Nuclear War and NZ: Impact and Mitigation Approaches


  • The McGuinness institute has released a report summarising the likely impacts of nuclear war on NZ and calling for a national risk assessment and strategy
  • This report was published the same week as our peer-reviewed paper on islands and nuclear war, which uses NZ as a case study
  • Nuclear war is a representative global catastrophic risk, and a national risk assessment would increase understanding of risk and mitigation strategies across multiple global catastrophes
  • There are additional reasons to undertake this kind of assessment which include the wellbeing of future generations, preservation of complex functioning society in the wake of global catastrophe, and potential synergies with other risk mitigation plans such as a net-zero carbon transition
  • It may be strategically better for this kind of assessment to be conducted from outside of the traditional national security silo, given recent indications that Cabinet might move to narrow the scope of the NZ National Security System
  • A Parliamentary Commissioner for Extreme National Risks is one possible approach


The world still faces the risk of nuclear conflict and resulting severe cascading global impacts. A new paper from the McGuinness Institute provides a summary of the excellent work on the nuclear risk to NZ that was completed in the 1980s. This work found that the likely impact of a Northern Hemisphere nuclear war on NZ would be felt largely through collapse of global trade, as combatant and non-combatant Northern Hemisphere nations dealt with what would be the most significant internal catastrophe they have ever faced.

The known impacts of nuclear weapon use including blast, thermal radiation, and ionizing radiation would be spectacularly devastating wherever the weapons are detonated.

The uncertain impacts of nuclear weapon use potentially raise the stakes. We know the lower bound of impact could be severe, but the effects of any electromagnetic pulse, nuclear winter, ecological catastrophe, and cascading impacts of destruction on the interrelationships among sectors, trade, social cohesion, and international relations could be beyond comprehension.

It is important to note at the outset, that it is not just nuclear war that threatens these kinds of severe cascading global impacts. Risk is also posed by natural hazards such as supervolcano eruptions, massive solar flares, asteroid or comet impacts, and other disasters. Contemporary civilization may be more susceptible to these risks than ever before.

The 1980s work on NZ and nuclear war emphasized that radiation and physical destruction are not likely to be the problem for NZ and focused on establishing potential impacts of a Northern Hemisphere nuclear war on NZ health, agriculture, energy, trade, transport, communications, social responses, the impacts on government and sector interactions.

If trade were to collapse as anticipated, then a cursory look at a list of commodities imported to NZ demonstrates how wildly impactful this would be for every sector. Notably surveys in the 1980s found that only 4% of respondents recognised the impact on trade as most concerning. This view may be gaining more recognition now, given NZ’s experience with Covid-19 and the Russian invasion of Ukraine, but is probably still not fully recognised as the dire threat it is likely to be.

Key points in the McGuinness Report

The core vulnerabilities NZ possesses in the face of nuclear war (or other trade disrupting global catastrophes) still exist or, as the report notes, have gotten worse across the last 35 years. This is because:

  1. NZ’s energy security has decreased, the country has become less energy self-sufficient in recent years and is also completely dependent on imports of refined fuel for almost all road transportation, and therefore all industrial and agricultural functioning.
  2. Dependence of almost all communication on digital technologies operated by external entities is also a key vulnerability for societal function.
  3. Social cohesion is more fragile, as evidenced by the social responses during the Covid-19 pandemic.

Key examples demonstrate a lack of strategic thinking around these issues, such as the closure of the Marsden Point oil refinery, which in the context of global catastrophes is a strategic asset.

It is problematic that NZ appears to have no rationing or resource allocation plan to smooth the shock of massive disruption to the import of essential industrial inputs.

There remain key knowledge gaps, which should be explored to better understand the impact of nuclear war (and other trade disrupting global catastrophes) on the functioning of NZ society.

There is a need to collate and provide information about the impacts of nuclear war to the public. This would serve two purposes. Firstly, it would allow feedback and peer review of the findings, thereby enhancing their robustness. Secondly, it would help encourage wide-ranging resilience thinking by businesses and individuals beyond the direct reach of policy.

