Coral Ensemble Estimates of Central Pacific Mean Climate During the Little Ice Age
Abstract
Multi-century, robust records of tropical Pacific sea-surface temperature (SST) and salinity (SSS) variability from the pre-industrial era are needed to quantify anthropogenic contributions to present-day climate trends and to improve the accuracy of regional climate projections. However, high-resolution reconstructions of tropical Pacific climate are scarce prior to the 20th century, and only a handful exist from the Little Ice Age (LIA, 1500-1850CE) immediately prior to the documented rise of anthropogenic greenhouse gases. Modern and fossil corals from the northern Line Islands (2-6°N, 157-162°W) have been used to extend the instrumental climate record back into the LIA and beyond, primarily for paleo-ENSO investigations [Cobb et al., 2003, 2013]. However, large offsets in mean coral Sr/Ca and δ18O values observed across overlapping coral colonies translate into 1-2°C (1σ) uncertainties for mean climate reconstructions based on any single fossil coral colony. Here we present the results of a new approach to reconstructing mean climate during the LIA using a large ensemble (N>10) of relatively short (7-15yr long), U/Th-dated fossil corals from Christmas Island (2°N, 157°W). We employ pseudo-coral estimates of paleo-SST and paleo-seawater δ18O variations as benchmarks for our reconstructions, with a focus on quantifying the maximum and minimum potential tropical Pacific SST changes during the LIA that are consistent with our new ensemble of coral data. Lastly, by comparing bulk and high-resolution coral d18O and Sr/Ca records, we identify the strengths and limitations of using a high-N, ensemble approach to climate reconstruction from fossil corals. References:Cobb, K. M., et al. (2003) Nature. doi:10.1038/nature01779Cobb, K. M., et al. (2013) Science. doi: 10.1126/science.1228246
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMPP51D2329S
- Keywords:
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- 4916 Corals;
- PALEOCEANOGRAPHYDE: 4920 Dendrochronology;
- PALEOCEANOGRAPHYDE: 4926 Glacial;
- PALEOCEANOGRAPHYDE: 4958 Speleothems;
- PALEOCEANOGRAPHY