Outlooks

Mō ngā uri whakatipu

In this section, for the first time in reporting, we have used structured analytical techniques to produce assessments about the outlook for our climate and atmosphere based on international and domestic evidence. This represents an important shift in our approach to environmental reporting. The shift is away from a focus on what has happened towards the inclusion of assessments about what may happen in future, to improve public awareness of issues and decision-making.

The future will always be uncertain. For this reason, the assessments in this section should not be read as statements of fact but as assessments of what may occur based on what we know now. To support this, we have used expressions of likelihood and confidence to help in interpretation. This ensures we can make assessments about current and emerging issues even when our confidence in them may be low due to the limitations of the evidence base. Expressions of likelihood are underlined in the text. Footnotes at the base of each page provide the associated quantitative values. Expressions of confidence, which give an indication of the reliability and level of corroboration of evidence used in an assessment, are presented in brackets at the end of each assessment (see appendix B, for further explanation).

Those familiar with the Intergovernmental Panel on Climate Change (IPCC) approach to climate outlooks will notice the expressions of likelihood and confidence in this section (while similar) represent a departure from that framework. The approach taken here recognises the need for Aotearoa New Zealand’s environmental reporting programme to align its outlooks assessment language with that used by other government departments, to support effective cross-agency decision-making. It also acknowledges the need for an assessment approach that can be applied across all environmental domains and knowledge systems, including mātauranga Māori (Māori knowledge). Importantly, the evidence and analysis produced by the international community and IPCC on climate change, along with other domestic evidence and knowledge, has been incorporated into the assessments contained here.

To support the development of assessments contained in this section, assumptions were required to be made about the future across a spectrum of issues. To ensure alignment with the international scientific community, the assumptions contained in the Shared Socioeconomic Pathway 2 (SSP2-4.5) were used, because they represent an intermediate pathway consistent with historic patterns of behaviour (Riahi et al, 2017). The scenario narrative and assumptions for SSP2-4.5 are that:

• the world follows a path in which social, economic and technological trends do not shift markedly from historical patterns
• development and income growth proceed unevenly, with some countries making relatively good progress while others fall short of expectations
• global and national institutions work toward but make slow progress in achieving sustainable development goals
• environmental systems experience degradation, although improvements occur and, overall, the intensity of resource and energy use declines
• global population growth is moderate and levels off in the second half of the century
• income inequality persists or improves only slowly and challenges to reducing vulnerability to societal and environmental changes remain.

The evidence in this section shows we have already had a profound impact on our climate, and the underlying drivers behind these changes are not evolving at the rate required to meet Paris Agreement targets. This means we should expect these impacts to become more significant and observable over time. In some contexts, impacts might present as slow and weak background signals that we do not notice in our day-to-day lives until they manifest in a significant event, such as species extinction. In other contexts, such as severe weather, impacts may be abrupt, severe and short-lived but profoundly affect our safety, security and economic wellbeing. Lowering global greenhouse gas emissions is the most effective way of reducing these risks.

It is also highly likely we will exceed the aspirational goal of limiting global warming to 1.5 degrees Celsius by 2040 (moderate confidence) 

• The IPCC Sixth Assessment Report (AR6), Summary for Policymakers states that policies implemented by the end of 2020 are projected to result in higher global greenhouse gas emissions in 2030 than emissions implied by Nationally Determined Contributions (NDCs) (IPCC, 2023).
• The IPCC AR6 estimates that following current trajectories for greenhouse gas emissions will result in a best outcome of temperature increase ranging from 2.1 degrees Celsius to 3.5 degrees Celsius by 2100. Major reductions in global greenhouse gas emissions would be required to meet current temperature targets (Armstrong McKay et al, 2022; IPCC, 2023).
• The average global surface temperature between 2011 and 2020 was 1.09 degrees higher than between 1850 and 1900 (IPCC, 2023). Current trajectories will result in a best outcome of average temperatures ranging from 1.2 degrees Celsius to 1.8 degrees Celsius by 2040 (IPCC, 2023).
• Increasing global temperatures increase the chance of triggering climate tipping points, at which time some large-scale environmental changes will become irreversible (Armstrong McKay et al, 2022; Wang et al, 2023).

* The likelihood of this occurring is between 75 percent and 85 percent. 

