Influence of mean climate change on climate variability from a 155- year tropical Pacific coral record from NOAA/NGDC/WDC paleoclimatology

This data set is a 155-year ENSO reconstruction from a central tropical Pacific coral that provides new evidence for long-term changes in the regional mean climate and its variability. A gradual transition in the early 20th century and the abrupt change in 1976, both towards warmer/wetter conditions, co-occur with changes in variability. In the mid-late 19th century, cooler/drier background conditions coincided with prominent decadal variability; in the early 20th century, shorter-period (-2.9 years) variability intensified. After 1920, variability weakens and becomes focused at interannual time scales; with the shift in 1976, variability with a period of about 4 years becomes prominent. Our results suggest that variability in the tropical Pacific is linked to the region's mean climate, and that changes in both have occurred during periods of natural as well as anthropogenic climate forcing. Sampling and isotopic analysis: Cores (8.5 cm diameter) drilled from living coral colonies were slabbed and x-rayed to identify annual density bands and optimal sampling transects. Samples were drilled analysis (d180 and d13C) of powdered samples was performed on a Micromass Optima with Isocarb automated preparation system at the University of Colorado's Institute for Arctic and Alpine Research. Analytical precision is =10.08 d180 and =10.05 d13c. The Maiana record is continous except for a gap from 1901-1905, which we bridged through straight forward comparison and splicing of data from a coral record from nearby Tarawa Atoll. The URL for this data set is: http://www.ngdc.noaa.gov/paleo/pubs/urban2000/. Contact: World Data Center-A for Paleoclimatology, NOAA/NGDC Code E/GCx3, 325 Broadway, Boulder, CO 80303, USA; tel: (303) 497-6160; fax: (303) 497-6513; e-mail: [email protected]; internet: http://www.ngdc.noaa.gov/paleo (source: Global Change Master Directory, http://gcmd.nasa.gov).