Interannual-decadal variability in tropical climate systems: Stable isotope records and general circulation model experiments

A thorough understanding of natural climate variability requires characterizing the patterns and causes of interannual-decadal climate change. The El Nino/Southern Oscillation (ENSO) system of the tropical Pacific imparts interannual variability to climate worldwide, but its past behavior remains poorly documented. Oxygen isotope records from corals that grew at Tarawa Atoll (1;Ice-core isotopic records, though commonly interpreted as temperature proxies, incorporate the isotopic content of precipitation, which also depends on amount and seasonality of precipitation, conditions of water vapor evaporation and transport, and air mass mixing and stability. A 180-year record of ;General circulation models that include isotopic tracers in the hydrologic cycle may clarify the isotopic response to climatic change and improve paleoclimatic interpretation. Simulations of ENSO-related climate variability suggest that interannual temperature variations often occur via advective changes. Changing advection alters the sources and transport of water vapor as well as local temperature and precipitation, complicating the isotopic response to climatic factors. In the tropics, simulated rainfall amount determines isotopic variability, in quantitative agreement with observations.