Undersea Landslide Complex
(Image source: Sea-level–induced Seismicity and Submarine Landslide Occurrence.)
At the end of the last ice age as the climate warmed, glaciers began to thaw, and sea level began to rise, a troubling spike in the number of undersea landslides and related tsunami events occurred. In total, almost half of all the undersea landslides of the past 125,000 years occurred during this period of deglaciation occurring from 8,000 to 15,000 years ago. A rate many times that seen during either the glacial period or during the Holocene.
This large increase in subsea landslide events had long been observed in the science. But, up until this point, there has been little research to determine why so many landslides occurred. But this year, a team of scientists developed a model to investigate the cause of these continental shelf slope failures and large undersea landslides. The report, published in Geology, is available here: Sea-level–induced Seismicity and Submarine Landslide Occurrence.
The findings of this study and related model run were stark. According to results, rising sea waters spurred by climate change greatly increased the pressure on undersea slope and fault structures. This pressure, rising over 7,000 years to roughly equal that of a human bite over every inch of these undersea fault systems, was found to result in numerous catastrophic failures.
In a slope failure, a strain on an undersea fault in a debris, rock or sediment zone first begins to grow. The region of sediment already rests over a sloping undersea terrain and so the weight of the ocean above constantly pushes down on these structures. Over time, the stress increases due to slow structural change, seismic stresses, the passing of large waves and/or strong storms, and/or loss of slope integrity. If sea levels rise, the added weight of a deeper ocean overhead further increases stress. Eventually, the fault line catastrophically fails causing separation and rapid collapse of slope material toward the ocean bottom.
Undersea Slope Failure
(Image source: UNCW)
Slope collapse zones can stretch for miles and miles along seabed drop-off zones. A slope failure can release millions or billions of tons of material, displacing an equally high volume of water. Under the right circumstances, such large slope failures can result in very large tsunamis, similar to those caused by major ocean earthquakes.
More ominously, perhaps, is the fact that large slope failures can directly expose previously buried deposits of methane hydrates. If large stores of this substance are rapidly uncovered in a warming sea environment they can swiftly out-gas and greatly contribute to an already ongoing warming.
The most vulnerable regions for slope collapse include large, shallow continental shelves that have multiple or large fault zones and that border an ocean drop-off to deeper water. A particularly sensitive region is the shallow East Siberian Arctic Shelf which contains numerous fault zones and extends out into deeper Arctic waters as well as slope structures near the Gakkel Ridge. The ESAS also contains one of the Arctic’s largest stores of methane, estimated at 500 gigatons. Many structures in these regions are already emitting significant, but not catastrophic, volume of methane from undersea hydrate stores. A slope collapse of the kind mentioned in this report in any of these locations would have severe consequences for ESAS, Arctic and global methane release.
Rate of Sea Level Increase During the End of the Last Ice Age
Changes in Sea Level at the End of the Last Ice Age.
(Image source: Commons)
During the period of deglaciation at the last ice age’s end, a global temperature rise of about 5 degrees Celsius caused a 395 foot sea level rise over the course of 70 centuries. On average, sea level rise matched pace with temperature increase. Once ice sheet destabilization began, each .1 C temperature rise coincided with about a 6 foot rise in sea level, or a rate of slightly more than 5.5 feet per century.
Current glacier systems hold enough water to increase sea levels by about another 200 feet. Ocean thermal expansion will add its own increase to this potential sea level rise. At a .8 C temperature increase since the 1880s, current temperatures are near or just above the Holocene maximum, large ice sheet destabilization has begun, and rates of sea level rise are continuing to increase. With temperatures expected to rise between 4 and 7 degrees Celsius by the end of this century under business as usual fossil fuel emissions, a temperature increase roughly equivalent to one that took 7000 years to complete at the end of the last ice age, it is highly likely that a 5 foot per century rate of sea level increase will be matched or exceeded. Such a rapid rate of sea level rise would create stresses to sub-sea ocean slope systems that meet or exceed that seen during the end of the last ice age, greatly increasing the risk of catastrophic slope failure and resulting tsunamis and potential methane release scenarios.