It is encouraging that the recent Draft National Security Long-term Insights Briefing explicitly calls for more public national risk information and engagement.

For these reasons we suggested in consultation feedback to DPMC that nuclear war as a representative global catastrophic risk warrants inclusion in the final version of the Long-term Insights Briefing.

The McGuinness report highlights the wide range of risks that could all to some degree have similar deleterious impacts on NZ:

“the seriously disruptive consequences of more likely crises such as severe global economic difficulty or breakdown, regional conflicts that seriously disrupt trade, oil price shocks, far more deadly pandemics, and climate-change-induced disruptions. All these risks have in common a focus on building more resilience into our social, economic and political systems to better weather and recover from major shocks.”

Importantly, a focus on analysing nuclear war could accelerate the analysis and therefore potential mitigation strategies for the entire suite of global catastrophic risks.

The McGuinness report further notes that:

“Resilience, the ability to sustain/recover essential functions, would be the difference between a tolerable, cooperating society or social collapse and conflict”

However, it is even more important than that, because:

  • Social collapse and conflict might lead to future generations being much worse off than they might have been. It is striking that ‘future generations’ is not one of the ‘interests to protect’ proposed in two 2022 Cabinet papers outlining an approach to restructuring the NZ National Security System.
  • New Zealand is often argued to be one of the regions of the world most ‘safe’ from nuclear catastrophe and other global catastrophic risks. If even NZ is vulnerable to devastating collapse of industry due to the cascading impacts of global trade disruption, then the future of industrial civilization could be threatened. Such potential outcomes greatly strengthen the argument for nuclear war being analysed as a national threat.

As the McGuinness report argues, there should be a short-term phase of investigation (one should add followed by cost-effectiveness analysis and an intervention prioritisation process) and then a long-term phase of implementation.

The implementation phase should focus on resilience strategies that cut across multiple global catastrophic risks, and which also further other interests of value such as a green transition and decarbonisation. For example, it is striking that some of the most effective measures to mitigate the risk of global catastrophe on NZ are also those that would advance a carbon net-zero goal. Expected cost-utility of these kinds of projects should include the impact in expectation of global catastrophes across the rest of this century.  

Key strategic questions remain open

Although operational stockpiling of critical imported resources is mentioned in the report it may be the case that there are just too many ‘critical’ imported commodities. It’s quite likely that focus on pivoting at least a proportion of each sector to a ‘self-sufficient’ posture would help mitigate global catastrophes. Analysis and crowdsourcing should investigate how this might successfully be achieved.

The McGuinness report advocates for the inclusion of nuclear war as a risk overseen by the National Security System and the Department of Prime Minister and Cabinet. The rationale given is that in recent years an ‘all hazards’ approach to National Security has been taken (with the inclusion of a wide range of hazards in a classified National Risk Register).

However, this is at odds with Cabinet papers proactively released in 2022 that appear to chart a course away from the ‘all hazards’ approach to National Security, and, particularly in the wake of the Royal Commission of Inquiry into the Christchurch terror attacks, towards a more specific focus on malicious agential risks against NZ (counter to present global trends in national risk assessment).

It certainly sometimes appears that the National Security System can become politicised with a focus on recent striking events rather than the largest longer term risks to NZ. A related problem occurred in Switzerland. Switzerland’s first national risk register of 1999 illustrated the precedence of civilian public dangers before military issues so clearly that the Ministry of Defence rejected its publication.

The issues identified above show clearly that the likely impact of nuclear war (and other global catastrophes) on NZ are predominantly civil rather than security issues. We have therefore offered constructive critique of these Cabinet papers and the approach to revamping the National Security System.

For the reasons just given, we favour a National Risk Assessment entity independent of the silos of DPMC, the National Security System (and even NEMA – with its traditional focus on natural hazards), that is anticipatory, central/aggregating, coordinating, apolitical, transparent, adaptive and accountable, and looks across all major national risks, providing the short-term assessment work and advising on longer-term implementation work as mentioned above. A Parliamentary Commissioner for Extreme National Risks (or similar, with a well-resourced office) could play such a role providing open, independent, wide-ranging analysis and advice.

