Food for thought: Frost resistant crops to hedge against the impacts of nuclear winter

By Matt Boyd, Ben Payne, & Nick Wilson

Image: Midjourney


  • The risk of nuclear war is probably rising due to geopolitical tensions and modernisation of nuclear arsenals.
  • New Zealand (NZ) would suffer severe consequences, including trade collapse, shortages of liquid fuels, and potential nuclear winter effects.
  • Nuclear winter could lead to reduced agricultural production and necessity of growing frost-resistant crops.
  • NZ has good potential to produce food in a nuclear winter if optimal strategies are followed.
  • In our just published study, we analysed frost resistant crops to estimate the minimum cropped land area to meet food needs of the NZ population.
  • Wheat and carrots are the most efficient frost resistant crops for food supply, but a range of other cereal and vegetable crops were also identified.
  • Pre-catastrophe analysis, a cooperative national approach, and a national food security strategy are needed for ensuring food security.
  • Ensuring food security for one global catastrophe will likely help with food security for other scenarios such as climate change, deglobalisation, or industrial collapse due to eg, major volcano, global conflict, or solar flare.

Technical paper in Scientific Reports here

Summary video

Risk of nuclear war

The risk of nuclear war is plausibly rising due to geopolitical tensions, active warfare, expansion and modernisation of arsenals, and erosion of international arms control agreements.

Some nations would be devastated by direct targeting with nuclear weapons, but others such as NZ, would likely suffer severe secondary consequences due to collapse of trade and potentially the onset of a ‘nuclear winter’.

Climate modelling studies suggest that a nuclear winter (blocking sunlight and reducing crop yields) could be catastrophic. Agricultural production could fall 8–61% in NZ.

Importantly there could be a large increase in the number of frost days. There is historical precedent as summertime frost occurred in Europe, China, and North America following the eruption of Mt Tambora in 1815.

Compounding the climate impacts could be shortages of liquid fuel. This is because NZ is 100% dependent on imported liquid fuels. The government has recently mandated 21 days of diesel reserves are stored onshore (with another 7 days to be stored by the government) but this fuel might quickly run out.

Communications difficulties due to internet and satellite disruptions could make coordination of a response difficult.

NZ is a very good food producer and exports far more food than is needed by the domestic market, mostly in the form of dairy products, as well as meat and fruit. In one analysis, we found that export dairy alone could provide over three times the daily energy requirement for all NZers if it could be directed to the domestic market.

However, in a context of scarce liquid fuel to transport milk daily, and impaired pasture growth due to low average temperatures, along with possible limitations to long-distance communication and coordination, it may be preferable to prioritise production of other food sources.

Our new study

Given the possible scenario above, we conducted an optimisation study to assess the minimum arable land use required, specifically for frost resistant crops, to supply the food needs of all NZers. We required that the analysis satisfy both dietary energy and dietary protein requirements.

We restricted the analysis to frost resistant crops because a nuclear (or volcanic, or asteroid/comet) winter could make winters more severe and add many additional frost days to the year.

NZ food needs

The estimated dietary energy intake of the entire NZ population has previously been estimated at 44.4 billion kJ per day, equivalent to 8686 kJ (2076 kcal) per person per day. Using nutritional survey data, we calculated the protein intake to be 413 tonnes per day (81g/person).

Image: Midjourney

Frost resistant crops

Frost resistant cereal crops such as winter wheat can take better advantage of the early spring growing season than their spring planted equivalents. They are typically relatively efficient sources of food energy and are usually much cheaper to produce than dairy products, meat, and fish. Other frost resistant crops include carrots, sugar beet, onions, cabbage, and so on. High yield crops such as potatoes were excluded because the foliage is frost-sensitive. You can see details of various crops and their resistance to frost in our published table.

In one scenario we aimed to supply sufficient calories and protein solely through frost resistant crops. In another scenario, we considered 50% of nutritional needs supplied from frost resistant crops and the rest from other food sources (that might still be produced but with decreased yields, eg, frost sensitive crops in greenhouses, or grass fed livestock products).

Comparisons were made with the total area of crop land used in 2019 in NZ, which was 132,717 hectares in horticulture and 487,763 hectares in grain.

Our results

We found that wheat (97%) and carrots (3%) was the best combination of crops when optimising for minimal land use. Wheat provides 1400 kJ and 13.4g protein per 100g. Standard yields in NZ are around 9.9 tonnes per hectare (vastly more than Australian yields). Carrots provide only 156 kJ and 0.6g protein per 100g but can yield a massive 120 tonnes per hectare.

As a baseline, wheat and carrots could provide all the dietary energy and protein for the NZ population using 116,000 hectares of land, which is equivalent to 19% of the current cropping land used for all crops.

However, the impact of nuclear winter on sunlight reaching the ground means that these yields could be reduced by up to 61%. In such a scenario NZ would need 297,000 hectares of wheat (48% of current cropping land) or 149,000 hectares assuming 50% of food could still come from non-wheat/non-carrot sources.

