Ice Age Floods cause mass extinctions?

[nannoh]

Atlantic conveyor runs around a million cubic kilometers per year, global run-off is around thirty thousand cubic kilometers per year. Slugs of a few thousand cubic kilometers here and there (huge floods) aren't all that significant. Missoula, annual flooding on Nile, or Mississippi, or Yangtze are measured in hundred(s) of cubic kilometers. These are remarkable events if you happen to be living in the run-off path; they aren't remarkable events in terms of the global hydrologic cycle.

I can see the disparity between the amounts of water but not the effect temperature change would have on a specific current. It may also be true that the temperature of the floods would not necessarily be much colder than the ocean after sitting as a lake or traveling several hundreds of miles over the surface and in a warming atmosphere.

I also wonder if the introduction of what we see as a large amount of fresh water into a saline ocean would have a slowing or halting effect on the current.

_____________________________

Its interesting how the geologic information gathered about the Ice Age Floods™ is now being used to explain some terrains on mars.

Scientific study of the Ice Age Floods is contributing to the understanding of cyclical climate change and of very large and destructive contemporary floods on Earth. The Ice Age Floods have also been considered as an analog to understand geologic processes on Mars, where landforms strikingly similar to those in Eastern Washington exist.

http://www.iceagefloodsinstitute.org/aboutfloods/relatedphenomena.html

I was back on that site looking for the stats on the volume of fresh water that was released by the disintegration of the ice dams in that region. As I remember it the volume was more like 150,000 cubic kilometres but I can't find the stat. And this was only one reservoir behind an ice dam in the NW.

I think we have to remember that the Ice Fields were commonly 2 miles thick. They covered an area of about 70,000 sq miles. That translates into a lot of melt water even if it melted over 2000 years or more.

 

[Bystander]

(snip)I think we have to remember that the Ice Fields were commonly 2 miles thick. They covered an area of about 70,000 sq miles. That translates into a lot of melt water even if it melted over 2000 years or more.

http://www.gsajournals.org/perlserv/?request=get-document&doi=10.1130%2F0016-7606(2003)115%3C0624:NASOLM%3E2.0.CO%3B2

"Lot of melt water..." 70k x 2 x 4 = 560 k cubic kilometers; 2000 yrs. x 30 k/a = 60 M cubic kilometers. Global runoff is 1% higher during the ice age meltdown? Effects on ocean circulation associated with rising water level are going to be far greater than odd little discharge spikes.

 

[nannoh]

http://www.gsajournals.org/perlserv/?request=get-document&doi=10.1130%2F0016-7606(2003)115%3C0624:NASOLM%3E2.0.CO%3B2

"Lot of melt water..." 70k x 2 x 4 = 560 k cubic kilometers; 2000 yrs. x 30 k/a = 60 M cubic kilometers. Global runoff is 1% higher during the ice age meltdown? Effects on ocean circulation associated with rising water level are going to be far greater than odd little discharge spikes.

Very nice math! I'm not sure that we are calculating the effects of the changes caused by a: fresh water or b: temperature to the system of the Gulf Stream. Simply stating volume vs volume does not look into the
effects of these factors. Is there a text on the effects of fresh water and colder water on warm currents?

 

[Bystander]

Your turn to do the math: come up with a mechanism for stalling the conveyor, and the energy or power necessary to do so that can be derived from excess fresh water runoff.

 

[nannoh]

Your turn to do the math: come up with a mechanism for stalling the conveyor, and the energy or power necessary to do so that can be derived from excess fresh water runoff.

No math yet but there are some factors reported by various research endevours.

These have to do with mineral content in meltwater and its effects on biomass and ocean saltwater but may work somewhat to help or hinder the idea that glacial meltwater can disrupt an ocean current of warmer, denser water. There really didn't seem to be much information specifically pertaining to the focus of this side issue.

