Research Aim 1

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Improving Climate Projections

Improving Climate Projections will update and improve processes to generate regional-scale projections of New Zealand climate trends & variability to 2100 and maximise their utility and relevance for impact modelling. This research will principally occur in Years 1 and 2.

Leadership of Research Aim 1:

Primary Support:


NIWA and Bodeker Scientific will combine validated data from the National Climate Database, output from NIWA’s core-funded regional climate modelling, and the latest global modelling from the CMIP5 activity in support of the IPCC 5th assessment report (AR5), to develop downscaled projections over New Zealand for a range of climate variables that are consistent with global trends. Improved climate projections will be packaged into formats relevant for:

  • Modelling (RAs 2 & 3)
  • Enhanced Decision-Making (RA4)
  • Scenario Development (RA5)

Key Questions

  • How can we best use the most up-to-date global climate models currently being run for the IPCC AR5 to develop regional-scale climate projections?
  • How can climate modelling innovations (i.e. multi-model ensembles, probabilistic information) improve climate projections, especially variability in extremes or frequencies of high impact events?
  • What can climate modellers do to maximise the utility of climate projections for modelling (RAs 2 & 3) and scenarios (RA4) and the relevance to evidence-based decision making (RA5)?

Key Results

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  • Over 35 TB of global climate data were downloaded from the Coupled Model Inter-comparison Project (CMIP-5) data repository from over 40 General Circulation Model (GCM) runs, performed for the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5).
  • The six best-performing GCMs for the New Zealand region were selected, based on comparisons with observations over the historical data period of the models. These models are: HadGEM2-ES (UK), CESM1-CAM5 (USA), NorESM1-M (Norway), GFDL-CM3 (USA), GISS-E2-R (USA) and BCC-CSM1.1 (China). Each of these models performs better than the 12 CMIP-3 models used previously for New Zealand climate change assessments.
  • Sea surface temperature (SST) data from these six GCMs were bias-corrected and, together with a global atmospheric GCM, were used as initial and boundary conditions for the higher spatial resolution (~27km) NIWA Regional Climate Model (RCM). Temperature and precipitation data from the RCM were bias corrected using the Linked empirical Modelled and Observed Distribution (LeMOD) correction method and all climate variables and indices were further downscaled to the ~5km grid of the Virtual Climate Station (VCS) data. Contact climate-enquiries@niwa.co.nz to learn more about accessing these data.
  • The Ensemble Projections Incorporating Climate (EPIC) model uncertainty method was developed to generate large ensemble projections of maximum and minimum temperatures at daily resolution for all of New Zealand, out to 2100. These data can be used to generate probability density functions (PDFs) of future maximum and minimum temperature. Contact jared@bodekerscientific.com to learn more about accessing these data.
  • The New Zealand-downscaled GCM and RCM data have been analysed and the results presented in a comprehensive report for the Ministry for the Environment (available here).
  • Maps of projected climate changes have been produced for several variables, with the temperature and precipitation maps available for each of the six GCMs and the 6-model-average, via Our Future Climate New Zealand. The OFCNZ tool also allows users to view time series charts of changes in temperature and precipitation for 15 locations around the country.
  • The Future Extremes web page has also been developed. This tool allows the user to select any location in New Zealand and the variable of interest (hot days, frosts, hot spells or cold spells), the emissions scenario, and whether the results should be shown as probabilities, number of events per year, or number of events per decade.
  • The CCII RA1 climate dataset is a landmark dataset that will be used by multiple researchers and stakeholders for many years to come, to produce a consistent baseline of knowledge on climate change impacts and implications for New Zealand.

Click here to download a full copy of the RA1 Synthesis Report.

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