Providing climate change advice for New Zealand
National-scale climate change projections
Following the release of the Fifth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), in 2016 NIWA developed national-scale climate change projections for the Ministry for the Environment. These projections were updated in 2018 with the addition of results from a report on very extreme rainfall (the HIRDS report; Carey-Smith et al., 2018).
Regional variation in climate change impacts across New Zealand
The impacts of climate change will vary across different parts of New Zealand. For example, the west coast of the South Island is projected to experience more rainfall than at present, while the east of the South Island is projected to experience reductions in rainfall. Similar variations are expected for other aspects of climate – such as average temperatures, hot days, frost days, humidity and wind.For this reason, regional-scale climate change projections can be more useful for New Zealand's local and regional councils. Regional-scale projections can help with assessing local risks from a changing climate and preparing communities for future impacts.
Regional-scale climate change projections
NIWA has provided regional-scale high resolution (5 km x 5 km) maps and detailed reports to five New Zealand councils – Northland Regional Council, Auckland Council, Bay of Plenty Regional Council, Horizons Regional Council, Greater Wellington Regional Council, Tasman District Council, Environment Canterbury, Otago Regional Council, and the councils of Southland (see links at the bottom of this page). A report for Gisborne District Council and Hawke’s Bay Regional Council is underway (as of mid-2020).
These maps show projections for a large range of climate variables at 2040 and 2090 and for two different climate change scenarios (based on what happens with greenhouse gas emissions in the future).
Along with descriptions of the projected future changes to different climate variables, these reports have been tailored to each region following discussions about sectors of concern. These may include impacts of climate change on aspects including biodiversity, biosecurity, river flows, aquaculture, agriculture, storm surges and groundwater, among others. Climate variables that were mapped include temperature, precipitation, wind, humidity, soil moisture, and solar radiation. Indices and threshold information has also been produced (e.g. changes to the numbers of ‘hot days’ or days above 25 degrees per year). GIS layers of the climate projections have also been provided so that the councils may use them in their planning processes.
Find out more
You can read more about climate change scenarios under the IPCC’s Fifth Assessment Report and NIWA’s work in developing national-scale climate change projections.