http://snobear.colorado.edu/Markw/Research/06_ppp.pdf

And

Finally, the input of meltwater can have a significant influence on the formation of sea ice in this region. In fresher water, the freezing point of water is higher and less energy is required to produce sea ice. Additionally, the amount of stratification in the upper water column also significantly influences the heating and cooling rates of the sea surface. Both the salinity and cooling rate of the surface layer will influence the onset of sea ice formation, which has important implications from oceanographic, climatological, and biological perspectives. Sea ice is an important component of the ocean-atmosphere heat flux and critical to the formation of Antarctic bottom water (17). The annual advance and retreat of sea ice is also a major physical determinant

http://www.pnas.org/cgi/content/full/99/4/1790

And from the same source

Meltwater Interactions Onshore to Offshore. Vertical contours of salinity (Fig. 4 Left) and Chl (Fig. 4 Right) are presented for a transect extending from shore out to 160 km. These example profiles were obtained along the 600 line (Fig. 1A) from five summer cruises (January 1993-1997). Lower salinity is associated with waters close to shore, and salinity gradually increases with distance from shore. Highly stratified meltwater layers extending nearly 100 km offshore are observed in 1995 and 1996. This observation also coincides with the on- to offshore gradient in biomass. The low-salinity surface water is generally mixed between 50 and 80 m within 100 km offshore.

Here's more,

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/crls.rxml

http://www.viking.no/e/travels/weather/e-current.htm

Some fairly simple models of the world's oceans do simulate a rapid break down of the THC, when the density of the water in the North Atlantic Ocean is lowered by adding fresh water (rain) and/or by warming. Increased rainfall and warming over the North Atlantic are both expected as a result of increased greenhouse gas concentrations, and so it can be argued that global warming may cause a rapid collapse of the thermohaline circulation. The self-sustaining system described above is, however, much more complex in reality, and the more complete climate models, that take some of these complexities into account, generally simulate only a gradual weakening of the THC in response to global warming. Nevertheless, observations and palaeoclimate evidence both indicate that the THC has fluctuated both recently and in the distant past.

http://www.cru.uea.ac.uk/cru/info/thc/

 

[Andre]

There is a problem though with those "meltwater pulses", Here, are three studies that form a big conflict together around a sudden sea level rise that is known as “Melt Water Pulse 1A”. Curiously enough one person, Prof Clark of the Oregon Uni, (co)authored all three of these papers. So I wonder if he wonders about those problems. Let’s start with the most recent one.

Clark et al (2004), http://www.geo.oregonstate.edu/people/faculty/clark_publications/Clarketal.-Science-2004.pdf. Science 21 May 2004: 1141-1144

In which it is shown that clear geologic evidence exists that the great melting at the end of the ice ages started 19,000 years ago, which is a bit odd since the ice cores of Antarctica did not start to show any warming before 17,300 years ago, whilst the Greenland Ice cores waited until some 14,600 years ago. So Clark et al contend:

The initiation of warming at 19,000 years B.P. at Atlantic and Antarctic sites (Fig. 3, D to F) records this expected ocean response to the 19-ky MWP. In particular, we note that warming occurred at Antarctic sites before any substantial rise in atmospheric CO2 (23) and despite a gradual decrease in austral summer insolation.

We have two remarkable things here that the warming began some 2000 years before the CO2 rose, which is held responsible for a large role in that warming and second, that it was Antarctica that warmed and hence started to melt. Let’s keep that in mind when we look at a second study about that Meltwater Pulse 1A.

Weaver A.J. et al (2003) http://www.geo.oregonstate.edu/people/faculty/clark_publications/weaveretal.-science-2003.pdf 14 March 2003 Vol 299 Science pp1710 - 1713

Meltwater pulse 1A (mwp-1A) was a prominent feature of the last deglaciation, which led to a sea-level rise of about 20 meters in less than 500 years. Concurrent with mwp-1A was the onset of the Bølling-Allerød interstadial event (14,600 years before the present), which marked the termination of the last glacial period. Previous studies have been unable to reconcile a warm Northern Hemisphere with mwp-1A originating from the Laurentide or Fennoscandian ice sheets. With the use of a climate model of intermediate complexity, we demonstrate that with mwp-1A originating from the Antarctic Ice Sheet, consistent with recent sea-level fingerprinting inferences…

That’s pretty clear. If you scan the article you’ll see that Clark is amongst the authors and it’s also mentioned again that the warming in the south started as early as 19000 years ago. BTW this is not the only study that gives Meltwater Pulse 1A an Antarctic origin.

Also keep in mind that the current ice sheet of Greenland, central in the public interest, is good for a sea level rise of 7 meters. Apparently, Meltwater Pulse 1A was equivalent to the melting of almost three Greenland ice sheets within 500 years.

