Scientists say stalagmites, the mineral spears that rise from the floors of some caves, could help Australia prepare for drought. Researchers at a rainfall conference in Sydney say the cave formations have accurately recorded past rainfall patterns, and can help predict what the future holds. From Sydney, Phil Mercer reports.

The rainfall conference is looking at ways to manage increasingly scarce water resources on the world's driest inhabited continent.

Scientists believe one way is to study stalagmites, which hold the key to Australia's rainfall patterns over centuries.

The upward-growing mounds are created by minerals dropping in water from the roof of a cave. Carbon dating techniques of stalagmites have been able to identify dry and wet periods in Australian history.

Scientists say the stalagmites could therefore be a valuable and accurate ecological archive - especially in Australia, where the climate has been documented only over the last century or so.

Environmental scientist Ed Hodge says learning more about the amount of rain that has fallen in the past could provide a great insight into what is in store in the years ahead.

"The instrumental records for Australia only go back 100 to 150 years in most places," Hodge explained, "so the real goal is to extend these patterns - for example the drought cycles - back for several hundred years to maybe a thousand years, so that we can get a better idea of how the patterns occur over time, and then we can feed this into climate models, which hopefully will tell us what to expect in the future specifically under changing climate conditions."

Scientists say the predictive techniques involving stalagmites are also being used in other dry parts of the world, including Africa.

Shedding light on future levels of precipitation could be vital for a country prone to situations that are exacerbated by climate change: widespread flooding at the moment in the northern state of Queensland, the worst drought in memory elsewhere.

Managing the supply of water to Australia's cities and farms has emerged as one of the key challenges of the 21st century. Millions of residents are subject to tough water restrictions, and drought has forced many farmers off the land.

Concerns about climate change have prompted much political debate. Following last November's nation elections, the first formal act of the new government was to ratify the Kyoto Protocol on climate change, ending Australia's international isolation on the issue.

The Sydney one-day rainfall conference has brought together environmental researchers, water companies, weather forecasters and government representatives.