2020, 2021 and now continuing into 2022 for some time yet, has been arguably the wettest period over eastern Australia for 80 years or more. So, what does that say about climate change?
One theory posed by climatologists is that with global warming, there will be more evaporation of the Earth’s water resources, virtually all from the oceans, and that what goes up must come down somewhere. The theory also says that annual precipitation will tend to move away from the tropics, so reducing the intensity of the monsoons, and increase further into the northern and southern latitudes. It further predicts that periods of drought, especially in Australia, would be longer. There have been some probable examples of this predicted trend. Europe and North America too have had a few seasons of heavy precipitation of rain and snow, even at lower latitudes, like the recent crippling snowfalls in Greece and Turkey (January 2020).
It can be shown that the climate and prevailing weather patterns in Australia are primarily a function of the combined effects of the summer monsoons in the north, the periodic (but irregular) El Nino/La Nina cycle in the east, the Indian Ocean Dipole in the west and the south-west cold air masses from the Antarctic.
A wet season over eastern Australia is generated primarily by monsoonal activity and the periodic La Ninja event. However, watching the weather charts and satellite images each day, one could question if there has been less precipitation in the monsoonal regions – it does not look like it.
Although this wet season follows a long and severe drought, there is no statistical1 evidence that droughts, which are endemic to Australia because of its geographical position and topography, are getting more frequent or longer. Nor is there evidence that the devastating bushfires of the summer of 2019-20 were a consequence of climate change, rather than of the parching effect on vegetation by an extended drought, by the avoidable build-up of the fuel-load in bushland and forests, and the penetration of housing and commercial development into these vulnerable zones.
However, if global precipitation patterns change as predicted by climatologists, especially if droughts get longer, even if separated by very wet seasons, what should Australia be doing about it?
- First and foremost, it should not be subsidising and so wasting resources on reducing greenhouse gas emissions (mainly CO2), given that Australia’s total impact on global emissions is and will remain miniscule.
- Australia should be concentrating on drought-proofing the country by capturing the masses of precipitation during wet periods, with dams and through replenishment of our vast, but depleting artesian basins.
 ‘Statistical’ means formally recorded frequency and main characteristics of weather events, over extended periods, preferably over a century, and the analysis of trends, within specified levels of confidence.