a loon.

John Tillman
Reply to  David Middleton
June 4, 2021 8:14 am

I’m going to steal that!

Nicholas McGinley
Reply to  MarkW
June 6, 2021 2:16 am

First time I heard about the Younger Dryass, I thought they were talking about those new ultra absorbent diapers.

Nicholas McGinley
Reply to  John Tillman
June 6, 2021 2:13 am

If by, “it now appears”, you mean, “someone has claimed to have found some evidence that tentatively suggests that it may possibly be the case”, then I agree with you.

John Tillman
Reply to  Nicholas McGinley
June 7, 2021 3:07 pm

It means that the evidence is better for drainage that way than any of the alternatives.

H. D. Hoese
Reply to  David Middleton
June 3, 2021 11:12 am

Regardless, everybody needs to see that as I did twice after a friend went there on a geological field trip. I have a piece of gravel bigger than a grapefruit, thought that it took many such massive flood events, as shown by the lake levels above Missoula. As the petroleum industry expands in the Gulf of Mexico more of large floods among other events may be becoming evident. Is there a recent survey of this? I have read that the worst Mississippi River flood was in 1858.

Texas beach below Corpus Christi just received a Louisiana alligator, I saw one of similar size well offshore during the 70s floods, they, bigger than typical sedimentary pieces, get moved around, also get pneumonia during freezes.

Nicholas McGinley
Reply to  H. D. Hoese
June 6, 2021 2:03 am

The word “gravel” refers to a particle size.
If it is as big as a grapefruit, or in fact anything bigger than 2.5 inches, about chicken egg size, it is by definition not gravel, but a cobble.

Ron Long
Reply to  David Middleton
June 3, 2021 11:29 am

Although there are several different opinions about the age of the floods, the most common ages are underway by 18,000 mya, peaking at 15,000 mya, and ending at 13,000 mya. Your moving Meltwater 1A figure shows the melting going north of the ice dam area early in the process. For pictures of this amazing area check out “Seven wonders of Washington State”.

Reply to  David Middleton
June 3, 2021 12:47 pm

Randall Carlson and Antonio Zamora on Youtube have lots of inormation and evidence of a comet/meteorite hitting the ice sheet….Younger-Dryas event. The temp rose about 20 C out of the Ice Age and then plunged back 20 C and then rose 20 C to the approximate level of today. Lots of action roughly 12, 500 to 15,000 years ago….it’s what is called Real Climate Change.

John Tillman
Reply to  Anti-griff
June 3, 2021 2:11 pm

No, they don’t. They’ve got zilch.

Even impact advocates no longer cite the Carolina Bays as evidence. They’re aeolian features.

Reply to  John Tillman
June 3, 2021 3:18 pm

Well, I know you are the world renowned authority on the subject but…black matte….some Carolina Bays overlap so explain that by wind rather than a projectile ….Antonio Zamora is the man on Carolina Bays to consult…the flood evidence is abundant….ice dam not so much…there is a hole in Michigan which under a sheet of ice is maybe an impact crater…there is probably 10 to 20 hours on Youtube from Randall Carlson who has made trips to the flood areas. Mega fauna extinction…disappearance of Clovis Point people…it’s a pretty big subject…..but highly unlikely that the Clovis people killed the Mega Fauna or….put CO2 in the atmosphere causing the problem.

John Tillman
Reply to  Anti-griff
June 4, 2021 7:08 am

It is highly likely that people wiped out the megafauna. All the evidence in the world is against an impact having done so. Megafauna survived on Caribbean islands until people arrived there, thousands of years after the YD.

If the megafauna on North America and South America were k1lled off by an impact, then so would have been the island species of ground sloths, etc.

Please read the work of real scientists rather than falling for gibberish spewed by YouTube goons.

Reply to  John Tillman
June 5, 2021 7:38 am

Uh, Randall Carlson might sit on you due to the insult….but he has heard worse insults.

Reply to  John Tillman
June 5, 2021 7:47 am

Real scientists??????? Are you talking about Mikey Mann?…..about that 97% consensus mentioned by the Great Obomba? I never heard of scientist John Tillman.

John Tillman
Reply to  Anti_griff
June 5, 2021 10:58 am

I’m talking about real the geologists, paleontologists and paleoclimatologists who have shown the YDI hypothesis false.