• Based on Aotearoa New Zealand’s existing policies and measures, our gross emissions are projected to steadily decrease by 27.6 percent between 2020 and 2050 (MfE, 2022).
• Projected emissions reductions across all sectors are driving the projected decrease in gross emissions (Bodeker et al, 2022).
• The land use, land-use change and forestry sector offset around 30 percent of gross emissions in 2022, and this is projected to continue out to 2050 (New Zealand Treasury, 2023b).

* The likelihood of this occurring is between 55 percent and 70 percent.

• How changes in climate may vary across the country in the future is uncertain. This uncertainty is increased by patterns of natural variability, such as the El Niño Southern Oscillation, Southern Annular Mode and mid-latitude jet stream, which have a strong influence over Aotearoa New Zealand’s climate (Bodeker et al, 2022; IPCC, 2021).
• Aotearoa will warm at a slightly slower rate than the global average because of the influence of the ocean on our regional climate, but we will experience increased average air temperature over land and sea across the course of the century. The level of warming depends on global emissions pathways (Bodeker et al, 2022).
• Compared with recent decades (1995–2014), an increase in average air temperature over land and sea, in the range of +1 (0.60 to 1.32) degrees Celsius or higher +1.3 (0.91 to 1.66) degrees Celsius, is expected by mid-century if current emissions pathways continue (Bodeker et al, 2022).
• Summers are projected to have a more pronounced warming than springs and autumns, and some regions will experience greater warming than others (Bodeker et al, 2022).

* The likelihood of this occurring is between 75 percent and 85 percent.

• Rainfall is projected to increase in the west and south of Aotearoa (Bodeker et al, 2022; Shu et al, 2021).
• Winter and spring rainfall is projected to follow the annual increase in the west and south, but with less rainfall in the east and north (Bodeker et al, 2022).
• More summer rainfall is expected in the east of both islands, with less rainfall in the west and central North Island (Bodeker et al, 2022).

* The likelihood of this occurring is between 75 percent and 85 percent.

• While significant knowledge gaps exist regarding projections for extreme heat, research indicates Aotearoa will follow the global trend of extreme heat events increasing in frequency, duration and intensity (Harrington & Frame, 2022; Thomas et al, 2023).
• The frequency of tropical cyclones is projected to decrease slightly over the South Pacific basin, with a predicted increase in severity (Bodeker et al, 2022, Chand et al, 2022). Tropical cyclone activity in the southern hemisphere is expected to decrease overall (Roberts et al, 2020).
• Drought intensity is projected to markedly increase with the rise in greenhouse gas emissions. The most significant increases in drought intensity are predicted to be in the northern and north-eastern regions of the North Island (Bodeker et al, 2022).
• Atmospheric rivers near Aotearoa are projected to continue to get bigger and carry more moisture, which, upon landfall, can result in highly destructive precipitation (Espinoza et al, 2018; Payne et al, 2020; Shu et al, 2021).
• River flooding is projected to increase across the country (Bodeker et al, 2022).
• Extreme wind speed over the South Island and the southern part of the North Island is predicted to increase by mid-century, along with wind patterns becoming more north-easterly in summer, with westerlies becoming more intense in winter. These predictions are made with low confidence (Bodeker et al, 2022).
• The frequency of coastal overtopping and inundation due to storm surge and wave run up will increase as sea levels rise. The potential for more frequent coastal flooding will increase as ground water table elevations change in response to sea-level rise. These effects will be highly variable at a local scale due to complicating factors including vertical land movement, sediment supply and landform resilience (Jones & Bickler, 2022; MfE 2017).

* The likelihood of this occurring is between 75 percent and 85 percent.

