OPINION
Here in my part of Tasmania, it’s said to be a sure sign of rain if you hear the call of black cockatoos flying down from the mountains. But everywhere in the world, there’s no surer sign of summer than the demented screeching of the brain-dead parrots of the Climate Cult.
The northern hemisphere variety are currently locked in a deafening chorus of screaming about what is, even climate scientists admit, a far from unprecedented hot summer. For all the lying media howling about “hottest summer on record” — which, in practical terms, means “since around 1979” — more sober climate scientists are pointing out that summers in even the 1930s were almost certainly hotter.
Meanwhile, it might be wise to stock up on earplugs, here in the antipodes. Because we’re almost certainly in for a nice hot summer, which will provoke the howler monkeys of the media into fresh paroxysms of lunatic hooting.
Despite the fact that it will be due to entirely natural climate cycles.
While El Nino dominates the headlines, a lesser-known climate influence is rapidly forming to our west, and is likely to bring hot and dry weather to Australia for the remainder of the year.
A positive Indian Ocean Dipole (IOD) is the Indian Ocean’s version of El Nino, and typically brings reduced rainfall and an increase in temperatures through winter and spring.
As might be expected, the IOD is similar to its better-known Pacific cousins, El Nino and La Nina. As in the Pacific, the Indian Ocean has two alternating phases of sea surface temperatures. In normal years, the effect is neutral, meaning that water temperatures are close to long-term average. Occasionally, though, sustained periods of warm or cold water develop in the tropical western and eastern Indian Ocean, as they do in the Pacific.
A positive IOD, which we have now entered, is the dry phase for Australia and occurs when waters cool around Indonesia and warm off the Horn of Africa.
Since cloud and rain tend to follow the warmer waters, this leads to less rain through winter and spring across most of the country.
While the longevity of an IOD event is shorter than the Pacific counterparts of El Nino and La Nina, the intensity is more severe.
Also like El Nino/La Nina, monitoring is used to create an “index” which suggests a positive or negative event.
The index used to monitor the Indian Ocean surged to 0.79 last week, the highest value in four years, which is nearly double the threshold for a positive phase.
If values above 0.4 are sustained for eight weeks, as predicted by all modelling, then 2023 becomes a positive IOD year, the first since 2019.
Bear in mind that the IOD was only discovered less than a quarter of a century ago — so much for settled science — but that retrospective analysis of climate records hints at its occillations over the past century. Consecutive positive IODs were recorded in 2006-08, and likely in 1913-14.
The last positive IOD four years ago was one of the major influences behind the Black Summer bushfires.
Although there is no indication this fire season will be as severe, bushfires will almost certainly be more active than the last three years.
The opposite phase, a negative IOD, played a major role in the widespread flooding through the spring of both 2021 and 2022.
Australia sitting between the two oceans, the interplay of the two oceanic oscillations has major effects on the continent’s climate.
While El Nino mostly impacts eastern Australia through winter and spring, during positive IODs the only areas not affected include eastern NSW, southeast QLD and parts of WA.
The reduction in cloud also leads to an increase in daytime temperatures, most pronounced across WA and southeast Australia […]
About half of all positive IODs occur simultaneously with El Nino, due to complex interactions between the Indian and Pacific oceans.
When El Nino and a positive IOD coincide together, the drying effect is enhanced, and unfortunately, this will likely occur in spring.
ABC Australia
The two combined in 2015 without major drought, but in both 1982 and 2006, the combination caused some of the worst droughts recorded (which, again, means in Australia, “since 1901”). What was likely the worst drought to hit Australia in modern history, the Federation drought of 1895-1902 (where the Murray river almost completely dried), coincided with fluctuations in the IOD. As did the World War two drought and the Millennium drought.
But expect all that inconvenient history to be cast aside, as always, when the honking chorus of the Climate Cult heralds the arrival of summer downunder.