The least efficient use of land to produce dietary energy was grass-fed lamb which was 310 times less productive in dietary energy per hectare than carrots (beef was the next most inefficient).

The least efficient source of protein was also lamb which was 62 times less productive in dietary protein per hectare than wheat (beef, then milk, were the next least efficient).

The following table appears in our paper and illustrates the minimum land area required across various scenario combinations (link to published table).

NZ already grows a range of frost resistant crops. However, current levels of production were estimated to be capable of providing 74% of the dietary energy of the population in the no nuclear winter scenario (ie, leaving a 26% shortfall). But this level of provision was only 29% for the severe nuclear winter scenario (ie, leaving a 71% shortfall).

This means that if there was a substantial increase in the frost period (likely with a severe nuclear winter), then frost resistant cropping may need to be scaled up in NZ. Our results suggest that planting wheat and carrots are likely to be an efficient approach. Nevertheless, in reality there would likely be specific climatic/soil conditions that would make other crops more efficient in particular localities eg, onions in Pukekohe, oats in parts of Canterbury.

Agricultural energy inputs

We have so far considered only land area, frost resistance, yield, and dietary requirements. Wheat typically requires additional processing post-harvest (though can be cooked and eaten as a grain) and an analysis of all energy inputs may find other frost resistant crops to be the most efficient in a context of severe energy insecurity.

The Energy Efficiency and Conservation Authority estimates that the agriculture sector in NZ uses 295 million litres (L) of diesel per year, with sheep and beef farming using the most (108 million L, [37%]), followed by dairy farming (95 million L, [32%]).

NZ’s new requirements for diesel reserves amount to about 270 million L  (when tallying commercial requirements and new government reserve requirements).

Even with the strictest prioritisation and rationing, the reserves could barely keep the current agricultural sector running for one year, let alone the rest of the economy including essential services.

In a protracted catastrophe (and nuclear winter could last a decade), rational prioritisation of liquid fuel use within the agricultural sector would be needed. Wheat and carrots appear promising within these constraints and could be grown near population centres and along electrified railway networks.

Image: Midjourney

Wheat production has many benefits

For food, NZ mostly produces milk products, meat, and fruit (all mainly for export markets). Whereas much NZ bread is made from wheat sourced from Australia. In part this is because it is cheaper to transport grain in bulk from Australia to Auckland than it is from the South Island to other locations in NZ where flour is produced.  

NZ wheat production in 2021 was 43,500 hectares. Processing capacity appears to exceed this given the milling of Australian grains locally. Only one flour producer (Farmers Mill in South Canterbury) sources grain entirely from NZ farms, which is about commercial objectives of allowing manufacturers and bakers to pass on the promise to their customers of baking from 100% NZ grown wheat for a 100% NZ made product.

Economies of scale mean that a handful of foreign owned flour mills in NZ process most of the wheat, yet as recently as the 1980s NZ was self-sufficient in wheat production and operated 30 or 40 mills.

In a no-trade scenario NZ might need to return to increased grain production to allow for a flexible diet.

Additionally, in a world where there appears to be a trend towards deglobalisation and towards regionalism, more countries might have to start scaling up their own wheat production. Expanding the amount of wheat cropping now would provide a suite of resilience benefits across a range of trends and risks.

Benefits of wheat production:

  • Greater food security in a world where supply chains are vulnerable.
  • Greater food security in a deglobalised and regionalised world.
  • Greater food security in a catastrophe situation (eg, nuclear war), if global trade collapses abruptly.
  • Greater food security if another abrupt sunlight reducing catastrophe occurs, such as volcanic winter, or asteroid/comet impact winter.
  • Substitution of animal food sources with high greenhouse gas emissions for grain production with lower emissions.

Wheat also has the advantages of not requiring refrigeration, being relatively energy dense (which reduces food transportation costs), and excess can be fed to livestock (eg, chickens for egg production).

However, more work is needed to understand the yield of wheat (and other frost resistant crops) in various regions under nuclear winter conditions, and the impact that the absence of imported agrichemicals (including fertiliser, herbicides, pesticides, and fungicides) would have. This analysis will be important as there are virtually no agrichemical facilities left in NZ (just an ammonia-urea plant that makes fertiliser).

The greater the impact of nuclear winter, and the more constrained the supply of agrichemicals, the more land is needed to feed everyone and the greater the consumption of precious liquid fuels.

Next Steps

To enhance resilience, NZ should conduct locally-specific climate modelling for nuclear winter scenarios, incentivise frost-resistant crop production in normal times, and analyse the feasibility of a local frost resistant crop seed stockpile.

Vulnerabilities of agriculture to disruptions in infrastructure and critical inputs must be identified and addressed.

Further analysis, exploring crops under catastrophe conditions (eg, extreme climates and a lack of agrichemicals), is essential and coordination and collaboration through a non-partisan government centre for mitigating extreme risks could ensure comprehensive planning.


