Science Interviews


Sun, 19th Nov 2006

Science Update

Chelsea Wald and Bob Hirshon, AAAS, the Science Society

Part of the show Science in Antarctica


Bob - This week for the Naked Scientists, Science Update goes polar. I'll talk about some singing Antarctic icebergs, but first, Chelsea takes us up near the North Pole, where we find not Santa Claus, but something that to some scientists seems almost as unlikely.

Chelsea - In the Arctic, plants and animals have to survive three months of total darkness in the winter. Today, very few species are up to that task; but 45 million years ago, during a period called the Eocene, vast forests thrived there. Earth scientist Hope Jahren of Johns Hopkins has found that they were home to conifers that grew to 100 feet tall and 10 feet wide, thanks to an unusual ability.

Hope - We believe that they went into a dormant state, not unlike a deciduous tree like the maples that you see today that are losing their leaves. However, these were conifer forests, and the conifers that we see today are evergreen all year round. So the idea of a conifer forest that shuts down and loses its leaves once a year is a very different ecosystem than anything we have on Earth today.

Chelsea - She adds that the Earth was warmer in the Eocene, so studying its ecosystems could help scientists predict what might happen if today's Earth continues to warm.

Bob - Thanks, Chelsea. This low, restless moan is the song of an Antarctic iceberg, sped up so that humans can hear it. Northwestern University seismologist Emile Okal and his colleagues are studying these strange, ultra - low-frequency melodies with seismic microphones they've planted on the ice. Okal says each iceberg resonates on a surprisingly specific note, which fluctuates over time.

Emile - And this creates a kind of symphony: like, if you slightly adjust the length of a violin string, you're going to be able to slightly change the musical note that you play.

Bob - It's not clear where the rumbling comes from. Okal says it may be the sound of icebergs scraping together, or the vibrations of water flowing through cracks like air through an organ pipe. He says figuring out what these songs are, and understanding why an iceberg might change its tune, could help scientists keep tabs on the shrinking polar ice.

Chelsea - Thanks, Bob. We'll be back next week with more stories from the left side of the Atlantic. Until then, I'm Chelsea Wald.

Bob - And I'm Bob Hirshon, for AAAS, The Science Society. Back to you, Naked Scientists.


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