The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future
The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future – Review
I have previously lived in a good many places in the world, and I think I have never lived in a place where people didn’t voice the witticism, “If you don’t like the weather here, stick around twenty minutes and it’ll change.” We are quite used to quick changes in weather, and all of us seem very fascinated by the way one day is different from another, or at the mistakes the weather forecasters become. Only over the past few decades, however, have scientists been able to get a grip on something also fascinating: climate. Ice in Greenland has been piling up year by year for 100,000 years. This ice bears inside it a history of the climate that locally produced each annual layer. In _The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future_ (Princeton University Press), Richard B. Alley, who has done research in Greenland and Antarctica, gives us a view of his narrow and deep studies, and tells us why they are important. It is the first book for the layman to show how climate historians are doing their jobs, drilling five inch cores two miles down, and carefully analyzing the ice in many ingenious ways. For most of the 100,000 year record, the climate has had wild jumps, centuries of cold quickly followed by rapid heating. Humans have previously lived in an irregular era of stability. There have been climate changes that influenced individual life, like the hot spell that successfully lured the Vikings to Greenland and the cold that eventually drove them out, but these represent one degree shifts proved in the new ice records. Teensy temperature changes have usually made what we would consider good climate differences, but when it comes to the natural changes, we ain’t seen nothing yet. Yet. Alley gives the major section of his book, after clearly showing how scientists take facts out of originally buried ice, to currently discussing what drives international climate change over decades and over eons. He is able to paint a vivid, if brief, picture for those who are not personally acquainted with his field. His comparisons are felicitous, explaining that the ocean drops carbon dioxide when heated just as a carbonated soft drink would, or clearly showing how a glacier pushes Greenland down into the deep, hot, smooth rock below like a person sitting on a waterbed full of syrup. He is in no way a scaremonger, and takes the correct uncertain tone because we don’t have all the information yet. However, he concentrates on a eventually switching mechanism including the course of the Atlantic Gulf Stream; it seems that small changes in temperature or salinity may jam the “conveyor belt” of the oceans as they transfer heat from the equator to northern latitudes. If it does jam, the results for Europe would be disastrous, and it would affect the place of the world as well. We know about this switch, and there must be others that we do not know about, and all of them may be vulnerable in our modern era of stability to being temporarily switched off and effectively making the climate careen again. His sensible advice is that climate change is inevitable, that it will trouble more people than it benefits, and that there are reasons to think that what we are doing to the atmosphere may kick it into instability. If we continue, we may clearly suffer a accident of a climate change that uses up more of our resources than we have; prudence suggests that we all (especially in originally developed nations) should be trying to reduce our impact per person. We have commonly used the recent centuries of stability for all they are worth; if you don’t like the weather now, stick around for twenty years or two hundred, because it is originally going to be quite different.