IPCC identifies climate change impacts & vulnerability for New Zealand

10 April 2007

Water security, natural ecosystems, and coastal communities are the three sectors most vulnerable to climate change in New Zealand, according to an Intergovernmental Panel on Climate Change (IPCC) report finalised in Brussels last Friday.

Changes already observed since 1950 include:

A warming in mean temperature for New Zealand of 0.4 °C;
A decrease in cold nights and frosts by 10–20 days per year;
Sea level rise of about 70 mm;
Loss of at least a quarter of alpine ice mass;
Increased seed production in beech forest.

Referring to New Zealand, the report’s findings include:

As a result of reduced precipitation and increased evaporation, water security problems are projected to intensify by 2030 in Northland and some eastern regions.
Sites at risk of loss of biodiversity include the alpine areas and sub Antarctic Islands.
Ongoing coastal development and population growth in areas such as Northland to Bay of Plenty are projected to exacerbate risks from sea-level rise and increases in the severity and frequency of storms and coastal flooding by 2050.
Production from agriculture and forestry is projected to decline by 2030 over parts of eastern New Zealand due to increased drought and fire. However, initial benefits to agriculture and forestry are projected in western and southern areas and close to major rivers due to a longer growing season, less frost, and increased rainfall. A southward shift in agricultural pests and diseases is likely with New Zealand becoming more susceptible to the establishment of new horticultural pests.

Dr Jim Salinger of NIWA, who was a lead author of the chapter in the report referring to Australia and New Zealand, says: "This chapter is the product of a comprehensive survey of the science since 2001. ’s based on over 550 research studies of what’s happening in Australia and New Zealand. In addition, over 50 independent experts reviewed the chapter."

"The potential impacts of climate change for New Zealand are likely to be substantial without further adaptation. The most vulnerable sectors are natural systems, water security and coastal communities."

"Apart from natural systems, New Zealand has substantial adaptive capacity to cope with small amounts of climate change. This is due to our well-developed economy and strong scientific and technical capabilities. But there are considerable constraints to implementation and there will be major challenges from changes in extreme events and larger amounts of changes in climate," Dr Salinger says.

Key findings – what the report says about New Zealand

NZ & Australia: Adaptation

Planned adaptation can greatly reduce vulnerability.

For Australia and New Zealand, the magnitude of investment in adaptation is far outweighed by that in mitigation [measures to reduce greenhouse gas emissions]. The latter is intended to slow global warming. However, there is unlikely to be any noticeable climate effect from reducing greenhouse gases until at least 2040.

In contrast, the benefits of adaptation can be immediate, especially when they also address climate variability. Adaptation options can be implemented now for Australia and New Zealand at personal, local and regional scales. Enhancing society’s response capacity through the pursuit of sustainable development pathways is one way of promoting both adaptation and mitigation.

Changes since the Third Assessment (2001)

Since the Third Assessment Report, Australia and New Zealand have taken notable steps in building adaptive capacity by increasing support for research and knowledge, expanding assessments of the risks of climate change for decision makers, infusing climate change into policies and plans, promoting awareness and better dealing with climate issues. However, there remain formidable environmental, economic, informational, social, attitudinal and political barriers to implementation of adaptation.

Natural ecosystems

For many natural ecosystems, impacts have limited reversibility. Planned adaptation opportunities for offsetting potentially deleterious impacts are often limited due to fixed habitat regions (e.g. the Wet Tropics and upland rainforests in Australia and the alpine zone in both Australia and New Zealand). One adaptive strategy is to provide corridors to facilitate migration of species under future warming. This will require changes in land tenure in many regions with significant economic costs; although schemes to promote such connectivity are already underway in some Australian states. Another strategy is translocation of species. This is a measure of "last resort" due to cost, but may be considered desirable for some iconic or charismatic species.

Water

For water, planned adaptation opportunities lie in the inclusion of risks due to climate change on both the demand and supply side. In urban catchments, better use of stormwater and recycled water augment supply, although existing institutional arrangements and technical systems for water distribution constrain implementation. Moreover, there is community resistance to the use of recycled water for human consumption (e.g. in such cities as Toowoomba in Queensland, and Goulburn in NSW). Installation of rainwater tanks is another adaptation response and is now actively pursued through incentive policies and rebates. For rural activities, more flexible arrangements for allocation are required, via expansion of water markets, where trading can increase water use efficiency. Existing attitudes toward water pricing and a lack of political will to adjust the structure of the existing system are significant barriers.

