There's a lot to worry about here, and frankly I'm worried. The main disaster that I didn't know about until I read this intriguing little book is the volcanic "super-eruption." Take your standard volcanic blast and multiply it by something like a thousand and one begins to get the picture. Not only that, but a super-eruption isn't necessarily going to happen around the old fault lines or Vulcan sites. No, a super-eruption with enough power to usher in a "volcanic winter" can happen suddenly without warning virtually anywhere.
The really scary thing about super-eruptions is that not only can't they be predicted, they can't be prevented. In this sense they are worse than an earth-crossing asteroid or unleashed Oort Cloud comets. We might be able to see a meteor coming our way and with current technology nudge it off its course or blast it into smaller pieces, but there is absolutely nothing we can do about a super-eruption. Even if the super-eruption takes place halfway around the world, its effects, possibly leading to a civilization-ending volcanic winter, will be felt everywhere. With the social disruption, the disease, and the cold and starvation, the living (to recall a phrase from the Cold War) may very well envy the dead.
McGuire, who is Benfield Greig Professor of Geophysical Hazards at University College London, recalls for our delectation, "perhaps the greatest volcanic explosion ever" that took place at Toba in northern Sumatra 73,500 years ago. It qualified as a Volcanic Explosivity Index 8 (VEI 8) event, which means it was about one thousand times as powerful as the VEI 5 1980 blast at Mount St. Helens. It tore a hole in the ground one hundred kilometers across and sent an estimated 3,000 cubic kilometers (that's kilometers)of debris into the atmosphere, enough "to cover virtually the whole of India with a layer of ash one metre thick." (pp. 98-103) A volcanic winter of perhaps six years followed with "up to 5,000 million tonnes of sulphuric acid aerosols" in the air, enough to "cut the amount of sunlight reaching the surface by 90 per cent." (p. 104) An ice age followed, perhaps triggered by the mammoth eruption. McGuire goes on to speculate that so many humans died world wide that humanity went through a "population bottleneck" that almost sent us the way of the dinosaurs. (pp. 105-107)
McGuire, who sometimes refers to himself as "Disasterman" (p. 131), also looks at "The Threat from Space" (Chapter 5). He separates the asteroids from the comets and guesses that our chance of being killed during an asteroid or comet walloping is "750 times more likely than winning the UK lottery." To me, the really scary "from outer space" scenario is a hoard of comets being dislodged from their normal orbits to fly toward mother earth, so many that we would have no ability to ward them off.
Global warming and the coming ice age are also topics explored by the good professor. Earthquakes and tsunamis have their chapter and there is an Epilogue (in which he notes, e.g., that come the year 2100 "an extraordinary 50 per cent or so of the people in Japan and western Europe will be 60" years old or older). There are a couple of appendices showing "threat" and geological timescales, and a modest index. The chapter on global warming, I must say, left me somewhat confused. Clearly McGuire believes human activity is a factor in making the nineties the hottest decade ever recorded, but whether our pollution will melt the ice caps or help to usher in an ice age is not clear.
Some other items of interest in this very readable book:
There was a geological episode in the earth's history referred to as "the Cryogenian" in which the earth was covered by "a carapace of ice a kilometre thick." McGuire calls this "Snowball Earth" and when it finally melted 565 million years ago, the Cambrian explosion of life followed. (p. 69-71)
An earthquake in the Tokyo-Yokohama region similar in intensity (8.3 on the Richter Scale) to that which struck in 1923--a reprise, McGuire says, is "thought to be only decades away"--would cripple the Japanese economy and have disastrous world wide effects. (pp. 123-131)
The so-called "Contraction & Convergence" plan "to reduce greenhouse gas emissions" that would require monitoring and billing polluters for their emissions on a per capita basis: to me, this requirement would reveal the true cost of various enterprises and would help us to move toward renewable production and ecologically sound business practices.
Not to be picky, but on page 18 McGuire reports that Hurricane Andrew of 1992 "brought to bear on the city" of Miami "wind speeds of up to 300 kilometres per second." That's about 670,000 miles per hour! (I suspect he meant wind speeds of 300 kilometres per HOUR.)
Bottom line: fascinating, a little flippant at times, but a full-out good read by a man who knows what he is talking about.
--Dennis Littrell, author of "The World Is Not as We Think It Is"