At current production levels, frost resistant food crops could not feed all NZ citizens following a nuclear war and nuclear winter that substantially increased the frost period.

However, this problem could be overcome by increased pre-war production of frost-resistant crops and/or post-war scalability; growing enough frost sensitive crops (ie, in greenhouses or the warmest parts of the country); and/or ensuring continuing production of food derived from livestock fed on frost resistant grasses.

A close analysis of the liquid fuel, agrichemical and seed stock requirements of achieving this is needed.

The NZ Government should conduct a detailed pre-catastrophe analysis on how these issues are optimally addressed. A cooperative non-partisan approach can ensure food security throughout even the worst scenarios. NZ needs a national food security strategy.

Nuclear War – help NZ insure against global catastrophe: Complete the NZCat Survey


The Aotearoa NZ Catastrophe Resilience Project (NZCat) is developing an evidence base and policy agenda for resilience to major global catastrophe.

Anyone with expert knowledge pertaining to NZ can contribute by completing the NZCat Survey.

If you know about NZ transport, energy, food, water, ICT, economy, trade, resilience, or any other aspect of NZ society, then we would value your perspective.

The survey presents a catastrophe scenario beyond that usually considered when assessing nationally significant risks.

Ignored, these scenarios could lead to catastrophic loss and suffering.

Solutions are possible, and we seek innovative contributions about the risks, and how such scenarios could best be addressed both before and after the fact.

Please share the survey with others who might provide valuable insights.

The NZCat Project

The NZCat project began in late 2022. We will publish findings in Nov 2023.

Progress to date:

  • Developed a Hazard Profile for the risk to NZ of a Northern Hemisphere nuclear war.
  • Conducted a workshop to validate the Hazard Profile and frame knowledge gaps.
  • Deployed a survey across ten key sectors seeking to better understand the catastrophic impacts of this scenario and crowdsource innovative solutions.
  • Published a series of blogs and papers that provide information on global catastrophic risk and NZ risk and resilience processes.
  • Made submissions through a global catastrophe lens on key NZ Government work streams.
  • Wrote letters to Ministers advocating for increased focus on global catastrophe.

Project components also underway include:

  • A quantitative analysis of liquid fuel requirements for minimum food production, based on frost resistant crops for nuclear winter, and estimating necessary biofuel scale-up.
  • Assessment of where solutions to mitigate global catastrophe intersect with existing national priorities.

You can see a video about our work here:

Next Steps

Following analysis of all your survey responses, we will publish a summary of the results (~July) and convene an expert roundtable (~August) to discuss the findings.

The roundtable will be followed by a set of in-depth interviews (~September) to clarify important threats and opportunities to integrate in the policy agenda, and how these intersect and complement existing resilience initiatives.

You can express interest in the roundtable event, or volunteer to be interviewed, by completing the survey.

Finally, we will run a workshop (~October) to determine the most critical and high-impact areas to focus recommendations from this work.

To contribute to the NZCat project, click here to complete our survey.

Risk and Resilience in the Face of Global Catastrophe: A Closer Look at New Zealand’s Food Security

By Matt Boyd & Nick Wilson

Image: DALL-E


  • Recent global events have highlighted the need for resilience planning in the face of catastrophic risks.
  • In a new peer-reviewed paper (paywalled, preprint here) we estimate the impact of nuclear winter scenarios on New Zealand’s food export production, finding it dramatically reduced.
  • New Zealand’s food supply is a critical variable in resilience, but the country’s ability to feed itself through a global catastrophe is likely to be limited by critical imports such as the supply of liquid fuels needed to power tractors, harvesters and trucks.
  • Analysis is needed to examine the most efficient production approach, reliable supply of liquid fuel, and a detailed fuel rationing plan that prioritizes food production/processing/distribution.
  • A robust, systematic, National Risk Assessment is needed to identify the most cost-effective and impactful action points to achieve long-term strategic resilience.
  • The Aotearoa NZ Catastrophe Resilience Project seeks to map a policy agenda that could help mitigate the cascading impacts of global catastrophes – but this is no substitute for serious Government consideration now.

Risk and Resilience

In the wake of shocks such as Covid-19, the Russian invasion of Ukraine, Cyclone Gabrielle, and many other recent events, resilience has become a central concern for industry and government. Many organisations, including the Ministry of Transport, the Productivity Commission and the New Zealand Infrastructure Commission have turned their attention to resilience issues.

Luckily New Zealand has been able to muddle through these disasters, however, a much more significant global catastrophe could emerge at any time. Such risks include a great power war, nuclear war, more extreme pandemic, massive volcanic eruption, asteroid/comet impact, major solar flare, or a catastrophic scenario precipitated by emerging technologies (eg, artificial intelligence, bioengineering).