Sea Level Increase Since 1992.
(Image source: AVISO)
*****
Links:
Sea-level–induced Seismicity and Submarine Landslide Occurrence
robertscribbler 
susan2196
/ August 23, 2013Reblogged this on abraveheart1.
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bearspawprint
/ August 24, 2013Another outstanding post. have you considered submitting your articles to paying periodicals? I think you should. — Bear
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robertscribbler
/ August 24, 2013Thx Paw. Maybe I’ll give it a shot.
How about you go for Congress? We could use some wisdom there.
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bearspawprint
/ August 24, 2013Someone once told me, in a VERY LOUD voice that a large room full of people, who all knew me, turned to look and erupted into guffaws…. “Sharon, you are about as thick skinned as a condom!!” Dunno if I’d last very long in such abrasive company.
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robertscribbler
/ August 24, 2013Hah. Maybe. Or maybe they’d just piss off the wrong lady 😉
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prokaryotes
/ August 24, 2013Reblogged this on Climate Force.
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prokaryotes
/ August 24, 2013Climate forcing of geological and geomorphological hazards http://climatestate.com/2013/05/31/climate-earthquakes-i/
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prokaryotes
/ August 24, 2013Video: Will climate change cause earthquakes? http://climatestate.com/2013/05/02/will-climate-change-cause-earthquakes/
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prokaryotes
/ August 24, 20132013
Historical 20th Century simulations show a steady increase in whole atmosphere ozone RF through 1970 after which there is a decrease through 2000 due to stratospheric ozone depletion. Ozone forcing increases throughout the 21st century under RCP8.5 owing to a projected recovery of stratospheric ozone depletion and increases in methane, but decreases under RCP4.5 and 2.6 due to reductions in emissions of other ozone precursors. RF from methane is 0.05 to 0.18 W/m2 higher in our model calculations than in the RCP RF estimates. The surface temperature response to ozone through 1970 follows the increase in forcing due to tropospheric ozone. After that time, surface temperatures decrease as ozone RF declines due to stratospheric depletion. The stratospheric ozone depletion also induces substantial changes in surface winds and the Southern Ocean circulation, which may play a role in a slightly stronger response per unit forcing during later decades. http://pubs.giss.nasa.gov/abs/sh05600u.html
2001
According to Shindell there are two driving forces behind the change in stratospheric moisture. “Increased emissions of the greenhouse gas, methane, are transformed into water in the stratosphere,” Shindell said, “accounting for about a third of the observed increase in moisture there.”
The second cause of change in the upper atmosphere is a greater transport of water from the lower atmosphere, which happens for several reasons. Warmer air holds more water vapor than colder air, so the amount of water vapor in the lower atmosphere increases as it is warmed by the greenhouse effect. Climate models also indicate that greenhouse gases such as carbon dioxide and methane may enhance the transport of water into the stratosphere. Though not fully understood, the increased transport of water vapor to the stratosphere seems likely to have been induced by human activities.
“Rising greenhouse gas emissions account for all or part of the water vapor increase,” said Shindell, “which causes stratospheric ozone destruction.” http://www.giss.nasa.gov/research/news/20010417/
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prokaryotes
/ August 24, 2013McGuire conducted a study that was published in the journal Nature in 1997 that looked at the connection between the change in the rate of sea level rise and volcanic activity in the Mediterranean for the past 80,000 years and found that when sea level rose quickly, more volcanic eruptions occurred, increasing by a whopping 300 percent. http://www.livescience.com/7366-global-warming-spur-earthquakes-volcanoes.html
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prokaryotes
/ August 24, 2013The process of submarine talik penetration is likely to be reinforced by the impact of bottom thermal erosion and of geothermal heat flow. Formation of the open taliks is also dependent on seismic events; that is why numbers of open taliks are formed along the active fault zones. We can therefore expect open taliks to exist anywhere within the 90 m isobath, correlated with area seismic activity. Taking this fact into account, we can better understand the sharpness of spatial gradients in dissolved methane distribution obtained during our study. Thus, we can assume the origin of bottom plumes measured in 2004 within Dmitry Laptev Strait to be a sub-sea bottom talik which might have been penetrated due to the simultaneous influence of Lena River heat efflux, the upward geothermal flux typical of active fault zones, and seismic activity within these zones. The near-shore system of the ESAS widely consists of ICs, which are ice-rich syncryogenic deposits with massive ice wedges. This system has been strongly affected by global warming and exhibits the highest range of coastal erosion in the world, compared to other near-shore systems (Stein and Macdonald, 2003).
