Forecasting the future of NZ’s oceans and weather

University of Auckland Associate Professor Melissa Bowen is leading Te Moana Mahana: Ocean change forecasting for climate resilience in Aotearoa.

The five-year project received $8.9 million from the Ministry of Business, Innovation and Employment’s Endeavour Fund.

“About 93 percent of the extra heat caused by global warming has been absorbed by the ocean, so we want to figure out how much that is driving extreme weather.

“We’ve had some devasting floods and landslides in the past few weeks, with tragic loss of life.

"This highlights the importance of having this kind of research to inform the government and communities,” says Bowen, who has spent the past 25 years studying the impact of oceans on weather patterns.

The ocean around New Zealand is warming each decade by about 0.2 degrees Celsius, which is about twice the global rate, she says. Wind patterns are a primary driver of rising temperatures in our oceans.

Warmer seas can increase the levels of moisture in the atmosphere, leading to more rainfall.

Higher sea temperatures are also a key ingredient in the development of tropical cyclones, says Bowen, who is involved with the University's School of Environment and Centre for Climate, Biodiversity and Society - Ngā Ara Whetū.

The research team will use global climate models to create computer simulations that can predict future ocean temperatures and currents around New Zealand.

They will predict future marine heatwaves and ocean-driven weather patterns up to the end of the century.

By considering the effect of the future ocean on the atmosphere, the team will predict how recent extreme weather, such as the Auckland Anniversary Day floods of 2023, might turn out in the future.

“We want to see how ocean temperatures are influencing weather systems, in terms of the amount of rainfall, winds, and the movement of weather systems.

“The purpose is for us to develop ocean and climate predictions that will help New Zealand prepare for what might happen in the future,” says Bowen.

The research team has an ambitious plan to map the ocean “heatscape” for the Southwest Pacific Ocean and around New Zealand’s coasts.

Two self-driven ocean gliders will explore the entire stretch of New Zealand’s coastline.

The gliders will collect information from the edge of the continental shelf about ocean temperatures, salinity, oxygen content, and levels of phytoplankton, which is the foundation of the marine food chain.

Information on ocean temperatures will also be gathered by up to 150 commercial fishing boats.

“We will build up a picture of what’s happening along the coast and how it’s connected to the deeper ocean offshore.

“We want to know where there are hotspots and where there are refuges providing cooler waters – and why these patterns are occurring,” says Bowen.

The research will look closely at the Hauraki Gulf and the Otago Shelf, examining how extreme events, such as high rainfall and marine heatwaves, impact on temperatures, oxygen and phytoplankton levels in the coastal ocean.

The researchers will hold co-creation labs and conduct surveys on people’s relationships with the ocean. They will also evaluate existing policies and plans affecting the ocean.

The project is expected to provide information that will help Earth Sciences New Zealand make more accurate seasonal forecasts, and regional councils make more climate-resilient decisions.

The fishing industry will receive predictions about expected changes to ocean health and temperatures, which could cause fish stocks to shift.

Aquaculture companies could also benefit from ocean temperature predictions, which would allow them to select sites for marine farms that can withstand future ocean changes, says Bowen.

The research team includes 14 experts from the universities of Auckland, Otago and Canterbury; Earth Sciences NZ; and Australia’s national science agency, CSIRO.