New Zealand oceans warming 34% faster than global average, putting homes and industry at risk, report finds | New Zealand
New Zealand’s oceans are warming 34% faster than the global average, with N$180 billion ($104 billion) worth of homes at risk of flooding, a new report on the country’s marine environment has revealed.
The NZ Department of Environment and Statistics’ three-annual update, Our Environment 2025, brings together statistics, data and research across five areas – air, atmosphere and climate, freshwater, land and marine – to paint a picture of the state of New Zealand’s marine environment.
The latest in the series, Our Marine Environment 2025, painted a sobering picture for the nation’s oceans and coasts – defined by warming and rising seas, intensifying marine heatwaves and ocean acidification, driven by global heating.
“Climate change is not just something far away and distant… it has impacts on our ocean and on our coast,” Dr Alison Collins, the department’s chief scientific adviser, told the Guardian.
“The coastal zone is under real pressure… and the importance of that coastal environment is absolutely critical – it’s what we rely on in terms of our homes, our communities, our livelihoods and ultimately our connection to place.”
The report outlined a wide range of risks associated with marine change, including threats to native marine species, coastal flooding and flooding of homes, as well as stronger and more devastating storms, and risks to communities and the economy.
It noted that 219,000 homes worth $180 billion were located in coastal flooding and inland flood zones, while more than $26 billion of infrastructure was vulnerable to damage. Around 1,300 coastal homes could face significant damage from extreme weather.
Some regions will see an 8- to 12-inch rise in sea level by 2050, a tipping point for some communities, Collins said.
“Sea levels reaching this size mean a coastal storm that used to occur every 100 years could start every year,” she said.
The world’s oceans have absorbed around 90% of the extra heat created from the human-caused climate crisis.
New Zealand bears the brunt of these warming seas due to its position in the ocean, making it more vulnerable to atmospheric circulation and changes in ocean currents.
Between 1982 and 2023, New Zealand’s sea surface temperatures in its four ocean regions increased, on average, by 0.16 to 0.26 degrees Celsius per decade, and its ocean warming rate exceeded global averages by 34%.
Coastal waters are also warming faster than the global average, he said.
Meanwhile, the subtropical front – the boundary between cold subantarctic water and warmer subtropical water that is biologically and economically significant – is moving 120 km to the west, the report said, noting that this was the first time a large-scale ocean circulation shift around New Zealand had been observed.
The shift, which is driven by warming water, will have “huge impacts” on ecosystems, the food line and on species such as corals, sponges, kelp and fish, Collins said.
Ocean acidification and warming also affects the country’s fishing and aquaculture industries – which contribute $1.1 billion to the economy – and can lead to toxic algae blooms in shellfish. Marine heat waves, for their part, are becoming more intense, more lasting and more frequent.
New Zealand has been hit by unprecedented marine heatwaves in recent years, which have been linked to mass sea sponge bleaching, southern bull kelp die-offs, large-scale fish flocks and penguin deaths.
Monitoring and research on the marine environment was increasing, but there were still gaps in understanding, the report noted, adding that more comprehensive research would reduce risks to people, promote climate resilience and promote sustainability.
Lack of understanding of how climate change, oceans, weather events and ecosystems interact, Collins said.
“It’s a bit like pulling a thread from a fabric and the whole thing can fall apart – understanding these interactions is perhaps the biggest blind spot for us.”