• Average sea surface temperatures around Aotearoa are warming at a faster rate than the global average (0.22 degrees Celsius per decade, compared with 0.16 degrees Celsius) and will continue to increase under current trajectories (Bodeker et al, 2022; IPCC, 2021; Law et al, 2018b; Sutton & Bowen, 2019).
• Marine heatwaves are projected to increase in frequency and severity. Heatwave conditions are forecast to become permanent by the end of the century under current conditions (Behrens et al, 2022; Bodeker et al, 2022).
• Global mean sea level has increased by an average of 1.5mm a year since 1900, due to ocean warming, and is predicted to rise by another 30cm by 2100 (Frederikse et al, 2020). Sea level around Aotearoa will rise by 5 percent to 10 percent more than the global average, due to local glacial isostatic adjustment. Local land subsidence or uplift will also have a significant effect on the rate and amount of sea-level change at a local scale (Ackerley et al, 2013; Kopp et al, 2014).
• Coastal areas are expected to experience worsening effects of more frequent and extreme flooding, caused by the compounding impacts of sea-level rise (Collins et al, 2013).
• Changes to ice melt around Antarctica are reducing the concentration of oxygen in the ocean. Estimates show that, with anthropogenic warming, global ocean oxygenation will decline by 1 percent to 7 percent in the next 100 years (Gunn et al, 2023; IPCC, 2021).
• Uptake of atmospheric carbon dioxide has decreased sea surface pH by 0.1 units since pre-industrial times. Sea surface pH will continue to decrease if the current rate of fossil fuel burning persists (Calderia & Wickett 2003; Hartin et al, 2015; Law et al, 2018a).
• Modelling shows increases in mean annual river flow along the west and south of the South Island and decreases in the north and east of the North Island by the end of the century (Collins, 2020).
• Regional snowlines are expected to continue to retreat to higher altitudes across Aotearoa. Snowlines in the Southern Alps could be displaced by an elevation of 200m higher in the next 20 years (Lorrey et al, 2022).
• Increase in total precipitation has been identified as a factor in the increased probability of landslides and rockslides occurring (Bodeker et al, 2022). Statistical modelling of landslide inventory and rainfall data has found that landslides in response to storm rainfall are anticipated to become more common with climate change (Smith et al, 2023).
• By the end of the century, some North Island soft-rock hill country catchments and a marginal number of South Island soft-rock hill country catchments (less than 1 percent to 28 percent and less than 1 percent to 8 percent, respectively) may experience increases of over 100 percent in sediment yield (Neverman et al, 2023).
• Wetlands in coastal areas are vulnerable to climate change impacts including rising sea levels, storm surges, coastal erosion, fire, and territorial and marine heatwaves. Our wetlands may release a large amount of their stored carbon if disturbed, which will amplify carbon emissions and global temperature rise (Lovelock et al, 2017; Ross et al, 2023).

* The likelihood of this occurring is greater than 90 percent.

• Native forest in Aotearoa is expected to change in distribution and composition, based on projected climate changes. Native tree species, such as tōtara and rimu, have shown some level of resilience to habitat changes and warmer temperatures (McGlone & Walker, 2011; Ryan, 2017).
• Climate change affects high-elevation species at a faster rate than other terrestrial habitats. Projections show a mean annual temperature increase of 3 degrees Celsius would result in the loss of 80 percent of the discrete alpine areas in Aotearoa, and extinction of between 200 and 300 species of indigenous vascular plants (up to half the alpine total) (Halloy & Mark, 2003).
• Rising temperatures will have increasingly negative effects on the habitats and range of native cold-adapted freshwater species. Increased temperatures allow cyanobacteria to take advantage of nutrient over-enrichment (eutrophication), which affects the underwater ecosystems needed for biodiversity (Boddy & McIntosh, 2017; Paerl & Huisman, 2008, 2009; Puddick et al, 2022; Wells et al, 2015).
• Ocean acidification will continue to directly affect marine organisms that build calcium carbonate shells. Habitat-forming marine organisms, such as oysters, bryozoans and deep water corals, are likely to be particularly affected, though uncertainty remains due to spatial and seasonal variability in pH (Hartin et al, 2015; Law et al, 2018a).
• Sea-level rise puts native coastal ecosystems at risk of ‘coastal squeeze’ where habitats can be restricted by inundation from the sea. The effects of inundation will reduce nesting sites for shorebirds, habitat for wading birds, and further reduce suitable spawning sites for native freshwater fish (Rullens et al, 2022).
• Climate stress is likely to increase host vulnerability to pathogen infection (Wakelin et al, 2018) and ranges of plant pathogens will expand, for example, myrtle rust (Beresford et al, 2018).

* The likelihood of this occurring is greater than 90 percent.

