Insights into sea surface temperatures from the Cayman Islands from corals over the last ~540 years

Abstract

Seven large corals (Orbicella annularis and Montastrea cavernosa) from Grand Cayman and Cayman Brac, which grew between ~1474 to 1512 CE and ~1815 to 2014 CE, are characterized by growth banding that reflects bi-annual growth periods. Some of these growth bands, however, include micro-scale bands that reflect sub-annual growth phases. Paleotemperatures derived from the oxygen isotope composition of these corals indicate that Sea Surface Temperature (SST) between ~1474 to 1512 CE and ~1815 to 2014 CE ranged from 18 to 34 °C and included four main periods of temperature change with smaller-scale warm or cool intervals superimposed on these periods. Cool Period 1 (~1474 to 1512 CE) coincided with decreased temperatures that existed in the northern hemisphere during the Little Ice Age (LIA. ca 1450–1850 CE). Cool Period 2 (~1815 to 1924 CE) coincided with a Caribbean wide reduction in temperatures that was probably related to the final phase of the LIA. Warm Period 1 (~1924 to 2006 CE), is characterized by an overall increase in SST consistent with the pronounced global warming since the 1970's. Modern Period 1 (~2006–2014 CE), is characterized by temperatures that fluctuate around 28.5 °C, the current average water temperature for Grand Cayman. The overall ~3 °C ± 0.96 °C increase in SST since ~1815 CE, derived from the Cayman corals, is consistent with the Caribbean and global temperature increases since the 1850's. Smaller scale deviations in the Cayman temperature profiles from the general Caribbean/global temperature trends probably reflect local factors such as increased storm and/or cold-air front frequencies, a reduction in the size and/or intensity of the Atlantic Warm Pool, shifts in the phase of the Atlantic Multidecadal Oscillation, and/or weakening of the Cayman Basin current.