The World's Biggest Popsicle
Stored in a commercial freezer in France, along with quite a lot of frozen meat and cheese, is about 15 kilometers' worth of ice cores, taken from glaciers in Greenland and Antarctica. Each giant 'popsicle,' ranging from one to three yards in length and about 5 inches in diameter, is carefully labeled.
These big popsicles are ice cores drilled from as much as 3 kilometers beneath the surface. Since ice and snow in Antarctica are deposited year after year and never completely melt, the layers pile up for thousands of years. The ice near the bottom of the latest core was laid down 740,000 years ago! Each layer is separated by a thin film of dust, so scientists can count back through the layers, year by year, and use the ice core to get information on what the earth was like thousands of years ago.
Air bubbles trapped in the ice contain a record of what the earth's atmosphere was like thousands of years ago. Levels of carbon dioxide, air pollutants, and oxygen can be calculated, and scientists can see how these levels have changed. Other measurements can give us a hint about the earth's temperature in the distant past.So now, scientists all over Europe are busily crushing and measuring their samples of the popsicles. When they're done, that ancient snow and ice that fell 740,000 years ago will melt and end up in the nearest river.
