Poster's note: offtopic - but interesting as a result of potential comparison with (non)-geoengineered near term future scenarios
http://thinkprogress.org/climate/2013/03/24/1760921/doubling-of-co2-levels-in-end-triassic-extinction-killed-off-three-quarters-of-land-and-sea-species/?mobile=wt Doubling Of CO2 Levels In End-Triassic Extinction Killed Off Three Quarters Of Land And Sea Species By Joe Romm Mar 24, 2013 at 12:26 pm “There are very strong indications that the current rate of species extinctions far exceeds anything in the fossil record.” That’s from a 2010 special issue on climate change and biodiversity from the UK’s Royal Society.In 2011, a Nature Geoscience studyfound humans are spewing carbon into the atmosphere 10 times faster now than 56 million years ago, the Paleocene-Eocene Thermal Maximum (PETM), a time of 10°F warming and mass extinction.An even more ancient extinction is the subject of a new study in Science (subs. req’d), with the tongue-twister title, “Zircon U-Pb Geochronology Links the End-Triassic Extinction with the Central Atlantic Magmatic Province.”As the MIT News release puts it:Some 200 million years ago, an increase in atmospheric CO2 caused acidification of the oceans and global warming that killed off 76 percent of marine and terrestrial species on Earth.Whereas human activity is the source of the rapid surge in CO2 emissions today, the source of the surge 200 million years ago is now widely thought to be volcanoes:… most scientists agree on a likely scenario: Over a relatively short period of time, massive volcanic eruptions from a large region known as the Central Atlantic Magmatic Province (CAMP) spewed forth huge amounts of lava and gas, including carbon dioxide, sulfur and methane. This sudden release of gases into the atmosphere may have created intense global warming and acidification of the oceans that ultimately killed off thousands of plant and animal species.Now researchers at MIT, Columbia University and elsewhere have determined that these eruptions occurred precisely when the extinction began, providing strong evidence that volcanic activity did indeed trigger the end-Triassic extinction.Today, of course, notwithstanding the claims of some disinformers, “Humans emit 100 times more CO2 than volcanoes,” as Skeptical Science explains in one of their classic myth-debunking posts.So what is the connection between what happened in the End-Triassic Extinction and our current mass extinction? As ClimateWire (subs. req’d) explains:“In some ways, this event is analogous to the present day,” said study lead author Terrence Blackburn, of the Carnegie Institution for Science.Morgan Schaller, a research associate in earth systems history at Brown University, has previously published work in Science showing that these massive eruptions led to a doubling of carbon dioxide levels from 2,000 parts per million to 4,400 ppm.Although researchers are not sure how quickly this doubling occurred, it could have been within a period as short as 1,000 years.This leads them to draw analogies between today’s rapid CO2 increase and the past. Even though the base-line levels of CO2 were much higher 200 million years ago, a doubling of carbon dioxide concentrations leads to a 3 degree Celsius increase whether it’s from 2,000 to 4,000 ppm or from 280 to 560 ppm, Schaller said….Paul Olsen, a geologist at Columbia University’s Lamont-Doherty Earth Observatory and a co-author on the paper released yesterday, said the extinction, however it happened, occurred in 20,000 years or less — but like the speed of the carbon dioxide doubling, it could have been a lot less.In any case, what humans are doing to the biosphere today is mostly without precedent in the geologic record and poised to be far worse than most previous extinctions, according to recent research:Study finds “mass biodiversity collapse” at 900 ppm, and possibly a “threshold response … to relatively minor increases in CO2 concentration and/or global temperature.”Nature Climate Change: “The proportion of actual biodiversity loss should quite clearly be revised upwards: by 2080, more than 80% of genetic diversity within species may disappear in certain groups of organisms“Scientist: “When CO2 levels in the atmosphere reach about 500 parts per million, you put calcification out of business in the oceans”A 2009 study in Nature Geoscience warned that global warming may create expanding “dead zones” in the ocean that would be devoid of fish and seafood and “remain for thousands of years.”“Geological Society: Acidifying oceans spell marine biological meltdown “by end of century.”There will always be zoos … won’t there? -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
