The Great Dying
251.4 million years ago, the earth experienced the most severe extinction event ever recorded. The Permian-Triassic (P-Tr) extinction event (informally referred to as the Great Dying) involved the loss of 90% of all extant species. This included about 96% of all marine species and 70% of terrestrial vertebrate species.
There are a number of theories about what caused the event:
- A comet or meteor impact
- Massive volcanic activity
- Continental evolution
- A supernova destroying the ozone layer
- Methane clathrate release
Some combination of such factors may well be responsible. Regardless of the initial cause, one of the defining elements of the P-Tr event was a high degree of global warming. Mean global temperatures increased by about 6°C, with much higher increases at the poles. This period also involved the large-scale failure of ocean circulation, leaving nutrients concentrated at the ocean bottom and an acute lack of oxygen in the sea. The latter was the product both of decreased circulation and the large-scale die off of the kind of phytoplankton species that now produce about 90% of the planet’s oxygen.
The study of such historical occurrences is useful, largely because it helps to improve our appreciation for how climatic and biological systems respond to extreme shifts. Just as the re-emergence of life after a forest fire and a clearcut may have some common properties, perhaps the patterns of decline and reformation after the P-Tr event can offer us some insight into macro level processes of ecological succession after traumatic climatic events.
August 29th, 2007 at 8:37 pm
Something like that will sure make seperating my paper from plastics seem like a big waste of time.
August 30th, 2007 at 12:59 am
Interestingly, the only large terrestrial vertebrate to survive the End-Permian was Lystrosaurus, a stout quadruped which looked like a reptilian pig, complete with tusks and a shovel like snout.
This leads me to conclude that should we warm the earth sufficiently to bring about such a catastrophe, that the only survivors will be humans mutated into hideous pig-reptiles by the last of the biotech wars. They will scratch out a meager subsistence using their tusks and acute sense of smell to forage for the thorium fortified tubers of the mutato, a hybrid staple crop designed to survive the nuclear winter brought about by a nuclear exchange fought between the leaders of the Rangoon Pact and the Holy McGoogle Empire.
August 30th, 2007 at 8:17 am
That Lystrosaurus is one handsome beast.
Its Pokemon-like appearance will also create affection for it among children.
September 29th, 2008 at 7:38 am
[...] The Great Dying [...]
October 8th, 2008 at 4:09 pm
Although the atmospheres and climates of Venus and Earth differ very greatly today, it is generally believed that the two planets started out in a rather similar state, but subsequently evolved along divergent paths. Venus succumbed early to a “runaway water vapor greenhouse,” in which the increased water vapor content arising from increased temperature reached an end state with much of the ocean evaporated into the atmosphere. Once this happens, it is easy for the water vapor to decompose in the upper atmosphere, whereafter the light hydrogen escapes and oxygen either escapes or reacts with rocks. One hypothesis is that the weak magnetic field at Venus, which otherwise would protect the planet from the solar wind, is one reason for why the oxygen and hydrogen escaped faster into space. Once water is lost, the reaction that turns carbon dioxide into limestone can no longer take place, so CO2 outgassing from volcanoes accumulates in the atmosphere instead of staying bound up in the rocks. The end state of this process is the current atmosphere of Venus, with essentially no water in the atmosphere and essentially the planet’s whole inventory of carbon in the form of atmospheric CO2.