Scorched earth for 5My after Permian Extinction

Capt'n Midnight

snowball earth it wasn't
http://www.theregister.co.uk/2012/10/19/lethally_hot_ancient_earth/

The global wipeout that ended the Permian era, before dinosaurs, wiped out nearly all of the world's species. Mass extinctions like these in Earth's history are usually followed by a "dead zone", a period of tens of thousands of years before new species crop up. But the early Triassic dead zone lasted millions of years, not thousands.

Boffins now reckon that the extra-long five million year dead zone was caused by screaming hot ocean temperatures in the tropics, making the land's forecast a balmy 50° to 60°C and 40°C at the sea-surface.

“Global warming has long been linked to the end-Permian mass extinction, but this study is the first to show extreme temperatures kept life from re-starting in Equatorial latitudes for millions of years," said study lead author Yadong Sun, a researcher at the University of Leeds.

In the dead zone, the tropics would have been very wet but with almost nothing growing, no forest, only shrubs and ferns, no fish or marine reptiles, just shellfish and virtually no land animals. Only the polar region would have offered any refuge from the blistering heat.

Before this study, scientists thought that the sea surface couldn't get any hotter than 30°C and certainly not the 40°C level at which marine life dies and photosynthesis stops.

Sun and his team figured it out by collecting data from 15,000 ancient teeth. The conodonts, tiny teeth from extinct eel-like fishes, were pulled from two tonnes of rock in South China. They form a skeleton using oxygen, and the oxygen isotopes are temperature-controlled. By examining the conodonts, the researchers were able to see how hot it was millions of years ago.

https://www.sciencemag.org/content/338/6105/366.abstract?sid=30432342-322c-45ac-a683-e8fd8059bbcc

Abstract

Global warming is widely regarded to have played a contributing role in numerous past biotic crises. Here, we show that the end-Permian mass extinction coincided with a rapid temperature rise to exceptionally high values in the Early Triassic that were inimical to life in equatorial latitudes and suppressed ecosystem recovery. This was manifested in the loss of calcareous algae, the near-absence of fish in equatorial Tethys, and the dominance of small taxa of invertebrates during the thermal maxima. High temperatures drove most Early Triassic plants and animals out of equatorial terrestrial ecosystems and probably were a major cause of the end-Smithian crisis.

Rubecula

For a long time I have thought (and this is my own opinion by the way) that the Permian extinction was due to a Gamma Ray Burst from a distant (too close for comfort) Supernova explosion.

Capt'n Midnight

Rubecula wrote: »

For a long time I have thought (and this is my own opinion by the way) that the Permian extinction was due to a Gamma Ray Burst from a distant (too close for comfort) Supernova explosion.

http://www.theregister.co.uk/2012/10/23/supersonic_cosmic_jet_spotted/