Future Extreme Weather in Aotearoa/New Zealand

Deep South National Science Challenge

The aim of the research is to provide comprehensive information to New Zealanders on how we expect climate, and in particular climate and weather extremes, to change in the coming decades. Research outputs will assist New Zealanders in building their capacity to adapt to climate changes ahead, and guide planning and policymaking, including that related to climate change mitigation.
While it is known that we anticipate gradual shifts towards a generally warmer climate in most parts of the world, including Aotearoa New Zealand, it is likely that the impacts of climate change will be most keenly and immediately felt through the changes in climate extremes – of rainfall, temperature and windiness primarily. Along with many parts of the world, New Zealand is vulnerable to the damage inflicted by flooding and extreme wind. Between 2007 and 2017, insured and economic losses due to flooding and drought totalled more than $4.7bn, of which approximately $840m was estimated as attributable to human influence on climate.

New Zealand is also particularly vulnerable to the impacts of extreme rainfall on transport networks: the country depends critically on a relatively skeleton roading infrastructure which can easily suffer devastating impacts if blocked by landslide or flood, with severe consequences for transportation and economic losses as a result.
A deeper, more comprehensive picture of how some of the most potentially damaging extreme weather events might be expected to change in the future across the whole nation is an expected key outcome of this project. This project will contribute to the Mission of the Deep South National Science Challenge (NSC) by providing the general public and key stakeholders with information they can use to plan for changes in the severity and frequency of some of the rarest, and most intense, extreme weather events.

The objective of the project is to produce a novel data set of future climate and weather extremes, for use by stakeholders and other researchers, that provides national-scale information for Aotearoa New Zealand using an unprecedented amount of climate model information.
The project team will create new very large data sets of the ‘weather@home Australia/New Zealand’ regional climate model sufficient to simulate and count very rare weather extremes. We will apply statistical fits to these data sets, test how well these fits perform, and then subset the large data sets to mimic the smaller data volumes typically obtained from other climate models, including the New Zealand Earth System Model.
This will help us to extract as much information as possible from these smaller data sets and enable us to compare different models. We will communicate the results in a new way, seeking to describe expected future climates in terms of climates that may already exist today but in other locations.
We will inform and consult with the general public regarding our findings and encourage their participation in climate change science via the ‘weather@home’ project, which allows anyone to run a climate model and depends on their doing so.