But now the third study:

Clark P.U. and Mix A.C (2002)http://www.geo.oregonstate.edu/people/faculty/clark_publications/clark&mix-qsr-2002.pdf, Quaternary Science Reviews 21 (2002) 1–7

We are interested in table 1 about the contribution of the several Ice sheets to the sea level rise. For Antarctica we see a series of 24,5 meters from the oldest studies to 14,0 meters in the more recent studies. Given the fact that there is hardly any tectonic post glacial rebound at Antarctica, that only land ice counts and that there is no room whatsoever to have 2-3 additional Greenland Ice sheets anywhere on the Antarctic continental shelf, 14 meters does seem to be quite a bit already. Now as the melting apparently started 19,000 years ago and lasted several thousand years as the end of the Ice age is marked at 11,600 years ago, you’d expect only millimetres per year from Antarctica but no, it was 20 meters in 500 years, meltwater pulse 1A.

Now this all happened in concert with the high spikes in Greenland, suggesting that it got warmer over there, hence suggesting that the thermohaline current increased in strength, which would also have followed from a sudden and rapid drop of the sea surface temps in the Caracio basin near Venezuela. Did the meltwater pulse increase the thermohaline current?

At this point it could be clear that the reality was much different.

There is a pet idea...

 

[nannoh]

Did the meltwater pulse increase the thermohaline current?

At this point it could be clear that the reality was much different.

There is a pet idea...

I'm not sure what your pet idea is other than the methane release in the eastern Atlantic. But several times there was mentioned the effect of freshwater (meltwater) not mixing with the denser saline waters of the ocean and particularly the Gulf Stream.

The whole effect of the fresh water incursion was to stablize the surface water and for it to stay on the surface. This is where it acts as a "lens" which transfers sunlight into deeper portions of the ocean than usual. And I imagine this lens would not only raise chlorophyll production and biomass numbers but also raise the temperature of the water at that depth. This may have actually agitated the thermohaline current making it stronger, sending it further north at a stronger pace.

 

[Andre]

I'm not sure what your pet idea is other than the methane release in the eastern Atlantic. But several times there was mentioned the effect of freshwater (meltwater) not mixing with the denser saline waters of the ocean and particularly the Gulf Stream.

The essence here is that the meltwater pulse 1A has no source. It's neither from the Northely ice sheet nor from Antarctica. But yet, it was about three Greenland ice sheets in a few decades. Now, out-of-the-box-thinkers would investigate the possiblility that the Meltwater pulse wasn't a meltwater pulse at all, wouldn't you think?

 

[nannoh]

The essence here is that the meltwater pulse 1A has no source. It's neither from the Northely ice sheet nor from Antarctica. But yet, it was about three Greenland ice sheets in a few decades. Now, out-of-the-box-thinkers would investigate the possiblility that the Meltwater pulse wasn't a meltwater pulse at all, wouldn't you think?

Yes.
Something very large entering the ocean causing displacement and consequently sea level rise. (But would also cause a nuclear winter after a global fire storm)

Or
an introduction of magma to the lithosphere causing displacement and the ocean's level rise.

Or methane (primary atmosphere) release?

19,000 you is in the middle/end of the LGM isn't it? Not much would be melting at that point. No Ice Age Floods causing levels to rise.

 

[Bystander]

(snip)The whole effect of the fresh water incursion was to stablize the surface water and for it to stay on the surface. This is where it acts as a "lens" which transfers sunlight into deeper portions of the ocean than usual.(snip)

Fresh water is 3% less dense than sea water --- it floats on the surface --- only so long as there is no mechanical agitation to mix it with seawater (no wind and wave motion --- the situation that holds beneath Arctic pack ice for Canadian shield runoff). Other than that, take a look at the Amazon for effects of 5-7 thousand km³/a fresh water runoff into salt water and "stabilization" of ocean surface. Fresh water does not act as a "lens" in any optical sense; it's generally silt laden (opaque), and is not magically transferring sunlight more deeply into the ocean; it is also laden with nutrients which do enhance biological activity, but, again, this is nothing particularly magical, confers no greater inertia upon water masses that are trivial in comparison to ocean mass to affect major changes upon ocean circulation.

