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Chapter 4: Effects on Local Government Functions and Services
4.1 Introduction
This chapter provides guidance on identifying which local government functions and activities could be affected by the climate changes and fluctuations identified in Chapters 2 and 3. It lists key climate influences and possible effects of climate change for each of these functions and activities. It provides guidance on data, sources of information, models and specialist expertise in New Zealand which councils can use, along with the climate change scenarios covered by Chapter 5, to quantify the likely magnitude of particular effects. Examples are given of some expected climate change effects from studies carried out in various parts of New Zealand.
The interactions between climate change and local government functions and services are likely to be quite complex, as illustrated through Tables 4.1 and 4.2. Identifying which effects are important in terms of responding now might seem quite a daunting task. However climate change assessments can be broken down into manageable pieces, as explained in Chapter 1, and risk assessment can be used to guide judgements on where to focus adaptation effort (Chapter 6). Practical hints are.
- Staff responsible for a particular council function or service should integrate consideration of climate change into their assessment and planning activities. It is not necessary to address climate change impacts on all functions and services at once.
- Prioritise, by focusing on only those functions and services of importance to a particular council and for which climate change may have a material effect.
- For a particular function or service, start out with a straightforward initial screening analysis using simple initial estimates of how climate factors relevant to this function may change (Chapter 5). It is only necessary to embark on a more detailed effects study if this initial analysis indicates material climate change impacts or opportunities are likely.
Making use of this chapter
This chapter provides resource material to help users follow through the assessment processes outlined in the "roadmaps" in Chapter 1. We recommend reference to Figures 1.1 and 1.2, and to the Risk Assessment chapter (particularly Section 6.4) for background. There are two particular ways in which information from the current chapter can be applied:
(a) When assessing effects of climate change on a particular council function or responsibility (the Figure 1.1 "roadmap"). In this case, examine the entry for this particular function in Table 4.1 and the related entries in Table 4.2, to identify key climate variables and possible climate change effects. Then use Table 4.3 for guidance on sources of information, models and expertise for use in quantifying these effects, in combination with the climate scenario guidance from Chapter 5.
(B) When identifying and prioritising climate change risks and opportunities across all council functions and opportunities (the Figure 1.2 "roadmap"). In this case most of the entries in Tables 4.1 and 4.2 should be examined, as an aid to identifying the council functions possibly affected by climate change and the key climate influences on them. Once the affected functions which are important enough to a particular council to warrant further investigation have been identified, an initial screening analysis can be performed (the fifth box on the left of Figure 1.2), using scenarios from Chapter 5 and information from Table 4.3.
Making use of Tables 4.1, 4.2 and 4.3 is described more fully below.
Making use of Tables 4.1, 4.2 and 4.3
Central to these tables is the link between:
Key climate influence ------------------- Possible effects
Table 4.1 looks at this relationship from the perspective of:
Who Function/asset/activity (primarily of interest to city and district councils)
Table 4.2 looks at this relationship from the perspective of:
What Resource (primarily of interest to regional councils)
Table 4.3 provides useful information for all councils.
Tables 4.2 and 4.3 both help the reader look at the process of analysis:
- Table 4.2 by looking at present and future
- Table 4.3 by identifying who has expertise and what tools could be used.
In using these tables, keep in mind that climate change and its effects should be considered relative to other changes. Climate change will not occur independently of other future changes, including changes due to natural climate variability, and future social and economic changes.
4.2 Links between climate influences and possible impacts
Table 4.1: Local government functions and possible climate change outcomes
View local government functions and possible climate change outcomes (large table)
Table 4.2: Sensitivity of natural resources to present climate and climate change
View sensitivity of natural resources to present climate and climate change (large table)
4.3 Assessing effects - methods, data, sources of information
There are three main approaches in assessing the effects of climate change at regional and local levels in New Zealand:
(1) Modelling approaches. These incorporate computer generated scenarios of climate change. An example is modelling which links historical weather data and information generated from GCMs (translated to New Zealand's situation, see Chapter 2) to a river flow model. This approach can be readily applied within existing models and data used by hydrologists and engineers. A variation on this approach is to draw on historical data (such as past flood events) to determine possible effects in the future (for example, what if floods comparable to those experienced in the past, such as those connected with ENSO or different IPO phases, become more prevalent?).
