Expected climate change effects in New Zealand
The climate is changing. Increased greenhouse gas concentrations have already started to affect the climate in ways that will take time to reverse. Even if significant global action is taken now to reduce these, a degree of climate change is inevitable in our lifetime. New Zealand, as a country heavily dependent on agriculture and tourism for its revenue, can expect to be affected by even small changes in climate.
We cannot predict exactly what climatic changes will occur in New Zealand over future decades, both because of uncertainties around levels of future greenhouse gas emissions and incomplete knowledge about the processes governing climate and natural climate variability. Changes in rainfall, temperature and sea level will also vary from region to region.
However, the trend of change is well accepted. For example, on average, New Zealand can expect the following climate change effects:
- A rise in sea level. The Ministry recommends planning for the following projection of future sea-level rise:
- For planning and decision timeframes out to 2090–2099, a base value sea-level rise of 0.5m relative to the 1980–1999 average be used along with an assessment of potential consequences from a range of possible higher sea-level rise values. At the very least, all assessments should consider the consequences of a mean sea-level rise of at least 0.8m relative to the 1980–1999 average.
- For planning and decision timeframes beyond the end of this century an additional allowance of 10mm per year be used.
- Average temperatures across the country are projected to increase about 0.9°C by 2040, 2.1°C by 2090.
- More rain is likely to fall in the west of the country and less in the east.
- Extreme weather events (e.g. floods, droughts and storms) are expected to become both more frequent and more intense.
The Ministry for the Environment has developed up-to-date information on climate change impacts for New Zealand by region. It is recommended that councils use this information as a basis for assessing the effects of climate change, unless more detailed local modelling is available.
Further background information on climate change science and the international context is available.
What could climate change mean?
A changing climate is expected to create both opportunities and risks for New Zealand, including:
- agricultural productivity is expected to increase in some areas but there is the risk of drought and spreading pests and diseases. It is likely that there would be costs associated with changing land-use activities to suit a new climate
- people are likely to enjoy the benefits of warmer winters with fewer frosts, but hotter summers will bring increased risks of heat stress and subtropical diseases
- forests and vegetation may grow faster, but native ecosystems could be invaded by exotic species
- drier conditions in some areas are likely to be coupled with the risk of more frequent extreme events such as floods, droughts and storms
- rising sea levels will increase the risk of erosion and saltwater intrusion, increasing the need for coastal protection
- snowlines and glaciers are expected to retreat and change water flows in major South Island rivers.
Both potential opportunities and risks should be considered when making decisions relating to climate change effects.
Climate change effects are expected to affect a number of key local government functions and operations which are outlined in further detail in this guidance note.
Assessment of climate change effects
As a general guide, wherever current climate is significant to an activity, hazard or plan, expected future climate should also be assessed for its impact.
Councils should explicitly consider whether the effects of climate change have significant implications for:
- natural hazard management
- land-use planning;
- the design and location of new infrastructure/assets with a lifetime of more than 30 years.
Of particular importance, given their long-term effect, are decisions relating to:
- housing and infrastructure development in areas prone to natural hazards such as river and sea flooding, erosion, slippage and inundation;
- stormwater system capacity and design;
- water allocation and irrigation in areas prone to drought.
Identification of significant climate change effects
When assessing whether climate change is likely to have a significant impact on a particular activity, hazard or plan, key factors to take into account include:
1 - Duration of activity. Local government decisions have a range of implications in terms of time horizons. Climate change should be considered for all climate-sensitive decisions with a long-term horizon (if the effects of the decision will last 30 years or more). Local government decisions have a range of implications in terms of time horizons. For example:
- Approval for a new development area or a coastal reclamation is effectively permanent.
- A building consent assumes new structures have a life of 50 years but many structures are intended to, or do, last much longer.
- Infrastructure decisions generally assume a 50 to 80-year life, but some can be designed to be built on a staged basis to provide extra capacity in response to climate change over time.
- Decisions on structures in rivers, most coastal structures, and infrastructure that involves regional council consents, have a term of 35 years or less, but in reality their lifetime may be much longer (e.g. significant bridges). Some should be recognised as near-permanent.
- Decisions on land care, biodiversity and pest management strategies may be in the context of a three, five or 10-year strategy, but some decisions may have enduring consequences so a long-term view may be appropriate.
2 - Presence of a particular 'driver'. Climate change considerations are particularly important for infrastructure decisions. Any significant investment should be preceded by a risk assessment that includes climate change implications and a cost-benefit analysis. Climate change effects should be factored in to infrastructure design where the resulting asset 'life-cycle' costs are less than the expected additional costs from premature retirement of the asset or unprogrammed upgrades. In some situations, the design of new infrastructure may 'lock in' resource requirements in a way that makes later upgrading virtually impossible.
