Oceanographers say sea temperatures east of the island state are as much as two degrees warmer than they were 60 years ago, while other ocean hotspots around the world have warmed at two to three times the average over the past century.

``We would expect natural change in the oceans over decades or centuries but change with such elevated sea surface temperatures, in a growing number of locations and in a synchronised manner, was definitely not expected,'' said the CSIRO's Dr Wenju Cai, co-author of a paper published in the journal Nature Climate Change.

The international scientific team working on the project said the ocean hotspots were a result of strengthening wind systems caused by greenhouse gases that had driven ocean currents beyond their known boundaries.