(2) Expert opinion. This can involve the presentation of plausible scenarios of climate change for your region (Chapters 2 and 3) to knowledgeable people in your region, or national experts to seek their views. In a flooding example, quantitative analysis as in (1) above could be continued with the opinions of experts. In many cases (see Table 4.3), there may be insufficient data and modelling capability, and reliance may have to be placed strongly on expert opinion. For example, local pest management people will have a good knowledge of current pest problems, and will have the capability to provide some 'expert opinion' on the likely effects of climate change.
(3) Monitoring. The real effects of climate change will only emerge through ongoing monitoring. In some cases, it may be the only way that effects can be quantified over time. See Chapter 7.9 for further discussion on monitoring.
When selecting the assessment method, some judgement will be required as to which is most applicable to the problem or issue you are dealing with. Considerable capability already exists for assessing physical impacts - in terms of expertise, data, and quantitative models. For example, there is a strong capability in New Zealand for prediction of river flows in many parts of the country. In general, there is a much lower capability for quantitative assessment of biological and social/human impacts. In areas such as asset management (where investment in infrastructure is required) quantitative modelling is the principal approach. For issues such as biodiversity, a combination of approaches may be used, with monitoring playing a very important role. A broad summary of the capabilities that exist for identifying effects on key local government services and functions is provided in Table 4.3.
4.3.1 Uncertainties and assumptions
Whichever method or approach is chosen, there will be inherent uncertainties or assumptions that are made. These need to be taken account of, along with the uncertainties that presently exist in projections of future climate.
In a study by Lincoln Environmental (see Table 4.4) on the impacts of climate change on water resources, [Lincoln Environmental (2001).] there were key assumptions made with the models that were used. For example, key assumptions made with the river flow model were:
- "There will be no hydrologically significant changes in vegetation (e.g. no major conversions between pasture and forest)", and
- "There will be no new diversion or abstraction of river water (nor any new extraction of groundwater that sustains river flow)".
Table 4.3: Data, sources of information and expertise and assessment capabilities relating to effects of climate change
4.4 Examples of what is known about effects
The following examples demonstrate how the information presented in the preceding tables might be drawn together. The summary information on effects comes from a variety of sources. In the first example relating to water allocation, results from a published study are briefly presented. In the other examples, information on effects is mostly based on the expert opinion of regional council staff. Finally, a brief example of the interrelationships between climate change and climate variability (in this case the IPO) is presented, drawing from an Environment Bay of Plenty study.
4.4.1 River flows and irrigation
Local government function: water allocation for irrigation
Natural resource: rivers
Key climate variables: 30-year time series of daily precipitation, maximum temperature, minimum temperature, dew point temperature, solar radiation and wind run
Climate change effects: reduced river flows possible in eastern New Zealand
Key risk: less surface water available for irrigation
Uncertainty: changes in river flows in catchments that reach into the Main Divide or central North Island are dependent on precipitation changes in these areas, which are uncertain
A recent study for the Tukituki catchment in Hawke's Bay predicted that river flow would generally decrease by 2050 with climate change. Based on the climate change scenarios used, rivers flows would decrease by 20-30% in summer and autumn and by 0-10% in winter. It was concluded that peak irrigation demand could increase by 10% by 2050, but there would not be any change in irrigation days lost (principally because there is already a 100% frequency of occurrence of irrigation seasons with some irrigation time lost). This study was based on mean changes in climate and did not take account of the possible effects of changes in frequency or intensity of climatic extremes. (Source: Lincoln Environmental 2001.)
4.4.2 Erosion and landslides
Local government function: erosion control
Natural resource: land
Key climate variables: intense rainfall events
Climate change effects: increasing frequency of intense rainfall events
Key risk: increased erosion risk
Uncertainty: lack of regional detail
On the West Coast of the South Island an increase in rainfall would also increase the potential for landslides, and potentially landslide dam-break flood events, as occurred in the Poerua River catchment in 1998. (Source: West Coast Regional Council 2002.)
Erosion risk is high over significant tracts of land in Manawatu. For example, 500,000 hectares of hill country is at risk of accelerated erosion in Manawatu. This risk could be exacerbated with any increase in rainfall frequency and intensity. (Source: Horizons.mw 2002.)
4.4.3 Water supply and demand
Local government function: water supply
Natural resource: surface and groundwater
Key climate variables: average rainfall (monthly, seasonal, annual)
Climate change effects: decreased rainfall in the north and east of New Zealand
Key risk: decreased security of water supply
Uncertainty: average decreases in rainfall appear more likely in the east of New Zealand than in the north
Peak daily water demand in Wellington is usually at the end of an extended dry, hot spell of 10 days or more. If such events increase with climate change, then the number of peak days can be expected to increase. (Source: Wellington Regional Council 2002.)
