Word: planetful
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...years or so. But if last week is any indication of winters to come, it might be more to the point to start worrying about the next Ice Age instead. After all, human-induced warming is still largely theoretical, while ice ages are an established part of the planet's history. The last one ended about 10,000 years ago; the next one -- for there will be a next one -- could start tens of thousands of years from now. Or tens of years. Or it may have already started...
...into ice ages, with average temperatures in parts of the Northern Hemisphere falling 15 degrees over hundreds or thousands of years. During long, frigid winters and short, cool summers, snow piled up much faster than it could melt, and mile-thick sheets of ice gradually covered much of the planet's land surface. After 100,000 years or so, scientists believed, the glaciers made a dignified retreat, stayed put for about 10,000 years and then began to grow again...
...looking for explanations. Several suggested that astronomical cycles were involved, and by the 1930s the Yugoslav astronomer Milutin Milankovitch had constructed a coherent theory. The ice ages, he argued, were triggered by changes in the shape of the earth's slightly oval orbit around the sun and in the planet's axis of rotation. Studies of the chemical composition of ocean-floor sediments, which depend on climate conditions when the material was laid down, more or less supported Milankovitch's predicted schedule of global glaciation...
...reason to think the next full-fledged Ice Age is upon us, a shorter episode of frigid conditions could happen at any time. The last interglacial period was warmer than this one and also, arguably, more unstable. It is conceivable that the greenhouse effect could heat up the planet for a while but then trigger changes that could plunge the earth into a sudden chill. And for an idea of what a mini-Ice Age might be like, just imagine last week's cold wave lasting all winter, every winter -- for the next thousand years...
California is an earthquake zone because it lies on the boundary, marked by the San Andreas Fault, between two huge sections of the earth's crust, known as plates. Gliding atop a sea of superheated rock that surrounds the planet's molten outer core, the Pacific plate -- a thick slab to which Los Angeles is attached -- is very slowly pushing its way north and west, past the North American plate to the east, which is moving in the opposite direction. Most of the time, in most places, the two plates are snagged; they block each other's progress, and tremendous...