Even without a meteorite, the stage was set for the extinction of the dinosaurs: ScienceAlert
The explosive end of non-avian dinosaurs is the worst blow to life on Earth. But there have long been hints that the asteroid may not have been the main cause of this mass extinction, but just a more dramatic isolated contribution.
Before this dramatic event, 66 million years ago, toxic winds of change were already blowing in the air.
New analysis by an international team of researchers has added evidence to claims that the world before the asteroid strike was anything but a paradise, with sulfur levels in the atmosphere reaching critical levels.
Along with other studies on mercury levels, the research provides a sign of volcanic activity strong enough to cause major climate disruptions.
In 1991, the timing of this volcanic activity was dismissed as being too early to have caused the mass extinction event. but More recent studies Proving that the timing can be close enough to matter.
“Our data suggest that volcanic sulfur gas degassing from such activity could cause frequent, short-term global drops in temperature,” University of Oslo geoscientist Sarah Calligaro and her colleagues wrote in their paper.
The team examined rocks from the Deccan Traps – one of the largest volcanic features – in what is now western India. They applied a new technique they developed to measure sulfur concentrations.
Models suggest that persistent sulfur emissions from the Deccan traps would have been enough to significantly alter global climate. This volcanic area alone released one million cubic kilometers of molten rock.
What’s more, the formation of highly concentrated sulfur containing lavas at Thakurvadi to Bush, within the region, coincides with a cool Cretaceous climate, the team noted.
While much of the basalt in the area is generally low in sulfur, this may indicate climate – The cooling molecule was slowly released into the atmosphere from the solidified magma after the eruptions.
As a result, global temperatures could have fallen in bouts of up to 10°C, between periods of rapid recovery, within 100,000 years before the Chicxulub meteorite delivered the final blow.
“Our research shows that climate conditions were almost certainly unstable, with recurring volcanic winters that could have lasted decades, before the extinction of the dinosaurs,” explains McGill University geochemist Don Baker.
“This instability could have made life difficult for all plants and animals and set the stage for a dinosaur extinction event.”
Fossilized bone fragments Thousands Eggshell remains indicate a global decline in non-avian dinosaur species over this long time period.
But these declines have conflicted with other studies, continuing a long-running and sometimes bitter scientific debate between the asteroid and volcano theories. Some researchers suggest that the asteroid may have sparked greater activity from the Deccan Traps, while others claim that volcanic activity may have helped recover life from the asteroid strike.
The arguments in favor of eruptive pulses seem to be accumulating, and it is volcanoes, after all, that ended three-quarters of life on Earth during the previous mass extinction.
“Volcanic activity in the Deccan Traps set the stage for a global biotic crisis, repeatedly deteriorating environmental conditions by forcing frequent short volcanic winters,” the team concluded.
Their research has been published in Advancement of science.