koan ... re: CO2... I was gonna pass as I rearely talk about this stuff any longer.. figuring I'll do wait and see... but we have not jousted in soooo long I could not resist.. :o)
That is really an incomplete story. Here is one source but Google (everybody's friend) has gazillions..
en.wikipedia.org
Appears the CO2 may have been a symptom... not a cause.. All these stories seem to make liberal use of the word may :O)
To be fair and forthright when proposing that the Permian mass extinction was caused by CO2... you should be sure to include the rest of the story ..
Volcanism
The world around the time of the P-Tr extinction. The Siberian Traps eruptions occurred on the eastern shore of the shallow sea (paler blue) at the north of the map. The earlier Emeishan eruptions occurred on the north edge of the almost enclosed shallow sea just north of the equator - at this time the blocks that currently form China and South-East Asia were just emerging.
The final stages of the Permian saw two flood basalt events. A small one centered at Emeishan in China occurred at the same time as the end-Guadalupian extinction pulse, in an area which was close to the equator at the time.[83] The flood basalt eruptions which produced the Siberian Traps constituted one of the largest known volcanic events on Earth and covered over 200,000 square kilometers (77,220.4 sq mi) with lava. The Siberian Traps eruptions were formerly thought to have lasted for millions of years, but recent research dates them to 251.2 ± 0.3 Ma — immediately before the end of the Permian.[2][84]
The Emeishan and Siberian Traps eruptions may have caused dust clouds and acid aerosols which would have blocked out sunlight and thus disrupted photosynthesis both on land and in the upper layers of the seas, causing food chains to collapse. These eruptions may also have caused acid rain when the aerosols washed out of the atmosphere. This may have killed land plants and mollusks and planktonic organisms which build calcium carbonate shells. The eruptions would also have emitted carbon dioxide, causing global warming. When all of the dust clouds and aerosols washed out of the atmosphere, the excess carbon dioxide would have remained and the warming would have proceeded without any mitigating effects.[80]
The Siberian Traps had unusual features which made them even more dangerous. Pure flood basalts produce a lot of runny lava and do not hurl debris into the atmosphere. It appears, however, that 20% of the output of the Siberian Traps eruptions was pyroclastic, i.e. consisted of ash and other debris thrown high into the atmosphere, increasing the short-term cooling effect.[85] The basalt lava erupted or intruded into carbonate rocks and into sediments which were in the process of forming large coal beds, both of which would have emitted large amounts of carbon dioxide, leading to stronger global warming after the dust and aerosols settled.[80]
There is doubt, however, about whether these eruptions were enough on their own to cause a mass extinction as severe as the end-Permian. Equatorial eruptions are necessary to produce sufficient dust and aerosols to affect life worldwide, whereas the much larger Siberian Traps eruptions were inside or near the Arctic Circle. Furthermore, if the Siberian Traps eruptions occurred within a period of 200,000 years, the atmosphere's carbon dioxide content would have doubled. Recent climate models suggest that such a rise in CO2 would have raised global temperatures by 1.5 °C (2.7 °F) to 4.5 °C (8.1 °F), which is bad but unlikely to cause a catastrophe as great as the P-Tr extinction.[80]
However, one theory, popularized by the documentary Miracle Planet, is that the slight volcanic warming caused a melting of methane hydrate, and this created a positive-feedback warming loop, as methane is 45 times more efficient than CO2 at exacerbating global warming.
I notice you are not hanging around the gold threads much these days..
Whassup with that ?
Hope all is well
The Black Swan
Alias Alladin Sane alias Spotted Cat alias KastelCo :O) |