Such analysis should start to focus particularly on sectors not addressed by the 1980s NZ Nuclear Impacts Study, such as manufacturing, and welfare, and a better understanding of recently emerging vulnerabilities such as social cohesion, misinformation, and our dependence on digital technologies. Secrecy is not going to solve these issues.

Figure 1: Possible structure of a National Risk Approach

Figure caption: Global catastrophes such as a regional or great power nuclear war, supervolcanic eruption/industry-disabling solar flare, or devastating accidental engineered pandemic should be assessed in comparison with other traditional NZ threats and hazards. An independent office could look across the entire National Risk Approach and conduct an integrated risk assessment, advising parliament and providing information to the public. This information and advice can feed into rationally targeted action based on expected consequences and uncertainty.

Next steps

The 1980s NZ Nuclear Impacts Study identified four major themes of NZ’s vulnerability to major global catastrophe. These were dependence on trade, interdependence among sectors, the fact that vulnerabilities are increasing (largely with technological dependence and globalisation), and a lack of contingency planning.

A Phase II study was proposed at the time but never progressed due to bureaucratic impedance. This study would have aimed to improve public knowledge, coordinate a rationale for preparing contingency plans, and identify strategic areas where NZ’s vulnerabilities could be reduced.

Such a project must be initiated, should assess the risk, and should recommend a long-term strategy to address low-hanging fruit in neglected areas of risk mitigation likely to have the largest marginal cost-benefit when all goals are considered. Contingency planning should only be one element to such a project.

Governments often defer to a ‘response’ focus regarding hazards, but in cases of severe global catastrophe there may not be much role for government in the response phase. However, government must play a critical role in preparing the social conditions, resources, and infrastructure of the nation to maximize the chance that such uncertain but inevitable catastrophes can be weathered. A strategy to build the most resilient ecosystem of NZ industry ahead of inevitable catastrophe (whatever form the next catastrophe takes) is probably the most important plan.

We have started work on such a project, although the 1.7 FTE that we can deploy across one year is in stark contrast to the 8.0 FTE across three years recommended by the McGuinness report for nuclear war alone. We will only be able to take a ‘quick look’ across most issues and present a bullet point strategy and plan building on our recent work through 2022 on the impact of nuclear war (and other global catastrophes). We invite those with additional resourcing, or additional government resources, to complement or integrate with our approach.

Finally, we emphasise that the business case for analysing nuclear war and its impacts on NZ is not just the usefulness of a plan for this (hopefully unlikely) eventuality, but that the same analysis also contributes to resilience and mitigation plans to combat the whole spectrum of global catastrophic risks, which collectively have a concerning probability and large consequences in expectation.

The case for action is enhanced not just by the need to protect New Zealanders alive today and their interests, but to ensure stable wellbeing for future NZ generations, to help accelerate other important transitions such as carbon-zero, and to increase the probability that hubs of functioning social and industrial complexity survive such global catastrophes for the benefit of all humanity. All these benefits need to be assessed in the relevant cost-utility assessments.

Development of a National Security Strategy (plus NEMA) is one part of a National Risk Approach

Matt Boyd & Ben Payne


  • Following the Royal Commission of Inquiry into domestic terrorism, two Cabinet papers outline how NZ might improve the National Security System
  • A proposed National Security Strategy would address malicious threats
  • Improved national security oversight, and links with agencies such as NEMA would form a more comprehensive national risks approach
  • However, this approach still omits accountability and resources for analysing, prioritising, and mitigating large global catastrophes and their impact on NZ
  • Potentially, most of the risk to NZ lies in such rare but devastating scenarios
  • An integrating office is still needed, which looks across all risks, comparing likely harms and prioritising resources. 


The Department of Prime Minister and Cabinet proactively released two Cabinet papers describing a plan for improving how security risks of national significance are managed in New Zealand.

