Finding the Missing Ice Age

Maureen Raymo puts what looks like a pinch of sand on a glass slide and powers up her microscope. Under magnification, the grains are revealed to be fossilized shells of tiny ocean creatures that existed millions of years ago. Raymo, a College of Arts and Sciences earth sciences research professor, is a paleoclimatologist, and these remains are to her what dinosaur bones are to paleontologists: keys to the past.

Raymo studies these shells to better understand the ice ages that have waxed and waned over millions of years on our planet. At the moment, she’s searching for evidence to support a theory she and several colleagues recently proposed to explain a conundrum that has puzzled researchers for years: why the timing of ice growth and decay was different between one million and three million years ago compared to the pattern observed for the last million years.

Scientists know that irregularities in the Earth’s orbit, which occur every 23,000, 41,000, and 100,000 years, affect global climate cycles. Those deviations can nudge the northern hemisphere farther from the sun, causing ice to remain through the summer and auguring a new ice age, like the one that ended 10,000 years ago in North America. But starting in the late Pliocene era, some three million years ago, evidence of the 23,000-year cycle of climate change disappeared from the climate record.

Read the rest at BU Today.

Good grief. People are finding microscopic fossils to confirm the existence of ice ages millions of years ago. In the meantime, I can't find car keys, glasses, watches, or books that I had the previous evening. I feel so inadequate now. Thanks a lot.