Evidence of El Niņo Events
Recorded in Middle Pliocene Corals of the Tartaro Formation, Bulacan
Tsuyoshi
Watanabe (Hokkaido Univ., JPN), Atsushi Suzuki (AIST, JPN), Tomoki
Kase (National Science Museum, JPN), Shoshiro Minobe (Hokkaido
Univ., JPN), Yolanda Maac Aguilar (Bureau of
Mine and Geosciences, Philippines), Koji Kameo (Chiba Univ.
JPN), Kayo Minoshima (AIST, JPN), Ryoji Wani (National Science
Museum, JPN)
and Hodaka Kawahata (Univ. of Tokyo, JPN)
Abstract
During
the Pliocene warm period (PWP; 5-3 Ma), the global surface
temperature was higher by about 3°C than the present. In this epoch,
the oceanic condition can be studied in the context of global warmth
relative to today. However, the role of El Niņo-Southern Oscillation
(ENSO) in this greenhouse warming remains controversial because of
the lack of the information about seasonal to inter-annual
variability of sea surface water in the low latitude regions. Here,
we present a 35-years coral oxygen isotopic record with monthly
resolution deduced from well-preserved fossil corals in muddy sand
layers of the Middle Pliocene (3.5-3.8 Ma) Tartaro Formation in
northern Luzon, Philippines. Several significant attenuations of
seasonal amplitude were found in 18O/16O ratios of PWP coral record,
which were also detected in the recent corals during modern El Nino
events. Our data suggests that east-western movements of Western
Pacific Warm Pool (WPWP) are still active and caused ENSO events
during this warm period. |