Kristine DeLong, South Central CSC affiliate at Louisiana State University, recently published a coral-based reconstruction for the Gulf of Mexico from 1734 to 2008 in the journal Paleoceanography with her collaborators at the U.S. Geological Survey. Large corals live for many centuries and contain rings similar to trees that can be counted to determine the year. The chemistry of the coral skeleton gives the temperature of the water when the skeleton was formed thus providing long continuous histories of water temperature. This reconstruction finds summer temperatures have been warming for the past 274 years whereas winters temperature have not.
For more information on the project, please see the full paper: http://onlinelibrary.wiley.com/doi/10.1002/2013PA002524/abstract