The so-called “dinosaur extinction” is one of the most famous and infamous blows to life on our old planet Earth. The idea that asteroids were the main culprits behind this mass extinction has been debated for some time. Asteroids are now seen as “one of the culprits”.
In fact, new research suggests that toxic winds of change were already blowing before this dramatic event 66 million years ago.
A new analysis by an international team of researchers has added evidence to claims that Earth was far from being an “idyllic place” before the asteroid impact and that measurements of sulfur in the atmosphere had reached critical levels. This research, along with other studies of mercury levels, points to the presence of volcanic activity strong enough to cause significant climate disruptions.
A 1991 study on the timing of this volcanic activity suggested that it occurred too early to have been behind a mass extinction event. More recent research, however, suggests that it is possible that the volcanic activity was close enough to have a significant impact on the extinction.
Geologist Sara Callegaro from the University of Oslo and colleagues write in their paper:
Our data suggest that volcanic sulfur degassing from such activity could cause short-term and repeated global drops in temperature.
The team studied rocks from the Deccan Traps, one of the largest volcanic formations in the region now known as western India. They applied a new technique they developed to measure sulfur concentrations. The models show that the continuous sulfur emissions from the Deccan Traps are enough to significantly alter the global climate. This volcanic region alone has exposed a staggering one million cubic kilometers of molten rock.
Even 100,000 years ago, temperatures may have dropped
Moreover, the team notes that the formation of high concentrations of sulfur-bearing lava from Thakurvadi to Bushe coincides with the cooling Cretaceous climate.
Although most basalts in the region are generally low in sulfur, this may indicate that the molecule that cooled the climate was slowly released into the atmosphere from the magma that hardened after the eruptions. As a result, 100,000 years before the Chicxulub meteor delivered the final blow, global temperatures could have dropped by as much as 10°C between periods of rapid recovery.
Geochemist Don Baker from McGill University explains:
“Our research shows that climatic conditions were almost certainly unstable due to repeated volcanic winters that could have lasted for decades before the dinosaurs went extinct. This instability would have made life difficult for all plants and animals and set the stage for the extinction of the dinosaurs.
Fossilized bone fragments and thousands of eggshell remains show that non-avian dinosaur species declined globally over such a long period of time.
However, this contradicts long-standing and sometimes fierce scientific debate between the “asteroid” and “volcano” theories. Some researchers suggest that the asteroid may have triggered more volcanic activity in the Deccan Traps, while others even argue that volcanic activity may have helped life recover after the asteroid impact.
The arguments for eruptions seem to be piling up, and after all, it is also known that it was volcanoes that ended three-quarters of all life on Earth during the mass extinction. This is the team’s conclusion:
“Deccan Traps volcanism set the stage for a global biotic crisis by forcing repeated short volcanic winters and continuously worsening environmental conditions.”
