The National Science Foundation funds most of the projects, and the U.S. Geological Service Factual error again. Look it up. The Laboratory is located on the Denver Federal Center campus. Scientists carefully examine the ice cores alloted to them. I don't mean to be harsh here, or to make you discouraged.
Science writing can be a difficult thing.
Believe me, I understand that, having written stories like this myself. My purpose here is to prod you into thinking more carefully about the big picture of this story, and then the little details that will make it fly. Samples of coral are used to determine the temperature of the water in which it grew. This is a sudden, unexpected transition. Fossil pollen helps identify the kinds of plants that were growing when the sediment was deposited in the glacial ice.