Ice Age Floods cause mass extinctions?

[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/