The Intergovernmental Panel on Climate Change (IPCC) is the international body tasked with assessing the science of climate change. Since 1988, the IPCC has informed policy makers on the physical science of climate change, its impacts and future risks, and options for adaptation and mitigation.
The IPCC released its Fifth Assessment Report (AR5) in 2014. The Fifth Assessment Report explores five different Representative Concentration Pathways (RCPs). Each RCP corresponds with a level of radiative forcing (and degree of global warming) by 2100.
The IPCC released its latest the Sixth Assessment Report (AR6) in 2021. The Sixth Assessment Report explores five different Shared Socio-economic Pathways (SSPs) combined with Representative Concentration Pathways (RCPs). These AR6 scenarios are referred to as the ‘SSP-RCP’ scenarios (or the ‘SSPX-Y’ scenarios).
Read more about the IPCC’s Fifth Assessment (AR5) and Sixth Assessment (AR6) scenarios
Downscaled AR5 data
NIWA is a crown research entity that has previously conducted modelling to downscale the IPCC’s Fifth Assessment Report (AR5) climate projections to the New Zealand scale.
‘Downscaling’ is the process of deriving local climate information from a larger-scale model or observational data. The output of the downscaling process is regional level climate projections for New Zealand.
Read the ‘Climate Change Projections for New Zealand’ report (2018) based on the IPCC AR5 data (PDF, 8.2 MB)
Our Future Climate New Zealand is an interactive website designed by NIWA. It gives users the ability to explore climate change projections for New Zealand (based on AR5 data) [NIWA website]
Explore a list of technical reports produced by NIWA [NIWA website] on behalf of local governments. These technical reports provide climate projections specific to certain regions in New Zealand (based on AR5 data).
Downscaled AR6 data
NIWA will also be downscaling the IPCC’s latest Sixth Assessment Report data (2021) to the New Zealand scale. ‘Downscaling’ involves deriving local climate information from a larger scale model. The downscaled AR6 data for New Zealand is due for publication in 2024.
Read more about the NIWA project underway to downscale the IPCC’s Sixth Assessment Report projections for Aotearoa New Zealand [NIWA website]
Read guidance on interpreting the latest IPCC AR6 report findings for Aotearoa New Zealand (PDF, 1.7 MB)
There is one aspect of the IPCC’s latest Sixth Assessment (AR6) projections that have already been downscaled for Aotearoa New Zealand: future sea-level rise.
The NZ SeaRise: Te Tai Pari O Aotearoa programme has published location specific sea-level rise projections out to the year 2300. These projections are based on the IPCC’s latest Sixth Assessment Report (AR6) scenarios.
Maps showing different sea-level rise projections for each scenario are available on the NZ SeaRise website. Be sure to read the limitations and disclaimers provided on the NZ SeaRise website before using these projections.
In the context of creating climate scenarios to test a policy or strategy, climate change projection data for Aotearoa Zealand can be used to:
- align each of your scenarios with corresponding physical climate change data points to help ‘tell the story’
- describe how physical climate impacts play out under each scenario using figures to complement the written narratives
- add credibility to the scenarios by grounding the narratives in climate projection data from a reputable source
Use of Aotearoa New Zealand climate change data for climate risk assessment
Downscaled climate projections for New Zealand (based on the IPCC scenarios) are also used to carry out climate change risk assessments – which are not the focus of this toolkit.
Whereas climate scenarios inform strategy through the use of plausible futures, climate change risk assessments identify risks to things of value in communities due to potential changes in the climate. Risk assessments can help to prioritise risks, driving targeted action and investment.
Read A guide to local climate change risk assessments to understand more about how climate change data is used in the context of climate change risk assessments.
The available climate data for Aotearoa New Zealand, except for the NZ SeaRise sea-level rise data, is based on the IPCC’s AR5 (2014) Representative Concentration Pathways (RCPs). This data will soon be superseded by new NIWA data downscaled from the latest IPCC AR6 SSP-RCP scenarios (expected to be published 2024).
There is complexity and uncertainty inherent in climate modelling and downscaling.
Read about NIWA’s methodology for downscaling the AR5 RCPs in Chapter 2 of Climate Change Projections for New Zealand (PDF, 8.2 MB).
Read more about limitations of the IPCC’s climate scenarios (PDF, 8.1 MB) on which the downscaled data for Aoteaora New Zealand is based.