Catastrophic disruption to trade in any of these situations could be unbearable for New Zealand. Critically, modelling studies have indicated that in some scenarios (eg, nuclear war, volcanic eruption, asteroid/comet impact) the catastrophe could be amplified because the sun is partially blocked by soot, sulfur dioxide, or dust. Such impacts could last a decade or more.

Civilization and industry flourish thanks to increasing connections (trade), but this leads to increasing dependence. When catastrophe strikes connections can be rapidly lost as the immense impact disables trade, yet dependence remains.

Food supply is a critical variable for resilience and the potential for a society to bear the unbearable. New Zealand produces a lot of food, but production, processing, and distribution are dependent on connections to imports of oil products, fertilizer, seeds, pesticides and equipment.

Although New Zealand has demonstrated its ability to muddle through lower-level disasters, weathering much more impactful global catastrophe, with society and industry relatively intact, is likely to require significant pre-planning and persistent shifts towards resiliency.

Critical Questions

Some fundamental questions include the following:

  1. How much food does New Zealand produce in normal times and how would production be impacted by global catastrophe (eg, the climate impacts of nuclear or volcanic winter)?
  2. How much is the production/processing/distribution dependent on connections to the world, and what yield is possible without such connections (also accounting for 1 above)?
  3. What adaptations might be possible to pivot production/processing/distribution to maximize calories given the conditions?
  4. What policy agenda ought to be followed to achieve food security for all citizens considering the above?

It is notable that the Draft Food and Beverage Strategy published by the Ministry of Primary Industries (Dec 2022) does not mention risk beyond climate change or commercialization risks, focuses on scale and efficiency, and does not deal with resilience of production sources. The Strategy basically says nothing about how to protect food supply from catastrophe – possibly the single most important factor across the sector.

These omissions could be partly because New Zealand needs a new systematic National Risk Assessment, that examines major global and national risks, and provides information and direction across all of government. There have been repeated calls for this, including from New Zealand’s former Chief Science Advisor Sir Peter Gluckman. We echo these calls and have written elsewhere about the importance and structure of National Risk Assessment.

New Zealand Food Export Calories during Nuclear Winter

We have just published a peer-reviewed analysis that attempts to answer question (1) above. In a paper appearing in the New Zealand Medical Journal (Apr 2023), we aimed to estimate the current dietary energy content of food exports for Aotearoa New Zealand and food security during “nuclear winter” scenarios following a nuclear war.

We combined data from New Zealand nutrition surveys, food export weights from the New Zealand Harmonised System for export data, and data from modelled New Zealand specific nuclear winter impacts. We then determined the per capita caloric supply accounting for wastage, but assuming sufficient industrial inputs (diesel, fertilizer, seed stock, etc)

New Zealand export food production (which accounts for the majority of New Zealand food production, >70%) could be reduced by up to 61% due to the climate impacts following a global nuclear catastrophe. This would mean that instead of supplying the equivalent of 3.9 times (393%) the average daily energy intake of the population (largely in the form of milk powder), export food production would only total 1.5 times (153%) the average calorie intake.

Our paper contains the following table, which illustrates the dramatic drop in export calorie production under the various nuclear winter scenarios and the large concentration of these calories in dairy exports.

Fuel Energy is Critical

Most critically, the results in the table are before any adjustment is made for a potentially catastrophic reduction in the supply of diesel, fertilizer, pesticides, and seed stock. Without diesel to power tractors, milk tankers, and distribution trucks, the ability to supply food calories to all New Zealanders could become marginal.

A plan to pivot export food production to the domestic market would be valuable. This is needed because food produced for the domestic market, when reduced by the likely impact of nuclear winter (excluding the impact of fuel/fertilizer/seed supply etc) could be substantially insufficient to feed the population. Also valuable would be plans to divert crops currently used to feed livestock towards directly feeding humans and to upscale production of frost resistant crops.

It appears that at present the most critical variable in New Zealand’s ability to feed itself through a global catastrophe is likely to be the supply of liquid fuels, which would make or break New Zealand’s food production buffer.

This is where question (2) above comes in. Analysis should now examine how much liquid fuel is needed to ensure the minimum food production, what the most efficient production approach is (this may need to account for the ability of crops to withstand additional frost in a nuclear winter scenario – eg, expanding wheat/carrots as we discuss in our paper on frost resistant crops and nuclear winter) and how New Zealand can achieve this degree of reliable supply of liquid fuel.

A Resilient Solution to Food Security

It is likely that a resilient solution involves some combination of increasing onshore stocks of imported diesel, increasing capability and capacity to produce biofuels (eg, by planning to strategically pivot cropping towards canola to make biodiesel), electrifying machinery and transport, and possibly developing the ability to refine Taranaki crude oil, as a backstop, all in the context of optimizing which crops and production are prioritised.