• Climate change will continue to trigger modifications to habitats across marine, terrestrial and freshwater ecosystems from shifting rainfall patterns, increasing temperature and extreme events, exacerbating vulnerabilities of native flora and fauna to invasive species. (Keegan et al, 2022; Macinnis-Ng et al, 2021).
• A warmer climate will expand habitable ranges of some existing pests and diseases, including possums and rats (Monks, 2022). These geographic range and distribution shifts will create competition between native and invasive species for habitat (Macinnis Ng et al, 2021).
• Invasive plants and mammals, along with more frequent fire weather in some areas, will increase fire frequency and severity (Wyse et al, 2018). Native species may have limited adaptations for recovery after fire, which results in competitive advantage in fire prone areas for invasive species, reducing the biodiversity values of these systems (Perry et al, 2014).

* The likelihood of this occurring is greater than 90 percent.

• The northern districts of the North Island are projected to become more suitable for sub tropical pest species, including those that pose threats to the primary sectors (Keegan et al, 2022).
• As temperatures increase and winters become milder, some pests that are currently temporarily established could become more permanent features of our landscape, although the establishment of some species could be limited by aspects of their lifecycle (such as requiring specific habitats for breeding) (Kean et al, 2015).
• A southward expansion of the habitable ranges of pests currently limited by winter cold is likely (Qin, 2019; Watt et al, 2019).

* The likelihood of this occurring is greater than 90 percent.

• Ecosystems are increasingly at risk from the indirect impacts of climate change. Indirect impacts manifest by interacting with other drivers of global change or by altering ecological processes such as predation, parasitism and pollination (Jaureguiberry et al, 2022; Ling, 2008; Macinnis-Ng et al, 2021; Pecl et al, 2017; Tylianakis et al, 2008).
• Warmer air temperatures may increase competition for pollination between native and invasive plants because of increased overlap in the timing of their flowering (Giejsztowt et al, 2020), potentially disrupting plant-pollinator networks and affecting broader ecosystems (Ruiz et al, 2019).
• Rising sea surface temperatures may reduce the abundance of marine food or impede seabirds’ capacity to access it, most likely due to complex food-web responses that are expected to occur more frequently in the future (Keegan et al 2022, Macinnis-Ng et al, 2021).
• Changes in drought frequency and severity affect forest tree recruitment, disease susceptibility, and mortality (Macinnis-Ng et al, 2021), favouring drought-tolerant species. This has flow-on effects for the biodiversity that forests and other vegetation types support (Batlori et al, 2020).
• Increased groundwater extraction for irrigation during droughts cause declines in groundwater dependent ecosystems including wetlands, springs and trees that access groundwater for their water needs (Eamus et al, 2015). This can result in plant water stress, crown dieback and eventual death of trees (Cooper et al, 2003; Eamus et al, 2015) and a wide range of impacts on spring and wetland ecosystems (Stevens et al, 2022).
• Although there are few cases of well documented indirect climate-change impacts in Aotearoa it is unclear if this is due to a paucity of data, the complexity of responses, or a lack of measurable effects (Macinnis-Ng et al, 2021).

* The likelihood of this occurring is between 75 percent and 85 percent.

• Changing climatic conditions alter the occurrence and timing of traditional and seasonal tohu (environmental indicators) that forecast the onset of critical periods for many Māori practices (Matamua, 2017; Warbrick et al, 2023). The maramataka is one well-known example that will need to adapt to changing tohu, to continue to guide recreation as well as daily and seasonal activities, providing an opportunity to enact active kaitiakitanga (guardianship) over the local environment (see Te ao Māori, whakapapa and our connection to atmosphere and climate for a definition of the maramataka) (Kenney et al, 2023).
• It is expected any obstruction to accessing taonga (treasured) species may adversely affect the ability of whānau to manaaki (or host) visitors with customary resources and affect Māori customary practice, cultural identity and wellbeing (Awatere et al, 2021; Jones et al, 2014; Warmenhoven et al, 2014).
• Projected incremental and abrupt changes in climate this century are expected to exacerbate many of the risks facing different culturally important flora and fauna, and, in some cases, vulnerable taonga species may face extinction (Awatere et al, 2021; Egan et al, 2020; Reisinger et al, 2014; Renwick et al, 2016).
• Loss of taonga species will have a cascading effect on the transfer of customary practices and knowledge for future generations. It will also add to existing social and political risks for the maintenance and transfer of traditional skills, expertise and values relating to mahinga kai (traditional food gathering practices) (Awatere et al, 2021).

