Holocene Tropical Sea Surface Temperature and Climate

We are interested in reconstructing tropical temperatures and climate of the late Holocene. One reason for this interest relates to evidence, based largely on high latitude and high altitude terrestrial archives, that the earth's temperatures have not been as warm as today during the last 500 years, and possibly during the last 1300 years (e.g IPCC, 2007). The tropics, which are ~75% ocean, are under-represented in these temperature reconstructions. Therefore, in order to improve estimates of past temperature change, it is extremely important to include records from the tropical oceans. The hydrological cycle is very sensitive to even small changes in tropical SSTs and gradients. Thus, in order to understand mechanisms of climate change, better reconstructions of past tropical SSTs are needed.

We have taken two approaches so far to reconstruct tropical SSTs. First, we have been working on extracting SST from coral growth rates (Saenger et al., 2009). This approach has provided a detailed record of SST variabilty since ~1550AD from the tropical Atlantic. We have plans to core older corals to extract longer records. We have also used the Mg/Ca of foraminifera from rapidly accumulating deep-sea sediments to extract SST records. While not as detailed as coral records, it is more feasible to go back several millennia using marine sediments, which we have done in the Indo-Pacific Warm Pool (Oppo et al, 2009).