One of the many papers to that effect:

https://www.sciencedaily.com/releases/2014/05/140513113605.htm

Last edited 10 days ago by John Tillman
Randy Karst
Reply to  John Tillman
June 4, 2021 9:05 am

The belief that the Clovis people with their elegant spear points, killed off most of the mega-fauna of N.A. is even more absurd than the belief that 2 extra molecules of CO2 per 10,000 molecules in atmosphere will kill off today’s mega-fauna, including us. Unfortunately, we can’t study the Clovis culture’s evolution through time because it didn’t survive the YD either.
Aeolian source for Carolina Bays is almost equally absurd. Earth would be even more pox-marked than the moon if it wasn’t wiped clean by weathering + time.

Reply to  David Middleton
June 5, 2021 7:44 am

The impact of a ballistic projectile produces the same max width to max length ratio as the bays…odd, no? Why are the bays found no where else in the world? How about that black matte that is evidence of massive fires and an asteroid hit?

Reply to  David Middleton
June 3, 2021 8:08 pm

The Carolina Bays extend from New Jersey to Florida….there is an orientation pointing towards the Great Lakes….if wind created the bays then it should be reproducible but no one has done it….the ages of the bays would all be the same if caused by ice when a meteor hit the ice sheet so all someone has to do is date some of the bays but no one has produced dates and there are bays that overlap which means one was formed and then a second projectile landed close and overlapped the first one. The wind did it is about equivalent to my dog ate my homework and that wind somehow changed the orientation so that bays in Florida point more northward than bays in Virginia. In regard to ice dams….some have been observed in Iceland but where oh where has anyone observed an ice dam holding back water 300 feet deep or deeper?

John in Oz
Reply to  Ron Long
June 3, 2021 5:20 pm

Based on all of the responses to your comment, it’s comforting to see so much ‘settled science’ to base our futures on /sarc

David L. Hagen
Reply to  Ron Long
June 4, 2021 6:12 pm

Megafloods
Overall conclusions are that glacial Lake Missoula was extant and producing floods for at least 3–4 ky during 20–14 ka. At least ~75 floods preceded Mount St Helens Set S, followed by 30 or more after the tephra fall. Most floods entered glacial Lake Columbia, impounded by the Okanogan lobe, for 2–5 ky between about 18.5 and 15 ka. Glacial Lake Columbia outlived Lake Missoula by >200–400 yr but may have been born later since at least one flood came down the Columbia valley before the Okanogan ice lobe blocked the Columbia valley at 18.5–18 ka. The maximum extent of the Okanogan and Purcell Trench lobes, many Missoula floods, substantial erosion of upper Grand Coulee, and the widespread tephra falls from Mount St. Helens eruptions all happened about 17–15 ka. People, in the area since 16.6–15.3 ka, almost certainly witnessed the last of the Missoula floods and later large floods from other ice-dammed lakes in the Columbia River basin.”
O’Connor, J.E., Baker, V.R., Waitt, R.B., Smith, L.N., Cannon, C.M., George, D.L. and Denlinger, R.P., 2020. The Missoula and Bonneville floods—A review of ice-age megafloods in the Columbia River basin. Earth-Science Reviews, p.103181. The Missoula and Bonneville floods—A review of ice-age megafloods in the Columbia River basin (usgs.gov)
Part of Special Issue: Megaflooding on Earth: A Global Perspective
Edited by Paul A Carling, Victor Baker, Juergen Herget

Nicholas McGinley
Reply to  Ron Long
June 6, 2021 2:08 am

As fast as MWP 1A was, it still only amounted to about 1.5 to 2.5 inches per year.
Perhaps even slightly under 1.5 inches/yr.
“Fast” is a relative term, and for geologists, a snail walks at something like just under the speed of light.

Rud Istvan
June 3, 2021 10:43 am

Since sea level rise has not been accelerating as climate alarmists have been predicting for now over 40 years, in the past decade they turned to a related SLR alarmist idea—but it will because it happened before!

There are two time periods that they have focussed on for evidence that ‘it happened before’, the Eemian rise about 121kya and MWP-1a about 14.5kya.

With respect to the Eemian, the most prominent paper is by O’Leary and comprises provable scientific misconduct, exposed in essay ‘By Land or by Sea’ in ebook Blowing Smoke.

