OXYGEN ISOTOPES IN WESTERN-AUSTRALIAN CORAL REVEAL PINATUBO AEROSOL-INDUCED COOLING IN THE WESTERN PACIFIC WARM POOL

We present a 12-year (1981-93) near-weekly oxygen-isotope (delta(18)O) record from a western Australian (Ningaloo Reef) Porites lobata coral precisely positioned to record the sea-surface temperature (SST) vari ation of the Leeuwin Current. The predictability of the Ningaloo Reef coral-based SSTs may be unparalleled since it can be shown that SST ch anges in the Western Pacific Warm Pool (WPWP) are strongly correlated with, and lead by about 2.5 years, SST changes in the Leeuwin Current. Consequently, the ordinary SST variation in the Ningaloo coral record can be anticipated and removed to reveal unexpected cooling of 0.6 de grees C (1992) and 0.9 degrees C (1993) following the June 1991 erupti on of Mt. Pinatubo. This cooling signal at Ningaloo Reef is likely to be produced by Pinatubo aerosol-induced cooling of the southwestern WP WP averaging 0.5 degrees C by early 1992 which is sustained at least t hrough early 1993, It is suggested that this magnitude of volcanic coo ling in the southwestern WPWP could have prolonged, in part, the exten ded 4-year (1991-94) negative phase of the Southern Oscillation.