These Cabinet papers address aspects of the Royal Commission of Inquiry into the Christchurch terror attacks, the ongoing development of NZ’s first National Security Strategy, and cover some common ground with the recently released Draft National Security Long-term Insights Briefing (LTIB), upon which we have commented here.

Two National Security papers proactively released by Cabinet/DPMC

The Cabinet papers are:

·  Charting a New Path for Aotearoa New Zealand’s National Security: Developing our first National Security Strategy

·  Charting a New Path for Aotearoa New Zealand’s National Security: Strengthening the design of our machinery of government

Two primary Boards govern the existing National Security System (NSS) outside of crisis scope:

·  The Security Intelligence Board (focusing on malicious threats)

·  The Hazards Risk Board (focusing on civil contingencies)

In the Cabinet papers, however, national security is narrowly defined as, “actively protecting Aotearoa New Zealand from malicious threats to our national security interests, from those who would do us harm” (emphasis added). This very much limits the set of risks managed by the NSS, which is perfectly fine provided all other risks are picked up elsewhere.

At present 42 risks of national significance are compiled in a classified National Risk Register. The Cabinet papers propose creating a clear division between risks of a national security nature (ie threats from malign agents) and natural hazards and civil contingencies such as earthquakes and floods. This is because the ‘securitisation’ of risk in somewhat ad hoc fashion over time has stretched the national security apparatus, which is under-resourced and roles within it are not always formally legislated or appropriately funded. 

This issue, perhaps best summarised as the question of ‘who is responsible?’ is highlighted in the Cabinet paper on design of our machinery of government, which states that the NSS relies: “on mechanisms of coordination that do not impose formal responsibilities or specific accountabilities [across a wide ecosystem of agencies]”

Addressing National Security shortcomings

The Cabinet papers highlight that a core task moving forward will be to identify an “appropriate system leader” for the NSS (malign risks), as well as “independent statutory oversight for any new agency and/or the system as a whole”. The Cabinet papers are clear that any structural change must ensure, “our national security and hazard risk systems as a whole are not left worse off by piecemeal change, and are supported by an all-of-government National Risk Approach”.

It is this kind of ‘National Risk Approach’ that we particularly favour, which would account for security risks, hazards and civil contingencies such as those concerning the National Emergency Management Agency (NEMA), and also other major risks that fall through the cracks of the present system (as we discuss below).

Risks and risk amplifying factors 

The Cabinet papers acknowledge important risk amplifying factors including low social cohesion and stability, misinformation, and the impact of climate change. Other risk amplifying factors plausibly include rising technological capabilities (eg AI, bioengineering), geopolitical tensions, threats to trade, and consolidation of power in, and dependence on, large multinational firms (for example polarising and immensely powerful social media and technology firms). 

The Cabinet papers note that social and environmental policy are needed to address some of these issues. Trends across some, though not all, of these risk amplifying factors are discussed in the recent draft LTIB. 

These issues are examples of risks that currently fall outside NEMA and the National Security System. Important global risks and risk factors need to be identified as part of a complete set of national risks and risk factors. Analysing and addressing risk in ad hoc fashion means that resources may not be directed where they are most effective. 

Also missing from the discussion in the Cabinet papers is the intent to analyse and mitigate global catastrophes, which could include the future risk of nuclear conflict/winter, extreme climate change scenarios and potential for super-pandemics of significantly greater scale and impact than Covid-19. 

Global catastrophic risks are often not traditionally seen as ‘national risks’, due to uncertain probabilities of occuring in the nearer timeframes often applied in national level risk management and planning. However, we argue that the potential for such events across the longer-term should be central to national risk profile development and anticipatory governance and that a large amount of critical risk to NZ arising from these external sources may be missed by what amounts to a clear separation of NEMA and NSS with some additional aims of building interconnections between these risk entities.

