NZCCRI Seminar Series: New Zealand’s changing climate Where are we heading in the next 100 years?

NZCCRI Seminar Series: New Zealand’s changing climate Where are we heading in the next 100 years?

Date: 20 August 2015 Time: 12.00 pm

Speaker:  Dr Abha Sood, NIWA Climate Scientist, Climate Variability Group, Greta Point, Wellington

 

The multi-decadal to centennial scale regional climate projections for New Zealand recently completed at NIWA are able to provide valuable climate information for guiding relevant policy issues such as for water management, primary industries, health care and urban infrastructure. The projected global mean temperatures increase over the next hundred years and beyond as a function of anthropogenic radiative forcing as described in IPCC’s 5th Assessment Report (IPCC-AR5). This is also true for the New Zealand region as is seen in the regional climate projections presented here. While the temperatures increase unabated and dramatically a hundred from now for the most anthropogenic forcings (RCPs 4.5-8.5), only for the most optimistic lower end of the forcing spectrum, the temperature increase over New Zealand may halt or even decrease toward the end of the century.

In this seminar, the development leading to NIWA’s Regional Climate Model Projections ensemble for the New Zealand region will be presented. The HadAM3P global atmospheric model was run on NIWA’s supercomputer forced by sea ice and bias-adjusted sea surface temperatures taken from six “best performing” global CMIP5 (Coupled Model Intercomparison Project, Phase 5) models over New Zealand, under each of the four RCPs up to 2120. The lateral boundary conditions from these HadAM3P simulations are then applied to the HadRM3P regional climate model (RCM) thus dynamically downscaled the large-scale circulation to resolve climatic processes over New Zealand’s complex topography at ca. 30-km resolution. The raw RCM output data are bias corrected and further downscaled on a 5 km grid to provide forcing for downstream climate impact models. The changes in mean and extremes of downscaled precipitation and temperature fields are presented and discussed on several time scales ranging from seasonal to interdecadal.