The above approach needs to be wedded to a detailed fuel rationing plan that prioritizes food production/processing/distribution and identifies quantities consumed per caloric output and rations fuel accordingly. Unfortunately, the current publicly available National Fuel Plan lacks this level of detail. Curiously, the ‘Critical Customer Sectors’ identified for priority fuel include ‘transport and storage of food’ but not ‘food production’. A cursory glance at the priority customers reveals that Corrections, Search and Rescue, and other sectors are prioritized, but these surely are secondary to food production after a global catastrophe. Some more clarity on the details of the Fuel Plan is needed.

To avoid the potential for confusion, conflict and disagreement, the detailed plan needs to be developed with stakeholder engagement and disseminated ahead of time to give society confidence that there is a feasible plan for feeding the nation through a global catastrophe.

A New Zealand Global Catastrophe Policy Agenda

A full policy agenda is beyond the scope of this blog, but it is worth noting a few starting points:

  • A single global catastrophe could wreak more harm than all local natural hazards combined. Global catastrophe should therefore be seen as an unbearable situation requiring a strategy and planning (this is evidenced by one event, Covid-19, arguably a relatively ‘minor’ global catastrophe, causing 95% of all disaster deaths globally in the 21st Century to date).
  • Other countries have legislated requirements that global catastrophes be analysed. For example, the US Global Catastrophic Risk Management Act 2022 requires cross-agency federal plans for ensuring a bare minimum of essential functions under such circumstances.
  • New Zealand should cooperate with other governments on global catastrophic risks. Some problems will be unique to geographic locations (eg, New Zealand is very remote) but others will be common and cooperation will be important (eg, New Zealand and Australia could share food security plans and investigate ways to ensure trade between them continues).
  • The New Zealand Government should undertake a robust, systematic, National Risk Assessment. The assessment should seek common catastrophic impacts across a range of nationally consequential risks, to identify the most cost-effective and impactful action points. This would inform long-term strategic resilience projects. The issues described above are just a taste of the potential impacts of global catastrophe and consider only a handful of global catastrophes. A broader systematic approach is very much needed.

As was noted in the independent report on Auckland’s January 2023 flood response, ‘citizens deserve and expect’ that such thinking/planning has been undertaken. This is true for local natural hazards, but it is most true when the consequences would be national and unbearable.


Our analysis of New Zealand food export production during nuclear winter scenarios suggests that there could potentially be excess food production capacity. However, this benefit may only be short-lived if the agricultural system is not made more resilient to potential lack of international trade and socio-economic collapse in a post-war setting. Further analysis is needed to clarify catastrophe impacts on the interlinked domains of energy, transport, manufacturing, finance, industrial materials, trade, and societal functioning.

Our current project, the Aotearoa NZ Catastrophe Resilience Project (NZCat) seeks to map a policy agenda that expands on the above. We have a survey that is currently live, which aims to collect a cross-sector brainstorm of how scenarios such as the above (beyond what risk analysts might have previously considered) might have cascading impacts within and across sectors, and therefore ideas for how to mitigate these cascades and build resiliency. If you wish to contribute to this survey and give your ideas for a more resilient country, please get in touch.

NZ Economic Resilience: Submission to the Productivity Commission – Focus on Global Catastrophic Risks

Image credit: DALL-E

The New Zealand Government asked the Productivity Commission to undertake an inquiry into the resilience of the New Zealand economy to supply chain disruptions.

The major risks to New Zealand are those that arise elsewhere and impact the entire world.

Adapt Research and the Aotearoa NZ Catastrophe Resilience Project (NZCat) have made a detailed submission to this inquiry.

In the submission we propose that global catastrophic risks such as major volcanic eruption, extreme pandemic, great power war, nuclear war, asteroid/comet impact, major solar flare, etc are the greatest threats and any resilience planning should consider these scenarios, which collectively are not unlikely.

The most severe common impact across these scenarios for NZ is an extreme collapse in global trade.

We made 12 recommendations in our submission:

  1. Include global catastrophic risks in National Risk Assessments.
  2. Replicate the 2022 US Global Catastrophic Risk Management Act.
  3. Prepare strategies and plans to ensure food security under circumstances of global catastrophe and/or trade isolation.
  4. Conduct interagency/multi-sector scenario-based simulation to explore the impact and response of New Zealand to major global catastrophes.
  5. Red-team the above exercises and include scenarios where New Zealand is isolated from global trade for an extended period.
  6. Introduce a new National Science Mission to study global catastrophes.
  7. Conduct analysis of risk and response, provide data and information that industries and communities can use to make decisions about adaptation.
  8. Support industries and communities to produce commodities that local export markets (eg, Australia) will likely need, to hedge against the collapse of long-distance trade.
  9. Develop a plan to keep domestic and local regional trade and supply operating.
  10. Nurture a global catastrophic risk think tank based in New Zealand.
  11. Undertake rapid cost-effectiveness analyses across a suite of potential mitigation measures.
  12. Ensure that the above analysis is conducted at national level, but also identifies regional variation in capabilities and needs.

