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January 25, 2011

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Eruption may have caused worst extinction ever

Jan. 25, 2011
Courtesy of the University of Calgary
and World Science staff

New evidence suggests a vol­can­ic erup­tion caused the larg­est mass ex­tinc­tion in Earth’s his­to­ry, about 250 mil­lion years ago, re­search­ers say.

About 95 per cent of life was de­stroyed in the sea and 70 per cent on land in that in­ci­dent, ac­cord­ing to sci­en­tists. Re­search­ers at the Uni­vers­ity of Cal­ga­ry in Can­a­da be­lieve they have found ev­i­dence that mas­sive vol­can­ic erup­tions burnt huge vol­umes of coal, pro­duc­ing ash clouds that broadly af­fect­ed the oceans.

Re­search­ers walk through sed­i­ments de­posited short­ly af­ter the worst ex­tinc­tion event in earth his­to­ry, on the shores of Bu­chan­an Lake, Ax­el Hei­berg Is­land, Nu­na­vut, Can­a­da. (Cred­it: Steve Gras­by, U. of Cal­gar­y/NR­Can)

“This could lit­er­ally be the smok­ing gun that ex­plains the lat­est Per­mi­an ex­tinc­tion,” as the event is called, said Steve Grasby, a geo­sci­en­tist at the uni­vers­ity and at Nat­u­ral Re­sources Can­a­da. Grasby and col­leagues found lay­ers of coal ash in a lay­er of rock as­so­ci­at­ed with the time of the ex­tinc­tion. Lo­cat­ed in Can­a­da’s High Arc­tic, the rocks give the first di­rect proof to sup­port the new the­o­ry, say the re­search­ers, who have pub­lished their find­ings in the jour­nal Na­ture Ge­o­sci­ence.

Un­like the de­mise of the di­no­saurs, 65 mil­lion years ago—for which there is wide­spread agree­ment among sci­en­tists that a me­te­or­ite im­pact was at least the par­tial cause—it’s un­clear what caused the late Per­mi­an ex­tinc­tion. Pre­vi­ous re­search­ers have sug­gested mas­sive vol­can­ic erup­tions through coal beds in Si­be­ria would gen­er­ate sig­nif­i­cant green­house gas­es caus­ing run­away glob­al warm­ing.

“Our re­search is the first to show di­rect ev­i­dence that mas­sive vol­can­ic erup­tions – the larg­est the world has ev­er wit­nessed – caused mas­sive coal com­bus­tion,” which could have led to “sig­nif­i­cant genera­t­ion of green­house gas­es at this time,” said Grasby. At the time, the Earth con­tained one big land mass, a “supe­rcontinent” known as Pan­gaea. The en­vi­ron­ment ranged from des­ert to lush for­est. Four-limbed ver­te­brates, or back­boned an­i­mals, were be­com­ing more di­verse; among them were prim­i­tive am­phib­ians, early rep­tiles and synap­sids—a group that would, one day, in­clude mam­mals.

The ar­ea of the vol­ca­noes, known as the Si­be­ri­an Traps, is now in north­ern Rus­sia, cen­tred around the Si­be­ri­an city Tu­ra and en­com­pass­ing Ya­kutsk, No­ril’sk and Ir­kutsk. They cov­er an ar­ea just un­der two mil­lion square kilo­me­ters, a size great­er than that of Eu­rope, re­search­ers said. The ash plumes from the vol­ca­noes would have trav­eled to re­gions now in Can­a­da’s arc­tic where coal ash lay­ers were found.

Grasby stud­ied the forma­t­ions with Uni­vers­ity of Cal­ga­ry col­leagues Be­noit Beau­champ and Ha­med Sa­nei. “We saw lay­ers with abun­dant or­gan­ic mat­ter and Ha­med im­me­di­ately de­ter­mined that they were lay­ers of coal ash, ex­actly like that pro­duced by mod­ern coal burn­ing pow­er plants,” said Beau­champ. “Our discov­ery pro­vides the first di­rect con­firma­t­ion for coal ash dur­ing this ex­tinc­tion, as it may not have been rec­og­nized be­fore,” added Sa­nei.

The ash, the au­thors sug­gest, may have caused more trou­ble for a plan­et that was al­ready heat­ing up, its oceans start­ing to suf­fo­cate be­cause of fall­ing ox­y­gen lev­els. “It was a really bad time on Earth. In ad­di­tion to these vol­ca­noes caus­ing fires through coal, the ash it spewed was highly tox­ic and was re­leased in the land and wa­ter, po­ten­tially con­tri­but­ing to the worst ex­tinc­tion event in earth his­to­ry,” said Grasby.

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A volcanic eruption caused the largest mass extinction in Earth’s history, about 250 million years ago, scientists say in a new study. About 95 per cent of life was destroyed in the sea and 70 per cent on land in that incident, according to scientists. Researchers at the University of Calgary in Canada believe they have found evidence that massive volcanic eruptions burnt huge volumes of coal, producing ash clouds that broadly affected the oceans. “This could literally be the smoking gun that explains the latest Permian extinction,” as the event is called, said Steve Grasby, a geoscientist at the university and at Natural Resources Canada. Grasby and colleagues found layers of coal ash in a layer of rock associated with the time of the extinction. Located in Canada’s High Arctic, the rocks give the first direct proof to support the new theory, say the researchers, who have published their findings in the journal Nature Geoscience. Unlike the demise of the dinosaurs, 65 million years ago—for which there is widespread agreement among scientists that a meteorite impact was at least the partial cause—it’s unclear what caused the late Permian extinction. Previous researchers have suggested massive volcanic eruptions through coal beds in Siberia would generate significant greenhouse gases causing runaway global warming. “Our research is the first to show direct evidence that massive volcanic eruptions – the largest the world has ever witnessed – caused massive coal combustion thus supporting models for significant generation of greenhouse gases at this time,” said Grasby. At the time, the Earth contained one big land mass, a “supercontinent” known as Pangaea. The environment ranged from desert to lush forest. Four-limbed vertebrates, or backboned animals, were becoming more diverse; among them were primitive amphibians, early reptiles and synapsids—a group that would, one day, include mammals. The area of the volcanoes, known as the Siberian Traps, is now in northern Russia, centred around the Siberian city Tura and encompassing Yakutsk, Noril’sk and Irkutsk. They cover an area just under two-million-square kilometers, a size greater than that of Europe, researchers said. The ash plumes from the volcanoes traveled to regions now in Canada’s arctic where coal-ash layers where found. Grasby studied the formations with University of Calgary colleagues Benoit Beauchamp and Hamed Sanei. “We saw layers with abundant organic matter and Hamed immediately determined that they were layers of coal-ash, exactly like that produced by modern coal burning power plants,” said Beauchamp. “Our discovery provides the first direct confirmation for coal ash during this extinction as it may not have been recognized before,” added Sanei. The ash, the authors suggest, may have caused even more trouble for a planet that was already heating up with its oceans starting to suffocate because of decreasing oxygen levels. “It was a really bad time on Earth. In addition to these volcanoes causing fires through coal, the ash it spewed was highly toxic and was released in the land and water, potentially contributing to the worst extinction event in earth history,” said Grasby.