Ancient eruptions warn of climate change and mass extinctions

A Curtin University of Technology researcher has shown that some ancient periods of massive volcanic eruptions released greenhouse gases so quickly that they caused rapid climate change and mass extinctions.

Research Fellow Dr Fred Jourdan said this was of concern because we are now adding carbon dioxide to the atmosphere faster than even the most rapid sequence of eruptions.

“Past extinctions can be used as a guide to see how modern greenhouse gas emissions could affect life on Earth,” Jourdan said.

“We have carefully dated minerals contained in the volcanic rocks and shown that only the fastest sequences of eruptions caused significant species extinctions.

“To understand the long-term climatic and biological effects of the massive injections of greenhouse gas in the atmosphere by modern society, we need to understand how climate was affected in the past.”

For years, controversy has raged about whether mass extinctions over the past 550 million years were caused by the impact of giant asteroids or by huge volcanic eruptions.

“Both mechanisms can release a colossal amount of greenhouse gases,” said Jourdan.

“The key to discriminate between these two possibilities is to see if there is a link between the timing of mass extinctions and geological events.”

Using radioactive dating techniques, Jourdan and his colleagues have determined the age, duration and rate of volcanic activity of three major volcanic provinces in Africa, Australia and the continents now surrounding the Atlantic Ocean.

“Each eruption covered an area the size of Western Australia and our results demonstrate that volcanism in the Australian and Circum-Atlantic provinces occurrred very quickly, over a period of one or two million years.

“In both cases, these events were simultaneous with major mass extinction, implying that volcanic gases strongly affected the climate and life.

“However, volcanism in the African Province appears to have occurred over a longer time period and is not associated with an extinction event, suggesting that most species can withstand climatic changes produced by volcanic eruptions provided they have time to adapt.”

Jourdan is one of 15 early-career scientists who recently presented their research for the first time at a Melbourne conference thanks to Fresh Science, a national program sponsored by the federal government.