 

[nannoh]

Fresh water is 3% less dense than sea water --- it floats on the surface --- only so long as there is no mechanical agitation to mix it with seawater (no wind and wave motion --- the situation that holds beneath Arctic pack ice for Canadian shield runoff). Other than that, take a look at the Amazon for effects of 5-7 thousand km³/a fresh water runoff into salt water and "stabilization" of ocean surface. Fresh water does not act as a "lens" in any optical sense; it's generally silt laden (opaque), and is not magically transferring sunlight more deeply into the ocean; it is also laden with nutrients which do enhance biological activity, but, again, this is nothing particularly magical, confers no greater inertia upon water masses that are trivial in comparison to ocean mass to affect major changes upon ocean circulation.

I'm not sure why you interpret lenses as magical.

However, I may have misinterpreted the use of the term "lens" in this passage from one of the links I provided above.

A conceptual model for the meltwater input into the system is described below. With solar heating, the snow and ice melts from the glaciers and land surfaces. Being less saline, the runoff enters the water column and creates a lens of fresher water on the sea surface. In the shallow nearshore waters, the resulting lens can be mixed from just a few meters down to 50 m in the water column. The nearshore stations exhibit pulses of freshwater input that occur throughout the growing season (Fig. 2). The salinity of the meltwater lens on the sea surface can be as low as 30.5, but averages around 33.2. Meltwater is more common in the late summer to early fall (January-March).

Under meltwater conditions, the initial radiance reflectance typically increases as more of the light is scattered upward by particles released into the water column. This increased turbidity is likely caused by the presence of highly scattering minerogenic particles that make the waters optically distinct from typical conditions. By station E, 3.7 km offshore, radiance reflectance is half of that at station B (Fig. 3A). Hence, meltwater particles sink out rapidly and are not carried away from shore.

http://www.pnas.org/cgi/content/full/99/4/1790

 

[Bystander]

I'm not sure why you interpret lenses as magical.

I don't. "This is where it acts as a "lens" which transfers sunlight into deeper portions of the ocean than usual," said Nannoh.
(snip)

Tails don't wag dogs. Fresh water runoff doesn't dominate ocean circulation.

 

[Andre]

Yes.
Something very large entering the ocean causing displacement and consequently sea level rise. (But would also cause a nuclear winter after a global fire storm)

Or
an introduction of magma to the lithosphere causing displacement and the ocean's level rise.

Or methane (primary atmosphere) release?

19,000 you is in the middle/end of the LGM isn't it? Not much would be melting at that point. No Ice Age Floods causing levels to rise.

The big sea level rises around the equator (elsewhere it seems to be different) are basically identified in two areas, in the Carribean (Barbados) by dating deep corals, which supposedly have died because of getting too deep due to the rising water and the Indonesian area with inundated mangrove remains (Sunda shelf), following the same logic. In both locations a 20-25 vertical zone dates all the same, 14.5 Ka Cal BP which lead to the conclusion that this 25 meters would have to be flooded in a very short time.

There is the case, data, information and conclusions based on that. The idea is to skip the conclusion and review the data again, realizing that Occam Razor did not work. What else can kill corals and mangroves?

 

[nannoh]

The big sea level rises around the equator (elsewhere it seems to be different) are basically identified in two areas, in the Carribean (Barbados) by dating deep corals, which supposedly have died because of getting too deep due to the rising water and the Indonesian area with inundated mangrove remains (Sunda shelf), following the same logic. In both locations a 20-25 vertical zone dates all the same, 14.5 Ka Cal BP which lead to the conclusion that this 25 meters would have to be flooded in a very short time.

There is the case, data, information and conclusions based on that. The idea is to skip the conclusion and review the data again, realizing that Occam Razor did not work. What else can kill corals and mangroves?

Some sort of exponential bloom of bacteria and algae may have caused the die-off of coral.

http://www.sciencedaily.com/releases/2006/06/060612221839.htm

Extreme volcanic and seismic activity would have a similar effect were it in the proximity of the coral population.