* The likelihood of this occurring is between 75 percent and 85 percent.

• Māori culture and whakapapa (genealogy) are positioned geographically and will be affected by the impacts of climate change (Hakopa, 2011).
• Te ao Māori beliefs hold that all aspects of life are interrelated and interconnected, and the effect of a changing climate is expected to fundamentally alter the way many Māori interact with their environment, each other, and other communities (Awatere et al, 2021).
• Climate impacts, such as sea-level rise, will displace Māori from tūrangawaewae (a place to stand, where one has the right to stand), which will disrupt the geographic transmission of te reo Māori and tikanga (customs and protocols) (Awatere et al, 2021).
• As iwi, whānau and hapū need to relocate from their tūrangawaewae, opportunities to enact kaitiakitanga and actively manage resources and important sites will diminish (Awatere et al, 2021; Wehi et al, 2023).
• To maintain intergenerational mātauranga (knowledge) and tikanga practices, many Māori will have to adapt and plan the relocation of marae or culturally significant sites such as urupā (burial grounds) (Awatere et al, 2021).
• Climate change is likely to have both direct and indirect effects on the coordination of, and participation in, cultural arrangements such as tangihanga (funeral). It is highly likely that marae or coordinators will be burdened with mitigating risks when planning and managing such important ceremonies (Awatere et al, 2021).

* The likelihood of this occurring is between 75 percent and 85 percent.

• The economic and fiscal impacts of climate change are expected to be extensive and unevenly felt, because some industries and sectors are more exposed than others, such as agriculture, forestry, fisheries, tourism, and energy and transport networks (New Zealand Treasury, 2023b).
• Increasing risks to the economy from both the physical impacts of climate change as well as transition risks have flow-on effects for the overall soundness of the financial system as a whole. Some impacts, such as more extreme weather events, are largely baked in for the next few decades. These impacts may also contribute to higher net core Crown debt (Reserve Bank of New Zealand, 2021).
• Important horticultural crops, such as apples, kiwifruit and grapes, are anticipated to have positive responses to the changing climate, with no compromised yield, fruit size or quality. Although, other factors that affect horticultural crops could pose increasing risks with climate change, such as water availability, pollination, pest and diseases, and extreme weather (Clothier et al, 2012; MPI, nd).
• Flowering and ripening of grapes is predicted to become earlier overall by mid-century, and further by the end of the century (Ausseil et al, 2021).
• It is almost certain dairy farming will be at increased risk from extreme weather events, with increased drought frequency, and a projected increased intensity of floods and heavy rainfall (Griffin et al, 2023; Nguyen et al, 2022).
• Irrigation schemes will become less efficient in warmer and windier climates. Water extraction will need to increase, to compensate for increased rates of evaporation, which affects source reliability and results in higher loss in both the storage and supply of water to crops (Collins et al, 2013).
• The Māori economy is projected to be severely affected by climate change because it has a high proportion of interests in the primary sector, including forestry and fisheries. Fisheries investment is dependent on resilient ecosystems and biodiversity, with hoki, pāua and kōura (freshwater crayfish) among the many at-risk commercial fishing species (Awatere et al, 2021; King et al, 2010).
• Replenishment of groundwater resources is integral to our primary sector and will be affected by changing rainfall and water demand patterns. These changes are likely to vary seasonally and regionally (Mourot et al, 2022).

* The likelihood of this occurring is greater than 90 percent.

• Remote communities, those with limited economic resources, populations that are under represented in local and central government and those in vulnerable climatic areas will be disproportionately affected by climate change and extreme weather events globally and domestically (King et al, 2010).
• Sea-level rise will increasingly affect low-lying and coastal communities, including stormwater and wastewater services critical for health and sanitation. Wastewater services will be affected by climate change on short and long timescales, which will have social, environmental, economic, health and cultural consequences (Hughes et al, 2021; Kool et al, 2020; Lawrence et al, 2020).
• Other critical infrastructure, including built assets, transport links (for example, roads, railways, airports) and electricity (transmission lines, structures, sites), are also at risk of coastal flooding, which will increase through time (NIWA, 2019).
• Coastal properties and cultural sites will be affected by coastal erosion and flooding, which will accelerate with sea-level rise. Local variability and complicating factors will occur, including vertical land movement, sediment supply and landform resilience (Awatere et al, 2021; Bailey-Winiata, 2021; Bell et al, 2022; Jones & Bickler, 2022; Lawrence et al, 2020; New Zealand Archaeological Association, 2022; Wehi et al, 2023).
• Climate change induced drought conditions can also increase the risk of wildfires, which will pose risks for cultural infrastructure and kainga (settlements) (Awatere et al, 2021).

