Ocean temperatures in New Zealand have reached record highs, more than three times the global average in some areas, raising concerns about the health of the country’s marine life and ecosystems.
new Statistics Bureau data Since 1982, ocean surface temperatures have increased on average by 0.16 to 0.26°C per decade, and coastal waters by 0.19 to 0.34°C per decade.
Each marine and coastal region experienced its hottest year on record in 2022 or 2023.
Comparing data from the past 20 years, sea levels around New Zealand have been rising at twice the global average of 0.18 degrees Celsius per decade, and an area known as the Chatham Plateau has been three times warmer than the global average, said Matt Pinkerton, chief scientist at the National Institute of Water and Atmospheric Research.
New Zealand may be experiencing increased temperatures because of its geographic location and the way global ocean currents move and carry heat, he said.
“New Zealand sits between the Pacific Ocean, the Tasman Sea and the Antarctic Ocean, and because all three of these regions are warming, we’re getting heat from all directions.”
Pinkerton said New Zealand’s high temperatures dispelled the notion that the island nation was protected from extreme temperatures.
“We are surrounded by the sea, [thought] Although it has been somewhat protected by global warming, [data] I’m saying that’s not true.”
Marine heatwaves – extended periods of abnormally warm ocean water – also reached new levels: the western North Island experienced a heatwave for 89% of the year in 2022, the highest of any coastal region, and the Tasman Sea experienced a heatwave for 61% of the year, the highest of any marine region.
“Even small increases in temperature could disrupt marine ecosystems, triggering migration of some species and increasing the risk of disease,” said Stuart Jones, environment and agriculture statistics manager at Statistics New Zealand.
Previous severe marine heatwaves have included mass bleaching of sponges in New Zealand; Southern Bull KelpThere have been large-scale fish strandings and penguin deaths.
“Intense marine heatwaves can kill habitat-forming species such as kelp and cause large-scale ecosystem shifts,” said Dr Christopher Cornwall, lecturer in marine biology at Victoria University of Wellington.
“Both background warming and more frequent, more intense and longer-lasting marine heatwaves are likely already permanently altering marine ecosystems within Aotearoa.”
Both Cornwall and Pinkerton added that it’s still not clear how much warming ocean temperatures will affect ecosystems, and long-term monitoring is needed to predict and plan for changes, especially when assessing fishing quotas.
another Statistics NZ DatasetPhytoplankton, the microscopic algae that form the base of the marine food chain, is in decline in New Zealand’s warmer northern waters, a report released Wednesday showed. The data suggests there is a correlation between the decline in phytoplankton and rising sea surface temperatures.
Meanwhile, New Zealanders will also feel the effects of warming oceans because much of New Zealand’s weather is determined by the ocean, said Dr Georgia Grant, a climate scientist at GNS Science.
The world’s oceans are approximately 90% of excess heat It is the result of human-induced climate change.
“Warming ocean temperatures are one of the reasons storms like Cyclone Gabriel are expected to become more intense due to climate change.”