Decisions on subdivisions and developments are most usually driven by applications from the private sector. Councils are required to make decisions quickly. But decisions need to be carefully made if there is a high likelihood that climate change effects will exacerbate existing natural hazards. If such factors are relevant, and the council thinks an application has shown inadequate consideration of climate change effects, further information should be sought in preference to proceeding without that information.
3 - Location of activity. Some locations are particularly vulnerable to climate change. Decisions on significant activities near the coast should consider expected sea-level rise over the next century, as well as other consequential effects such as increased coastal erosion and salt water intrusion into aquifers. Development in flood plains should factor in potentially reduced flood return periods and greater peaks.
4 - Extent of activity. Decisions that involve, for example, a single building or a small part of an infrastructure asset (unless the latter constrains the rest of the system) are less likely to have fundamental and long-term implications than decisions that affect larger areas. The exception is where a small development sets a precedent, leading to acceptance of subsequent applications.
5 - Nature of activity. An activity may be affected by a single climate change parameter, or by complex parameters with multiple effects and implications over time. The latter can best be addressed at the policy level, with decision-making applied consistently over time. Relatively general information may be adequate to start policy development and information can be refined over time within a generic policy context. For example, in planning an urban extension, if there are options, low-lying coastal areas should be avoided, and if flood plains are being considered, higher and more frequent floods than in the past should be assumed.
Councils may find it helpful to use a series of 'decision-making steps' of increasing complexity to assess whether climate change is significant for a particular activity, hazard or plan, and how significant its impact might be.
The first step is to identify qualitatively whether a specific activity, hazard or plan could be significantly affected by climate change. Special consideration should be given to activities, hazards or plans which are vulnerable at present to climate and climate variability.
If a potentially significant climate change effect is identified at this stage, a brief quantitative assessment or 'screening' analysis can be undertaken. This consists of considering the expected climate change effect (for example, a rainfall increase of between 2%-10% by 2030) and any other relevant planning variables that may change over the period in question (for example, a projected population increase of 15% by 2030), to develop scenarios in order to test quantitatively the likely significance of climate change. From this screening analysis, further analysis can be made as to whether existing planning provisions and/or hazard management responses have a sufficient safety margin to cover any resulting change in risk or resource availability.
If it appears that existing provisions/responses do not adequately cover the future change in risk, a more complex technical risk assessment can be undertaken, followed by an analysis of response options to manage the risk over appropriate timeframes.
Climate change is not a stand-alone issue. Councils already consider and respond to climate and climate variability as they develop plans, mitigate risks and provide services and facilities to the community. Climate change considerations will therefore not drive or initiate local government action on their own. Rather, they may modify an outcome. It is therefore recommended that, where possible, councils consider climate change within the context of existing resource management, risk-assessment and policy-making processes.
The primary effect of climate change is expected to be in changing the level of risk from weather-related natural hazards. Such hazards are already addressed in district plans and in many regional plans.
Similarly, the methods available to councils to respond to the effects of climate change are generally those contained within the toolbox for natural hazard management. It is expected, therefore, that climate change effects can be assessed and managed through existing hazard management plans and/or other processes which are used to control or manage natural hazards (e.g. s106 of the RMA, s36 of the Building Act, the Long Term Plan process, and other RMA requirements to plan for natural hazards).
Response framework and options
Responses by decision-makers to a changing climate can be classified into eight different categories (also known as 'adaptation measures'). These categories are listed below in descending order from no action to proactive response:
- Bear losses - "Do nothing". The costs of adapting to climate change effects are considered too high in relation to the risk/expected damages.
- Share losses - Work with the wider community to share the costs of any losses (i.e. through private insurance schemes, post-hazard reconstruction and rehabilitation of land)
- Modify the threat - Exercise control over the risk e.g. modify flood prevention works or seawalls.
- Prevent effects - Avoid exacerbating/creating new risks by "down-zoning", increasing restrictions/imposing prohibitions to avoid intensification or commencement of at-risk development, and designing assets to cope with future climate conditions.
- Change use - Encourage or require changes in land use away from high-risk use to uses not susceptible to a changing climate.
- Change location - Direct development away from areas susceptible to a changing climate.
- Research - Support research into new technologies to minimise risks from a changing climate and new methods of adaptation.
Responding to the effects of climate change will involve the planning sections of councils (possibly both policy and consents sections, where these are separate). A number of operational arms within a council may also need to be involved, such as those responsible for:
- Infrastructure and asset management (roading, water supply, wastewater, stormwater);
- Reserves management and planning;
- Finance (particularly where there are likely to be implications for capital or operational expenditure).
Strategically, a regional-local or cross-council approach is the best way to ensure that climate change is adequately considered in line with RMA requirements.
