Finally, human civilization is starting to get global warming events that it can FEEL.
Earthquakes, tsunamis, and volcanoes. Something real, something hard, fast, and impossible to ignore. Increasing evidence and statistical analysis links increased seismic activity to global warming.
This alarming notion was first discussed in 1998 and is now more widely mentioned in university studies and recent publications - from the Journal of Geodynamics to National Geographic, to blogs reporting opinions of scientists (below).
Some intuitive calculation may help understanding: A cubic yard of ice weighs nearly a ton. The Antarctic ice sheet is a few miles thick. Earth adjusted to that immense weight over the millennia - now, as ice caps melt, this weight is slowly lifting..
Today the Pine Island Glacier in Antarctica is quickly melting downward
from the surface - dropping in altitude at nearly 16 meters per year.
With an area over 5 thousand square kilometers, this glacier holds a lot of cubic meters of ice and means that a lot of weight is now getting shifted into
the ocean. Similarly, the melting of glaciers in Greenland and
elsewhere will trigger seismically elastic reactions that should be noted
for their frequency, intensity and novel locations.
“…relative to the time period from the mid-1970s to the mid-1990s, Earth has been more active over the past 15 years or so.” — geophysicist Stephen S. Gao, Missouri University of Science and Technology.
This idea is consistent for our age: The Anthropocene Epoch - a geological age where humans make a significant impact. Who knew that human industrial CO2 emissions warming the atmosphere then melting the ice and then the shifting weight would provoke such a rapid and palpable reaction. Such a sudden, fast impact of global warming has so far been missing from this crisis.
It is worth watching carefully and keeping score.
Just how much does one of these ice sheets weigh?
1 cubic foot of water weighs 62.4 lbs./ft3
Ice (@ .9 specific gravity) = 56.16 lbs./ft3
1 square mile (5280’ X 5280’) = 2.8 X 107 ft2
(2.8 X 107 ft2) X 56.16 lbs./ft2 = 1.57 X 109 lbs./mi2
Canadian Shield sheet (4000 mi2 X 4000 mi2) = 1.6 X 107 mi2
(1.57 X 109 lbs./mi2) X (1.6 X 107 mi2) = 2.5 X 1016 lbs./vertical foot
Assume 10,000’ thick (2.5 X 1016 lbs.) X (1 X 104) = 2.5 X 1020 lbs. or 250,000,000,000,000,000,000 pounds! (Assume ice sheet was 10,000’ thick = 561,600 lbs./ft2) or 281 tons of ice per square foot (3900 lbs./in2)!
And this is assuming that the entire sheet is composed of ice. If we assume that 30% of it is rock material, at an average specific gravity of 3.0, we can essentially double the total weight of the sheet.
————————- News, Sources and Links:
University of London conference on Climate Forcing of Geological and Geomorphological hazards, Oct 2, 2009 http://www.deccanherald.com/content/25152/earths-fiery-future.html
Dr Margaret Lillian is an independent science journalist specializing in global trends.
As reported only this year, Harvard seismologist Göran Ekström has found a striking increase in the frequency of glacial quakes, particularly in Greenland, but also in Alaska and Antarctica.
Greenland quakes have risen from 6 to 15 a year between 1993 and 2002, to 30 in 2003, 23 in 2004 and 32 in the first 10 months of 2005, closely matching the rise in Greenland’s temperatures over the same period. Their source was traced to surges and slips within ice sheets, where rapid melting is causing water to collect under glaciers, making them glide faster into the sea, triggering quakes…
The science suggests that as redistribution of the Earth’s mass induced by global warming disturbs the relative equilibrium of its crust, monumental forces in the form of increasing earthquakes, tsunamis and volcanic activity could be unleashed. And the forecasts from some quarters are dramatic - - not only will the earth shake, it will spit fire
Impact of Global Warming On Seismic ActivityArticle by Preetam Kaushik published Apr 13, 2009
Read more: http://www.brighthub.com/environment/science-environmental/articles/31846.aspx#ixzz0SiEWd5jO
…opinion that is endorsed by geologists around the world is that glacial melting caused by global warming is causing a rise in water levels beyond the bearing limit of the Earth’s crust. This, they believe, is causing the spate of devastating geological events that have struck nations in recent times.
Global Warming May Trigger Greater Seismic Activityby Michael Renner on July 31, 2006
The melting of glaciers driven by global warming portends a seismically turbulent future. When glaciers melt, the massive weight on the Earth’s crust is reduced, and the crust “bounces” back in what scientists call an “isostatic rebound.” This process can reactivate faults, increase seismic activity, and lift pressure on magma chambers that feed volcanoes.
Sharon Begley, “How Melting Glaciers Alter Earth’s Surface, Spur Quakes, Volcanoes,” Wall Street Journal Online, 9 June 2006.
Link: http://online.wsj.com/public/article/SB114981650181275742-sOx58NXvfKz2szefZXutgTSbaDI_20070608.html; and
Bill McGuire, “Climate Change: Tearing the Earth Apart?,” New Scientist, 26 May 2006,
American Scientist 1998 http://www.americanscientist.org/issues/pub/j-klhlaup
The Guardian http://www.guardian.co.uk/environment/2007/sep/08/climatechange
Writing in New Scientist magazine, Bill McGuire, professor of geological hazards at University College in London, said: “All over the world evidence is stacking up that changes in global climate can and do affect the frequencies of earthquakes, volcanic eruptions and catastrophic sea-floor landslides. Not only has this happened several times throughout Earth’s history, the evidence suggests it is happening again.”
Melting Ice Sheets Can Cause Earthquakes, Study Finds http://news.nationalgeographic.com/news/2008/03/080314-warming-quakes.html
Thinning of Ice Sheets http://www.sciencedaily.com/releases/2009/09/090923143331.htm
Pine Island Glacier
This is not a new notion. Called Isostatic rebound. http://en.wikipedia.org/wiki/Post-glacial_rebound It is just that the inevitable evidence may be starting to be seen now
Volcanoes too update April 2010
(Reuters) - A thaw of Iceland’s ice caps in coming decades caused by climate change may trigger more volcanic eruptions by removing a vast weight and freeing magma from deep below ground, scientists said on Friday.
“Our work suggests that eventually there will be either somewhat larger eruptions or more frequent eruptions in Iceland in coming decades,” said Freysteinn Sigmundsson, a vulcanologist at the University of Iceland…