NIWA-led multinational research team achieves breakthrough in climate research

Internationally significant new evidence of the vital role in global climate change played by the Southern Ocean has been assembled by a multi-national New Zealand-led research team during a 30-day scientific expedition into Antarctic waters, 2500 miles southwest of New Zealand.

Dr Rob Murdoch, Regional Manager of the National Institute of Water and Atmospheric Research (NIWA) said today in a message from NIWA’s research vessel Tangaroa that the studies had been extremely successful and "scientists are excited by the preliminary results.

"This study has shown that the lack of iron limits the abundance of marine life in Southern Ocean waters southwest of New Zealand and therefore its ability to absorb atmospheric carbon dioxide."

The research group led by Philip Boyd, of NIWA, consisted of 10 NIWA scientists and 16 international scientists from the United Kingdom, the US, Australia, Holland, and Canada. They set out from Wellington on 1 February to fertilise a target zone of 50 square kilometres in Antarctic waters about 60 degrees South in a bid to boost growth of microscopic plants known as phytoplankton.

These plants are believed to play a key role, similar to that of grasslands and forests on land, in reducing the build up of carbon dioxide in the atmosphere which is causing global warming. Although the waters of the Southern Ocean are rich in nutrients, there are constantly low numbers of phytoplankton, and scientists believed this was due to an absence of iron.

"An initial area of 55 square kilometres was fertilised with 36,000 litres of a sea water-iron mixture from Tangaroa. The patch was refertilised on three additional occasions over the following 12 days, and measurements showed there were considerably higher levels of iron.

"The addition of a tracer with the iron allowed us to distinguish the fertilised patch from the surrounding waters and to follow the patch as it was transported by surface currents.

"By the end of the study the patch had moved 40 miles to the east and had spread to cover an area of about 150 square kilometres. The patch will return to normal ocean conditions within the next few weeks.

"Not only did the numbers of phytoplankton bloom extensively, but they were also responsible for the absorption of a significant amount of carbon dioxide during the study period relative to the seas outside the patch area.

"The growing patch of phytoplankton also produced significant quantities of gases known to be important in cloud formation.

"This study has shown that the lack of iron limits the abundance of marine life in the Southern Ocean and therefore its ability to absorb atmospheric carbon dioxide.

"It also provides further evidence to support the theory that high amounts of iron in the Southern Ocean and low amounts of atmospheric carbon dioxide in past ice ages are linked. Higher phytoplankton growth in periods when the oceans were naturally fertilised with iron would account for the lower levels of carbon dioxide and the cooling of the earth."

Dr Murdoch said the maintenance and tracking of the patch from Tangaroa over 13 days was "remarkable".

"An experiment of this size was thought to be unachievable by many in the international science community because of the ferocious conditions normally found in the stormy Antarctic ocean.

"The odds of success were extremely low, but the study has been successful and scientists are excited by the results so far."

He said following the patch was difficult due to storms with 55 knot winds and 10 metre seas.

"But on the whole we have been lucky with the weather. Air temperatures on deck have been 0 and 3 degrees C, with occasional showers of sleet and snow.

"The patch of phytoplankton was continuing to grow at the time Tangaroa left. We hope it will be visible from satellites if a cloud-free day occurs over the next week or so.

"Analysis of the samples and data collected by scientists during the voyage is expected to take more than a year. Details of the final results will be much anticipated."

The million-dollar expedition is being funded by NIWA, the Foundation for Research, Science and Technology, the United Kingdom NERC Science Programme and other international collaborators.

Tangaroa is expected to reach her home port of Wellington on Monday.