Impacts of El Niņo in a Warmer World

The El Nino / Southern Oscillation (ENSO) phenomenon is the most energetic form of year-to-year climate variability in the climate system.  ENSO impacts can be severe in regions in and surrounding the tropical Pacific, and can extend around the globe.  It is also known that characteristics of ENSO variability (i.e. its return period and intensity) are very sensitive to changes in mean conditions in the tropical Pacific – conditions that are notoriously difficult to simulate using the present generation of global climate models.   How, then, can we estimate global warming’s impact ENSO variability?

This talk will present results from a new tool designed to estimate changes in the characteristics of ENSO variability under different mean state conditions.  The tool (the linear ocean atmosphere model, or LOAM) is applied to the suite of models that contributed to the IPCC 4^th Assessment Report, and a range of potential changes in ENSO variability are estimated.  Results will be discussed, as will limitations of the methodology.