An Argo float: one of the tiny fleet of automatic
oceanic sensors that are helping unlock the secrets
of the Leeuwin Current.
Image by Bruce Miller, CSIRO Marine Research

Warmer seas off the Western Australian coast could ultimately change the seasons and give the state even milder winters with summers that extend on an extra 10 to 20 days.

The predictions are an informed ‘guess’ by Dr Ming Feng, a Perth-based oceanographer with CSIRO’s Wealth from Oceans National Research Flagship, who is two years into a five-year research project aimed at gaining greater understanding of the Leeuwin Current - the powerful body of water that courses south from North West Cape and silently shapes much of WA's environment on its way to the Great Australian Bight.

Thanks to climate change, the current's temperature over the past 50 years has risen by 0.6 to 1 degree C altering the marine habitat - and impacting weather patterns along the adjacent coast.

By the time Dr Feng and his colleagues complete their investigation they hope to be able to forecast the Leeuwin Current's strength and temperature over the next 50 to 70 years - and with it, the likely future impacts on fishing and offshore industries as well as the coastal weather patterns.

The project is part of the research program of the Western Australian Marine Science Institution, a collaborative body drawing on the expertise of such organisations as the Bureau of Meteorology, CSIRO, Department of Fisheries and WA universities.

According to Dr Feng, the first two years of research have focused on the past - using data already collected mainly from satellites and the so-called Argo floats  - the tiny fleet of automatic oceanic sensors that have been measuring ocean temperatures and salinity off the coast since 1990.

"From what we know so far, it seems there are seasonal fluctuations in the current's temperature and that since the 1970s, the strength of the current has been weakening," he told ScienceNetwork WA.

"As well as look to the next 50 to 70 years we will want to determine whether this trend is likely to continue."

To help in the process, this year will see another set of ocean sensors being moored on the Continental Shelf between Shark Bay and Perth - 10 in all.

"We really need more than that," Dr Feng said. "But hopefully the results we achieve will persuade people that a bigger investment in oceanic monitoring is justified."

In the past few days oceanographers at the Proudman Oceanographic Laboratory in England have reported that sea levels could climb one-and-a-half metres by the end of the century - far more than has been predicted in last year's report from the Intergovernmental Panel on Climate Change.

Dr Feng had yet to see the report when ScienceNetwork WA spoke to him, but doubted that the acceleration in polar ice melts that had prompted the European researchers to make their predictions would significantly alter the way the Leeuwin Current functioned.

Much would depend on how quickly the extra water flowed into the system. And although global warming was threatening to bleach WA's coral reefs, the extra level of water above the coral might prove just as detrimental, he said.

"If the sea levels rise too fast and exceed the level at which the coral can grow, then there will be a negative effect," Dr Feng said. "The rising water levels could slow growth."