New research could draw a "curtain of fire" on the current dinosaur extinction theory by demonstrating the role volcanic activity played in the phenomenon was much less significant than previously believed.
The two most widely believed causes of the extinction of the dinosaurs are an ancient asteroid impact and volcanic activity called flood basalts, the University of Leeds reported. Both of these events would have propelled gas and dust into the atmosphere, causing a global change in climate. Until now, the impact of years of sulphur dioxide emissions from continental flood basalts was unknown. To fill in these gaps, a team of researchers created the world's first quantitative estimate of the degree and nature of the effects that volcanic activity had on the ancient world's climate, landscape, and oceans.
"At the time when the dinosaurs reigned, numerous long-lasting eruptions took place over the course of about a million years. These eruptions, called 'continental flood basalts' were not like volcanic eruptions we often see today, with lava gushing from the ground like a curtain of fire," said study lead author Anja Schmidt, from the University's School of Earth and Environment. "Each eruption is likely to have lasted years, even decades, and eruptions were separated by periods without volcanic activity. The lava produced by an eruption of average intensity would have filled 150 Olympic-size swimming pools per minute."
To make their findings, the researchers used a sophisticated computer simulation of gas and aerosol particles. The simulations revealed the climatic impacts of flood basalts was less severe than researchers had previously estimated. The only way these flood basalts would be able to have major climate impacts would have been if they had oozed for hundreds of years.
The findings showed the Earth did cool by as much as 4.5 degrees Celsius as a result of the volcanic activity, but the temperatures would have returned to normal within 50 years of the end of the flood basalts.
"Perhaps most intriguingly, we found that the effects of acid rain on vegetation were rather selective. Vegetation in some but not all parts of the world would have died off, whereas in other areas the effects would have been negligible," said Schmidt said.
The findings were published in a recent edition of the journal Nature Geoscience.