Geoscience Reference
In-Depth Information
figur e 29. Paleoclimate researchers drilling
Porites
coral heads in the Red Sea using a
large hydraulic rig. Coral cores are used to reconstruct past seawater conditions. (Photo
courtesy of Konrad Hughen, Woods Hole Oceanographic Institute.)
coral and ancient el niño
We owe much of our understanding of past climate change on Earth to the
tiny polyps that create coral reefs. Each polyp, no bigger than the head of
a pin, secretes a calcium carbonate skeleton to protect itself. Collectively,
over the millennia, millions of generations of polyps have built the mag-
nii cent coral reefs found in shallow tropical seas. Coral ecosystems, among
the richest communities of species found anywhere, have persisted for over
200 million years, a span of the earth's history that has seen monumental
climate changes. Each generation's fossilized skeletons, stacked upon the last,
bear testament to many of those changes.
h e most recent changes—those occurring over the past several thousand
years of the Holocene epoch—provide valuable information for understand-
ing our current climate. Paleoclimate scientists have developed methods of
coring through the calcium carbonate coral skeletons, whose annual layers
have recorded information on water temperature, salinity, and nutrients (see
i gure 29). For instance, scientists have probed coral reefs across the tropical