[]
. Following permafrost degradation due to bottom thermo- and chemoabrasion and upward heat flux within fault zones, gas hydrates can become vulnerable and begin to decay, allowing the release of methane from the gas hydrates. Using a modeling approach, Semiletov et al. (2004) demonstrated such a mechanism for Barrow (Alaska) where gas hydrates appeared to decay. Development of taliks beneath submerged thaw lakes can also be considered as a potential mechanism by which deep methane gas hydrates, which lie beneath the sea bottom at depths below 100 m (Romanovskii et al., 2000), may be disturbed. Considerable gas levels in permafrost were revealed under the floor of Arctic seas and on land (Are, 2001). A particularly powerful gas discharge erupted from a well drilled through the sub-sea permafrost on the Pechora sea shelf; a gas–water fountain originated from the hole 50 m beneath the sediment surface (at a water depth of 64 m), and at one point the fountain rose 10 m above the ship. The echo sounding carried out at the drilling site 10 days after this event revealed an underwater fountain 10 m in diameter, with a height 40 m above the sea floor. We know of one case when the release of gas bubbles from the sea floor was not only observed visually, but also measured. As early as the 1960s, M. Ivanov measured gas bubbles sampled in the foredelta of the Yana River at the edge of the Lapev Sea (Are, 2001). Measurements showed a high CH4 content (38.6%) and significant amounts of helium and argon which were indicative of the deep origin of this gas.
According to our data; one of the bottom plumes (spot 1, 3, Fig. 5) is correlated with the location of a geological fault zone called the “Bel’kovsko–Svyatonosskiy Rift” (Imaev et al., 2000). According to the results of direct measurements of geothermal heat within main normal faults of the ESS, the value of the heat flux ranged from 64 mW m2 to 124 mW m2 (Soloviev et al., 1987). The magnitude of the geothermal heat flux is a crucial component of the LS geological model, which predicts the existence of open taliks under fault zones with high geothermal heat flux values (100 mW/m2 and more) (Romanovskii and Hubberten, 2001). Together with surface sea floor heat flux this energy input would trigger disturbance of gas hydrates deposits.
Click to access Shakova%20and%20Semiletov%202007.pdf
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prokaryotes
/ August 24, 2013Quote: “Ocean thermal expansion will add its own increase to this potential sea level rise. [..] Such a rapid rate of sea level rise would create stresses to sub-sea ocean slope systems that meet or exceed that seen during the end of the last ice age, greatly increasing the risk of catastrophic slope failure and resulting tsunamis and potential methane release scenarios.”
Yes, because the bottom ocean pressure will increase AND the entire planets gravitational field will readjust, because of the redistribution of mass and isostatic rebound.
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Colorado Bob
/ August 25, 2013This rebalancing is most worrying . The most important example comes from Hawaii , and Australia. A large part of the big island in Hawaii fell in to the sea , It was a southwest facing slope. The evidence of the wave in Australia is 300 feet high on the coast, The material on the seafloor in Hawaii is well mapped. Climate Change had nothing to do with this , just a loose volcano shedding some of it’s ejecta. .
It crossed the entire Pacific Ocean , and It was 3oo feet high when it got there.
I think Iceland is the place to watch today. With Greenland melting and unloading it’s weight of ice, and Iceland so close. and on the Mid Atlantic Ridge.
All hell will break loose. As Greenland loses it’s weight, it changes the forces in Iceland . And Iceland is melting along with every other ice cube on the Earth.
