Climate change is increasingly threatening New Zealand’s coastal farms through the combined effects of slow-onset changes such as sea level‑driven groundwater rise and more frequent extreme weather events. Together, these shifts raise flood risks and cause persistent waterlogging of soils, reducing pasture health and pushing farm profits downward over time.
The study in the Future Coasts Aotearoa programme found that without changes in management, coastal lowland farms may remain marginally profitable up to year 2100, but earnings would steadily decline - especially in low lying areas where groundwater is already close to the surface. Profitability could remain positive in the future due to the high value of farming. Nevertheless the analysis shows that greater profits might be secured through adaptation. Adaptive responses and acting sooner rather than later could make a substantial difference to long-term economic outcomes.
Possible adaptive responses
To explore how farmers might respond, we developed a conceptual framework combining expert insights and practical on-farm considerations. Thirteen potential adaptation strategies were evaluated, ranging from short-term “absorptive” measures such as wintering stock off-farm, to “adaptive” investments like upgraded drainage, pumping systems, or water-tolerant pasture species. More transformative options included converting portions of farmland to wetlands, salt marshes, mangroves, or other alternative land uses such as solar energy.
Notably, pathways involving mangrove restoration delivered the largest apparent benefits because they provide valuable ecosystem services. However, these benefits currently offer little direct income to farmers, since wetlands are not included in New Zealand’s emissions trading scheme and payments for the wider ecosystem services they provide is not readily available. If wider wetland restoration and ecological enhancement is desired, new incentive or cost-sharing mechanisms such as biodiversity credits, would be needed.
Considerations for the future
Our research shows just how much money is at stake for coastal dairy farms depending on how they respond to climate change - whether it’s quick fixes, bigger upgrades, or even completely changing how the land is used. What really matters is timing: as the climate keeps changing and things get tougher for farmers, acting sooner rather than later is key.
We also need smart policies that put a price on the important work coastal wetlands do for everyone’s well-being - not just farmers, but communities and the environment too. If we start valuing these natural benefits in today’s dollars and cents, it will help farmers make better decisions, reduce future risks, and plan for the long haul.
Without these kinds of policies and incentives, the best changes for our land and climate might end up out of reach for many farmers, especially as we head towards end of the century.
For more information:
Holland, P., Qu, Z., Etheridge, Z., Rautenbach, C. and Tanner, C.C. (2026) A Risky and Potentially Costly Future: Implications of Climate-Induced Changes in Groundwater and Flooding for Coastal Dairy Farming in New Zealand. Land, 15(2), 341. https://doi.org/10.3390/land15020341
Adaptive Futures Conference 2025 poster presentation: Planning for change – managing coastal realignment in pastoral landscapes in the face of sea-level rise-induced rises in groundwater and flood risk [PDF 1.9 KB].