Massive waves at St Clair Beach, Dunedin, may become a more
common sight as the sea level rises. Photo by Stephen
While Otago and Southland's agricultural sector could
benefit from higher rainfall and warmer winters, the region's
coastal environments will be at risk from greater erosion and
storm events, Niwa climate scientist Dr Andrew Tait says.
Dr Tait, along with AgResearch scientist Dr Paul Newton and
New Zealand Agricultural Greenhouse Gas Research Centre
scientist Dr Andy Reisinger, were the lead authors of a
chapter on New Zealand and Australia in the Intergovernmental
Panel on Climate Change's Fifth Assessment Working Group 2
report released in Japan yesterday.
''It's a wake-up call.''
The report highlighted where signs of climate change
impacting on the environment were being seen and predicted
what the impacts were going to be as the climate continued to
be affected by increasing concentrations of CO2 and other
greenhouse gases in the atmosphere, he said.
Temperatures were predicted to increase by 2degC, depending
on what inroads into reducing greenhouse gases were made.
Drought was expected to increase in frequency, even in
Southland and Otago, and flooding was predicted to have a
serious impact in some places as big storm events increased
''The big ones will be even bigger. A 1-in-50-year could
become a 1-in-20-year time frame by the end of the century.''
This would create a real risk to coastal infrastructure and
create a need for communities to be well equipped if bigger
floods come downstream, Dr Tait said.
Sea level rise of 0.5m to 1m was predicted, again depending
on the reduction of greenhouse gas emissions, and if those
reductions were not made the rise might be greater.
As a result, a lot more thought needed to be put in, not just
at a local government level, at how coastal infrastructure
and the country's ecosystems were going to be protected, he
At present, the Government provided guidance on climate
issues while local government was charged with policy and
University of Otago geography department senior lecturer Dr
Daniel Kingston said the report's predictions of increases in
the strength of the prevailing westerly winds would mean
inland and southern areas of Otago would see an increase in
rain, primarily in winter and spring, and mostly in South
Otago and inland towards the Southern Alps.
The expected changes would be good and bad for the region,
such as reduced winter heating needs, but increased fire risk
in summer, he said.
''The temperature-driven decrease in snow/increase in
rainfall will be beneficial for hydropower generation in the
short term, but the longer-term decrease in meltwater from
snow and glaciers would increase vulnerability.
''Reduced winter snow will also mean more a greater reliance
on snow-making machines for the ski industry.''
While higher temperatures in Otago would better suit
conditions for pine forest growth, it would also be good for
pine disease and pests, he said.
Otago Regional Council engineering, hazards and science
director Gavin Palmer said the council had been including
climate change considerations into its work for many years.
''This reinforces the need for such things. With this
information, we'll review what we are doing and have
The regional council was working with the Dunedin City
Council on its district plan review to ensure inclusion of
Also as part of its regional policy statement review it was
working with other councils in Otago to ensure climate change
information was considered.
''We are taking it seriously.''
It was also including climate change considerations in
upgrades of its flood protection infrastructure such as its
recently commissioned Waipori pumping station.
• Rising snow lines, more frequent hot extremes, less
frequent cold extremes and increasing extreme rainfall.
• Annual average rainfall expected to decrease in the
northeast South Island and northern and eastern North Island,
to increase in other parts of New Zealand.
• Regional sea level rise likely to exceed the historical
• Rainfall changes projected to lead to increased run-off in
the west and south of the South Island and reduced run-off in
the northeast of the South Island, and the east and north of
the North Island.
• Annual flows of eastward flowing rivers with headwaters in
the Southern Alps projected to increase in response to higher
• Flood risk projected to increase in many regions due to
more intense extreme rainfall caused by a warmer, wetter
• 50-year and 100-year flood peaks for rivers in many parts
of the country will increase, with a corresponding decrease
in return periods for specific flood levels.
• Flood risk near river mouths will be exacerbated by storm
• Very high and extreme fire weather in many, in particular
eastern and northern, parts of New Zealand will increase
• Fire season length will be extended in many already
high-risk areas, reducing opportunities for controlled