The first academic studies are only just emerging on New Zealand’s last two years of heatwaves. ‘The ocean has been doing the heavy lifting’ As the oceans are warming it’s much easier to tip the ocean over into a marine heatwave, because you’re starting from a warmer baseline,” says Dr Robert Smith, an oceanographer who studies marine temperatures with the Moana project and University of Otago. “In the background of all of this you’ve got anthropogenic climate change. But as greenhouse gases heat the climate overall, oceans become hotter too. Marine heatwaves can be caused by a number of factors, including ocean currents, low pressure weather, and La Niña weather systems. The department of conservation concluded that the birds had died starving – as warm waters redistributed fish deeper and further, the penguins could not reach them. Their small bodies would lie part-buried in the sand of the Bay of Plenty – 183 one day, 109 another. When marine heatwaves began hitting New Zealand again in 2022, dead kororā began washing up on beaches in their hundreds. Studies over the last decade found that large hot blob events have killed more than a million seabirds in a year.Ĭarefully inspecting their tiny frames, he saw all the signs that they were starving when they died: no fat, no muscle mass, and thick dark blood in the gut.ĭaniel Thomas from Massey University necropsies kororā from the 2017-2018 die-off event Richard Robinson These birds came to Thomas’s dissection table after being gathered on the beaches in 2018 – another period of extreme heatwaves, the “hot blob year” in New Zealand when a huge warm expanse of water moved across the Pacific, raising water temperatures by about 1.5 degrees. “The biggest muscles in these birds’ bodies should be their flight muscles, sitting on their chest. “The very first thing we are looking for is – do they have muscle?” he says. Taking a scalpel, Thomas cut the dead bird open, unzipping its feathers from the chin down. The tubby birds are often spotted waddling together over the dunes of New Zealand’s coasts. The world’s smallest penguin species, the fairy penguin, is beautiful: their blue feathers shine. Heatwaves around New Zealand are already seeing spikes that high, giving a glimpse of what it can do to species under the surface.ĭr Daniel Thomas lifted the little kororā by its torso, and leaned in to take a closer look. No one yet knows what it will mean for the fish, seabirds, whales, dolphins, and New Zealand’s multi-billion dollar fishing industry.Īs scientists and communities begin to reckon with the impact, the conditions hitting Aotearoa provide a preview of the future of the world’s oceans under climate change: waters around the world are projected to rise by about 4C on average by 2100, if the world maintains its course on global heating. With little respite for species to recover between the waves of heat, scientists warn that some ecosystems are reaching tipping points under the surface, with effects that will be felt years into the future. In the north island’s Bay of Plenty, the waters remained in heatwave for an entire year. ![]() Some southern regions experienced marine heatwave conditions for more than 270 days during the period. New figures provided to the Guardian by scientists studying ocean temperature shifts show that on average, over the year to April 2023, New Zealand’s coastal waters sat stewing in marine heatwave conditions for 208 days. Marine heatwave data courtesy of NOAA Coral Reef Watch, Marine Heatwave Tracker and Dr Robert Smith, University of Otago, New Zealand In 30 years of fishing, and writing for the local fishing magazine, Langlands had never seen anything like it. Locals posted videos of them surging over the sandbanks or laid out in their hundreds on the sand of toddlers striding through the shallows to yank one out by the tail. ![]() Entire schools died flapping in the Otago bays, their scales a dark, briney silver – an offshore fish, meant for deeper, colder waters. The fish had been beaching for months now – masses of them, through April, May, June, July. Even as he thought ahead to the evening meal, though, Langlands felt a pang of worry. Later, he would fillet them, and cook the firm white flesh with spices for a curry. He had long been an active fisher on the coastlines of New Zealand’s South Island, and knew they were ray’s bream: good eating. Peter Langlands waded in, grabbing live fish one by one. Occasionally a fish would raise a single fin, worrying the water’s edge. In shallow pools created by the eddying tide, they lay piled on their sides. Some floated belly up, stunned and dying. In the shallows of Aramoana, fish roiled the surface of the bay, flickering through the water, reflecting the winter sunlight. Words by Tess McClure, data vizualisation by Andy Ball
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