Such inter- and intra-council consideration of the effects of climate change under the RMA can also occur as part of wider planning and programming processes. Coordination will ensure the most effective strategic and cost-effective combination of response actions, including in terms of both public investment and the management of private development.
The principles for guiding the development of strategic responses are:
- Know your community's risks: hazard, vulnerability, and exposure;
- Avoid new development in hazard areas to minimise future losses;
- Locate and configure new development that occurs in hazard areas to minimise future losses;
- Design and construct new buildings and structures to minimise damage to cope with future hazards and pressures on resources, and assess the likelihood and relative importance of future climate change to altering those risks over time;
- Protect existing development from losses through redevelopment, retrofit, and land reuse plans and projects;
- Take special precautions in locating and designing infrastructure and critical facilities to minimise damage; and
- Plan for contingencies (for example, evacuation, progressive retreat)
In the case of a coastal development project, coordination between various council sections is recommended in order to ensure climate change effects are adequately considered in:
- decision-making with regard to the location of public and/or private development
- the development and funding of coastal protection works
- the design of coastal reserves
- the type, design and location of infrastructure such as roading or reticulation systems.
The methods available to councils respond to the effects of climate change are generally those contained within the toolbox for natural hazard management.
There are a number of regulatory methods available under the RMA and through RMA plans, e.g. building setbacks, minimum floor areas and levels, restricted development areas, special zones or management areas, consent processes, and designations.
Outside of the RMA context, councils may use a number of other non-regulatory methods to facilitate consideration of and response to climate change effects. These include:
- Structure and development plans;
- Emergency Response Plans/Recovery Plans;
- Protective works;
- Local authority asset and infrastructure management;
- Community initiatives (for example, coastal dune care programmes);
- Codes of Practice; and
- Integrated input into other plans and strategies
Individually, none of these methods will be fully effective in addressing the effects of climate change and the effectiveness of each method will vary according to the circumstances. An integrated approach, which incorporates a number of these methods, is likely to be needed. The choice of methods that are used will be determined by a number of factors, such as:
- The nature of the hazard (both at present, and in light of expected future climatic conditions) and the level of information available;
- The nature and values of the area (developed vs. undeveloped);
- The assessed level of risk;
- Community expectations and levels of acceptance of risk;
- Costs and benefits; and
- Existing assets in use to mitigate the hazard (for example, seawalls).
Good practice for developing strategic response frameworks for any natural hazard generally includes some or all of the following aspects. They are equally applicable for consideration of climate change effects, which are primarily linked to a changing level of hazard risk:
- Management strategies are an effective way to coordinate and integrate actions on areas that require particular focus, especially where ongoing public investment needs to be coordinated with the regulatory framework under the RMA. Any strategic response can be developed within the framework and context of the broader community outcomes sought through a Council's Long Term Plan, prepared under the Local Government Act 2002.
- Ideally, a strategic management framework should be in place before the review of RMA planning policies. This framework would identify priorities, allocate funding for specific works and programmes, and identify community aspirations, expectations and roles
- A programme of consultation must be undertaken with the community and key stakeholders before instituting changes to RMA Plans. Given the increasing property values the consultation process on this issue is unlikely to eliminate controversy about including climate change effects in the Plan-making process, particularly if there are new restrictions proposed (e.g. coastal setback zones for areas expected to be at risk under a rising sea-level). The strategic management process will provide additional robustness and support for the RMA policy-making process by placing the regulatory framework within a wider programme of action that is put to the community for input.
- Sound technical input should be sourced from experts with knowledge of the expected localised effects of climate change to improve the overall robustness of the policy approach and to address the complexity of the methodologies involved. Technical input may also be useful from other relevant statutory bodies, where appropriate, including regional councils, other territorial authorities, the Department of Conservation, etc.
- The widely-used Hierarchy of Natural Hazards Management Options is a useful tool when considering how to respond to the effects of climate change. The Hierarchy recommends starting with avoidance and preventative methods, moving through to reactive methods, with hard defence mechanisms usually considered to be least preferable. This correlates with the priorities expressed through the New Zealand Coastal Policy Statement, which seeks to avoid the use of hard protective mechanisms as much as practicable.
- An ongoing monitoring programme is key to an effective and responsive strategy to address hazard risk. Even in areas with well-known risks from natural hazards, there is often a lack of comprehensive, long-term information on which to undertake risk assessments and consequentially to develop robust response policies. As climate change can make itself felt over a long period of time, any response strategy to address the effects of climate change should include the development of a regular monitoring programme that can be sustained over the long term.
A risk assessment process is recommended to evaluate the level of risk from coastal hazards under a changing climate. Such an approach could be adopted for developing strategic responses to other forms of natural hazards affected by climate change, including discussions about whether a response is warranted now or can be deferred until later.