Yes, NZ needs a systematic National Risk Assessment; but we must not repeat others’ mistakes

Image: Midjourney


  • Sir Peter Gluckman and Anne Bardsley have called for an apolitical NZ national risk assessment.
  • We support this call but note several weaknesses of existing national risk assessments both in New Zealand and globally.
  • The new assessment must be systematic, include global catastrophic risks, engage stakeholders, cooperate with other countries, and appropriately represent risk.
  • For more on global catastrophe and NZ resilience, you can read about our ongoing Aotearoa NZ Catastrophe Resilience Project (NZCat).

Risk and New Zealand

Risk analysis will be topical in New Zealand in 2023 argues a recent opinion by former NZ Chief Science Adviser Sir Peter Gluckman and Dr Anne Bardsley: Risk listening: rethinking how we understand and manage risk

Ongoing disruptions from the Covid-19 pandemic, and more recently extreme weather in the form of cyclone Gabrielle have highlighted New Zealand’s infrastructure gap and cut across multiple government agencies and ministries.

Gluckman and Bardsley note that there will be ongoing acute events, increasing climate impacts, and harms from a degrading digital and information environment. Programmes such as the UN’s sustainable development goals (SDGs), the Paris Climate Accords, and the Sendai Framework for Disaster Risk Reduction are all intended to work in concert to reduce risk and optimise development by 2030. However, progress remains variable, and the systemic disruption of the Covid-19 pandemic has impacted progress.

The opinion also notes that current shortcomings of the risk assessment process include:

  • Insufficient transdisciplinary science and knowledge brokerage between science and policy.
  • A low priority given to developing redundancy and resilience (reactive rather than proactive policy).
  • The problem of short-termism in decision making.
  • There is insufficient ‘risk listening’, ie decision makers are not open to taking on board the risk assessments

Gluckman and Bardsley’s article proposes that NZ undertake an ‘extended’ and ‘independent’ national risk assessment. The resulting product must be ‘public facing as well as policy facing’. We support this call.

However, we note that national risk assessment processes of the past have exhibited significant weaknesses. These will need to be explicitly overcome to ensure that these assessments can act as a repository for risk information and a foundation for action.

Problems with existing national risk assessments

Some very recent publications that have raised concerns about national risk assessment processes include the following:

  • A February 2023 report by Kevin Kohler of ETH Zurich on cross-border risks that describes discrepancies and shortcomings in their assessment across nine European national risk assessments.
  • An Feb 2023 academic paper describing two key weaknesses of existing national risk assessment processes, namely exclusion of almost all the major risks, and a lack of stakeholder engagement.
  • A March 2023 report commissioned by the UN Office for Disaster Risk Reduction that considers two major global risks often excluded by national risk assessments and notes that national risk assessments have failed to adequately account for them.

Important problems of national risk assessments can be summarised as follows:  

National risk assessments, even those with the best intentions, omit critical risks. This is evidenced in the omission of volcanic eruption as a risk in the UK National Risk Register prior to the immensely disruptive eruption of Eyjafjallajökull in Iceland in 2010, and also the assessment prior to the Covid-19 pandemic that a non-influenza emerging disease outbreak might kill ‘up to 100 people’ in the UK. Any assessment of national risks needs to be comprehensive. Including diverse known risks allows for comparison of risks and prioritisation of resources. Decision makers who exclude risks from the assessment are exposing countries to increased risk and are circumventing a democratic discussion of risk prioritisation.

National risk assessments often omit the entire class of global catastrophic risks (GCRs). Assessments thereby plausibly omit analysis of most of the actual risk. GCRs include anything that would impact the entire world, create severe systemic harm and/or kill a significant proportion of the global population. These risks include: engineered pandemics, risks from artificial intelligence, nuclear war/nuclear winter, major volcanic eruptions, rapid severe climate change, severe solar storms, asteroid/comet impacts, etc.

National risk assessments seldom engage the appropriate spectrum of stakeholders. This is evidenced, for example, in the Swiss national risk assessment (2020) in which members of the public accounted for 0% of stakeholders engaged in risk workshopping processes, and the NZ National Risk Register which was developed but then kept confidential. Decision makers need to analyse and address risks that an informed public is concerned about, and risk information must be freely accessible in order for all stakeholders to be able to prepare to mitigate the risks. Indeed, the UN has noted that lack of access to risk information is a critical weakness of present disaster risk reduction activities.

National risk assessments have produced highly variable assessments of cross-border risks. For example, the probability of impact from a major volcanic event in Europe was 1:4 to 1:20 per annum in the UK assessment, but 1:70,000 in the Swiss assessment. Neither assessment included the 1:625 likelihood of an even larger eruption elsewhere in the world that could cause massive disruption to global trade. This implies that working with other countries to share analyses and align expert findings would be valuable.

