Assessing the implications of sea level rise for lowland agriculture
The Future Coasts Aotearoa research programme aims to support New Zealand to adapt to sea level rise (SLR), while recognising the social, cultural and economic impacts of this change on wellbeing. Many of New Zealand’s valuable farms are located around the coastal lowlands which are highly exposed to SLR. What are the implications for lowlands farming for SLR? To assess this, the Economics of Resilient Infrastructure Tool (MERIT) was applied to identify the expected impacts on different forms of farming across the country. The report offers insights into how economic modelling can inform responses to climate change.
A wide set of socio-economic tools have been used to consider the impact of SLR and adaptation including:
- Systems mapping to explore how community wellbeing is impacted by change
- Serious games to explore management options and trade-offs across people when responding to sea level rise
- Real Options Analysis to weigh the costs, risks, and timing of alternative climate adaptation strategies
- Agent-based modelling to consider the ways in which different sets of people may respond over time to different policies and resource constraints.
This combination of tools is intended to ensure that one single impact (e.g., economic) does not dominate discussions, and to enable a balance of environmental, cultural, and social perspectives.
What is the MERIT model?
MERIT is a collection of models that can be used to investigate future changes in the New Zealand economy. It can be used to determine the flow-on and wider economic implications that occur to an economic system, given some type of direct impact or change to that system.
The use of the MERIT model in Future Coasts Aotearoa research
MERIT was used to assess the economic impacts of sea-level rise (SLR) on New Zealand’s coastal lowland agriculture. The assessment employed a national-scale case study, focusing on pastoral farming (dairy, sheep and beef) within rural coastal lowlands identified as vulnerable to inundation.
To achieve the assessment, a new Natural Capital and Inundation Module was developed that enables MERIT to simulate farm-level responses to sea level rise – including adaptation decisions and land use.
Findings
By the year 2080, analysis indicates that the direct economic impacts of SLR on pastoral farming are between $11.7 million and $19.5 million per year, depending on the SLR scenario considered. The impacts are not evenly felt over the country or among economic sector, with the dairy cattle farming industry modelled to experience losses approximately four times greater than sheep and beef farming, and approximately 28% of the impact is in the Waikato region.
Presently, the most severe impacts of sea level rise is already managed within existing drainage and defence schemes. Analysis suggests that only substantial increases in drainage costs would be likely to trigger significant changes in land use or scheme abandonment.
Limits
While helpful in identifying the economic impacts on agriculture across sectors (dairy farming, sheep and beef farming) and across the country, not all economic impacts can be captured at this point. For example, the study excludes smaller high-value intensive uses, such as horticulture, suggesting the total economy-wide flow-on consequences are likely underestimated for coastal agriculture. It also concentrates on measuring the overall or general trajectory in pastoral agriculture production but does not measure costs to repair/replace assets lost or damaged during episodic inundation (to some extent these losses will be covered by insurance).
Download
Rising Sea Levels and Agriculture in New Zealand. A new Natural Capital and Inundation Module for MERIT and application to a national case study. Technical report for the Future Coasts Aotearoa Research Programme. (May 2026). m.e research.