This rebalancing is most worrying .
It’s a real pinball machine.
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Colorado Bob
/ August 25, 20132 places not to invest in :
Iceland
Arizona
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Colorado Bob
/ August 25, 2013I think Iceland is the place to watch today.
Every vent on that island might wake-up , because Greenland is losing weight.
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Colorado Bob
/ August 25, 2013And Iceland if pops off , people die . And the sky turns red.
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Colorado Bob
/ August 25, 2013Iceland could really unzip, because Greenland is losing so much mass so quickly . Like opening a steam valve boiler. Iceland could get really nasty . And do it very fast.
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prokaryotes
/ August 25, 2013The three Storegga Slides are considered to be amongst the largest known landslides. They occurred under water, at the edge of Norway’s continental shelf (Storegga is Norwegian for “the Great Edge”), in the Norwegian Sea, 100 km (62 mi) north-west of the Møre coast, causing a very large tsunami in the North Atlantic Ocean. This collapse involved an estimated 290 km (180 mi) length of coastal shelf, with a total volume of 3,500 km3 (840 cu mi) of debris.[1] This would be the equivalent volume to an area the size of Iceland covered to a depth of 34 m (112 ft).
Based on carbon dating of plant material recovered from sediment deposited by the tsunami, the latest incident occurred around 6100 BCE.[2] In Scotland, traces of the subsequent tsunami have been recorded, with deposited sediment being discovered in Montrose Basin, the Firth of Forth, up to 80 km (50 mi) inland and 4 m (13 ft) above current normal tide levels. https://en.wikipedia.org/wiki/Storegga_Slide
In the northern hemisphere, under threat from underwater landslides are northern parts of Europe and the northern parts of the US East Coast as well. SLR is most pronounced (+25%) at the US east coast which could exacerbate impacts.
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Usman
/ August 26, 2013Hi Robert,
Do you have any knowledge of the potential consequences of an ice-free arctic summer? What kind of jet stream/oceanic circulation feedbacks could be expected? Would it be similar to the ongoing disruption of the jetstream or would you expect something else entirely?
Thanks.
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robertscribbler
/ August 26, 2013An ice-free Arctic summer, given the current ice sheet state, is unsustainable and highly unstable. If we hit ice free summers in the Arctic, we can expect large melt pulses from Greenland soon after, with all the chaos and mayhem that entails. Ice free Arctic waters will also radically enhance the burn and melt rate of permafrost and boreal forests surrounding the Arctic.
In my view, such a state would probably cause a disassociation of the Jet stream during the summer months with a retreat to circulate directly around Greenland and the ice sheets there. Such an altered path would cause highly unstable weather as you have warm air displaced latitudinally with the cold air over Greenland. This feature would set the stage for very powerful storms, especially as the season switches from summer to fall.
We are already in a hybrid weather state that mimics these conditions. If and when we transition to ice free Arctic waters, expect a Heinrich type melt event from Greenland to follow ‘soon’ after. I honestly don’t think Greenland can survive ice free summer Arctic Ocean states for more than a decade or two without issuing a large melt pulse. The insulation is gone.
As hinted at above, the danger for very high levels of Arctic carbon feedbacks is also apparent during ice free summers.
Not a stable state.
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Colorado Bob
/ August 26, 2013Rising ocean acidity will exacerbate global warming
Carbon dioxide soaked up by seawater will cause plankton to release less cloud-forming compounds back into atmosphere.
http://www.nature.com/news/rising-ocean-acidity-will-exacerbate-global-warming-1.13602
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Colorado Bob
/ August 26, 2013Massive Himalayan gorge partly carved by Lake Erie-sized floods
When glacial dams upriver from the gorge failed, massive floods tore through it.