And, perhaps something killed off the tiny crabs that help prevent coral death. (there are going to be a milllion possibilities concerning this topic)

Tiny 'Housekeeper' Crabs Help Prevent Coral Death In South…
(via sciencedaily.com) – Tiny crabs that live in South Pacific coral help to prevent the coral from dying by providing regular cleaning "services" that may be critical to the life of coral reefs around the world, according to scientists from the University of California, Santa Barbara.

http://science.netscape.com/story/2006/10/25/tiny-housekeeper-crabs-help-prevent-coral-death-in-south-pacificI'm reminded of the ruins off the coast of Cuba that were pointed out earlier in this thread. They are reportedly 720 meters below sea level. The question is similar in this case - what caused a rise in sea level of this magnatude? This could be related to your query.

However, my initial reaction to the position of the ruins is that they are out of situ and somehow lost their ground and sank to that depth.

 

[nannoh]

I don't. "This is where it acts as a "lens" which transfers sunlight into deeper portions of the ocean than usual," said Nannoh.
(snip)

Tails don't wag dogs. Fresh water runoff doesn't dominate ocean circulation.

You may be right.

_________________

I would like to look at what effects the Ice Age Floods had on human populations.

If someone has the time they could post scientific data that explores population numbers along the coasts of the world at the end of the Last Glacial Maximum and on how many of these people would have been displaced by a rapid sea level elevation. There is also the factor of the sheer volume of meltwater making its way to the sea across hundreds of miles of land and the effects this would have had on human habitation. These outbursts of meltwater were large scale "land tsunamis" and can easily be imagined as bringing devastating consequences to the established human communities of the time (14,000-10,000 years before present).

Time permitting I'm going to search out data to do with this factor of the Ice Age Floods as well.

 

[Bystander]

(snip)There is also the factor of the sheer volume of meltwater making its way to the sea across hundreds of miles of land and the effects this would have had on human habitation.

Examine the annual floods in the Nile and Amazon basins, and slightly less regular events for other major rivers. You'll find that such events create the habitable conditions for humans.

These outbursts of meltwater were large scale "land tsunamis" and can easily be imagined as bringing devastating consequences to the established human communities of the time (14,000-10,000 years before present).

Not "large scale," and not "devastating" --- the 2004 Xmas tsunami in the Indian Ocean presented the interesting contrast of modern tourist gawking at the stranded fish, and assorted "primitives" heading for high ground on their remote little islands.

Is there a point to your effort to make a mountain of the meltwater molehill?

 

[nannoh]

Examine the annual floods in the Nile and Amazon basins, and slightly less regular events for other major rivers. You'll find that such events create the habitable conditions for humans.



Not "large scale," and not "devastating" --- the 2004 Xmas tsunami in the Indian Ocean presented the interesting contrast of modern tourist gawking at the stranded fish, and assorted "primitives" heading for high ground on their remote little islands.

Is there a point to your effort to make a mountain of the meltwater molehill?

200,000 to 300,000 people died in the Indian Ocean tsunami. In contrast to today's world population that may not seem significant or "devastating". But, in contrast to the world population of 14,000 years ago, people would probably be convinced that their entire world had been wiped out.

My point is simply to explore the ramifications of the Ice Age Floods, be they hypothetical, theoretical or actual. If you think I am pushing biblical stories or alien intervention theories you are mistaken. I am simply fascinated by this rarely studied force of nature and how it has affected the Earth and ultimately mankind.

 

[Andre]

Some sort of exponential bloom of bacteria and algae may have caused the die-off of coral.

However, my initial reaction to the position of the ruins is that they are out of situ and somehow lost their ground and sank to that depth.

We're getting somewhere. So if we can establish that those large alleged sealevel rises were in fact another phenomenon that affected life around the sea levels of the equator.

To get the sunken city also in the picture we could speculate about global reactions to large ice sheets melting, perhaps leaving the Earth in unbalance, being too flat at the poles where the ice sheets no longer pressed the Earth down. Then of course we hypothese about glacial rebounce on a local scale. How about glacial rebounce at a global scale, the complete Earth resettling adjusting the shape to balance gravitational and centrifugal forces. This would also mean a lesser circumference for the equator as the Earth popped back to a more round shape. But water doesn't follow that logic as it always is close to the balanced position. Consequently, as the equator retracted, the water appeared to rise. Could something like that explain the meltwater pulse?

But it's only speculation, we can never know. If we want to prove it, we would need to melt Antarctica.

