Abrupt Shift in Subsurface Temperatures in the Tropical Pacific Associated with Changes in El Niño
Thomas P. Guilderson,
Daniel P. Schrag
Radiocarbon (14C) content of surface waters inferred
from a coral record from the Galápagos Islands increased abruptly
during the upwelling season (July through September) after the El
Niño event of 1976. Sea-surface temperatures (SSTs) associated
with the upwelling season also shifted after 1976. The synchroneity of
the shift in both 14C and SST implies that the vertical
thermal structure of the eastern tropical Pacific changed in 1976. This
change may be responsible for the increase in frequency and intensity
of El Niño events since 1976.
T. P. Guilderson, Department of Earth and Planetary Sciences,
Harvard University, Cambridge, MA 02138, USA, and Center for
Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory,
Livermore, CA 94550, USA. D. P. Schrag, Department of Earth and
Planetary Sciences, Harvard University, Cambridge, MA 02138, USA.