With respect to MWP-1a, this new paper puts to bed the ‘ice sheet collapse caused it’ theory.

More generally with respect to the Holocene, essay ‘Tipping Points’ in Blowing Smoke puts to bed any future collapse in either Greenland or Antarctica, despite many alarmist papers raising supposed concerns. Greenland’s Jacobhaven stopped receding. Oops. More generally, Greenland is bowl shaped; its ice sheet would have to melt; it cannot collapse. Both the Ronne and Ross ice sheets in WAIS proved stable, so NASA’s Rignot turned to WAIS’ Amundsen Embayment and published several alarmist papers that turned out to be based on false premises in models, shown in the Tipping Points essay.

Joel O'Bryan
Reply to  Rud Istvan
June 3, 2021 11:42 am

That’s why Pine Island and the Thwaites seabed grounded ice with claimed coming collapse are now the Alarmists’ latest exaggerations.

Rud Istvan
Reply to  Joel O'Bryan
June 3, 2021 12:22 pm

Joel, true. The Rignot alarm was predicated on PIG and Thwaites completely going, ‘unplugging’ the entire Amundsen catchment basin which would then lose ALL its ice and result in 4 meters of SLR, ‘only’ 1/4 ofMWP-1a (see, it happened before). Unfortunately for Rignot, others actually went out into the catchment basin and measured via DiffGPS transponders over a few years the actual ice creep. Near zero for half the catchment, and not high even on PIG and Thwaites. Even if they recede from ocean undermining, the most recent alarm ocean erosion model still has that happening over several hundred years. No collapse. The ref. citations are in the essay footnotes.

Gunga Din
Reply to  Rud Istvan
June 3, 2021 2:47 pm

And then there’s the cause of those ancient melts.
They claim Man’s CO2 is the cause of current melts.
How many bristlecone pines did ancient Man have to burn for his CO2 to cause ancient melts?

Last edited 12 days ago by Gunga Din
another ian
Reply to  Gunga Din
June 3, 2021 8:10 pm

Looks like it wasn’t ruminants wot did it

“There are 94 million head of cattle in the US.”

Once there were 50-to-100 million buffalo, they were the most numerous large mammals to ever exist… | by David Bunnell | Medium

So the last time there were 100 million bovines in America, CO2 levels were very low and earth was experiencing the coldest period of the last 10,000 years – but this time they are causing out of control global warming.”

https://realclimatescience.com/2021/05/let-them-eat-bugs/

MarkW
June 3, 2021 11:09 am

the world’s mean sea level rise was 17.9 meters over 500 years.

I thought 1 foot in a century was supposed to end all life on the planet?

LdB
Reply to  MarkW
June 3, 2021 2:11 pm

Yes you wouldn’t even get your ankles wet in a whole lifetime but it’s curtains for you … oh wait.

Gunga Din
Reply to  LdB
June 3, 2021 2:34 pm

I’m sure that they’ll come up with a stat that says “prune toes” can be fatal.

Andrew Burnette
June 3, 2021 11:13 am

18 meters in 500 years? Try outrunning 1.4 inches per year!!!!

Sounds like the hyperbolic worst-case is still pretty easily accommodated by adaptation, as long as you have cheap, abundant and reliable energy to run the machines it requires.

Last edited 12 days ago by Andrew Burnette
John Tillman
Reply to  Andrew Burnette
June 3, 2021 11:26 am

That pace of melting can’t happen today. The Northern Hemisphere retains only one small ice sheet, on Greenland. Most of MWP1A came from the long-gone Laurentide and Fenno-Scandinavian ice sheets.

MSL is still rising at the same low rate it has since the depths of the LIA during the Maunder Minimum in the AD 1690s.

Rory Forbes
Reply to  John Tillman
June 3, 2021 2:06 pm

Isn’t the sole of the Greenland ice sheet already below sea level, so Greenland can’t possibly melt completely until the land recovers from isostatic depression?

John Tillman
Reply to  Rory Forbes
June 3, 2021 2:42 pm

Yes.

Besides which, even during the Eemian, which lasted thousands of years longer than has the Holocene so far and was hotter, with hippos in the Thames at the site of London, only the Southern Dome of the GIS melted an estimated 25% more than during our current epoch. The Northern Dome appears to have been little affected.

