I read this book last week:
When Life Nearly Died - The Greatest Mass Extinction Of All Time, by Michael J. Benton.
Benton is a vertebrate paleontolgist at the University of Bristol.
I thought these Amazon reviews summed the book up pretty nicely:
www.amazon.com/When-Life-...636-5826358
Soooooooo,
The end of the Permian time period, which occurred at the end of the Paleozoic Era (some 251 million years ago; right before the Mesozoic Era and the 'age of dinosaurs') saw the hugest mass extinction that has ever occurred on the planet. Approximately 90% (or more) of all plant and animal life went extinct at that time.
Just what happened at the end of the Permian? No one knows for sure, but the author's theory is one that is gaining favor widely: multiple factors were at play, including global warming that spiraled out of control.
About 5 million years prior to the end of the Permian, and approximately 5 million years after the beginning of the Mesozoic, there was a very low amount of oxygen on the planet. Paleontologists started looking at the causes for that anomalous situation.
One starting point is the Siberian Traps eruptions. Repeated eruptions over time caused different gases (carbon dioxide, sulfur dioxide, and chlorine gas (causing acid rain (strontium 87 ->86)) to be pumped into the atmosphere. Carbon dioxide caused the greenhouse effects and anoxia, sulfur dioxide caused snap glaciation, which caused sea levels to fall in some part of the world, and chlorine produced acid rain.
The Siberian Traps eruption caused a global rise of 6C worldwide. The cool polar regions became warm and the frozen tundra thawed. The thawing may have reached the frozen gas reservoirs located around the polar oceans, and massive amounts of methane gas may have burst to the surface of the oceans in huge bubbles. This additional amount of carbon into the atomosphere caused more warming, which could have melted futher gas hydrate reservoirs. The natural systems that normally reduce carbon dioxide levels could not operate, and eventually the system spiralled out of control. The gasses cause the plants to die, causing erosion, so that when the rains come, the soil was lost. Dead plant and animal matter (on a very large scale) were washed into the sea. All of that decaying matter consumes oxygen, which leads to anoxia. Extra carbon dioxide then hits the upper levels of the ocesn (in the water column and below) killing the plankton, which kills the fish, and so on and so on.
Continued eruptions make things worse. Finally get the extinction were up to 90% of species are killed.
Another contributor: all of the continents were fused into a supercontinent called Pangaea, causing destruction of habitats in the oceans - for example, trilobites and brachiopods were declining well before the end of the Permian.
QUESTION: How relevant to global warming is this today. We don't currently have a Siberian Traps event, but what would it take today to mimic a Siberian Traps event?
extra info)
The Paleozoic divided up into its various time periods.
www.ucmp.berkeley.edu/paleozo...oic.html
About the Siberian Traps eruptions (diagram at the bottom of the page explaining the chemistry behind it)
palaeo.gly.bris.ac.uk/Palaeof...aps.html
Pangaea
en.wikipedia.org/wiki/Pangaea
P.S. No one can accuse me of not taking a long view! ;)
When Life Nearly Died - The Greatest Mass Extinction Of All Time, by Michael J. Benton.
Benton is a vertebrate paleontolgist at the University of Bristol.
I thought these Amazon reviews summed the book up pretty nicely:
www.amazon.com/When-Life-...636-5826358
Soooooooo,
The end of the Permian time period, which occurred at the end of the Paleozoic Era (some 251 million years ago; right before the Mesozoic Era and the 'age of dinosaurs') saw the hugest mass extinction that has ever occurred on the planet. Approximately 90% (or more) of all plant and animal life went extinct at that time.
Just what happened at the end of the Permian? No one knows for sure, but the author's theory is one that is gaining favor widely: multiple factors were at play, including global warming that spiraled out of control.
About 5 million years prior to the end of the Permian, and approximately 5 million years after the beginning of the Mesozoic, there was a very low amount of oxygen on the planet. Paleontologists started looking at the causes for that anomalous situation.