Agriculture

For agriculture, there are opportunities for planned adaptation via improvements in crop varieties, rotations, farm technology, farm practices and land use mix. Cropping can be extended to historically wetter regions. Implementation will require new investment and significant managerial changes. Farmers in the eastern New Zealand are engaging in local discussion of risks posed by future climate change and how to enhance adaptation options. They stress the need for support and education for ‘bottom-up’ adaptation. Farming of marginal land at the drier fringe is likely to be increasingly challenging, especially in those regions of both countries with prospective declines in rainfall.

Coasts

In coastal areas, there is solid progress in risk assessments and in fashioning policies and plans at the local and regional level in New Zealand. However, there remain significant challenges to achieving concrete actions that reduce risks. Consistent implementation of adaptation measures (e.g. setback lines, planned retreat, dune management, building designs, prohibition of new structures and siting requirements that account for sea-level rise) has been difficult. Differences in political commitment, lack of strong and clear guidelines from government, and legal challenges by property owners are major constraints.

Barriers to adaptation

Considering all sectors, four broad barriers to adaptation are evident:

Lack of methods for integrated assessment of impacts and adaptation that can be applied on an area-wide basis. Sector-specific knowledge and tools have steadily progressed. However, vulnerability of water resources, coasts agriculture and ecosystems of local areas and regions are inter-connected and need to be assessed accordingly.
Lack of well-developed evaluation tools for assessing planned adaptation options, like benefit-cost analysis, incorporating climate change and adapted for local and regional application.
Ongoing scepticism about climate change science, uncertainty in regional climate change projections, and a lack of knowledge about how to promote adaptation. This despite 87% of Australians being more concerned about climate change impacts than terrorism. Application of risk-based approaches to adaptation (e.g. upgrading urban storm-water infrastructure design demonstrate how developments can be "climate proofed". While a risk-based method for planned adaptation has been published for Australia, there are few examples of where it has been applied.
Weak linkages between the various strata of government, from national to local, regarding adaptation policy, plans and requirements. Stronger guidance and support are required from state (in Australia) and central government (in New Zealand) to underpin efforts to promote adaptation locally. For example, the New Zealand Coastal Policy Statement states that regional councils should take account of future sea-level rise. But there is lack of guidance as to how this should be accomplished and little support for building capacity to undertake the necessary actions. As a consequence, regional and local responses have been limited, variable and inconsistent.

Vulnerability varies between sectors, depending on adaptive capacity

Ecosystems, water security, and coastal communities of the region have a narrow coping range. Even if adaptive capacity is realised, vulnerability occurs for 1.5–2.0 °C of global warming.

Energy security, health (heat-related deaths), agriculture and tourism, have considerable coping ranges and adaptive capacity, but they become vulnerable if global warming exceeds 3.0 °C.

NZ Impacts: Agriculture

Cropping

In New Zealand, for C3 crops such as wheat, the CO₂ response is likely to more than compensate for a moderate increase in temperatures. The net impact in irrigation areas depends on availability of water.

For maize (a C4 crop), reduction in growth duration reduces crop water requirements, providing closer synchronisation of development with seasonal climatic conditions.

Horticulture

Kiwifruit: Warmer summer temperatures for Hayward kiwifruit are likely to increase vegetative growth at the expense of fruit growth and quality. Kiwifruit budbreak is likely to occur later, reducing flower numbers and yield in northern zones. Production of current kiwifruit varieties is likely to become uneconomic in Northland by 2050 because of lack of winter chilling, and be dependent on dormancy-breaking agents and varieties bred for warmer winter temperatures in the Bay of Plenty. In contrast, more areas in the South Island are likely to be suitable.

Apples: are very likely to flower and reach maturity earlier, with increased fruit size, especially after 2050.

Grapes: Earlier ripening and possible reductions in grape quality are likely by 2030. In cooler Australian climates, warming is likely to allow alternative varieties to be grown. With warming in New Zealand, red wine production is increasingly likely to be practised in the south, with higher yields. Higher CO₂ levels increase vine vegetative growth and subsequent shading is likely to reduce fruitfulness. Distribution of vines is likely to change depending upon suitability compared with high yield pasture and silviculture, and with irrigation water availability and cost.

New Zealand is likely to be more susceptible to the establishment of new horticultural pests. For example, under the current climate, only small areas in the north are suitable for oriental fruit fly, but by the 2080s it is likely to expand to much of the North Island.

