Marvel this: It would seem that massive volcanic eruptions in Australia wiped out 50% of all species 510 million years ago.
Try to imagine a volcano so big, the lava flow covers 2 million square kilometers. For US folk, that would be like a volcano that covered California, Nevada, Arizona, Utah, Oregon, Idaho and Washington State combined.
(And some people think we are facing a “crisis” today?)
It was, to put it mildly, quite bad news for trilobites which had only been around for a trifling 10 million years at that stage. Otherwise life at that time was sponges, fungi, algae, and on land, attractive sounding things like microbial mats. (I suspect a Cambrian-era-Greenpeace would have struggled to find cuddly photogenic targets. Oops, no cameras either.)
I love the grand big-picture in all its imponderable vastness and power. I’m not so enthused on their climate analysis. I half wonder – half marvel at whether we can really figure out what happened that long ago.
The poor researchers are burdened with the culture of bad climate models. You can feel their struggle: volcanic dust causes cooling, but CO2 causes warming. Which wins? Do we get the ultimate volcanic winter or will that be global warming? Answer, apparently “both”:
“The study states it would result in “rapid climate changes and climate oscillations.”
Translation, Jourdan said: “Game over.”
“It was a yo-yo effect,” Jourdan says. “You had a long-term warming with the greenhouse gasses, but also a back-and-forth between warming and a cooling.”” — Washington Post
I wonder what resolution they get on that climate yo-yo 510,000,000 years ago. Were those annual, decadal, or centennial swings?
Their climate speculation aside, I found the rest of the paper intriguing. It was first released at the end of May.
Australia’s deadly eruptions were reason for the first mass extinction
A Curtin University researcher has shown that ancient volcanic eruptions in Australia 510 million years ago significantly affected the climate, causing the first known mass extinction in the history of complex life.
Published in the journal Geology, Associate Professor Fred Jourdan from Curtin’s Department of Applied Geology, along with colleagues from several Australian and international institutions, used radioactive dating techniques to precisely measure the age of the eruptions of the Kalkarindji volcanic province — where lavas covered an area of more than 2 million square kilometres in the Northern Territory and Western Australia.
Dr Jourdan and his team were able to prove the volcanic province occurred at the same time as the Early-Middle Cambrian extinction from 510-511 million years ago — the first extinction to wipe out complex multicellular life.
“It has been well-documented that this extinction, which eradicated 50 per cent of species, was related to climatic changes and depletion of oxygen in the oceans, but the exact mechanism causing these changes was not known, until now,” Dr Jourdan said.
“Not only were we able to demonstrate that the Kalkarindji volcanic province was emplaced at the exact same time as the Cambrian extinction, but were also able to measure a depletion of sulphur dioxide from the province’s volcanic rocks — which indicates sulphur was released into the atmosphere during the eruptions.
“As a modern comparison, when the small volcano Pinatubo erupted in 1991, the resulting discharge of sulphur dioxide decreased the average global temperatures by a few tenths of a degree for a few years following the eruption.
“If relatively small eruptions like Pinatubo can affect the climate just imagine what a volcanic province with an area equivalent to the size of the state of Western Australia can do.”
The team then compared the Kalkarindji volcanic province with other volcanic provinces and showed the most likely process for all the mass extinctions was a rapid oscillation of the climate triggered by volcanic eruptions emitting sulphur dioxide, along with greenhouse gases methane and carbon dioxide.
“We calculated a near perfect chronological correlation between large volcanic province eruptions, climate shifts and mass extinctions over the history of life during the last 550 million years, with only one chance over 20 billion that this correlation is just a coincidence,” Dr Jourdan said.
Dr Jourdan said the rapid oscillations of the climate produced by volcanic eruptions made it difficult for various species to adapt, ultimately resulting in their demise. He also stressed the importance of this research to better understand our current environment.
Note the usual request for funds: pay us more money because it will help us to understand “climate change”.
“To comprehend the long-term climatic and biological effects of the massive injections of gas in the atmosphere by modern society, we need to recognise how climate, oceans and ecosytems were affected in the past,” he said.
I wish they felt they could ask for funds just because it’s fascinating.
Jourdan, F., et al (2014) High-precision dating of the Kalkarindji large igneous province, Australia, and synchrony with the Early-Middle Cambrian (Stage 4-5) extinction. Geology, 2014; 42 (6): 543 DOI: 10.1130/G35434.1