Now, Climate Change Minister Simon Watts has written to local councils raising concerns about the continued use of RCP8.5. He said, "...the Government does not consider it appropriate for worst-case assumptions to become the default basis for investment decisions that impose significant costs on current and future ratepayers."
In a reply to the Minister, Greater Wellington Regional Council made it clear that it has no intention of discontinuing the use of the extreme scenario model, saying the extreme (and implausible) scenarios "have helped ensure that the resilience of long-lived assets and services is considered under a range of possible future climate conditions."
In
other words, the council has effectively told the Minister to get lost.
Clearly, the Minister needs to do more than make suggestions to councils that
appear to be captured by climate change ideology.
LETTERBOX
will be writing to our local councillors asking when their council will retire
these extreme models and replace them with evidence-based alternatives.
MINISTER LETTER TO COUNCILS
Dear Mayors, Chairs and Chief Executives,
I am writing regarding the use of climate change assumptions in council planning, infrastructure investment, asset management, and regulatory decision-making.
The Government expects councils to continue planning for climate risks and ensuring communities are resilient to future climate impacts. Climate adaptation remains an important responsibility of local government.
However, the Government is increasingly concerned that some climate-related planning and investment decisions may be relying on high-end emissions scenarios in a way that results in unnecessary costs being imposed on ratepayers, businesses, and communities.
Recent international assessments indicate that SSPS-8.5 and its predecessor RCP8.5 are best regarded as less likely, high-impact emissions scenarios that are useful for stress testing and contingency planning. They should not automatically be treated as the central or most likely future when making decisions that affect infrastructure investment, land use, property rights, or rates.
New Zealand faces significant infrastructure challenges. Every dollar spent on resilience measures is a dollar that cannot be spent on fixing roads, upgrading water infrastructure, improving community facilities, or reducing pressure on rates. Councils must therefore ensure climate-related decisions are proportionate, evidence-based, and represent value for money.
Accordingly, the Government expects councils to:
• Use a range of credible climate scenarios when assessing infrastructure and planning decisions, including medium and high-end scenarios.
• Clearly identify which scenario has been adopted as the primary planning assumption and explain why.
• Demonstrate the additional costs associated with higher-end climate assumptions and disclose the impact on rates, debt, and long-term affordability.
• Prioritise adaptive pathways and staged investment approaches wherever practical, rather than defaulting to immediate construction of infrastructure designed solely around worst-case assumptions.
• Ensure that regulatory decisions affecting landowners, businesses, and communities are supported by robust evidence and are proportionate to the risks being managed.
• Subject major climate-driven capital expenditure proposals to rigorous cost-benefit analysis and independent challenge.
The Government’s expectation is clear: councils should plan for climate risks, but they must also plan for affordability.
High-end scenarios such as SSP5-8.5 remain useful for testing resilience and understanding extreme risks. However, the Government does not consider it appropriate for worst-case assumptions to become the default basis for investment decisions that impose significant costs on current and future ratepayers.
Councils should be able to demonstrate that climate-related investments are necessary, proportionate, and represent the best use of scarce public resources.
The Government will work with the sector to improve consistency and transparency in climate-related planning and infrastructure decisions. I have directed officials to undertake a stocktake of current council practices and provide advice on whether additional national direction, reporting requirements, or legislative changes are required to ensure climate-related decisions appropriately balance resilience, affordability, and value for money for ratepayers.
New Zealanders rightly expect councils to prepare for future risks. They also expect councils to avoid unnecessary gold-plating, focus on practical solutions, and exercise discipline when spending ratepayer money.
I encourage elected members and council executives to review their current planning assumptions and decision-making frameworks considering these expectations.
Yours sincerely,
Hon Simon Watts
Minister of Climate Change
OUR EMAIL TO WDC
Dear Councillor
I am writing as a ratepayer regarding the council’s use of extreme climate scenarios in planning and infrastructure decisions.
I’m aware that the Minister for Climate Change, Simon Watts, has written to all councils expressing concern about the over-reliance on RCP8.5 and similar worst‑case scenarios. These pathways have been deemed implausible by the UN body that sets the framework for climate modelling, and have been retired.
The use of these extreme scenarios has resulted in inflated infrastructure costs, unnecessary restrictions on development and housing, higher rates and debt, to name but a few.
I therefore request advice on when the Council intends to retire these measures and replace them with more reasonable, evidence‑based alternatives.
Below is the Minister’s letter – for your information.
Thank you for your attention.