Pastoral farming

In cool areas of New Zealand, higher temperatures, higher CO₂ concentrations and less frost are very likely to increase annual pasture production by 10 to 20% by 2030, although gains may decline thereafter.

Subtropical pastoral species with lower feed-quality such as Paspalum are likely to spread southwards, reducing productivity, particularly near Waikato.

The range and incidence of many pests and diseases are likely to increase.

Water security problems are likely to make irrigated agriculture vulnerable, e.g. intensive dairying in Canterbury.

NZ Impacts: Coasts

Sea-level rise is virtually certain to cause greater coastal inundation, erosion, loss of wetlands, and salt-water intrusion into freshwater sources, with impacts on infrastructure, coastal resources and existing coastal management programs.

The likely rise in sea-level, together with changes to weather patterns, ocean currents, ocean temperature and storm surges are very likely to create differences in regional exposure. In New Zealand, there is likely to be more vigorous and regular swells on the west coast.

Future effects on coastal erosion include climate-induced changes in coastal sediment supply and storminess. In Pegasus Bay, for example, shoreline erosion of up to 50 m is likely between 1980 and 2030 near the Waipara River if southerly waves are reduced by 50%, and up to 80 m near the Waimakariri River if river sand is reduced by 50%.

Coasts are also likely to be affected by changes in pollution and sediment loads from changes in the intensity and seasonality of river flows, and future impacts of river regulation.

NZ Impacts: Natural Ecosystems

The flora and fauna of Australia and New Zealand have a high degree of endemism (80–100% in many taxa). Many species are at risk from rapid climate change because they are restricted in geographic and climatic range. Most species are well-adapted to short-term climate variability, but not to longer-term shifts in mean climate and increased frequency or intensity of extreme events.

Many reserved areas are small and isolated, particularly in the New Zealand lowlands and in the agricultural areas of Australia. Bioclimatic modelling studies generally project reductions and/or fragmentation of existing climatic ranges. Climate change will also interact with other stresses such as invasive species and habitat fragmentation.

The most vulnerable for New Zealand include alpine areas, isolated lowland habitats, and coastal and freshwater wetlands. Little research exists on climate change for New Zealand species or natural ecosystems, with the exception of the alpine zone and some forested areas.

Major changes are expected in all vegetation communities.

Alpine zones: Reductions in duration and depth of snow cover are likely to alter distributions of communities, for example favouring an expansion of woody vegetation into herbfields. Alpine vertebrates dependent on snow cover for hibernation are likely to be at risk of extinction.

Freshwater: Saltwater intrusion as a result of sea level rise, decreases in river flows and increased drought frequency, are very likely to alter species composition of freshwater habitats, with consequent impacts on estuarine and coastal fisheries.

NZ native forest: fragmented native forests of drier lowland areas (Northland, Waikato, Manawatu) and in the east (from East Cape to Southland) are likely to be most vulnerable to drying and changes in fire regimes.

On the sub-Antarctic Islands, likely impacts include increased mortality of burrowing petrels, increased invasions by disturbance-tolerant alien plants such as Poa annua, increased abundance of existing rats, mice and rabbits on islands, and reduced distribution of Sphagnum moss.

NZ Impacts: Energy

Energy consumption is projected to grow due to demographic and socio-economic factors. However, average and peak energy demands are also linked to climatic conditions.

Increases in peak energy demand due to increased air conditioner use are likely to exceed those for base load, so more peak generating capacity is likely to be needed beyond that for underlying economic growth, and the risk of black-outs is likely to increase. However, annual total demand may be less sensitive to warming as there is likely to be a reduction in winter heating demand counteracting the increasing summer demand, e.g. New Zealand electricity demand decreases by 3% per 1 °C increase in mean winter temperature.

Climate change is likely to affect energy infrastructure in New Zealand through impacts of severe weather events on wind power stations, electricity transmission and distribution networks, oil and gas product storage and transport facilities, and off-shore oil and gas production. There are also likely to be costs and damages that can be avoided by adaptation and mitigation.

Increased westerly wind speed is very likely to enhance wind generation and spill-over precipitation into major South Island hydro catchments, and to increase winter rain in the Waikato catchment. Warming is virtually certain to increase melting of snow, the ratio of rainfall to snowfall, and river flows in winter and early spring. This is very likely to assist hydro-electric generation at the time of peak energy demand for heating.

