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New Zealand Climate Resilience Policy Indicator

  • New Zealand’s temperature increased 1.13°C between 1909 and 2019 and is projected to continue rising by about 1.0°C by 2040 and 3.0°C by 2090 compared to the 1995 baseline, under a high greenhouse gas emissions scenario1. The temperature rise could affect energy demand and require that the electricity grid be adapted to shifting peak demand.
  • Historical precipitation patterns show strong geographical disparities, with half of New Zealand’s monitoring stations reporting higher precipitation and the other half registering a decrease or stagnation since 1960. Precipitation is projected to increase in most parts of the country, and extreme precipitation events are expected to be more frequent. Greater drought frequency and intensity are also anticipated in the northern and eastern North Island and along the eastern side of the Southern Alps. Tropical cyclones and storms could also pose flooding, landslide and erosion challenges. Projected extreme changes to temperature and precipitation patterns could negatively affect hydropower generation and disrupt transmission and distribution.
  • New Zealand’s government legislated a Climate Change Response (Zero Carbon) Amendment in 2019 to prepare for and adapt to the effects of climate change. The amendment mandates the regular preparation of National Climate Change Risk Assessments and National Adaptation Plans, as well as establishment of an independent Climate Change Commission. The first National Climate Change Risk Assessment, published in August 2020, identifies electricity infrastructure risks created by temperature, rainfall, snow, extreme weather and wind changes, and by increased fire weather. The first National Adaptation Plan is to be published in August 2022 and will propose specific actions to address these risks.


Level of floods, drought and tropical cyclones in New Zealand, 2000-2020

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Level of warming in New Zealand, 2000-2020

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Temperature

New Zealand’s temperature increased by 1.13°C between 1909 and 2019, falling within the range of the global land average for the period (1.09‑1.4°C). In the past two decades, it increased 0.0387°C per year, slightly higher than the world average (0.0313°C). However, New Zealand’s annual average temperature in any given year is subject to high natural variability, driven by variations in circulation patterns and other natural fluctuations. 

The number of frost days has been falling while warm days and heatwave days increased between 1972 and 2019. The rise in warm and heatwave days, which has been faster in inland areas of the South Island than in other locations, is driving up summer electricity demand by spurring greater air conditioner use.

Compared with the 1995 baseline, New Zealand’s average temperature is expected to be about 1.0°C higher by 2040 and 3.0°C higher by 2090 under a high greenhouse gas emissions scenario2, with the north-eastern part of the country experiencing stronger warming than the southwest. Maximum temperatures are projected to increase more quickly than minimums, while hot days (above 25°C) increase 40-100% by 2040.

The rise in temperature is already affecting energy demand, reducing heating degree days and increasing cooling degree days. According to the National Climate Change Risk Assessment for New Zealand (the NCCRA), electricity demand could increase in the summer and decrease in the winter, requiring that measures be taken to adapt the electricity grid to changes in peak demand.

Temperature in New Zealand, 2000-2020

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Cooling degree days in New Zealand, 2000-2020

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Heating degree days in New Zealand, 2000-2020

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Precipitation

Half of New Zealand’s monitored stations indicate that precipitation has increased since 1960, while the rest show either no significant trend or a decrease. Most of the stations registering lower precipitation are in the northern part of the North Island, while the South Island and the west coast experienced higher annual rainfall. Whangārei and Tauranga have had the highest decrease in annual rainfall since the 1960s, while Whanganui and Milford Sound showed the largest increase. Drought trends are more uncertain, although short-term droughts increased in both frequency and intensity at 7 out of 30 meteorological stations between 1972 and 2019.

Projections show increased precipitation in most of the country except the north-eastern part of the North Island. While an increase in summer precipitation is expected in the northern and eastern regions of the North Island, higher precipitation in the South Island would occur in winter. Very extreme precipitation events are projected to become more frequent throughout the country, increasing the risk of floods. The magnitude of these changes increases with the emission scenario.

At the same time, the number of dry days is expected to increase in much of the North Island and on the South Island’s eastern and western coasts. Droughts are anticipated to be both more frequent and more intense in the North Island’s north and east and along the eastern side of the Southern Alps, particularly under a high greenhouse gas emissions scenario3.

