Analyst says rainfall pattern due to global warming

http://www.abc.net.au/am/content/2006/s1820751.htm]

AM - Wednesday, 3 January , 2007 08:08:00

PETER CAVE: Staying with the weather, and the Bureau of Meteorology's

annual report for 2006 is out, and surprisingly it says that the

country recorded more rainfall than average, it's just that it fell

in areas where people don't live.

The National Climate Centre's Dr David Jones says that's due to global warming.

He's been speaking to AM's Sabra Lane.

DAVID JONES: It is really two things. One it was a year of extremes,

you know, frost events, heatwaves, bushfires, floods, you name it, we

had 'em all last year, and much more than what we'd probably have in

a typical year.

The other story is the continuing overall warmth of Australia. You

know, it wasn't quite a record warm year like, say, 2005, but again

another warm year, averaging about half a degree above average.

SABRA LANE: Was it the second driest year on record?

DAVID JONES: No, not even close. Believe it or not, and I guess most

Australians probably won't believe it, we actually had above average

rainfall over Australia last year. The problem was where everybody

lives was dry, and where most of us don't live was wet. So Australia

as a whole actually had about 20 or 30 millimetres more than the

long-term average.

SABRA LANE: And tell us, what about the water catchment areas in the

south-east of the country, the Murray and Snowy Rivers?

DAVID JONES: Yeah, well really, you know, 2006 being a year of

contrast, and unfortunately the dry conditions had been exactly where

we live and also where our catchments are. So the catchments in,

particularly, south-east Australia, so the Snowy Mountains, the

north-east Victorian highlands and so on, and also the regions around

Perth and some of the catchments in Hobart's vicinity have

experienced phenomenally low rainfall, and in many of those areas in

fact the driest year on record. And these records go back well over

100 years.

SABRA LANE: And the capital cities, how did they fare?

DAVID JONES: With the exception of Darwin, all capital cities had a

very dry year. Really quite remarkable, Perth and Hobart had their

driest years on record, and by a large margin, we're talking sort of

30 to 50 millimetres, which is a clear separation from previous

records.

Other capital cities - Adelaide had second driest year on record,

Melbourne had its eight driest. So, you know, pretty much dry across

the board. Most capital cities, with the exception of Darwin, sort of

in their top 10 driest, or even worse, as in the case of Perth and

Hobart.

SABRA LANE: What is causing Australia to become hotter? Do we know that?

DAVID JONES: Yeah, well the reason why Australia's becoming warmer is

the reason why the world is becoming warmer, it's because of the

climate change associated with greenhouse gases.

Certainly there's natural processes go on underneath this. You know,

we have volcanic eruptions, we have cycles of El Nino and La Nina,

but this very long, slow warming trend that has been with us now for

50 years is linked to greenhouse gases.

SABRA LANE: There were some scientists who were putting forward a

little while ago that it might've been a climate shift, not a climate

change.

DAVID JONES: Yeah, well, you know, that's an interesting question,

you know, greenhouse gases of course go up slowly in the atmosphere

and you'd expect the climate to respond sort of slowly and

incrementally, but you know, climate's a pretty chaotic system.

Sometimes we see jumps and sometimes we don't know whether those

jumps are real or were they just sort of statistical artefacts.

You know, a clear one that we saw, for example, was in Perth in 1970.

Rainfall there dropped by about 10 maybe 20 per cent around near, the

vicinity of Perth, and it has actually never recovered, and we don't

really understand why that stepped down. Certainly expect Perth to

dry out under climate change, so under the enhanced greenhouse effect

Perth will tend to get drier, going through the course of this

century. But I think no scientist would've predicted in advance that

rainfall would drop something by 10 or 20 per cent overnight.

PETER CAVE: The National Climate Centre's Dr David Jones speaking to

Sabra Lane.

© 2007 Australian Broadcasting Corporation

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