According to the news, the ice from Greenland provides information about

Scientists say they can tell what air and sea conditions were like hundreds of thousands of years ago. They say pieces of ice taken from Greenland provide such information. Scientists took the ice from more than one and a half miles deep in huge masses of ice that float on the sea. That is the deepest scientists have ever drilled for ice. The ice represent 25, 000 years of history. It provides one of the clearest records of ancient weather. European and American scientific teams have been studying ice from the same area to confirm each other’s findings. The scientists examined the ice that was formed each year. They measured the oxygen and carbon dioxide in the ice. These measurements tell about the year’s temperature. From these measurements the scientific teams say the past ten thousand years is the only period during which the weather has not changed very much. Before that time, they believed very large and sudden changes in the weather were common. The ice appears to show that at some periods Earth’s weather changed from very hot to very cold in only ten years.