Projected precipitation changes could adversely affect the energy sector. New Zealand’s NCCRA states that climate change poses a range of risks for the country’s electricity infrastructure (listed under the domain of risks and opportunities in the built environment). Although the present-day risk level is low for generation infrastructure overall, seasonal changes in water availability due to climate change are projected to affect some hydropower plants in the South Island by 2050. Furthermore, transmission and distribution infrastructure is currently at risk of disruption and damage from climate hazards. Approximately 3 400 kilometres of transmission lines and 5 800 structures are in inland flood hazard areas.

Tropical cyclones and storms4

Even though New Zealand’s hazard level for tropical cyclones is low based on historical records, the intensity of tropical cyclones in the North Island and in the northern part of the South Island is projected to increase. This may lead to flooding, landslides and erosion that can negatively affect energy infrastructure. In April 2017, for instance, Cyclone Debbie hit New Zealand’s North Island, followed a week later by Cyclone Cook. The heavy precipitation, flooding and landslides of both cyclones caused power outages and economic damage. In 2017 and 2018, New Zealand had the highest extreme weather-induced costs since 1969.

Storms can also cause energy supply interruptions in New Zealand. In April 2018, winds of over 100 km/h swept through Auckland, bringing down power lines and interrupting electricity supply services to over 200 000 households and businesses (close to 10% of the country’s electricity customers). Insurers estimated damages to be over USD 72 million, making this the fifth most costly storm of the century. Although power was restored within one day for half of affected customers, some had to wait up to 12 days.

New Zealand has strengthened its commitment to climate change adaptation and resilience in recent years. The 2019 Climate Change Response (Zero Carbon) Amendment Act mandates that the Minister prepare an NCCRA every six years to detail the risks New Zealand faces from climate change, and that it formulate an accompanying National Adaptation Plan (NAP) within two years after. Furthermore, the Act also stipulates that the independent Climate Change Commission monitor and report on NAP implementation and effectiveness every two years after its publication.

In conformity with the Act, New Zealand published its first NCCRA in August 2020 together with a Method and Technical Reports. The NCCRA acknowledges the need for further awareness and understanding of climate impacts on transmission and distribution systems.

The NCCRA identifies 43 natural environment, human, economic, built environment and governance risks New Zealand will face in the next 6 years due to climate change. Ten of the 43 risks are considered significant because the need for action is urgent. Although “risks to electricity infrastructure, due to changes in temperature, rainfall, snow, extreme weather events, wind and increased fire weather” are recognised in the domain of the built environment, they are not considered among the ten most significant risks.

Although the NCCRA does not identify specific actions for energy system climate resilience, it recommends that companies begin to assess future climate risks and scenarios. The Climate Change Adaptation Technical Working Group’s 2018 Adapting to Climate Change in New Zealand report also recommended that state and private sector organisations update and regularly review organisational planning, climate risk management and disclosure requirements to encourage leadership in adaptation action.

Although the 2019 National Disaster Resilience Strategy includes the energy sector in the “built environment” category, it does not specify any particular activities. Similarly, national energy strategies such as the New Zealand Energy Strategy 2011-2021 and the New Zealand Energy Efficiency and Conservation Strategy 2017-2022 are concerned with making the energy system more resilient to general supply disruptions but do not place enough emphasis on the increasing possibility of climate-driven disruptions.

As New Zealand’s first NAP is due to be published in August 2022, specific actions are currently in development. Including measures in the NAP to address climate change threats to electricity infrastructure could boost climate resilience in the energy sector and improve policy preparedness considerably.

References
  1. RCP 8.5

  2. RCP 8.5

  3. RCP 8.5

  4. Storm indicates any disturbed state of the atmosphere, strongly implying destructive and unpleasant weather. Storms range in scale. Tropical cyclone is the general term for a strong, cyclonic-scale disturbance that originates over tropical oceans. In this article, we used these general terms, tropical cyclones and storms, but those can be divided into different categories in detail. A tropical storm is a tropical cyclone with one-minute average surface winds between 18 and 32 m/s. Beyond 32 m/s, a tropical cyclone is called hurricane, typhoon, or cyclone depending on the geographic location. Hurricanes refer to the high intensity cyclones that form in the south Atlantic, central North Pacific, and eastern North Pacific; typhoons in the northwest Pacific; and the more general term cyclone in the South Pacific and Indian ocean.