Mt Eyjafjallajökull, dramatic though it is, is tiny by comparison compared to the 1991 Mount Pinatubo eruption in the Philippines.
It was an enormous explosion that is estimated to have thrown out 10 billion tonnes of magma and sent ash clouds 34 km up into the atmosphere. It was one of the biggest volcanic eruptions of the 20th century.
Hundreds of people were killed, thousands evacuated and the ash ejected from the two week eruption drifted right around the world affecting flights and improving sunsets.
The sulphuric fire and brimstone coming from Mt Pinatubo was even enough to affect the world’s climate.
In the atmosphere, sulphur dioxide coming from volcanoes forms sulphuric acid – otherwise known as acid rain. This captures the heat from the sun high up in the stratosphere, preventing it from reaching Earth, cooling the Earth’s overall temperatures. Scientists estimate that the 15 or so million tonnes of sulphur dioxide spat out by Pinatubo temporarily cooled the globe by as much as 0.5 degrees Celsius.
How then might this latest volcano erupting in Iceland affect the climate? Will it provide the reprieve to global warming the world is looking for?
Mt Eyjafjallajökull is tiny by comparison.
Dr Andrew Bell, from the School of Geosciences at the University of Edinburgh, says “In both a global and an Icelandic context, this is a relatively minor eruption, involving only small amounts of magma.”
The sulphuric emissions from Eyjafjallajökull are accordingly small. Steve Sparks, director of the Bristol Environmental Risk Research Centre at the University of Bristol, says “the reported sulphur dioxide fluxes have been about 3,000 tons per day.”
Even if the eruption has released this much daily for a month, this equates to only about 90,000 tonnes of sulphur dioxide.
Australian industry emitted 2.7 million tonnes of sulphur dioxide in 2008/2009, or more than 7,000 tonnes per day.
Volcanoes also emit carbon dioxide in the toxic mix of gases that are released in an eruption. Carbon dioxide is one of the gases that cause climate change.
Last year Ian Plimer asserted that the carbon dioxide coming from all the world’s volcanoes was one of the major contributing factors to changes in atmospheric CO2.
“Over the past 250 years, humans have added just one part of CO2 in 10,000 to the atmosphere. One volcanic cough can do this in a day,” he said.
Could Eyjafjallajökull’s rumblings, or indeed Pinatubo’s, exacerbate climate change, rather than mitigate it?
Pinatubo is estimated to have belched 42 million tonnes of CO2 into the atmosphere in 1991. Globally, according to the US Energy Information Administration, human activity contributed 29,195 million tonnes of CO2 to the air in 2006 – nearly 700 times as much as Pinatubo’s colossal cough.
While Pinatubo was undoubtedly a big contributor to global CO2 levels in 1991, these figures contradict Plimer’s view of the relative importance of volcanic activity on the Earth’s carbon dioxide levels.
So overall, while Eyjafjallajökull might be coughing out all kinds of underground gases, the largest effect it will have on the world will be keeping planes on the ground. It is unlikely to have any lasting effect on our climate.
As Steven Sherwood, professor of physical meteorology and atmospheric climate dynamics at the Climate Change Research Centre, University of New South Wales said, “Satellite images show that the plume is not thick or expansive enough to significantly affect climate, though it could produce slightly cooler days in places where it lingers over one spot for the whole day, I’m not sure anyone would notice the effect.”