NZ Impacts: Forestry

The growth rates for plantation forestry (mainly P. radiata) are likely to increase in response to elevated CO₂ and wetter conditions in the south and west of New Zealand. Studies of pine seedlings confirm growth and wood density of P. radiata are enhanced during the first two years of artificial CO₂ fertilization.

Tree growth reductions are likely for the east of the North Island due to projected rainfall decreases.

Uncertainties remain regarding increased water use efficiency with elevated CO₂ , and whether warmer and drier conditions could increase the frequency of upper mid-crown yellowing and winter fungal diseases.

NZ Impacts: Human Health

One of the most significant health impacts of climate change is likely to be an increase in heat-related deaths. In Auckland and Christchurch, a total of 14 heat-related deaths occur per year in people aged over 65, but this is likely to rise to 28, 51 and 88 deaths for warmings of 1, 2 and 3 °C, respectively, assuming no planned adaptation. Demographic change is likely to amplify these figures.

The winter peak in deaths is likely to decline.

There are likely to be alterations in the geographic range and seasonality of some mosquito-borne infectious diseases. Parts of the North Island are likely to become suitable for breeding of the major dengue vector, while much of the country becomes receptive to other less efficient vector species. The risk of dengue in New Zealand is likely to remain below the threshold for local transmission beyond 2050.

Warmer temperatures and increased rainfall variability are likely to increase the intensity and frequency of summer-time (salmonella) food-borne and water-borne diseases.

Impacts on aeroallergens and photochemical smog in cities remain uncertain.

NZ Impacts: Māori

Changes in New Zealand’s climate over the next 50–100 years are likely to challenge the Māori economy and influence the social and cultural landscapes of Māori people.

Some Māori have significant investment in fishing, agriculture and forestry and down-stream activities of processing and marketing, as well as being important stakeholders in New Zealand’s growing tourist industry. Economic performance and opportunities in these primary industries are likely to be influenced by climate-induced changes to production rates, product quality, pest and disease prevalence, drought, fire-risk and biodiversity, which, in turn, will affect the ability to raise development capital in these industries.

While the majority of Māori live in urban environments, they also occupy remote and rural areas where the economy and social and cultural systems are strongly tied to natural environmental systems (e.g. traditional resource use, tourism), and where vital infrastructure and services are vulnerable to extreme weather events (e.g. flooding, landslides).

The capacity of Māori to plan and respond to threats of climate change to their assets (i.e. buildings, farms, forests, native forest, coastal resources, businesses) varies greatly, and is likely to be limited by access to funds, information and human capital, especially in Northland and on the East Coast where there are large populations of Māori and increased risks of extreme weather are likely. Other pressures include:

the unclear role of local authorities with regard to rules, regulations and strategies for adaptation;
multiple land-ownership and decision-making processes can be complex often making it difficult to reach consensus and implement costly or non-traditional adaptation measures; and
the high spiritual and cultural value placed on traditional lands/resources that can restrict or rule out some adaptation options such as relocation.

Many rural Māori also rely on the use of public and private land and coastal areas for hunting and fishing to supplement household food supplies, for recreation and the collection of firewood and cultural resources.

The distribution and abundance of culturally important flora and fauna is likely to be adversely influenced by climate change, so the nature of such activities and the values associated with these resources are likely to be adversely affected, including spiritual well being and cultural affirmation. These challenges compound the sensitivity of Māori to climate change.

NZ Impacts: Settlements, industry, society

Settlements, industry, and society are sensitive to extreme weather events, drought and sea-level rise. Many planning decisions involving settlements and infrastructure need to account for new climatic conditions and higher sea-levels, but little research has been done on climate change impacts. The planning horizon for refurbishing major infrastructure is 10–30 years, while major upgrades or replacement have an expected lifetime of 50 to 100 years. In New Zealand, there are 1.4 million homes valued at about US$0.2 million each, which is equivalent to about triple the national GDP. The average life of a house is 80 years and some last for 150 years or more.

Infrastructure

For infrastructure, design criteria for extreme events are very likely to be exceeded more frequently. Increased damage is likely for buildings (e.g. concrete joints, steel, asphalt, protective cladding, sealants), transport structures (e.g. roads, railways, ports, airports, bridges, tunnels), energy services, telecommunications (e.g. cables, towers, manholes) and water services.

Property values & investment

Climate change is very likely to affect property values and investment through disclosure of increased hazards, as well as affecting the price and availability of insurance. Insurance costs are very likely to rise in areas with increased risk.