4.4.4 Biosecurity
Local government function: pest management
Natural resource: land
Key climate variables: temperature and rainfall
Climate change effects: increasing temperatures and rainfall changes
Key risk: increased biosecurity threats
Uncertainty: the rate and magnitude of climate change, which remain uncertain, will determine the extent of the problem
Warmer conditions in recent years have highlighted the sort of pest problems that are likely to arise with increased frequency in coming decades. For example, the tropical grass webworm, a wind blown invader from Australia, has decimated all pasture species, in fact anything green, on the Aupouri Peninsula in the far north of Northland in recent years. There are several pest plants currently found in small or not very vigorous infestations in Northland that would become a serious pest, not only in Northland but also through other parts of northern New Zealand, if there were even a slight increase in temperature. (Source: Northland Regional Council 2002.)
Box 4.1: Effects of climate variability
A comment on IPO relationships with river flows from Peter Blackwood, Manager of Technical Services, Environment Bay of Plenty.
IPO is much more strongly correlated than ENSO, particularly to flood flows. Attached are graphs from the December 2000 Environmental Data Summaries showing peak flow for Waioeka, Whakatane and Rangitaiki. These show abnormally large floods during the phase of IPO prior to the mid-1970s and following 1998. The period from the mid-1970s to 1998, on the opposite phase of IPO, was conversely very benign.
Figure 4.1: Annual maximum flow as a proportion of the mean annual flood for the Rangitaiki, Whakatane, Waioeka and Kaituna rivers in the Bay of Plenty from 1950-2000
4.5 Published studies on effects
A number of recent studies and reports that have focused on effects of climate change in New Zealand are given in Table 4. While some of these contain results from quantitative assessments (such as the CLIMPACTS report (Warrick et al 2001) and the Lincoln Environmental study (Lincoln Environmental 2001), the majority are reviews of what is known, drawing from published studies and the knowledge of experts. Thus, in terms of regional and local detail there are many gaps in knowledge, along with the uncertainties that exist with future changes in climate.
Table 4.4: Recent reports on the effects of climate change on New Zealand
| Science reports |
|---|
| The Effects of Climate Change and Variation in New Zealand: An Assessment Using the CLIMPACTS System - Warrick et al 2001 |
| National reports |
| Australia and New Zealand (in Climate Change 2001 - Impacts, Assessment and Vulnerability, IPCC) - Pittock and Wratt 2001 Climate Change Impacts on New Zealand - Ministry for the Environment 2001 Climate Change: Likely Impacts on New Zealand Agriculture - Kenny 2001 Climate Change: Potential Effects on Human Health in New Zealand - Woodward et al 2001 Implications of Climate Change for the Construction Sector: Houses - Camilleri 2000 Linkages Between Climate Change and Biodiversity in New Zealand - McGlone 2001 Planning for Climate Change: Effects on Coastal Margins - Bell et al 2001 Report on some implications of climate change to Department of Conservation activities - McFadgen 2002 |
| Regional reports |
| Climate Change and Land Management in Hawke's Bay: A pilot study on Adaptation - Kenny 2002 Impacts of Climate Change on Agriculture Water Usage and Water Availability - Lincoln Environmental 2001 Meteorological Hazards and the Potential Impacts of Climate Change in the Wellington Region: A Scoping Study - Tait et al 2002 The impact of predicted climate change on hazards in the Auckland Region - Scoping study - Auckland Regional Council 2002 |
| Local reports |
| Impacts of Climate Change on Christchurch - Christchurch City Council 2002 Project CARE: Impacts of Climate Change to the Wastewater Network Strategic Improvement Plan - North Shore City Council, Meritec Ltd and Australian Water Technologies, Sydney 2003 |
Note: Full citations for these reports, including web locations for many of them, are provided in the collated references which are located immediately before the appendices in this Guidance Manual.
4.6 Best practice guidance
It is recommended that:
- Climate change impacts on local government functions and services are considered whenever an asset, consent, resource requirement or service function depends on a climate variable (see column "key climate influence" in Tables 4.1 and 4.2) and its lifetime exceeds 30 years.
- Climate change is considered in the context of a plan review or change, upgrade or maintenance review of an asset or infrastructure, or re-design of a service function, not as an issue on its own.
- Climate change risks are considered in the context of other long-term changes such as population and land-use changes, and long-term community expectations.
