There remains a variety of opinions on how climate change (or global warming by another name) will affect rainfall patterns in Australia in the coming years. A lot of models have been set up but give various results and so are not that useful at the moment. However, there is growing consensus that the ocean temperature patterns and changes will be a fairly significant influence when it comes to rainfall.
Ocean temperatures this summer have been the warmest recorded in the past 50 years and before that data is scarce. The warmer than normal waters off the east coast of the country resulted in more rain events than would normally be expected in an El Nino year but rainfall has been mostly convective in nature and therefore it has shown considerable variability.
In fact, the oceans have been the warmest on record throughout the world each month since April 2023. Sea surface temperatures continue to increase, with February 2024 setting a record for that month, and March 2024 on track to be the warmest March on record.
Away from Australia but a long-term influencer, the Atlantic Ocean is showing exceptional and prolonged warmth, and this global pattern of warmth is affecting the typical, historical global pattern of SSTs associated with Pacific Ocean variability. Since we have never seen global sea surface temperatures like this before, inferences of how this might affect conditions for the rest of 2024 that are based on past events can no longer be used with confidence.
In addition, a warmer world has resulted in more cloud in the tropics. Temperatures there have not warmed up as much as temperatures in the temperate zones around the globe and as a result the temperature differences have increased with potential to increase moisture transfer as well.
Factoring in all we know at the moment along with the warmer SSTs, then probably the favoured scenario for the future 20-30 years at the moment would see an increase in rainfall in eastern, northern and north west Australia especially in summer and autumn and a decrease in winter and spring rainfall in the south and south west of the country. There are also indications that rainfall variability would increase, with the likelihood of heavier short-term events being the main contributor to any increase in rainfall. There is likely to be increased periods of rainfall deficiencies between rain events and the timing and occurrence of such events will become more difficult to forecast.
Variability is likely to apply to temperatures as well, with generally slightly above average (and increasing) temperatures in coming years, interspersed by the occasional brief, but significant, cold outbreak.