Another scenario indeed is the large scale methane hydrate events at the Amazone fan area, drastically changing ocean currents, sending massive amounts of cool deep (and indeed less salty) waters to the surface. The proxies confirm both had happened. Corals in not too far away Barbados may not have been happy with that while the global climate changes may have killed off the Mangroves of Indonesia's Sunda Shelf, as it also caused the African Humid Period as well as the extinction of large mammals in North America and Europe, judging to the datings.

So we need no massive flooding without a logical source whereas other scenarios could explain more phenomena.

 

[Bystander]

200,000 to 300,000 people died in the Indian Ocean tsunami. In contrast to today's world population that may not seem significant or "devastating". But, in contrast to the world population of 14,000 years ago, people would probably be convinced that their entire world had been wiped out.

"The entire worlds of 200-300k were 'wiped out.' " If you're interested in human reactions to natural disasters, you might want to start another thread in Social Sciences.

My point is simply to explore the ramifications of the Ice Age Floods, be they hypothetical, theoretical or actual.

They are geologically insignificant. Far larger volumes of soil and rock were moved by the glaciers preceeding the meltdown. Sea level effects on ocean circulation were far larger than those of freshwater runoff. Two and three kilometer thick ice sheets had huge effects on northern hemisphere tropospheric circulation.

If you think I am pushing biblical stories or alien intervention theories you are mistaken.

No one called you a YEC, or a UFO nut case. This thread would be in S&D, or locked were that the case.

I am simply fascinated by this rarely studied force of nature and how it has affected the Earth and ultimately mankind.

It is extensively studied; cirques, kettles, eskers, morraines, and all the other jargon of the ice ages fill texts and journals. It ain't the biggest thing to happen to the planet, or the species. Take a peek at the speculations about the correlations of the Toba event 70ka (?) back, and the mitochondrial DNA "population bottleneck."

 

[nannoh]

Take a peek at the speculations about the correlations of the Toba event 70ka (?) back, and the mitochondrial DNA "population bottleneck."

Thank you for the reference. This is what I'm looking for in terms of contributions to this thread.

Originally I hastily entitled this thread "Ice Age Floods Cause Mass Extinctions?" (as a question) when my main focus was really on the Glacial Flood phenomenon and how it had shaped the terrain of areas on this planet - small scale, large scale or otherwise - and wanted to find out more about it.

However, since the title remained uneditable I did allow some material about species extinction to enter into the discussion. Therefore, whether these floods dealt a blow to the populations and species of the elk or mastadon, humans or phytoplankton of the period the information remained significant to the topic(s) of this thread (as long as its title reads Ice Age Floods cause mass extinctions?). Thanks again for the reference.

 

[nannoh]

Here is some information about the Toba Event mentioned earlier by Bystander

Volcanic winter and accelerated glaciation following the Toba super-eruption

Michael R. Rampino*† & Stephen Self‡

* Earth Systems Group, Applied Science Department, New York University, New York, New York 10003, USA
† NASA, Goddard Institute for Space Studies, New York, New York 10025, USA
‡ Department of Geology and Geophysics, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA

THE eruption of Toba in Sumatra 73,500 years ago was the largest known explosive volcanic event in the late Quaternary1. It could have lofted about 1015 g each of fine ash and sulphur gases to heights of 27–37 km, creating dense stratospheric dust and aerosol clouds. Here we present model calculations that investigate the possible climatic effects of the volcanic cloud. The increase in atmospheric opacity might have produced a 'volcanic winter'2—a brief, pronounced regional and perhaps hemispheric cooling caused by the volcanic dust—followed by a few years with maximum estimated annual hemispheric surface-temperature decreases of 3–5 °C. The eruption occurred during the stage 5a-4 transition of the oxygen isotope record, a time of rapid ice growth and falling sea level3. We suggest that the Toba eruption may have greatly accelerated the shift to glacial conditions that was already underway, by inducing perennial snow cover and increased sea-ice extent at sensitive northern latitudes. As the onset of climate change may have helped to trigger the eruption itself4, we propose that the Toba event may exemplify a more general climate–volcano feedback mechanism.

From
http://www.nature.com/nature/journal/v359/n6390/abs/359050a0.html

Sort of makes human influences on "global warming" or cooling look very insignificant.

