domenica 4 novembre 2012

Tropical Collapse in Early Triassic Caused by Lethal Heat: Extreme Temperatures Blamed for Dead Zone

©ScienceDaily #NEWS "Tropical Collapse in Early Triassic Caused by Lethal Heat: Extreme Temperatures Blamed for Dead Zone". The end-Permian mass extinction, which occurred around 250 million years ago in the pre-dinosaur era, wiped out nearly all the world's species. Typically, a mass extinction is followed by a 'dead zone' during which new species are not seen for tens of thousands of years. In this case, the dead zone, during the Early Triassic period which followed, lasted for a perplexingly long period: five million years.

A study jointly led by the University of Leeds and China University of Geosciences (Wuhan), in collaboration with the University of Erlangen-Nurnburg (Germany), shows the cause of this lengthy devastation was a temperature rise to lethal levels in the tropics: around 50-60°C on land, and 40°C at the sea-surface.
Lead author Yadong Sun, who is based in Leeds while completing a joint PhD in geology, says: "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." More Info and Image at: | The study, published Oct. 19 in the journal Science, is the most detailed temperature record of this study period (252-247 million years ago) to date. #Report "Lethally Hot Temperatures During the Early Triassic Greenhouse" #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. | ITA: © Le Scienze "Le letali temperature dell’inizio del Triassico"

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