The El Niño-Southern Oscillation (ENSO) is one of the most important sources of inter-annual climate variability. The past 20 years have experienced the two strongest El Niño events in recorded history, leading many to speculate that ENSO may be changing in response to global warming. Nevertheless, there is evidence to show that strong ENSO events have occurred over a much longer time frame (Cole 2001). Some of the best evidence comes from work by Tudhope et al. (2001) who studied the extensive raised fossil coral reefs on the Huon Peninsula in PNG. Using annually banded corals from Papua New Guinea, Tudhope at al. (2001) have shown that ENSO has existed for the past 130,000 years operating even during “glacial" times. During the 20th Century, ENSO has been strong compared with previous cool (glacial) and warm (interglacial) times. However, these data from Papua New Guinea are sparse and need to be supplemented by adding records from other locations and time-periods before it will be possible to attribute the sensitivity of ENSO to specific aspects of global change. This is necessary if we are to successfully predict the consequences of future greenhouse gas-induced warming on ENSO.



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Department of Environment and Heritage