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Before Iceland's Eyjafjallajökull volcano decided to let off some steam, few people would have guessed that a small volcanic eruption would be capable of grounding almost every flight across Europe for almost a week. We consider ourselves to live in a sophisticated, modern and resilient society, so it came as a bit of a shock to see how helpless we can quickly become.
Yet volcanoes are not the only trump cards that nature holds: there is a whole array of potential disasters that could have unpredictable and alarming consequences. Here are some of the main contenders. Solar weather
Every few days, variations in the Sun's magnetic field produce vast storms, known as coronal mass ejections (CMEs). "They thrust out billions of tons of particles at speeds up to eight million kilometres per hour," says Pål Brekke, of the Norwegian Space Centre in Oslo. And every so often, the Sun's weather blows our way.
In March 1989, a large CME slammed into the northern hemisphere, dumping 1,500 Gigawatts of electricity (25 times the amount in the National Grid) into the atmosphere. The Canadian power grid was fried, and six million people were left without power for nine hours.
Historical records suggest, however, that such solar storms can be up to 10 times more intense. "Very long durations of electric power outages might be plausible on a continental to planetary scale," says John Kappenman of the Metatech Corporation, the US government's principal investigator on the impact of severe solar storms.
Kappenman estimates that it could take months or years to restore power to the US or northern Europe after a hit from a big solar storm. Critical parts of our infrastructure, such as drinking water, perishable food and medicine, sewage treatment, transport and communications, would all be crippled within days. "Disruption to the supply of medication, for diabetes sufferers for example, would have a near-immediate and grave impact," says Kappenman. "Ironically, it is the most developed regions of the world, with the most interconnected power grids, that would be affected most severely."
Meanwhile, satellites are also likely to be knocked out, forcing ships and aeroplanes to resort to old-fashioned methods of navigation, and severely reducing our capability to forecast the weather.
CME's tend to be channelled towards the Earth's poles, meaning that latitudes above 40 degrees (ie everything north of Lisbon or San Francisco or south of Wellington or Concepción) are most at risk. Predicting CME events is hard, but they tend to coincide with the Sun's most active periods. "We have just started the new cycle and over the next few years we will observe more and more CMEs," says Brekke.
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