Reforms to the system need to ensure all risk finds a home

Overall, we agree with the Cabinet papers where they acknowledge that the NZ NSS needs to:

1. Be clear on what interests are being protected (a list is offered, but notably future generations are absent)

2. ‘Securitise’ fewer risks (while making sure that the NSS is one component of a wider risk assessment and approach)

3. Identify threats earlier and act to influence them before they manifest

4. Be more open and transparent with risk information (to foster engagement and the possibility of resilience-building) 

However, it is still not entirely clear where management of some risks would lie with the proposed clear separation of NSS and NEMA. For example, is nuclear war between, eg India and Pakistan, causing a global famine and trade collapse, a malicious threat to NZ, where some agent wants to do us harm? Or is it more like a natural hazard in NZ, that impacts us without there being an overt ‘security’ risk? What about major global catastrophes such as a climate changing supervolcanic eruption in Indonesia (akin to  the Toba eruption 70,000 years ago), or a similarly consequential asteroid impact, or a global industry-disabling solar flare? What about a bioengineered pandemic that occurs accidentally? Or an accidental AI catastrophe with global impact, or a great power war not involving NZ, or a yet unknown risk devastating key pinch points of global commerce? Which agency is responsible for assessing these global catastrophic risks, and advising on resource allocation for analysis and, if necessary, mitigation and investment in resilience? There needs to be some systematic assessment and prioritisation across the complete set of risks.

The Cabinet paper on Developing our First National Security Strategy hints at an important solution to managing such a diverse set of risks in paragraph 110:

“On the basis of the Policy Review findings, I [the PM] therefore recommend a transition to a national security system that manages the subset of national security risks, complemented by a hazard risk system and supported by an all-of-government National Risk Approach and strategic crisis management mechanism” (emphasis added).

We think that this ‘National Risk Approach’ should not be merely NSS plus NEMA and various strengthened interconnections between them (even with the addition of engagement with other external agencies). Such an arrangement could still result in important risks (perhaps the majority of all actual risk, if significant global catastrophes are considered) falling through the cracks. Figure 1 shows these cracks schematically and the kinds of risks that slip through. A backstop is needed to prevent this from occurring (as outlined below). 

Figure 1: There are important risks which neither NEMA nor a more focused National Security System appear responsible for managing

Figure caption: Global catastrophes such as a regional or great power nuclear war, supervolcanic eruption/industry-disabling solar flare, or devastating accidental engineered pandemic should be assessed in comparison with other traditional NZ threats and hazards. An independent office could look across the entire National Risk Approach and conduct an integrated risk assessment, advising parliament and providing information to the public. This information and advice can feed into rationally targeted action based on expected consequences and uncertainty, ie building resilience across a range of catastrophic scenarios. 

The Cabinet papers envision, “oversight across all nationally significant risks and a cohesive approach.” This should include all risks and should generate resource prioritisation advice based on the expected magnitude of the consequences, the marginal utility of action, and the likely value gained. If earthquake strengthening is costing tens of millions of dollars per life saved (as it plausibly is) but lives can be saved for $1m each elsewhere in the risk landscape, then those tens of millions should be shifted. The public needs access to risk information, but also to cost-effectiveness information in order to engage in informed prioritisation discussions (across the spectrum of multi-attribute risk impacts).

A fully comprehensive national risk approach (of which NEMA’s domain of expertise, and that of the NSS are important sub-components, along with assessment of risks that have yet to find a home) could be engineered. Indeed, the Cabinet papers ask, “who is best placed to lead and coordinate the National Risk Approach?” There are different possible answers to this question, and we discuss them (at least as they pertain to global catastrophic risks – the ones falling through the NEMA/NSS cracks) in our paper arguing for a Parliamentary Commissioner for Extreme National Risks.

Overall, resourcing needs to be allocated in proportion to the risk (while also considering the marginal benefit of additional resources, or reallocation of existing resources, and the likely value obtained). Both NSS risks and NEMAs traditional focus are subsets of all things that can go badly at a national level and should receive an appropriate slice of the national risk management pie (for analysis, resilience building, prevention, and mitigation). But overarching advice looking across these sets of risks, and all other risks, is needed to ensure comprehensive risk coverage. The new NSS (plus NEMA) will then be integral parts of a wider cohesive whole.

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