Kiwi climate gives glimpse into future

MATT STEWART
Last updated 13:33 10/11/2012
Sun
PHIL REID/Fairfax NZ
Ozone depletion and mounting greenhouse gas emissions have led to more blustery winds. A $1 million project will track New Zealand's weather-influencing role to help build a climate model.

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Studying the influence of ozone on New Zealand's climate is such a huge task that it will take the supercomputer at the National Institute of Water and Atmospheric Research (Niwa), the Wellington-based FitzRoy, to crunch the numbers.

Through it, researchers have begun to look at simulations of climate data from the early industrial era as part of a new project which aims to forecast our climate through the 21st century with as much precision as possible.

Heading the project is Olaf Morgenstern who, alongside Niwa colleagues, scientists from the University of Canterbury and the Australian Antarctic Division, will collaborate with Britain's Met Office to build a next-generation climate model.

Niwa chief atmosphere scientist Murray Poulter is excited about the project, saying it will "create a highly sophisticated model to help determine the role of ozone depletion and recovery in our future climate".

"The results will provide more information on what causes climate variations in our region. We hope that this will provide more reliable regional climate forecasts."

Backed by a Marsden Fund grant of nearly $1 million over three years, the ambitious project will track ozone chemistry, atmospheric and oceanic currents and the weather-influencing role that is played by New Zealand's rugged topography and the constant climate clash between land and sea.

Morgenstern says in the past few years, Kiwis living near the west coast have been getting used to more and more blustery westerly winds.

Both ozone depletion and mounting greenhouse gas emissions have buoyed these winds, accelerating and drawing them closer to the South Pole, but that trend could weaken or reverse if the ozone hole recovers.

Changes in the force and bearing of these westerlies, and the related storm tracks, hold great sway over the climate, so it's important to understand trends.

"Greenhouse gases affect climate by trapping heat in the lower atmosphere. Ozone is no exception, but unlike, for example, carbon dioxide, its concentration is highly variable, so it affects climate differently."

To better pinpoint climate change on a New Zealand zonal scale, the model will be coupled to a regional climate simulator to monitor nuanced local traits, such as the recent shift towards intensifying southerly winds.

So next time you curse that biting southerly wind, remember that, as the planet warms, the icy blast is one of the factors keeping New Zealand cooler than other nations lying on a similar latitude, such as Chile and Argentina.

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Morgenstern says the southerly phenomenon highlights how global models can fail to reproduce climate change at a regional scale, possibly because natural internal variation is not captured by other models or maybe because climates are not responding to external forces, such as increasing greenhouse gasses.

In this case, he says failure to reproduce regional micro-trends points to one or more problems common to most models, the poor or non-existent representation of ozone depletion being the prime candidate.

Morgenstern says his model will give a better picture of the physics and chemistry of ozone depletion than previous models.

"We propose to test the hypothesis that stratospheric ozone depletion is substantially affecting climate in the southern hemisphere and the New Zealand region, both during the past decades, characterised by a thinning of the ozone layer, and during the remainder of this century, characterised by both a recovery of the ozone layer from man-made depletion and global warming."

Findings will benefit global research, but will be of crucial interest to climate-sensitive sectors of the economy such as renewable electricity generation and agriculture.

- The Dominion Post

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