Australian seasonal forecasts challenged by Pacific Ocean warming

17 December 2019

Composite analysis of sea surface temperature during cold phases of the PDO using the HadISST v1.1 dataset during the period 1871-2010.

New CSHOR research has found global warming will make it more difficult to predict multi-year global climate variations, a consequence of changes to long-term climate variability patterns in the Pacific Ocean. The results, published today in Nature Climate Change, shed light on how the Pacific Decadal Oscillation (PDO) is responding to a changing climate, with implications for assessing multi-year risks to marine ecosystems, fisheries and agriculture.

When the PDO raises temperatures in the tropical Pacific Ocean, there is no robust relationship between year-to-year Australian climate variations and El Niño, but when the PDO lowers temperatures in the tropical Pacific, El Niño is closely associated with year-to-year variability in Australia rainfall and surface temperatures,  causing droughts and bushfires. Thus predicting the PDO multi-years  ahead is important for assessing multi-year  risks associated with El Niño. An investigation of available models shows that unabated greenhouse gas emissions is likely to make the PDO less predictable. This is because the life span of the PDO is shortened and its amplitude decreased  due to a faster warming in the upper ocean than the ocean below (i.e., increased ocean stratification), posing new challenges for predicting El Niño impact on Australia.

Read the full article by Dr Shujun Li et al. in Nature Climate Change at this link.