use a hydraulic drill to take a coral core sample.
species of tropical reef corals form annual growth bands,
samples of which can be obtained through underwater coring
with rock drills. Analysis of these samples allows scientists
to estimate historical sea surface temperature and salinity,
and to study the movement of surface water masses and deep-ocean
mixing. Some of these coral records are centuries old. By
following these patterns over time, we can better understand
the natural variability of the El Nino/Southern Oscillation
(ENSO), the single most important cause of inter-annual climate
variation on the planet. Understanding ENSO could lead to
improved climate predictions that might help save money and
ease the suffering of millions worldwide.
forms in layers like an onion. Here, each year is marked
with a black line.
the chemistry of coral bands in the equatorial Pacific is
closely correlated with tree-ring widths over northern Mexico
and the southwestern USA. This amazing long-range biological
connection between the growth dynamics of coral reefs and
forests is orchestrated by the global ocean-atmospheric interaction
referred to as ENSO, and illustrates the interconnectedness
of the Earth ecosystem.
ice is formed by the accumulation, compression, and
re-freezing of snowfall over many years.
annual layers of ice preserved in glaciers also provide interesting
records of past climate. In Antarctica, scientists have cored
over 3 kilometers down through the ice, uncovering a climatic
record that stretches back over 400,000 years. Some of the
most convincing evidence for global warming can be found in
these glacial archives of climate. At the same time, many
glaciers worldwide are undergoing massive retreat. The recession
of mountain glaciers has also been particularly dramatic,
and the high-elevation tropical glacier found on Mt. Kilamanjaro
in Africa may soon disappear completely.
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Marilyn & Maris Kazmers / SharkSong
Photography ; Rob Dunbar, Rice University; John T. Andrews,