Communities

There are major implications for amenities, cultural heritage, accessibility and health of communities. These include costs, injury and trauma due to increased storm intensity and higher extreme temperatures, damage to items and landscapes of cultural significance, degraded beaches due to sea-level rise and larger storm surges, and higher insurance premiums. Increased demand for emergency services is likely.

Climate change may contribute to destabilising unregulated population movements in the Asia-Pacific region, providing an additional challenge to national security. Population growth and a 1 m rise in sea-level are likely to affect 200–450 million people in the Asia-Pacific region. An increase in migrations from the Asia-Pacific region to surrounding nations such as New Zealand and Australia is possible.

NZ Impacts: Tourism

Tourism contributes about 5% of New Zealand GDP and 16% of exports. Most tourism and recreation in New Zealand rely on resources of the natural environment. Few regional studies have assessed potential impacts, but elsewhere there is evidence that climate change directly impacts on tourism.

Some tourist destinations may benefit from drier and warmer conditions, e.g. for beach activities, viewing wildlife and geothermal activity, trekking, camping, climbing, wine tasting and fishing. However, greater risks to tourism are likely from increases in hazards like flooding, storm surges, heatwaves, cyclones, fires and droughts. These adversely affect transport, personal safety, communication, water availability and natural attractions like coral reefs, beaches, freshwater wetlands, snow, glaciers and forests. Changes in species distribution and ecosystems in National Parks are likely to alter their tourism appeal.

Changes in seasonal snow cover are likely to have a significant impact on the ski industry. The snow line is likely to rise by 120–270 m based on seven scenarios for the 2080s. Tourist flows from Australia to New Zealand might grow as a result of the relatively poorer snow conditions in Australia.

Numerical modeling of Franz Josef glacier reveals that temperature is the dominant control on glacier length for New Zealand’s maritime glaciers. Noticeable shrinkage and retreat is very likely for even small temperature increases, and likely to reduce visitor flows through tourism dependent towns such as Fox and Franz Josef.

NZ Impacts: Water

Water supply

Proportionately more runoff is very likely from South Island rivers in winter, and less in summer. This is very likely to provide more water for hydro-electric generation during the winter peak demand period, and reduce dependence on hydro storage lakes to transfer generation into the next winter. However, industries dependent on irrigation are likely to experience negative effects due to lower water availability in spring and summer, their time of peak demand.

Increased drought frequency is very likely in eastern areas, with potential losses in agricultural production.

The effects of climate change on flood and drought frequency are virtually certain to be modulated by phases of the ENSO [El Niño Southern Oscillation] and IPO [Interdecadal Pacific Oscillation].

The groundwater aquifer for Auckland City has spare capacity to accommodate recharge under all scenarios examined.

Base flows in principal streams and springs are very unlikely to be compromised unless many dry years occur in succession.

Flooding

Rain events are likely to become more intense, leading to greater storm-runoff, but with lower river levels between events. This is likely to cause greater erosion of land surfaces, more landslides, redistribution of river sediments, and a decrease in the protection afforded by levees. Increased demands for enhancement of flood protection works are likely, as evidenced by the response to large floods in 2004.

Flood risk to Westport has been assessed using a regional atmospheric model, a rainfall runoff model and a detailed inundation model, assuming the current levee configuration. The proportion of the town inundated by a 1–in–50 year event is currently 4.3%, but rises to 13–30% by 2030, and 30–80% by 2080. Peak flow of the Buller River increases 4% by 2030 and 40% by 2080. In contrast, a flood risk study for Auckland using 2050 climate scenarios with 1–2°C global warming indicated only minor increases in flood levels. Higher flows and flood risk are likely in the Wairau catchment in North Shore City.

Water quality

In New Zealand, lowland waterways in agricultural catchments are in a relatively poor state and these streams are under pressure from land use intensification and increasing water abstraction demands. There is no literature on impacts on water quality in New Zealand.

The above material is excerpted from the final draft of the IPCC WGII Fourth Assessment Report, Chapter 11: Australia and New Zealand. This draft is subject to final editing changes, and is expected be published in full at www.ipcc.ch on 20 April 2007.

Note on Terminology:

Scientific authors of IPCC reports choose their words with care. The following words have a precise meaning:

Virtually certain >99% probability of occurrence, Extremely likely >95%, Very likely >90%, Likely >66%, More likely than not >50%, Very unlikely <10%, Extremely unlikely <5%.

NIWA