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Politics : President Barack Obama -- Ignore unavailable to you. Want to Upgrade?

To: T L Comiskey who wrote (44212)	11/10/2008 6:31:49 PM
From: koan	Read Replies (1) \| Respond to of 149317

Global warming, the largest danger: Go look at what happened in the Permian age, 290 million years ago, when 95% of all life on earth was wiped out. First the carbon dioxide levels rose, probably from volcanic action and this raised the temperature enough to start melting the methane hydrates. Methane is 23 times more of a greenhouse gas than CO2. Entire Arctic is frozen methane.And it is melting and scientists are now seeing increased amounts of methane in the atmosphere. And Oaklahoma reelected that idiot Jim Inhoff, who along with tom Delay calls global warming the biggest hoax ever prepetrated on mankind. He was chairman of the senate envirnmental committee when the GOP ruled! Permian-Triassic extinction event The Permian–Triassic extinction event, labeled "End P" here, is the most significant extinction event in this plot for marine genera which produce large numbers of fossils.Main article: Permian–Triassic extinction event The Permian ended with the most extensive extinction event recorded in paleontology: the Permian-Triassic extinction event. 90% to 95% of marine species became extinct, as well as 70% of all land organisms. On an individual level, perhaps as many as 99.5% of separate organisms died as a result of the event.[12] There is also significant evidence that massive flood basalt eruptions from magma output lasting thousands of years in what is now the Siberian Traps contributed to environmental stress leading to mass extinction. The reduced coastal habitat and highly increased aridity probably also contributed. Based on the amount of lava estimated to have been produced during this period, the worst case scenario is an expulsion of enough carbon dioxide from the eruptions to raise world temperatures five degrees Celsius, not enough to kill off 95% of life. Another hypothesis involves ocean venting of hydrogen sulfide gas. Portions of deep ocean will periodically lose all of its dissolved oxygen allowing bacteria that live without oxygen to flourish and produce hydrogen sulfide gas. If enough hydrogen sulfide accumulates in an anoxic zone, the gas can rise into the atmosphere. Oxidizing gases in the atmosphere would destroy the toxic gas, but the hydrogen sulfide would soon consume all of the atmospheric gas available to change it. Hydrogen sulfide levels would increase dramatically over a few hundred years. Modeling of such an event indicates that the gas would destroy ozone in the upper atmosphere allowing ultraviolet radiation to kill off species that had survived the toxic gas (Kump, et al, 2005). Of course, there are species that can metabolize hydrogen sulfide. Another hypothesis builds on the flood basalt eruption theory. Five degrees Celsius would not be enough increase in world temperatures to explain the death of 95% of life. But such warming could slowly raise ocean temperatures until frozen methane reservoirs below the ocean floor near coastlines (a current target for a new energy source) melted, expelling enough methane, among the most potent greenhouse gases, into the atmosphere to raise world temperatures an additional five degrees Celsius. The frozen methane hypothesis helps explain the increase in carbon-12 levels midway into the Permian-Triassic boundary layer. It also helps explain why the first phase of the layer's extinctions was land-based, the second was marine-based (and starting right after the increase in C-12 levels), and the third land-based again. An even more speculative hypothesis is that intense radiation from a nearby supernova was responsible for the extinctions. Trilobites, which had thrived since Cambrian times, finally became extinct before the end of the Permian. In 2006, a group of American scientists from Ohio State University reported evidence for a possible huge meteorite crater (Wilkes Land crater) with a diameter of around 500 kilometers in Antarctica. The crater is located at a depth of 1.6 kilometers beneath the ice of Wilkes Land in eastern Antarctica. The scientists speculate that this impact may have caused the Permian-Triassic extinction event, although its age is bracketed only between 100 million and 500 million years ago. They also speculate that it may have contributed in some way to the separation of Australia from the Antarctic landmass, which were both part of a supercontinent called Gondwana. Levels of iridium and quartz fracturing in the Permian-Triassic layer do not approach those of the Cretaceous-Tertiary boundary layer. Given that a far greater proportion of species and individual organisms became extinct during the former, doubt is cast on the significance of a meteor impact in creating the latter. Further doubt has been cast on this theory based on fossils in Greenland showing the extinction to have been gradual, lasting about eighty thousand years, with three distinct phases. The warm zone spread in the northern hemisphere, where extensive dry desert appeared. The rock formed at that time were stained red by iron oxides, the result of intense heating by the sun of a surface devoid of vegetation cover. The old types of plants and animals died out. Many scientists believe that the Permian-Triassic extinction event was caused by a combination of some or all of the hypotheses above and other factors; the formation of Pangaea decreased the number of coastal habitats and may have contributed to the extinction of many clades.