National risk assessment can become politicised or focused on recent salient events to the exclusion of major likely harms. It is well known that risk assessment processes can end up being manipulated for political gains, or to help consolidate the status quo or protect existing budgets. Resources often end up allocated to studying comparatively lesser risks in forensic detail, rather than addressing the low-hanging fruit for big inevitable ones. An example is plausibly the time and effort spent analysing domestic terrorism versus preparation for a catastrophic pandemic.

National risk assessments, and consequence-probability risk matrices, fail to appropriately represent the salience of risks. For example, categories are often used to represent the likelihood and consequences of hazards in a risk matrix. However, it is evident both that the categories chosen in many national risk assessments fail to adequately discriminate amongst risks, especially at the more serious end, and the salience of very severe risks such as global pandemics is not readily apparent. These shortcomings have been described by ourselves, and others.

Moving forward with NZ risk assessment

No one knows what the next catastrophe will look like, so preparation and resilience measures that cut across risks, and address systemic weaknesses (in trade, energy, transport, infrastructure, health, and plans to supply essential goods, etc) should be prioritised. There are many domains where investment in prevention offsets much greater impact costs.

Indeed, the biggest threats of undermining the SDGs globally, and of harming New Zealand specifically are global catastrophic risks. Yet, arguably, even with only short term (1 year) thinking, some GCRs appear to be the priority for mitigation measures as we have argued elsewhere.

We support Gluckman & Bardsley’s call for a comprehensive, public, apolitical, NZ national risk assessment. But the approach will need to address the key shortcomings we identified above.


  • A systematic national risk assessment should be a legislated requirement, and it should include global catastrophic risks. The recent US Global Catastrophic Risk Management Act (2022) could be used as a template.
  • The assessment needs to be cross-government and cross-sectoral and be undertaken by an anticipatory and apolitical entity. We have described how a well-resourced Parliamentary Commissioner could play this role (but other structures are possible, such as a Chief Risk Officer).
  • The national risk assessment needs to engage experts and stakeholders widely. This could help overcome the problem of poor foundational assumptions, for example around such things as scenario choice, discount rate, time-horizon, and decision rule. We have explained these issues in depth elsewhere.
  • Any national risk assessment needs to be connected to a capabilities analysis that assesses not just the consequences of a risk in expectation, but also the marginal benefit of various actions (eg CBA) and the value obtained from acting (eg equity or Treaty issues).
  • Options and trade-offs need to be put to stakeholders for a national discussion. We need more than a list of ‘bad things’, we need an agreed robust strategy to reduce risk across time.

Revolutionising National Risk Assessment (NRA): improved methods and stakeholder engagement to tackle global catastrophe and existential risks

By Matt Boyd & Nick Wilson

Photo by Marc Szeglat on Unsplash


  • In a recently published paper, we identified two major shortcomings of National Risk Assessment (NRA) processes: (1) Lack of transparency around foundational assumptions; (2) Exclusion of the largest scale risks
  • We demonstrate the potential problems and ambiguities that arise in NRA due to these shortcomings. 
  • We identify the exclusion of global catastrophic risks (GCRs) and existential risks (x-risks) from NRAs as a critical process error.  
  • Even when only considering people alive today, and with a time horizon of just one year, the consequence in expectation of several existential risks is higher than all other risks commonly included in NRAs. 
  • A ‘longtermist’ perspective is not needed to prioritise existential risk mitigation through NRA, and potentially detracts from getting such risks onto the agenda for assessment. 
  • We propose the development of a freely available, open-access, risk communication and engagement tool to facilitate stakeholder discussions on NRAs.
  • Decision-makers should include GCRs and x-risks in NRAs.

This post is a partial and high-level summary of our research paper on national risk assessment (NRA) published in the academic journal Risk Analysis in March 2023. This post also places our work in the context of another recent report on NRA identifying common ground. Consider reading our full paper for complete details of our thinking on NRA as it applies to global catastrophe, and existential risk. 

You can also find this post on the Effective Altruism Forum here


Many countries undertake National Risk Assessment (NRA) to evaluate risks of national significance, assessing for example, natural hazards, infectious diseases, industrial accidents, terrorist attacks, cyberattacks, organised crime, or institutional failure. The NRA process is complex and cross-sectoral, often excluding risks with low probability, and often has a short-term focus of less than five years. The outputs of NRA tend to communicate results in some form of National Risk Register (NRR) and/or consequence-probability (C,P) risk matrix. 

However, NRAs and NRRs can be criticised particularly where the common practice of presenting a two-dimensional risk matrix obscures uncertainties, stakeholder disagreements on values, bias, and systematic errors. Critically, the exclusion of large-scale (and cross-border) risks such as global catastrophic risks (GCRs) and existential threats to humanity (x-risks) is another limitation of NRAs.

The aim of NRA should be to find common understanding across stakeholders of risks and priorities, stimulate local authorities to build capacity and capability, and identify common consequences across multiple risks. Prioritisation of risks is sometimes explicitly intended through the NRA process, but methods for prioritisation depend on foundational assumptions of the NRA process that are not always clearly articulated. 