* The likelihood of this occurring is between 75 percent and 85 percent.

• Climate change is one of the most serious global threats for health and wellbeing, with potentially widespread effects, including introduced infectious diseases, food insecurity and reduced drinking water quality (Drew et al, 2020; IPCC, 2023; Jones, 2019).
• Complex health challenges reflect the interconnected nature of humans, animals and the environment. This is particularly important in Aotearoa due to our relatively isolated island ecosystem and the economic importance of agriculture (Harrison et al, 2020).
• Existing health and social system inequities will be exacerbated further by climate change. The already intersectionally disadvantaged, including young, elderly, disabled, Māori and Pasifika, will be disproportionately affected (Bennett et al, 2014; Jones et al, 2014; Masters-Awatere et al, 2023).
• The risk is increasing of arboviruses, such as the Zika virus and dengue fever, being introduced from overseas, with increased risk of local transmission as our climate becomes increasingly suitable (Ammar et al, 2021).
• Illness rates associated with pathogenic species from the dung of sheep and cows (Campylobacter and Cryptosporidium) may increase substantially with increased temperature and rainfall intensity, with children being the most vulnerable (McBride et al, 2014). In the Pacific Islands, food production and access to food will be adversely affected by climate change, including food from agriculture and fisheries. This puts at risk their basic need for access to sufficient, safe and nutritious food (Barnett et al, 2019).
• Emerging evidence indicates that children and young people are experiencing greater levels of mental distress due to climate change than any other age group, and research suggests they will be disproportionately burdened by the impacts of climate change (Gislason et al, 2021; Ma et al, 2022).

* The likelihood of this occurring is between 75 percent and 85 percent.

• With increasing extreme events, an increase in related health and wellbeing effects is expected, including injuries and deaths, displacement, and significant damage to community infrastructure; vulnerable groups including children, elderly and disabled will be particularly at risk of this (Grout et al, 2022; Mason et al, 2021).
• Extreme weather events, such as extreme rainfall, drought, wildfires and floods are linked to worsened mental health and higher mortality among people with pre-existing mental health conditions, with increased psychiatric hospitalisations and suicide rates (Charlson et al, 2021). Globally, increased exposure to extreme heat correlates with higher cardiovascular conditions, heat stress and, in extreme cases, fatalities, particularly among the elderly and people with pre-existing conditions (Chaseling et al, 2023).
• Regions that experience increased extreme rainfall could be at higher risk of waterborne diseases, including through contaminated water supplies (Hales, 2019; Lai et al, 2020).

* The likelihood of this occurring is between 55 percent and 70 percent. 

• Climate change is increasingly affecting daily life, for example, rising costs due to disrupted supply chains, power cuts caused by extreme weather, and the need to evacuate homes due to flooding or fires. This will continue, and lower income communities will be more susceptible these effects (MfE, 2022).
• Extreme weather events, such as flooding, pose threats to home security in Aotearoa. About 675,000 (or one in seven) people across Aotearoa live in areas prone to flooding (MfE, 2022). The costs of flooding will increase over time as the climate continues to change (NIWA, 2018).
• In Aotearoa, managed retreat may be necessary to reduce or eliminate exposure to intolerable risks caused by climate change. This displacement will disconnect people who are deeply connected to, and reliant upon, the security, networks and cultural values of their land, homes, communities and livelihoods (Hanna et al, 2019).
• Recreational activities and events will be affected by climate change both directly and indirectly, with changing climates dictating how, when and where activities can take place, if at all (Awatere et al, 2021).
• Climate change threatens to disconnect many Pasifika nations through voluntary or involuntary displacement. It is likely to be a catalyst for profound identity loss, fear and anxiety for many vulnerable communities and a loss of sense of place and belonging (Campbell 2010; Tiatia Seath et al, 2020).

* The likelihood of this occurring is between 75 percent and 85 percent.