In 2023, Cyclone Gabrielle triggered an estimated 800,000 landslides across the North Island, making it one of the most extreme landslide events ever recorded.

New research by Te Whare Wānanga o Waitaha | University of Canterbury (UC) and Earth Sciences New Zealand suggests that under a warmer climate, future storms similar to Cyclone Gabrielle could be even more extreme, triggering tens of thousands more landslides across parts of the North Island, and highlighting the need for targeted planning in vulnerable areas.

Published in Scientific Reports, the study examined landslide hazards in Tairāwhiti and Hawke's Bay under a +2°C warming scenario.

The researchers modelled how many landslides would have been triggered if Cyclone Gabrielle had occurred in this warmer climate.

As well as the number of landslides increasing dramatically, the results suggest these new landslides are likely to occur in areas already prone to slipping, intensifying the hazard in already vulnerable locations.

The research calls for action: map the riskiest slopes, avoid or restrict development there, prioritise funding in known hotspots, and integrate ‘silvopastoral approaches’ — planting trees within vulnerable areas to improve slope stability.

Lead author, UC PhD candidate Livio Dreyer, said the research will empower planning that protects communities in the future.

"By combining landslide observations from Cyclone Gabrielle with climate and landscape data, we were able to build a picture of which slopes are most hazardous and how that hazard could change in a warmer climate. This helps turn complex modelling into information that can support real-world planning."

Study co-author, Senior Lecturer Above the Bar Tom Robinson from UC's School of Earth and Environment, said the research provides a valuable tool for understanding the realities of climate change impacts.

"Cyclone Gabrielle clearly showed us how devastating these storms can be. This research uses the concept of a ‘storyline approach’ to take an event that communities have experienced and ask how it might behave in a warmer climate. That makes the technical aspects of future risk much easier to understand and, importantly, much easier to plan for."

Dr Kerry Leith from Earth Sciences New Zealand said the findings demonstrate the importance of using climate science to inform practical adaptation measures.

"We can't prevent extreme weather events from occurring, but we can reduce their consequences. Identifying high-risk areas and investing in targeted mitigation measures, including appropriate land management and vegetation cover, will help communities better withstand future storms."

The collaborative study, Increasing landslide susceptibility and intensity under climate change for Aotearoa New Zealand, was published in Scientific Reports. UC’s Associate Professor Marwan Katurji and Senior Lecturer James Williams were also part of the research and publication team.