Executive summary
The Waikato region is a stronghold for the New Zealand primary industries. With agriculture contributing above average levels of the regions GDP when compared to the rest of New Zealand (Keenan, Mackay, & Paragahawewa, 2023). This performance is off the back of strong pastoral farming performance, mostly dairy. The lack of diversity within Waikato’s agricultural land use brings both opportunities and risks.
The climate is changing, we have seen this in the past 10 years, with an increasing number of extreme weather events. The purpose of this study is to investigate the impact of these changes on potential land use to identify opportunities for new land uses and threats to the current land uses.
This study reviews relevant literature and spatially analyses the New Zealand climate projections data set (in ArcGIS) within the Waikato region. This analysis also includes consideration of the versatility of the land as classified by Land use capability (Classes 1-3).
From the literature review, there were some key findings that drove the spatial analysis for this study.
- THI is projected to increase, which may cause heat stress challenges for livestock based land uses.
- Whilst the dataset does not include THI 72 data the proxy hot days has been used to consider this. While this does not give a direct indication of heat stress it does indicate the likelihood of heat stress.
- Cold extremes are predicted to reduce, potentially making way for an increase crop type options.
- A study on the number of frost days has been used to investigate this.
- Nationally drought risk is predicted to increase, however within the Waikato this risk is mitigated by an increase in annual rainfall according to Wang et al (2014).
- Potential evaporation deficit (PED) has been used to indicate drought risk.
The dataset used is taken from the Ministry for the Environment, provided by NIWA as New Zealand’s most up to date climate change projections. Within the dataset there are a number of variables and for each variable there are a number of scenarios. This study looks at;
- Total annual rainfall
- Hot days (days where the maximum air temperature exceeds 25oC).
- Frost days (days where the minimum air temperature is below 0oC)
- Potential Evapotranspiration Deficit (PED)
- Growing Degree Days (GDD)
For each variable this study analysed the baseline period of 1995-2014 versus the following scenarios;
- The sustainability pathway (as defined by the IPCC AR6) – SSP1 – 2.6
- The middle of the road pathway (also defined by the IPCC AR6) – SSP2 – 4.5
Each for both of the future periods of 2021 – 2040 and 2080 – 2099.
- Mean annual rainfall projected change estimates are minimal
- Hot days are projected to increase by up to 61 days by 2100.
- The projected increase in hot days will increase the risk of heat stress for livestock and reduce livestock productivity.
- PED is projected to increase by 2100
- The increase in PED equates to increased likelihood of drought, increasing the importance of growing drought tolerant plants/pastures/trees etc.
- Frost days are projected to reduce.
- Enabling increased productivity for frost sensitive crops and diversification into these land uses.
- Growing degree days will increase.
- Enabling increased productivity and diversity of land uses as more subtropical and tropical species become viable land uses.
Current land use in the Waikato is dominated by livestock based production. This is potentially underutilising some of the high quality soils in our region. The projected change in the climate for the Waikato provides risk to the livestock-based production that we (Waikato) are so reliant on currently, it also provides opportunities for other land uses to be come viable.
Potential land uses this study considered include;
- Berries
- Sweetcorn
- Avocados
- Citrus
- Asparagus
- Peanuts
- Kumara
- Macadamia
Further research into;
- Mitigation options for heat stress,
- Pasture alternatives,
- Barriers to land use change,
- Where potential investment into the value chain should go in the Waikato,
are recommended for next steps.
Download and read the full report here:
