The models combined climate hazards, like heat and extreme rainfall, with the vulnerability of specific crops and farm systems.

They show increased risks of animal illnesses like facial eczema and parasites, droughts affecting pasture, and erosion due to storms, especially in the North Island. In general, suitable areas for crops will move south.

Scientists at Manaaki Whenua - Landcare Research worked closely with researchers from NIWA, AgResearch and Plant & Food Research to model the likely risks of a warming climate across different agricultural sectors in New Zealand. The results – which broadly indicate that current crop ranges move south, and animal health issues intensify and also move south – are available as geographical information systems (GIS) layers for download at the Whitiwhiti Ora Data Supermarket.

To create the maps, a set of models ranging in complexity were developed to outline risks and opportunities for arable, horticultural and pastoral land uses. The models combined an overall assessment of climate hazard events such as heat stress and extreme rainfall with the vulnerability of specific crops and farm systems to these hazards.

Four different scenarios of future greenhouse gas emissions were modelled, including a worst-case scenario of a global mean temperature increase of as much as 4 degrees C by 2100.

Results from the modelling – which are available off-the-shelf at the Data Supermarket – include the following likely changes:

• Heat stress may become more of an issue for the arable sector, especially for wheat farming areas, although rising temperatures and fewer frosts may bring new opportunities to crops such as onions, peas and potatoes in some areas.
• Cool-climate grape varieties may be able to move south, but grape ripening times will move closer together across the country, which might complicate harvest schedules.
• Pasture yields may increase, but also intestinal parasites and facial eczema in livestock may spread further in a warming environment, even under the most conservative climate change scenario.
• There will be more mass movement and erosion of soil, particularly in New Zealand’s soft-rock hill country, driven by increasing storm magnitude and frequency.

“The new maps are a powerful step forward in understanding and displaying the effects of climate change for the primary sector in New Zealand,” says Manaaki Whenua researcher Dr Linda Lilburne, “but there are still many questions to answer, especially about the timing of hazards or opportunities in the future. For example, are droughts becoming more frequent or longer, or will increasing pasture production mean that high-country farms are better able to finish their lambs?”

To address these questions, the researchers suggest that work is now needed with farm systems scientists and agricultural experts to develop detailed interpretations of the climate change impacts for a range of different farm types, locations and commercial interests. This research will also help the agricultural sector with future adaptation planning and developing resilience to climate change.