Last edited 12 days ago by John Tillman
Rory Forbes
Reply to  John Tillman
June 3, 2021 3:02 pm

So it would be fair to say there’s an abundance of unnecessary hysteria. /sarc

John Tillman
Reply to  Rory Forbes
June 3, 2021 3:11 pm

To put it mildly.

I know people who thought in 2012 that the GIS would be gone by now.

The Southern Dome did however apparently melt during the super-interglacial of MIS 11:

https://www.researchgate.net/publication/263431061_South_Greenland_Ice-Sheet_collapse_during_Marine_Isotope_Stage_11

Last edited 12 days ago by John Tillman
Reply to  John Tillman
June 4, 2021 1:16 am

John
I thought the Eemian was shorter than the Holocene. It looks more like a sharp peak in the ice core records, while the Holocene i more of a plateau.

John Tillman
Reply to  Hatter Eggburn
June 4, 2021 6:41 am

The Eemian is variously dated, but all longer than the Holocene so far. Our epoch however might turn out to be a super interglacial.

This study found it lasted 15,000 years, ie 115 to 130 Ka:

http://nora.nerc.ac.uk/id/eprint/500331/1/2012-07-09846-NEEM_revised.pdf

Joel O'Bryan
Reply to  Andrew Burnette
June 3, 2021 11:45 am

coral reefs everywhere yawn at even Meltwater pulse 1A rates.

Rory Forbes
Reply to  Joel O'Bryan
June 3, 2021 3:04 pm

Now there’s an image worth its weight in gold … yawning polyps.

Tedz
Reply to  Andrew Burnette
June 3, 2021 12:10 pm

I’m not so sure that it was always 1.4 inches a year.

Off the coast of the north west of India (Gulf of Cambay) and in the caribbean they’ve found pottery and other items at about 40m to 60m depth – also included stone tools.

If my kitchen and garage were going to be flooded by the sea I’d make sure to get my kitchenware and tools and take them with me. Unless I didn’t have time.

John Tillman
Reply to  Tedz
June 3, 2021 12:31 pm

Other reasons besides a meltwater pulse can explain finds of pottery and stone tools. After all, archaeologists uncover such artefacts frequently. In a coastal zone, however, tsunamis are also a possibility.

mkelly
Reply to  John Tillman
June 3, 2021 2:39 pm

Have seen several documentaries about the volcano in Canary Islands collapsing the west facing side sending large tsunami over the Caribbean islands.

Reply to  mkelly
June 5, 2021 7:23 am

….and tsunami over east coast USA.

Reply to  David Middleton
June 5, 2021 3:21 pm

I did not say there was any evidence of past tsunamis …just referring to the possibility of one from the Canary Isles hitting east coast of USA. I just hope Mr. Wind is not involved…Mr. Wind is a capricious figure….we have just seen his work on Mars…dust devils everywhere…the landscape is worn by millions of years of blown sand but….but….no Carolina Bays. Those bays on earth are disappearing…sad….they are so rare ….but on the move?….apparently to oblivion.

Gunga Din
Reply to  John Tillman
June 3, 2021 2:51 pm

And earthquakes that produce a sudden drop in the land’s elevation rather than the seas gradual “elevation”.

hiskorr
June 3, 2021 11:33 am

Inasmuch as the MWP 1a is supposed to have occurred when the sea level was about 100 meters lower than today, I was quite annoyed by the snow-melt graphic superimposed on the current outline of North America.

Reply to  hiskorr
June 3, 2021 12:15 pm

I saw only information when I saw that superposed graphic. Now that you have pointed out the flaw, though, I suddenly yearn to see the same, but with a realistic coastline. You got one?

John Tillman
Reply to  paranoid goy
June 3, 2021 12:43 pm
beng135
Reply to  John Tillman
June 3, 2021 1:08 pm

Can’t get Firefox or Microsoft Edge to run the .mov file.

Reply to  John Tillman
June 3, 2021 1:20 pm

My browser finds your link unappetising… “No secure connection available” etc.

dk_
Reply to  paranoid goy
June 3, 2021 1:29 pm

P. G.
FYI there’s a newish browser feature across the major developers. Happens by default when the server hasn’t switched to https, or when the secure link isn’t established. That link doesn’t work on mine either, but Firefox lets me click past if I choose. I won’t recommend either way.

