A few days ago I drew attention to work that suggested the Indian Ocean Dipole was responsible for causing drought in southern Australia . I contrasted that to a view from the Bureau of Meteorology that the change was caused by the hole in the ozone layer over the South Pole.
Now there is an another candidate – aerosols (a fancy name which covers any fine particle in the atmosphere including dust and soot). According to CSIRO scientist Leon Rostayn:
Recent climate modelling at CSIRO shows that there may be important effects on Australian climate due to aerosol pollution from the Northern Hemisphere. These include an increase of rainfall in north-western Australia, and an increase of air pressure over southern Australia, which may have contributed to less rainfall there.
Would be good to know whether either of the other two are included in this model.
If the climate models are as good as the economic models we are in for a rough time.
Why not fall back on the old eyeballs and ears? My senses (the basis of empiricism) tell me something drastic is happening in the world.
Perhaps the insurance companies, now struggling with the double blows of flood + fire, have the best data.
Comment by ronda jambe — February 12, 2009 @ 11:46 am
Good to see you being sceptical of modelling too! Problem with insurance company records is that they show the dollar value of damage, but that doesn’t necessarily relate to there being greater actual damage from natural causes, but often that there are more and richer people living in harm’s way.
I checked out Melbourne temperatures earlier today – they have records going back to 1855 – and nothing much has changed. Although the number of hot days in a row is probably unprecedented, this seems to be to do with weather systems rather than average temperature increases. The wind blew from the north for a longer period than normal.
Comment by Graham Young — February 12, 2009 @ 10:43 pm
My understanding is that the nighttime temps are higher.
I also see the firefighter’s union has written an open letter to the PM saying they can’t cope with even slight climate change.
Whether change is normal, has been greater in the past, or quicker, is now irrelevant, as never before have so many lived in the bush, on the sea coasts, or on the planet. Change is outrunning our ability to manage it, or ourselves.
Hang on, it will be interesting times for the rest of our lives.
Comment by ronda jambe — February 13, 2009 @ 8:14 am
Sorry I’m coming to this a bit late, I only just saw this. I interviewed Rostayn for Australasian Science (I’ve been covering his work there for almost ten years). He said the Indian Ocean Dipole hasn’t been included in his modelling, and thinks they are likely to be independent effects that (temporarily) are pushing in the same direction.
I didn’t specifically ask him about the ozone depletion, but from things he said I gathered he completely accepts that this is a contributing factor to the current drought in southern Australia. From conversations I’ve had with other climatologists it seems that there is pretty much universal acceptance that ozone depletion is contributing to the drought, but there is debate about how large a factor it is.
With Victorian rainfall entering its 13th below average year, the last 7 of them extreme, there is room for a lot of contributing factors. Every climatologist I’ve interviewed agrees that ozone depletion and Global Warming are part of the mix, the question is whether they are the whole story, or there are other factors. If the other factors exist, then the relative size of each of them is unknown.
BTW, the sense I get is that there is more of a handle on the causes of the long term rainfall decline in South West WA than in Victoria, but even here there’s debate about how much each factor contributes.
Comment by Stephen L — March 2, 2009 @ 12:16 pm