One starting point is the Siberian Traps eruptions. Repeated eruptions over time caused different gases (carbon dioxide, sulfur dioxide, and chlorine gas (causing acid rain (strontium 87 ->86)) to be pumped into the atmosphere. Carbon dioxide caused the greenhouse effects and anoxia, sulfur dioxide caused snap glaciation, which caused sea levels to fall in some part of the world, and chlorine produced acid rain.
The Siberian Traps eruption caused a global rise of 6C worldwide. The cool polar regions became warm and the frozen tundra thawed. The thawing may have reached the frozen gas reservoirs located around the polar oceans, and massive amounts of methane gas may have burst to the surface of the oceans in huge bubbles. This additional amount of carbon into the atomosphere caused more warming, which could have melted futher gas hydrate reservoirs. The natural systems that normally reduce carbon dioxide levels could not operate, and eventually the system spiralled out of control. The gasses cause the plants to die, causing erosion, so that when the rains come, the soil was lost. Dead plant and animal matter (on a very large scale) were washed into the sea. All of that decaying matter consumes oxygen, which leads to anoxia. Extra carbon dioxide then hits the upper levels of the ocesn (in the water column and below) killing the plankton, which kills the fish, and so on and so on.
Continued eruptions make things worse. Finally get the extinction were up to 90% of species are killed.
Another contributor: all of the continents were fused into a supercontinent called Pangaea, causing destruction of habitats in the oceans - for example, trilobites and brachiopods were declining well before the end of the Permian.
QUESTION: How relevant to global warming is this today. We don't currently have a Siberian Traps event, but what would it take today to mimic a Siberian Traps event?
extra info)
The Paleozoic divided up into its various time periods.
www.ucmp.berkeley.edu/paleozo...oic.html
About the Siberian Traps eruptions (diagram at the bottom of the page explaining the chemistry behind it)
palaeo.gly.bris.ac.uk/Palaeof...aps.html
Pangaea
en.wikipedia.org/wiki/Pangaea
P.S. No one can accuse me of not taking a long view! ;)
posted by:
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SF Bay Area
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Re: Talk about attrition!!!
Wed, January 23, 2008 - 9:01 AMSeveral cities have been killed off through history when volcanic lakes went off like a shook up soda. The idea that something like this could have been a major problem doesn't surprise me. -
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Re: Talk about attrition!!!
Thu, February 28, 2008 - 3:17 PMLast night I was reading the Feb. 23rd-29th issue of The Economist, and the Permian extinction came up again in a global warming context.
The author noted that what may be good for the atmosphere may not be good for the ocean. The oceans absorb a million tons of carbon dioxide per hour, which helps to slow global warming, but it also also makes the sea more acidic. This is because when carbon dioxide dissolves in water it forms carbonic acid.
Many invertebrates have shells or skeletons made of calcium carbonate - which dissolves in acid.
Flash back to the Permian. Sponges, corals and brachiopods all lost big time back then. With brachiopods, we only have one genus left out of out of god knows how many during the Paleozoic. Brachiopods were everywhere (well, everywhere in the ocean anyway). Molluscs and arthropods were better off, but still lost about half their numbers. The scientist interviewed felt that this was because molluscs and arthropods are able to buffer the chemistry of the internal fluids that they use to create their shells. Sponges, corals and brachiopods can't do this. Another scientist has done calculations that suggest that if the trends continue, the alkalinity of the ocean will have fallen by half a pH unit by 2100. Some parts of the oceans would become uninhabitable for corals. And this would have an effect on the marine food chain.
Experiments were done on purple sea urchins (my advisor's creature of choice in college) . They found that when they change that pH unit to levels that are predicted in 2100, that the sea urchins had to work up to three times harder than normal to form their skeletons, and even then, the skeletons were often deformed.
The upshot of the article was that we need to pay attention to what we're putting into the oceans as well as the sky.
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