Deep sea probe to track Australia climate change

SYDNEY (Reuters) - Australian and U.S. scientists will send an unmanned submersible 2.5 kms (1.5 miles) deep into the ocean off Australia next week to track climate change by studying coral at unprecedented depths.

The joint project will film live and fossilized deep-sea coral off the coast of Australia's southern island state of Tasmania, studying coral growth rings which like tree rings can store centuries of information about the environment.

"Like tree rings, growth rings in corals indicate age. They also reflect changes over centuries and millennia in ocean chemistry and the ocean environment," Ron Thresher from the Australian government's Commonwealth Scientific & Industrial Research Organization (CSIRO) said on Thursday.

"Deep ocean corals are a litmus test of the deep ocean when it comes to identifying how temperature and salinity have changed over decades and centuries," Thresher, who will set sail on Friday, said in a statement announcing the project.

"We hope to track two influential elements on the global climate system -- the formation of water masses at the Antarctic coast and the circulation of the Southern Ocean," he said.

The submersible Autonomous Benthic Explorer, on loan from the Woods Hole Oceanographic Institution in the United States, will be launched from an Australian marine research ship during the 23-day voyage. The submersible can reach depths of 4 kms (2.5 miles) and can stay underwater for seven hours.

CSIRO marine scientist Alan Williams said a dive to 2.5 kms will allow scientists to view biodiversity at depths never seen before in Australian waters.

"We have a good sense of the marine ecology around seamounts (submerged volcanoes) down to about 1,500m, but to be able to see and build an understanding of life beyond is a tremendously exciting prospect," said Williams.

(Reporting by Michael Perry, editing by Sanjeev Miglani)