Marine heatwaves & oceanic changes
New Zealand is surrounded by ocean, and both our climate and our climate extremes (such as droughts, heatwaves, floods and tropical storms) are highly impacted by ocean temperatures. The ocean is also changing rapidly – it’s absorbing more heat, ocean currents are shifting, and we’re experiencing longer and more intense marine heatwaves. The more we understand the pace and scale of these changes, the better we can plan to adapt.
In the summer of 2021-22, we saw one of our most intense marine heatwaves, and our work indicates that this will start to become “normal”. Marine heatwaves kill off corals, disturb ecosystems, pose risks to fishing and aquaculture, and contribute to heatwaves on land and other climate extremes across the country. We are also seeing changes to our oceanic system, with fish and marine species seen further south than ever before.
This suite of research is examining how the ocean system around New Zealand is changing. Using results from the New Zealand Earth System Model, we are currently trying to understand how the highly fertile environment of the sub-tropical front might change. Future changes will determine the locations of fishing hotspots, influence species’ distribution and provide pathways for invasive species. Improved modelling of the ocean system through this research will feed back into global modelling efforts. We are also engaging with other research programmes to make sure climate projections for Aotearoa take into account all current knowledge.
You can find detailed information about the research underway in the drop-downs below.
- 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).
- For some regions, such as southern tip of the South Island, there is a high chance that marine heatwaves start to last more than a year.
- In regards to 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.
- The datasets available through this project range from the complete model variable output (ocean temperature at different depths, horizontal velocities, salinity, etc.) and metrics related to marine heatwaves relevant to research purposes, to locally-specific temperature and heatwave projections most useful for industry members and practitioners. An infosheet describing these datasets and how to access them will be available shortly. In the meantime, please email our Knowledge Broker from more information.
- Salinity variability is more important to the Tasman Box than was previously understood, which impacts how the ocean sequesters heat and carbon dioxide and influences primary productivity.
How you can use this research:
- Fisheries managers and aquaculture companies can measure future risk (e.g. spread of invasive species or nutrient supply), and adjust business strategies (e.g. relocation of fish farms)
- Policy makers can consider these projections for the design of fisheries and ocean policy, quotas, and managing marine protected areas
- Researchers can use this research in impacts studies on marine ecosystems, for example, looking at the future health and distributions of particular marine species
- Policy makers can consider the severity of these findings when setting emissions reductions targets
Who we are engaging with:
- Fishing and aquaculture industry groups and members
- Coastal hapū and iwi researchers investigating local and taonga species
- Fisheries NZ and MPI
- DoC (for marine protected areas)
- Other research programmes such as the Moana Project and NZSeaRise
- NIWA gives dire warning about ‘severe’ marine heatwaves, 1News, TVNZ
- Marine heatwaves forecast to devastate, Otago Daily Times
- Marine heatwaves expected to get longer, hotter and more severe, Stuff
- Why scientists are expecting another ‘crappy’ year for glacier melt, NZ Herald
- Marine heatwaves: Why do they make our seas scorch?, NZ Herald
- Major climate modelling effort captures New Zealand’s exceptional oceanic conditions, leading to better climate simulations, Deep South Challenge
- Narrowing in on Southern Ocean eddies, Deep South Challenge
Both industry and recreational fishers are already noticing changes in the kinds of species that are caught and where. It’s hard to see current fisheries being resilient enough to withstand increases between 80% and 100% of median marine heave wave intensities by the end of the century.Tony Craig, partner with marine consultancy Terra Moana