NZ Antarctic voyage to pursue causes of climate change - ocean plant deficiency targeted


NIWA's research vessel Tangaroa sails from Wellington tomorrow [Sunday, 31 January] on a month-long million-dollar, multi-national scientific expedition that will take her 2000 miles southwest of New Zealand into the Southern Ocean around Antarctica.

The purposes of her voyage are to revitalise growth of microscopic plants believed by world scientists to be a key element in absorbing carbon dioxide out of the atmosphere and to better understand the role of the Southern Ocean in climate change. A carbon dioxide build-up in the atmosphere is considered a major contributor to global warming.

The 2282 tonne vessel will have on board 10 NIWA scientists who will be joined by 16 scientists from the United Kingdom, the US, Australia, Holland, and Canada. Their target zone of 70 square kilometres is in latitudes around 62 degrees south and the Tangaroa is ice strengthened to cope with the extreme conditions likely to be encountered in the region.

Once on site the scientists will pour into the Antarctic waters some 15,000 litres of a special iron slurry contained in two 7500-litre tanks specially installed on the decks of the Tangaroa. They will then monitor with the use of buoys and special tracers the impact of the mixture on the growth of the ocean plants known as phytoplankton.

NIWA Regional Manager Dr Rob Murdoch said today that the experiment is part of a major international effort to determine the role of the world's oceans in global climate change – "and the Southern Ocean, which makes up 30 percent of the world’s oceans, is considered an extremely significant contributor.

"Carbon dioxide levels in our atmosphere are increasing and scientists world-wide believe that this is one of the main causes of global warming. We want to better understand the role of the oceans in the removal of carbon dioxide from the atmosphere because research has suggested that the interplay between oceans and atmosphere is critical to future climate conditions.

"These single-celled, microscopic phytoplankton are found in abundance in the surface waters of the oceans and we believe they play a similar role to forests on land in absorbing carbon dioxide. Currently numbers of phytoplankton in the Southern Ocean are low even though there appear to be high levels of nutrients required for their growth.

"Previous laboratory experiments, and an ocean experiment in the equatorial Pacific Ocean similar to that we are embarking on, indicated that the presence of iron could stimulate growth in phytoplankton numbers.

"By fertilising more than 70 square kilometres of ocean with this iron solution we hope to see a rapid growth in numbers. With luck we may get some indications within a week of beginning the experiment."

The iron mixture will be stirred into the ocean by releasing it into the Tangaroa’s propeller wash. Fertilised patches of ocean will be tracked through drifting buoys that will transmit their position to the ship by satellite fixes. A huge range of measurements will then be taken to determine the effects of the fertilisation on the phytoplankton; on animals higher in the food chain, such as krill; on nutrient levels and carbon dioxide levels; and on the fate of the iron.

United Kingdom scientists will provide the expertise for the iron release because they developed techniques for the similar experiments carried out in the equatorial Pacific Ocean, which also has high nutrient levels and low phytoplankton numbers.

These experiments showed that iron fertilisation not only increased the growth of phytoplankton, but also increased the amount of carbon dioxide absorbed by the ocean. Weather and sea conditions in the Southern Ocean, however, contrast significantly with the warm and often placid waters about the equator. This means that the impact of iron fertilisation on the phytoplankton population may well be slower than that experienced in the Pacific.

"The large swells and rough conditions typical of the Southern Ocean are likely to make the experiment much more difficult to perform, and water temperatures are expected to be about zero degrees," said Dr Murdoch.

The programme is being funded by NIWA, the Foundation for Research, Science & Technology, the United Kingdom science programme, and other international collaborators.

NIWA’s Dr Murdoch will lead the voyage and the science programme will be jointly led by Drs Andrew Watson from the United Kingdom and Philip Boyd from NIWA.

For further information, contact:

Bruce Kohn
Media Relations
Tel: (04) 386-2793