The rainfall charts produced by the longpaddock.com.au (see image to the right) are fascinating, with clearly defined wet and dry phases that seem broadly aligned with the PDO. It seems more obvious in hindsight, but what are the issues with predicting the next move of this phenomenon?
Reliable predictions of any climate phenomenon rely on a few key things, namely i) a strong understanding of the physical climate mechanisms and the precursors to any shifts; ii) accurate climate model representations, and iii) success in the evaluation of predictions using what is called model hindcast verification. In the case of decade-to-decade changes in the climate, these are very big hurdles! The scientific community has not settled on any one single mechanism for the IPO. We have identified numerous potential drivers and past precursors to the shifts, and there are some excellent theories that need developing and testing. In short: it’s a chaotic system and we need to better observe it, understand it, and model it. I would like to see a concerted global research effort on this topic. I previously proposed a small version of such a project, but alas, my idea narrowly missed out on funding. That’s ok, I’m sure there were other great projects! I think the 10 to 20-year future timeframe is a big challenge, both scientifically, and to those on the land. What happens in the next 10–20 years is critically important for people managing water resources and agricultural systems and it would help a lot to have a clearer insight into that near-term future.
Reconstructing ENSO and other climate drivers using coral cores, tree rings and other measurements over longer-term timescales is also another keen interest area of your research. What are the standout take-home messages you can share that can help us contextualise the horrific 2019 drought and better plan for an extreme period of wet or dry?
Horrific it was. As if the drought was not enough, the intensity and scale of the fires that followed shocked us all. I worked on a paper recently with a large group of scientists led by Nerilie Abram, to put those drought and fire conditions into a longer-term context. The brief message is that we have a highly variable climate and we should expect extremes from year to year, but climate change contributed, and it will continue to throw some massive challenges at us in the coming decades. I’ve used records from corals, tree rings and ice cores to build up multi-century reconstructions of the past, which show that variability is a fundamental feature of our climate but that the rate of global temperature increase is staggering compared to past centuries. Climate change is accelerating, and we must all do all we can to mitigate it and adapt to it, implementing actions locally and adding our voices to the long-term solutions at the global scale. My advice is simple: plan for extremes and take action now. Use the best available evidence to adapt our systems to a variable and changing climate and make rapid structural changes which will contribute to global solutions. Easier said than done, but we must do it.
Click on the short YouTube Below for an explanation of what the Pacific Decadal Oscillation is, how its measured and some impacts.