John Tillman
Reply to  paranoid goy
June 3, 2021 2:03 pm

Sorry about that!

Here’s a site that works:

Reply to  John Tillman
June 4, 2021 5:10 am

Thank goodness I am a WUWT junkie with e-mail feed, otherwise I would have looked at you funny.
Got the link to work, watched the animation, did not see a pulse. 13 000 years for the ice to melt, so where’s the 500-year “pulse”?
Not registering my opposition to the theory, just my doubts.

John Hultquist
June 3, 2021 2:59 pm

Study of the Scablands of E. Wash. and the ice age floods continues, and documentation has gotten on line. See ‘Ice Age Floods Institute’ . . .
https://iafi.org

For dating information, watch this presentation (I was in the front row):

Clyde Spencer
June 3, 2021 3:20 pm

David,
Was the ice sheet animation done with a TRS-80? 🙂

ATheoK
June 3, 2021 4:06 pm

that melting ice sheets in North America, followed by Scandinavia, were the dominant drivers of MWP-1A and that the world’s mean sea level rise was 17.9 meters over 500 years.”

14,000 plus years ago, with a CO₂ level somewhere between 180ppm and 260ppm, they just proved the great melt wasn’t from CO₂ levels.

June 3, 2021 5:15 pm

Melt
Water
Pulse
Mediaeval
Warm
Period
Oh Noes!

John Tillman
Reply to  Leo Smith
June 4, 2021 6:44 am

Plus Minoan and Modern WPs.

Dena
June 3, 2021 5:50 pm

There is another way of proving/disproving this, How much heat would it require to melt this much ice to produce that much change in the ocean level and how long would it take the sun to do that? I suspect like today, a good deal of the energy would be radiated back to space so something is wrong with the 500 year figure. Either the melt took longer or it occurred over a much larger area. I leave it to somebody with a better feel for the numbers to carry out the calculations.

Earthling2
Reply to  Dena
June 3, 2021 11:55 pm

As things slowly warmed up due to more solar insolation at the higher latitudes starting about 20-18kya, instead of snowing on the ice sheets, it rained more than it snowed every year. Snow sticks and turns to ice and continues accumulating ice after a period of time. Warm rain water erodes ice much faster than just increased air temps and runs off very quick taking ice melt along with it and is all self reinforcing as the ice sheet declines in altitude.

Just like every spring, once it rains on the snow pack, freshet is right around the corner much quicker than warm sunny weather. A warm wind also erodes ice, and sublimates or melts quicker. The rain came from the tropics where the Sun was evaporating more water as the oceans warmed. 500 years is a long time, especially if you are waiting for the kettle to boil.

Last edited 12 days ago by Earthling2
sendergreen
June 3, 2021 6:22 pm

The graphic looks like a SAC wallboard projection in Cheyenne Mountain in 1967.

Pipo
June 3, 2021 6:31 pm

How come no “theories” as to what caused MWP 1A?
Is it because no one wants to admit to comets, or asteroids impacting Earth?

Reply to  Pipo
June 3, 2021 9:50 pm

Wrath of The Lord? The dating seems consistent with silt layers attributed to the Great Flood, no so?
In this context, please note that in some circles, planets are considered sentient, and are honored with the title “Lord”.
One motherlovin’ big body passing close enough to strip Mars of atmosphere would probably cause a bit of ruckus on Earth…
Venus would be a good guess, Nubiru is the understudy.

Last edited 12 days ago by paranoid goy
John Tillman
Reply to  Pipo
June 4, 2021 7:00 am

There is no shortage of hypotheses as to the origin of MWP1A.

This paper pretty conclusively rules out Antarctica as the main meltwater source. Most of the water came from North America, probably due to separation of the Cordilleran and Laurentide Ice Sheets, creating the Ice Free Corridor. Meltwater would have flowed out from a temporary ice-dammed lake between the ice sheets when the Arctic dam broke.

The outburst flood may be associated with the Older Dryas cold snap, but that interval is not well dated.

No impacts need apply.

Reply to  Pipo
June 5, 2021 8:06 am

Maybe the same forces that caused warming out of the previous ice age…and the one before ….and the one before? There is not much clock work in geology but the ice age thaws come close.

June 3, 2021 11:38 pm

Was this the lake Agassi dam burst event, or earlier than that? Thanks for this nice article.

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