What's interesting is that the authors point out that climate change during the period may have helped to contribute to the eruption of the Toba.
What I have seen mentioned again and again in my research on the Ice Age Floods is that during the recession of Glaciers there is the risk of great seismic activity because of Isostatic Lift. As the crust re-bounds, being freed of the weight of the ice, there are more avenues for magma to release into the lithosphere and there are more opportunities for subduction and resultant earthquakes and volcanos.

In fact it is the probable seismic activity created by isostatic lift (resulting from the melting of Glaciers and lifted weight) that speeds up the ice melt and creates the large (comparitively speaking) reserviors of meltwater. In turn, as ice dams melt these volumes of meltwater are released and could be very disruptive for any mammals, etc in the area!

 

[Bystander]

(snip)In fact it is the probable seismic activity created by isostatic lift (resulting from the melting of Glaciers and lifted weight) that speeds up the ice melt and creates the large (comparitively speaking) reserviors of meltwater. In turn, as ice dams melt these volumes of meltwater are released and could be very disruptive for any mammals, etc in the area!

--- and, the "isostatic lift" of seafloors resulting from sea level drop at the beginning of an ice age doesn't have any effect on seismic activity?

Cubic kilometers of molten rock per year contribute how much heat to the global budget? Will melt how much ice? Do the math --- don't take every new fact and leap to a wrong conclusion --- you are looking at another "molehill."

 

[Mk]

in the Carribean (Barbados) by dating deep corals, which supposedly have died because of getting too deep due to the rising water and the Indonesian area with inundated mangrove remains (Sunda shelf), following the same logic.

Wait, supposedly? They either died or they didn't—not supposedly.

the authors point out that climate change during the period may have helped to contribute to the eruption of the Toba.

That sounds absolutely preposterous to me, that the temperature on the surface would affect mantle circulation. Then again, I suppose significant isostatic changes could have an effect. No?

 

[nannoh]

--- and, the "isostatic lift" of seafloors resulting from sea level drop at the beginning of an ice age doesn't have any effect on seismic activity?

This is an interesting proposition. Are there any references that expand on the concept?

I've looked for papers regarding your statement primarily on the Google search engine and found no specific reference to Isostatic lift resulting from a lowered sea-level.

I did find some interesting papers

The most direct evidence of LGM ice vol-
ume comes from records of lower sea level.
But there are two difficulties: finding a well-
preserved and dateable record of LGM sea
level, and then distinguishing the isostatic
from the glacio-eustatic component of the
signal. Yokoyama et al.1 addressed these
difficulties by dating geological records on
the tectonically stable northern Australian
continental shelf, and deriving the glacio-
eustatic component by accounting for the
isostatic effect on the shelf caused by the sea-
level rise that accompanied deglaciation.
Their results resolve a long-standing con-
troversy. Furthermore, they suggest that the
LGM ice volume was relatively stable for at
least 3,000 years, implying that the ice sheets
approached isostatic and, perhaps, dynami-
cal equilibrium. Their analysis also indicates
that the LGM was terminated by a rapid rise
in sea level 19,000 years ago (Fig. 1). Such
an abrupt event may record a climatic or
other instability that triggered the demise
of the ice sheet.

http://72.14.253.104/search?q=cache...auses+Isostatic+lift&hl=en&gl=ca&ct=clnk&cd=8

This study looks at the 19,000 yo period that supposedly produced the hypothesised rise in sea level that is blamed for killing off the coral reefs. Andre may be interested in having a go at this one

 

[Andre]

This study looks at the 19,000 yo period that supposedly produced the hypothesised rise in sea level that is blamed for killing off the coral reefs. Andre may be interested in having a go at this one

And this study indeed signals the major problems that the ice age theory faces. You may go back to my first Melt water pulse 1A post to see that the refs discuss the same problems.

About the ice sheet by volume. That's a hypothesis (Rutherford) based on the isotope ratios in the oceanic proxies. During evaporation most light isotopes leave the oceans and hence during ice sheet build up, the light meltwater not returning, the oceans get enriched with heavy isopes. You can quantify that and ultimately find that you'd have to cover virtually the complete Northern hemisphere polar circle area, to stuff all that ice away.

