New Zealand vulnerable to the threats of climate change – report finds

It finds that climate change, already underway, will almost certainly accelerate this century unless drastic action is taken to reduce global emissions of greenhouse gases.

It identified six areas where global climate change could have significant implications for New Zealand’s prosperity and well-being. These are risks to:

• our coastal margins
• flooding from rivers
• availability of and competition for freshwater
• changes to our surrounding oceans
• threats to unique ecosystems
• flow-on effects from climate change impacts and responses elsewhere, which will affect New Zealand through our strong international connectivity.

Changes expected to impact New Zealand include at least 30cm and possibly more than one metre of sea-level rise this century – the report finds it likely that the sea level rise around New Zealand will exceed the global average, which will cause coastal erosion and flooding, especially when combined with storm surges.

“Many New Zealanders live on the coast and two-thirds of us live in flood-prone areas so we are vulnerable to these projected changes,” says Professor James Renwick, Chair of the Expert Panel who wrote the report. 

Even small changes in average conditions can be associated with large changes in the frequency of extreme events, he says.

“With a 30cm rise in sea level, the current ‘1 in 100 year’ extreme sea event would be expected to occur once every year or so in many coastal regions. Along the Otago coast for example, the difference between a 2-year and 100-year storm surge is about 32cm of sea level.”

Changes in rainfall patterns where the ‘wet gets wetter and the dry gets drier’, together with more frequent extreme events, will put pressure on our housing, infrastructure and industry, especially if changes are rapid, the report finds.

Freshwater resources will also likely be put under pressure, with decreasing annual average rainfall in eastern and northern regions of both islands, plus higher temperatures and increased demand from urban expansion and agriculture.

Fire danger is also predicted to increase in many parts of New Zealand.

Changes in the oceans, including water temperature, acidification and currents will have impacts on New Zealand’s marine life, including aquaculture. On land, existing environmental stresses to New Zealand’s unique species will likely be exacerbated, with increased ranges for animal pests and weeds predicted.

The report also considers New Zealand’s international connections and how trade relationships and migration patterns could change.

Royal Society of New Zealand President, Emeritus Professor Richard Bedford, says the report was sought to provide a clear summary of the scientific evidence and projections of climate change and to identify the key risks these changes pose to New Zealand.

“It is critical to communicate clearly New Zealand’s sensitivities to climate change and the need for responsive systems to address them. All New Zealanders will be affected and must be involved in the discussion. We hope this report can act as a basis for a wider national conversation.”

This report will be followed up soon by another expert panel report on how New Zealand can mitigate the impacts of climate change.

Copies of the report and supporting resources can be found at www.royalsociety.org.nz/climatechange

Key findings – New Zealand’s sensitivities to climate change

Coastal Change: New Zealanders live mainly near coasts

Shoreline ecology, public infrastructure, residential and commercial assets, community values and the future use of coastal-marine resources will be severely affected by changes to coasts due to sea level rise, and storm surge, and secondary effects such as erosion and flooding.

Flooding: many New Zealanders live on floodplains

Damaging flood events will occur more often and will affect rural and urban areas differently. At and near the coast, floods will interact with rising sea levels and storm surges. Increasing frequency and severity of high intensity rainfall events will increase these risks.

Freshwater resources: New Zealanders rely on the availability of freshwater

Increased pressure on water resources is almost certain in future. Decreasing annual average rainfall in eastern and northern regions of both main islands, plus higher temperatures, are projected to increase the frequency and intensity of droughts and the risk of wild fire. At the same time, urban expansion and increased demand for water from agriculture will result in increased competition for freshwater resources.

The Ocean: New Zealand is surrounded by sea

Changes in ocean temperature, chemistry, and currents due to climate change will have impacts on New Zealand’s marine life, fishing, aquaculture and recreation use.

Ecosystem change: New Zealand has unique ecosystems

Over half of New Zealand’s more than 50,000 species are found nowhere else in the world; over three quarters of the vascular plants, raising to 93% for alpine plants, and over 80% for the more than 20,000 invertebrates. Existing environmental stresses will interact with, and in many cases be exacerbated by, shifts in mean climatic conditions and associated change in the frequency or intensity of extreme events, especially fire, drought, and floods.

International Impacts: New Zealand is affected by impacts and responses to climate change occurring overseas

The ways in which other countries are affected by and will respond to climate change, plus commitments New Zealand makes to international climate treaties, will influence New Zealand’s international trade relationships, migration patterns and specific domestic responses. 

Climate Change Implications for New Zealand Panel Members

Professor James Renwick (Chair): Physical Geography Professor, Victoria University, Wellington

Dr Barbara Anderson: Rutherford Discovery Fellow, Landcare Research Manaaki Whenua, Dunedin

Dr Alison Greenaway: Social Researcher, Landcare Research Manaaki Whenua, Auckland

Darren King: Environmental Scientist, National Institute of Water and Atmospheric Research (NIWA), Wellington

Dr Sara Mikaloff-Fletcher: Atmosphere-Ocean Scientist, National Institute of Water and Atmospheric Research (NIWA), Wellington

Dr Andy Reisinger: Deputy Director (International), New Zealand Agricultural Greenhouse Gas Research Centre, Wellington

Dr Helen Rouse: Resource Management Scientist, National Institute of Water and Atmospheric Research (NIWA), Christchurch