A Second Opinion About Australian Drought

A useful second opinion about Australia's drought.

The weather forecasts for the next week actually look pretty favorable, with lots of rain hitting drought-stricken SE Australia. Various cut-off lows from the jet stream are helping out, which seems counter to my understanding that tropical rains are supposed to be making the biggest dent right now. But from wherever it comes from, it's welcome. Hopefully they'll get enough rain to keep all the forests from burning down and all the rivers from drying up.:

THE drought gripping southeast Australia is due to natural variations in climate rather than the greenhouse effect.

... "It is very, very highly likely that what we are seeing at the moment is natural climatic variability," researcher Barrie Hunt told The Australian, saying the CSIRO's model of 10,000 years of natural climate variability put the current drought into perspective.

... Mr Hunt's research focused on three 500 sq km sites in Australia: one on the Queensland-NSW border, going down to the coast; southeast Australia, which included Melbourne, Sydney and much of the Murray River basin; and southwest Western Australia, including the Perth region.

He looked at the frequency of dry sequences lasting eight years or longer.

"In each of those places there are about 30 occasions over 10,000 years where you get one of these eight or more years sequences," he said.

"The longest sequence was 14 years in Queensland-NSW, 11 in the southeast and 10 in the southwest."

Mr Hunt said the Queensland-NSW area had had an 800-year period without an eight-year dry, "but there is another period of 462 years where you get five of these".

Mr Hunt said the onset, duration and termination of the long dries could not be predicted because they were due to random processes. He said the current drought was an example of a dry sequence that began with an El Nino weather system.

"It starts a drought and you get sea-surface temperatures flickering backwards and forwards a bit. The rainfall may go back to fairly near normal but it is still below average, and then you get another El Nino," he said.

"This can go on for a decade. Eventually it breaks. You don't know why, it is a random thing. This is just part of the beauty of the climatic system."

Most of Victoria is in a 10-year dry sequence, the Murray River is in its sixth year of drought, while Brisbane and much of NSW are also experiencing a six-year dry.

"It is important that people realise that natural variability says it will break. It may not break next year, because one of these things went on for 14 years, but it will break," Mr Hunt said.

... Mr Hunt said the dry sequence in the southwest was different, with a decline over 30 years, which included the odd year of above-average rainfall.

"It isn't violating what I am saying, but it is a very unusual sequence of events there," he said.