But there are two major problems with that idea. Firstly, the isotope spikes in the oceanic cores are as sharp as those in the ice cores, while the ocean is a very inert system, where it would take thousands of years for mixing the isotopes and for the bottom dwelling Benthic foraminifera would have reacted.

Secondly, during the Last Glacial Maximum, there wasn't any ice sheet on Siberia, not a trace, only a few locally enlarged glaciers, moreover the ice sheets did not wax and wane simultaneosly. When the ice was still growing in the east (Kara sea) some 19,000 years ago it had already melted in the west (Cordilleran ice sheets)

 

[Bystander]

This is an interesting proposition. Are there any references that expand on the concept?

I've looked for papers regarding your statement primarily on the Google search engine and found no specific reference to Isostatic lift resulting from a lowered sea-level.

I did find some interesting papers



http://72.14.253.104/search?q=cache...auses+Isostatic+lift&hl=en&gl=ca&ct=clnk&cd=8

This study looks at the 19,000 yo period that supposedly produced the hypothesised rise in sea level that is blamed for killing off the coral reefs. Andre may be interested in having a go at this one

"Isostasy" isn't turned "off" for sea floors and "on" for continental plates; it's "on" all the time for the whole planet. The sea floor "rebound" (or lift) furnishes the volume to drive the continental "rebound" during melting --- it's called "conservation of mass."

 

[nannoh]

"Isostasy" isn't turned "off" for sea floors and "on" for continental plates; it's "on" all the time for the whole planet. The sea floor "rebound" (or lift) furnishes the volume to drive the continental "rebound" during melting --- it's called "conservation of mass."

The term is "hydro-isostacy". See page 10 of the link below

http://www.geography.wisc.edu/classes/geog527/sea_level.pdf

This ppt file has lots of info about glacio-isostacy and glacial eustasy as well as the oceanic/geological mechanism of hydro-isostacy which Bystander may be referring to.

 

[nannoh]

Ice Bergs make it to New Zealand (Nov 8/06)

Antartica has been losing some of its Ice Sheet to the ocean but the bergs are not melting like they usually do before they get to New Zealand. Does this suggest a cooler ocean than in the past? Or a cooler climate in the region?

http://au.news.yahoo.com/061108/2/11cfw.html

Its Mid-Summer in Australia and there was a snow storm and cold snap there this month.

http://www.abc.net.au/news/newsitems/200611/s1789527.htm

 

[nannoh]

Walk The Flood Route

You'll be able to walk in the wake of an Ice Age Flood near Seattle soon with the opening of this trail being built by the National Parks Conservation Association. The more this phenomenon is studied the more recognizable the features will be in other geological settings. This should be a good trail to visit!

http://www.commondreams.org/news2006/1005-10.htm

 

[Skyhunter]

Antartica has been losing some of its Ice Sheet to the ocean but the bergs are not melting like they usually do before they get to New Zealand. Does this suggest a cooler ocean than in the past? Or a cooler climate in the region?

It is mostly a function of the oceans currents. The heat in southern hemisphere is carried north by the currents. There was a good article in nature (unavailable now unless your a member )

Check this thread for links.

https://www.physicsforums.com/showthread.php?t=143165

 

[nannoh]

It is mostly a function of the oceans currents. The heat in southern hemisphere is carried north by the currents. There was a good article in nature (unavailable now unless your a member )

Check this thread for links.

https://www.physicsforums.com/showthread.php?t=143165

from the your link

The cores suggest that the climate shifts were local, not global like we are seeing today.

It is my contention that what you say remains true today. What I didn't think about was that any regional climate will have an effect globally since we're all on the same planet. Synergistically speaking if it warms up in Artic waters, something's going to change on another part of the planet.

What I find equally interesting is your mention of fresh water changing the course of ocean currents. Is there any physics, fluid mechanics or oceanographic evidence that shows how de-salinated water can shift a salinated current?

 

[baywax]

It is my contention that what you say remains true today. What I didn't think about was that any regional climate will have an effect globally since we're all on the same planet. Synergistically speaking if it warms up in Artic waters, something's going to change on another part of the planet.

What I find equally interesting is your mention of fresh water changing the course of ocean currents. Is there any physics, fluid mechanics or oceanographic evidence that shows how de-salinated water can shift a salinated current?

Here's something that might help out.

http://pubs.usgs.gov/sir/2004/5014/