Scientists Aim to Boost Southern Ocean CO2 Monitoring

David Fogarty, PlanetArk 2 Oct 08;

SINGAPORE - Australian scientists set sail later this week on a voyage that could lead to better data from the Southern Ocean, which plays a major role in acting as a brake on climate change.

Oceans absorb vast amounts of carbon dioxide and the Southern Ocean between Australia and Antarctica plays the greatest role of all the world's oceans, scientists say.

The problem is there is no permanent monitoring of the Southern Ocean because of its wild seas and remoteness and scientists cannot accurately determine how a warming world is affecting the amount of CO2 the ocean is absorbing.

So marine scientists based in the southern Australian state of Tasmania sail on Friday to test two newly designed ocean moorings to see if they can withstand the pounding of 20-metre (70 feet) seas to send back data over many months.

"The oceans are protecting us from climate warming by absorbing our CO2 out of the atmosphere. Most of that is happening in the Southern Ocean," said Tom Trull, leader of the Ocean Control of CO2 Programme at the Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart.

"We don't know if that'll continue and we're concerned it might not. This equipment will help us find out," he said on Wednesday.

Trull said the Southern Ocean captures CO2 in two ways, or what are known as pumps. The gas is absorbed by seawater, mixing with the turbulent surface layer and carried to the depths by ocean circulation patterns.

The gas is also absorbed by billions of tiny phytoplankton and other organisms, which fall to the ocean bottom when they die, trapping carbon in deep bottom layers of sediment. "As climate warms, the surface layer gets more and more difficult to mix with the waters below, so that reduces the physical pump of CO2," he said.

Also, as climate warms, the amount of CO2 released by the tiny animals that feed on phytoplankton increases, reducing the biological pump, he said.

The aim of the current voyage is to test equipment that by this time next year could lead to long-term monitoring of the surface layers of the Southern Ocean.

Trull said the monitoring equipment would involve a float on the surface and more equipment about 50 metres (165 feet) below. Both are attached to a tether to the ocean floor about 4 km (2.5 miles) below.

"We're trying to get at those kind of near-surface processes but sample them on the timescale that matters to them, which is days and weeks, rather than sampling them when a ship goes out there, which is maybe a couple of times a year," he said.

It was the only way of telling how climate change was affecting one of the Earth's main sinks of CO2, the greenhouse gas produced by burning fossil fuels in cars, power stations and by industry.

"If it turns out the Southern Ocean is not absorbing it (CO2), we're going to have to be even more stringent with controls on emissions," he said. (Editing by Jeremy Laurence)