Identification of frequent la Niña events during the early 1800s in the east equatorial Pacific

Abstract

We report measurements of near monthly Δ 14 C and δ 18 O during selected decades from an east equatorial Pacific coral that grew during the past four centuries. We find that El Niño events occurred regularly during the late 1700s. During the early 1800s, El Niño events occurred less often, and La Niña conditions prevailed, which were accompanied by unprecedented, low cool season Δ 14 C values and high cool season δ 18 O values. These results indicate that shallow overturning water (e.g., Central Mode Water) from the North Pacific was likely an important source of water to the Galapagos area during the early 1800s.