Climate change impacts on land use suitability

Primary production is the backbone of New Zealand’s economy, and
there is an opportunity to bring both challenges together to consider impacts of climate change on land use suitability. Our chief aim was to assess where and how climate change needs to be considered in long-term policy and forecasting trends and variability in agricultural production.

This research projects a significant seasonal shift in pasture production and changes to wine grape flowering across New Zealand under future climate conditions. Long-term adaptation strategies must be adopted at a faster pace across all primary sectors.

Rural New Zealanders are first to experience the most challenging effects of climate change. Farmers and growers are already under extreme pressure from flashpoint climatic conditions in 2020, with drought in Northland and extreme flooding in the south. New Zealand food and fibre producers are used to making tactical adjustments to a variable climate, but a new report suggests long-term strategies to adapt to a changing climate must be adopted at a faster pace across all primary sectors.  

This research will help scientists, regional councils and industry bodies understand the potential impacts of climate change on pastoral, arable and horticultural farm systems, and identify appropriate adaptation measures.

The research provides important data that will underpin user-friendly tools in development that aim to help landowners understand and visualise alternative land use opportunities.

The research used and compared several biophysical models to project future changes in production and impacts on nutrient loss and water demand under different climate scenarios over the next 80 years. The study focused on the Waikato, Hawke’s Bay and Southland – each region represented by one location with two contrasting soils.

The research findings suggest that pastoral farmers will probably see a small increase in overall pasture production in many regions of the country, due to increased carbon dioxide encouraging plant growth, but with a shift in production towards wetter springs and away from dryer late summers. Higher temperatures will pose a greater risk to livestock production, with more days where heat stress may occur.

For perennial crops such as wine grapes, the effect of climate change may require a change in cultivar, to grape varieties adapted to warmer and dryer climates. However, the warmer climate may also open new areas suitable for wine grapes that were previously too cool.

Pressure on fresh water is likely to increase. Extreme rainfall events will increase, leading to more extreme, more variable, more frequent nitrate leaching events. Increased rain during spring may also increase nitrate leaching.  

An increased risk of water shortage, especially in drought-prone regions such as the Waikato and Hawke’s Bay, will put pressure on freshwater ecosystems and require a continuous trend towards more efficient use of irrigation water. For pasture and arable crops, there is a trend towards higher water limitations during spring and summer (especially for the Hawkes Bay). The variability of water demand in Southland is predicted to increase.