A Mean Heat


How the climate is driving marine heatwaves

A Mean Heat - how the climate is driving marine heatwaves, a constant change seminar by the Deep South Challenge

In collaboration with the Sustainable Seas Challenge, we bring you this online seminar with Erik Behrens (NIWA), Tony Craig (Terra Moana) and João De Souza (Moana Project)

Anyone who’s been in the water this summer will have felt that things are heating up. Swimmers are talking about how the ocean is uncommonly warm and fishers are catching sub-tropical species further south than ever before. We’re on the tail-end of a marine heatwave, and new research tells us these are going to get longer and stronger.

Marine heatwaves are already becoming a common experience for New Zealanders. In newly released research, scientists say that by 2100, the 40-odd marine heatwave days we currently see in a normal year will increase to between 80 days (low emissions, best-case scenario) and 170 days (high emissions, worst-case scenario) by the end of the century. For some regions, such as the southern tip of the South Island, there is a high chance that marine heatwaves start to last more than a year.  

The research also explores the intensity of future marine heatwaves, or just how warm they will be. For coastal waters, average marine heatwave intensities will increase by 20% (best case) to 100% (double, worst case) by the end of the century. For the North Island, this means an average marine heatwave could be between 0.5°C to 2°C more intense than they are today.

Research lead Erik Behrens (NIWA) says that the chance of marine heatwaves becoming a permanent fixture is worrying.

“Marine heatwaves kill off corals, disturb ecosystems, and can also pose a problem for fishing and aquaculture, as well as contributing to land heatwaves and climate extremes across the country.”

In this seminar, Erik will take you through his research into “Marine heatwaves and the link with climate extremes,” alongside insights on what it means for our fisheries and marine ecosystems from Tony Craig (Terra Moana) and João De Souza (Moana Project).

A recording of this seminar will be available on our YouTube channel in the days following this seminar. Please subscribe to our newsletter to stay up-to-date.


Erik Behrens

Erik is an ocean modeller with expertise in developing high resolution nested earth system models. As part of the Deep South Challenge he developed a nested model for the New Zealand Exclusive Economic Zone (NZEEZ) to improve the representation of the oceanic circulation around NZ and, therefore, climate projections.

Tony Craig

Tony Craig is a project lead for the Sustainable Seas Challenge investigating risks to rural pāua fishery infrastructure from climate related sea-level rise and storms. He is a partner at Terra Moana and has a depth of experience in fisheries and marine management.

João De Souza

João is a physical oceanographer with vast experience in hydrodynamic ocean modelling and is a recognised expert in data assimilation modelling. João currently works as Science Manager at MetOcean Solutions, and is the Moana Project Science Lead. The Moana Project's goal is to revolutionize ocean observing and modelling in New Zealand to support the Blue Economy. The project has been investigating the drivers of marine heat waves around the country, and different strategies to forecast them.