Reef-Based Reconstructions of Eastern Pacific Climate Variability

In the eastern tropical Pacific, large spatial gradients in climate conditions are associated with oceanic upwelling and the position of the Intertropical Convergence Zone (ITCZ). Dramatic shifts in these systems occur during extremes of the El Niño-Southern Oscillation (ENSO), which also reverberate throughout the global climate system. Motivated by the need to understand ENSO history, and underpinned by ecological research, many of the earliest coral paleoclimate studies originated from the eastern Pacific. Early work in Galápagos, Costa Rica, and Panama highlighted the usefulness of a diverse array of tracers that record past environmental change. Longer records of coral d18O have delineated the range of natural variability in ENSO and identified a rich spectrum of tropical Pacific
variance that extends into multidecadal and century time scales. Coral-based reconstructions of ocean temperatures generally show strong warming trends, except in Galápagos, where existing records do not span the full 20th century and where strong interannual
variability impedes detection of smaller trends. Coral records complement sediment-based and terrestrial records in terms of their length, resolution, and sensitivity. A more complete understanding of variability in the eastern tropical Pacific should emerge from ongoing and
future work that integrates reef-based paleorecords with other paleoclimate reconstructions
and model simulations. In addition, analysis of additional proxies—e.g. of circulation, pH,
and salinity—is recommended to complement temperature reconstructions and provide
useful reconstructions of changes in climate, oceanography, and reef stress.