Hobart had its hottest day ever today. This occured after a night that broke the record for the warmest maximum by more than one degree (and its record for January by more than three). There’ll be plenty of other records broken before this burst is through. Mildura normally gets 5.5 days over 40ºC a year. Today was the second in a row, and its predicted to have five more in the next six days. That’s after it had two in December and a 45.5º day in November.
But the thing to remember here is that this shouldn’t really be an extraordinary summer. The nature of Southern Australia’s summers are determined in large part by ENSO (the El Nino Southern Oscillation) and the lesser known Indian Ocean Dipole. The last couple of summers were wet and relatively modest in temperature because of strong La Ninas keeping the temperature down. This year both ENSO and the Dipole are pretty close to neutral. On most measures we are slightly towards the El Nino side of ENSO, but not enough to be categorised as in that state, while the latest report on the Dipole has it dead on neutrality.
This, in other words, is a typical summer on our current trajectory towards a warmer world. If we were able to not only stop emissions now, but halt the feedback mechanisms that lock in more warming, this would be our average future.
So what will it be like in a bad year? What will it be like in a typical year when we have added another 50 or 100pmm carbon dioxide to the atmosphere and the feedback effects have had time to work.
Finally, what will it be like in an El Nino year when those things have happened?