An expedition to look 5 million years into the past in an attempt to predict the effects of climate change on our reefs and currents is about to set sail from Western Australia.

A group of leading international scientists are preparing for a $20 million ocean expedition up the coast of WA to drill deep into the seabed to gain insight into climate change.

The first of the its kind, the International Ocean Discovery Program (IODP) will examine the climatic conditions of the North West continental shelf over the past five million years.

Similar records of Australia's climate history date back less than half a million years, according to the IODP.

Over two months, 125 international scientists and crew scientists will drill up to one kilometre beneath the seabed to understand how modern reefs and currents off Western Australia were formed and may cope with climate change.

University of Melbourne Associate Professor Stephen Gallagher is co-leading the JOIDES Resolution research vessel, one of the world's biggest floating scientific research facilities.

He said knowledge of past oceanic systems in the region was limited.

"Other than the very top, we really don't know anything about these ancient climate history or environmental history of the region, and it's very significant because ... everyone thinks these reefs have been there forever," he said.

"However, we think that these reefs are younger. Nobody really knows when the reefs started and why they started.

"If we don't know ... then how do we know how these reefs will react with future climate change?

"Our Southern Hemisphere location is vitally important in solving global science problems such a determining the history of the Indonesian Throughflow current, which is a key part of the global oceanic circulation system."

Mr Gallagher said the teams would be drilling into a series of cores beneath the seabed to reveal millions of years of data.

"To get all layers with the fossils and they could be corals, they could be shells they could be anything that we find ... As we drill down deeper, all the layers reveal the climate change in the past, much like tree rings in a tree give you seasons," he said.

Mr Gallagher said it was not known how long the present climate of the western half of Australia has changed through various greenhouse and icehouse periods.

"We hope to understand Australian monsoonal behaviour during the last period in Earth's history, when CO2 levels were similar to today," he said.

'No pleasure cruise'

But Mr Gallagher said the expedition would be hard work for the crew.

"This is no pleasure cruise. This is 24 hours a day, 12 hour shifts, seven days a week continuously," he said.

A preliminary scientific report will be published online within two months after the expedition.

"A lot of the science can be done on the ship ... and the scientists are basically creating the framework for further work and we will have a fair idea when we get off the ship in Darwin whether we've got our five million year record," Mr Gallagher said.

Funding for the IODP is provided by international science organisations the National Science Foundation in the United States, the Ministry of Science and Technology in China and the Australian-New Zealand IODP Consortium.

The expedition departs from Fremantle on Monday August 3 and will make its way up the West Australian coast to land in Darwin on October 1, 2015.

