The big bang the­ory

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Mark Twain fa­mously ob­served: “Ev­ery­one talks about the weather, but no one does any­thing about it.” That’s true, un­less you are a vol­cano. Vol­ca­noes know how to do some­thing about the weather, es­pe­cially re­ally big ones. Nigel Calder, in his 1974 book and BBC TV se­ries told us about the ef­fect of Bali’s Mt Agung blow­ing its top in 1963. Vol­canic dust was spread by strato­spheric winds, and by in­ter­cept­ing the sun­light it cooled the world. The sur­face tem­per­a­ture of the Earth was ap­par­ently re­duced by a third of a de­gree in 1964 and 1965.

Then in 1991 we had an even big­ger one in our part of the world. Mt Pi­natubo in the Philip­pines helped cre­ate amaz­ing sun­sets and ex­tra­or­di­nary weather. It was aided by an­other erup­tion in Chile that same year. In 1992, like now, we sud­denly had some big late win­ter and early spring rains in South Aus­tralia. We had flood­ing from Gawler to Langhorne Creek. The Tor­rens be­came a tor­rent. Trag­i­cally, it swept through the Cudlee Creek car­a­van park and two peo­ple were killed.

The Pi­natubo erup­tion was so big it changed the world’s weather for the next cou­ple of years. It re­minded us that na­ture has its own arse­nal that can ri­val any­thing we can stock­pile. We might be able to cre­ate a nu­clear win­ter but na­ture can cre­ate a vol­canic one.

There are other blasts from the past. The In­done­sian Tamb­ora erup­tion of 1815 cre­ated the fa­mous “year with­out sum­mer”. And be­fore that, the Ice­landic erup­tion that be­gan in June 1783 and lasted eight months. The ash and gases from the Laki fis­sure helped cre­ate an­other bit­terly cold win­ter. Work by the Uni­ver­sity of Ore­gon shows it caused tem­per­a­tures in the US to fall by 4.8C be­low the 225-year av­er­age.

In Ice­land it­self, acid rain killed crops and live­stock. The famine that fol­lowed wiped out a quar­ter of Ice­land’s pop­u­la­tion. The gases and ma­te­rial spewed into the at­mos­phere acted as a global coolant. Mil­lions of lives were af­fected around the world. His­to­ri­ans now say the famines that fol­lowed in France helped cre­ate the con­di­tions that led to the French Revo­lu­tion. A big bang in Ice­land didn’t just change the world’s weather, it changed the world’s his­tory.

So, has the re­cent al­most un­pro­nounce­able Ey­jaf­jal­la­jokull erup­tion – once again in Ice­land – changed the world’s weather? It started in April and lasted five weeks. It threw dust up to 9km into the at­mos­phere. It’s es­ti­mated 250 mil­lion cu­bic me­tres of vol­canic ma­te­rial was pumped into the sky. Most ex­perts say al­though this bang was big enough to dis­rupt air travel it wasn’t big enough to have any real ef­fect on the world’s weather. But there has been a lot of other vol­canic ac­tiv­ity re­cently. Could there be a cu­mu­la­tive ef­fect? Could there be a link to the ex­cep­tion­ally wet weather here, the re­turn of big snow­falls in the alps, and the flood­ing in Vic­to­ria and the Out­back?

I am not a global warm­ing scep­tic. I don’t say it is na­ture not man that drives the Earth’s warm­ing and cool­ing. Like many things in life, it’s pos­si­ble both sides are right. When we are burn­ing bil­lions of tonnes of fos­sil fuel we are act­ing like an in­dus­trial vol­cano. We just take 200 years rather than two months to push the stuff out. We can’t stop vol­ca­noes but we can stop what we are do­ing. Let’s learn from na­ture, and in the mean­time, en­joy the change in the weather.

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