Snow, ice and glaciers in our changing climate

The impact of climate change on New Zealand’s frozen water resources

New Zealand is projected to warm by 1-4°C during the 21st century. This warming will melt our frozen water resources – our snow, ice and glaciers. However, the scale, area and timing of changes to our meltwater are unclear.

Mountain rivers in both the North and South Islands of New Zealand feed our largest hydro-electric power schemes, and provide critical water for irrigation, especially during drought. Melting snow and ice may also cause increased flooding.

Our aim with this research was to make projections about how runoff from New Zealand’s glaciers and seasonal snow will change into the future. We also engaged with iwi and with local authorities to determine the specific needs of communities that utilise water flows. This data is crucial for decision makers in government, communities and industry – all of whom rely on this climate-sensitive resource.

This project brought together, for the first time, New Zealand’s leading snow and glacier scientists. Together we developed computer models to simulate how snow and ice respond to climate change scenarios. We made projections of all New Zealand glaciers, and tested models to make projections of future snow and ice cover and the resultant runoff from alpine catchments. We investigated the future availability of spring and summer meltwater from snow, and probable changes in summer flow as glaciers are lost.

We also looked at extreme weather events, providing some insight into the frequency and likelihood of large snowfall events, for example, or ‘rain on snow’ events which can cause exceptional floods. We aimed to identify the extent to which snow and ice melt might ease the effects of drought, and whether this protective effect will continue in the future.

Improved water projections are essential for the development of climate change adaptation policies that can balance both the financial and intrinsic value of water.