WELLINGTON, Oct. 15 (Xinhua) -- New research reveals a warming trend in New Zealand's ocean waters alongside an increase in marine heatwaves, potentially impacting fisheries and marine ecosystems.
New Zealand's ocean temperatures are rising, with marine heatwaves -- periods of unusually warm ocean temperatures lasting for five or more days -- becoming more frequent and severe, according to a statement released Wednesday by Earth Sciences New Zealand (ESNZ).
The report by ESNZ, completed on behalf of Fisheries New Zealand, analyzed the regional impacts of long-term warming and temperature extremes on fish species around New Zealand, it said.
Average sea surface temperatures around New Zealand have warmed between 0.2 and 0.3 degrees Celsius per decade from 1982 to 2022, and about 0.1 degrees per decade in seafloor temperatures over the past 40 years, according to the report.
"Seas are projected to get hottest around the North Island, and to become longer and more frequent around the South Island. This is in addition to the continued, slower, general warming of New Zealand's waters," said ESNZ physical oceanographer Erik Behrens.
The warming trends in coastal waters off eastern New Zealand are particularly pronounced, along with offshore waters in the Tasman Sea, and east of New Zealand over the Chatham Rise, the report said.
Behrens said marine heatwaves could double in their intensity by the end of the century in high emissions scenarios compared to current levels.
"Some recent marine heatwaves have already exceeded historic baseline temperatures by 5 degrees Celsius. So, by the end of the century, these could be exceeded by 10 degrees Celsius," he added.
However, researchers said further data is needed to confidently predict how the ecosystems will respond, and what specific threats or opportunities ocean warming may bring. ■