http://arstechnica.com/science/2013/08/massive-himalayan-gorge-partly-carved-by-lake-erie-sized-floods/
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Colorado Bob
/ August 26, 2013Before and after satellite shots of Amur River-
Aerial views of Amur river, pictures taken in years 2008 and August 2013. Pictures: NASA
http://siberiantimes.com/ecology/casestudy/news/besieged-city-of-khabarovsk-faces-another-ten-days-before-reaching-the-peak-of-flooding-nightmare/?nf=News
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prokaryotes
/ August 26, 2013Methane release from the East Siberian Arctic Shelf and the Potential for Abrupt Climate Change http://climatestate.com/2013/08/26/methane-release-from-the-east-siberian-arctic-shelf-and-the-potential-for-abrupt-climate-change/
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Colorado Bob
/ August 26, 2013Climate change to harm all forms of marine life, study says
Read more: http://www.smh.com.au/environment/climate-change/climate-change-to-harm-all-forms-of-marine-life-study-says-20130826-2sklm.html#ixzz2d5CMBW00
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Colorado Bob
/ August 27, 2013RS –
My hail storm theory :
Amarillo, Texas Hail Toll at $500M; Loss at Par with Hurricanes
http://www.propertycasualty360.com/2013/08/23/amarillo-texas-hail-toll-at-500m-loss-at-par-with?t=auto
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robertscribbler
/ August 27, 2013I really think you’re onto something with this one. Have you read the recent research on sudden stratosphere warming episodes? With atmospheric warming, we’d expect an increasing number of instances where the troposphere invades the stratosphere (as you said), which could push storm tops higher and higher.
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Colorado Bob
/ August 27, 2013Heat seeks cold. This explains the large areas of rain fall as well . Most heat isn’t going to the poles, it’s going up to the closest condenser. Which is over head. Once these storms set-up the stove pipe of rising air to the very top of troposphere , the rushing water vapor will flow in the system. I think grapefruit hail will be a real pest in the near future.
Read this –
While experts disagree about the changes in the dust clouds over the decades, all agree this year’s cloud was remarkable.
Mojena said the dust arriving in Cuba has risen 10-fold in the last 30 years after severe droughts in northern Africa, though Omar Torres, a specialist in atmospheric physics at the NASA Goddard Space Flight Center in Maryland, said satellite studies since 1980 do not show increased Sahara dust emissions beyond normal seasonal variability.
Even so, “this year’s advancement all the way to Wyoming was totally unexpected,” Torres said. “I never saw anything like that in recent years.”
http://www.newsdaily.com/article/feabc72bdedb3f46c1a0af034ddd33cf/african-dust-clouds-worry-caribbean-scientists
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robertscribbler
/ August 27, 2013Oh I agree. I think we’ll be seeing a lot of heat going north in about 4-5 weeks though. Polar amplification lives in the fall winter and spring time.
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Colorado Bob
/ August 27, 2013I think grapefruit hail will be a real pest in the near future.
I think grapefruit hail killed dinosaurs in the past . I’ve thought this since I first visited the Dinosaur Monument, and saw all those bones piled along the bend of that ancient river.
I think rain drops will get to be the size ping pong balls.
When I was young in West Texas, A big thunder storm had tops of 45,000 feet . No more.
Heat seeks cold , it needs a condenser .
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Colorado Bob
/ August 27, 2013A few years ago I was driving near the Muleshoe Wild Life Refugee . In late morning. It was time for the sand hill cranes to fly north. Suddenly, I saw a giant double helix of cranes going straight-up , so high they disappeared. I drove on until I was as near as I could get, and stopped .
There, at just a few hundred feet above ground level, cranes were flying in from every direction on the compass. They were all singing with joy , because this thermal was going to take them all the way to the Platte River in Neb. Seeing that , lets me see water vapor today.
At that time there was probably 250,000 Sandhill cranes around Muleshoe. So they were a great metaphor for water vapor molecules.
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Colorado Bob
/ August 27, 2013They all got up and left that day. Nobody that was able, . stuck around. It was the greatest thing I ever saw in nature. And it was pure double helix of birds. Looking up through it , some were west bound , some were east bound all at different levels.
I was God Smacked by the whole thing.
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Aquatic Syndicate
/ November 29, 2014Reblogged this on aquaticsyndicate.
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