Aim of our paper

Our paper sought to demonstrate some shortcomings of existing NRA processes and outputs, namely: 

  1. How the choice of fundamental NRA process assumptions makes a material difference to the NRR output and any subsequent deliberation on risk.
  2. The weaknesses and ambiguity of risk matrices for communicating NRAs.
  3. A major class of risks often neglected by NRA (namely GCRs and x-risks).
  4. The difficulties that uncertainty poses. 

We then suggest how those undertaking NRA could enter a productive dialogue with stakeholders, supported by an interactive communication and engagement tool, to overcome some of these difficulties (details of that are in the paper, not the post below). 

We note that another report, by Kevin Kohler, titled National Risk Assessments of Cross-Border Risks was published in February 2023, shortly before our paper. Throughout this post we also highlight some of the key points therein.  

Important Assumptions of National Risk Assessments

In our paper, we introduce a hypothetical set of six risks A–F (which vary by probability and consequences) to illustrate some key issues when undertaking NRA and when using NRAs and risk matrices to communicate national risk or inform prevention and mitigation.

We demonstrate how changing fundamental analysis assumptions changes the ordinal prioritisation of the risks. The importance of this is that the basis of the assumptions is often opaque to end users, or has not been authorised by public debate and stakeholder input (noting that future generations are also stakeholders). 

The assumptions we systematically alter are: the scenario of choice (challenging scenario vs worst case), the time horizon of interest (one year, 50-years), the discount rate on future value (0%, 3%), and decision rule. 

We demonstrate how different assumption combinations alter the ordinal priority of the risks A–F (when considering just expected fatalities for simplicity). We show that varying the evaluation assumptions leads to different prioritisation of risks in 7 out of 8 analyses, thereby emphasising the critical importance of agreeing on process assumptions. 

Probability-consequence Risk Matrices

The next section of our paper reiterates some criticisms of probability-consequence risk matrices in the context of NRA. We note that such matrices are fairly arbitrary constructions. Risk matrices generally look something like the following figure. Risks are placed in categories according to likelihood and expected impact. Darker regions (purple, red, orange) allegedly represent more salient risks than lighter regions (yellow, green, blue).

Figure 1: A probability-impact risk matrix

We dispense with the colours and simply plot our demonstration risks A–F on axes representing likelihood and impact. A concrete example of the misleading nature of risk matrices (if categories are used) can be seen in the following figure. Risks ‘F’, ‘D’, and ‘B’ all appear to cluster in one region, towards the ‘upper right’, ie, the highest priority area of the risk matrix. Yet, the numerical consequence in expectation (fatalities) of risk D is 20x that of risk B. This may be somewhat apparent when the logarithmic axes are labelled and the risks are plotted in a scatterplot, but it would be completely obscure in the coloured matrix above.

Figure 2: Risks with vastly different consequences in expectation can cluster in risk matrices

We provide further examples in the paper illustrating how risks with the highest consequence in expectation can end up being equated with minor common events due to the heat-map nature of some risk matrices. 

Global catastrophic and existential risks

Not only do fundamental assumptions and communication choices bias the assessment of national risks, but cross-border risks and in particular global catastrophic and existential risks are seldom included in NRAs. 

Our analysis of five NRAs (and Kohler’s 2023 analysis of nine) shows that no NRA appears to include many, if any, GCRs or x-risks. Surprisingly the Norwegian NRA mentions in one sentence that a large volcanic eruption could ‘cool the earth by several degrees’. But then never mentions the global consequences of what could be the single most catastrophic impact contemplated by any NRA.

In our paper, we consider only the existential risks among a set of GCRs and ignore the more likely but non-existential manifestations of the same risks. Simple estimates reveal that several of these risks harbour annualised consequences in expectation greater than all typically occurring natural hazards combined. 

Even when only considering people alive today, and with a time horizon of just one year, the consequence in expectation of several existential risks appears higher than all other risks commonly included in NRAs. We identify the exclusion of GCRs and x-risks from NRAs as a critical process error.  

A longtermist perspective is not needed to prioritise existential risk mitigation and potentially detracts from getting such risks onto the agenda for assessment. Indeed, it appears that standard risk assessment processes, and standard government cost-effectiveness analyses should be enough to reveal the overwhelming priority of GCRs and x-risks in NRA.

We argue in the paper that deliberation over such risks and whether they ought to be prioritised for mitigation, can only happen if they are included in the NRA, characterised, communicated to stakeholders, and put forward to resource prioritisation processes for prevention or mitigation.

Kohler’s new paper notes that the European Commission specifically recommends that NRAs include risks (no matter how rare) if the likely impact exceeds 0.6% of gross national income and the time horizon of interest should ideally be at least 25–35 years. These instructions mean that all GCRs and x-risks should be assessed in NRAs. 

Indeed, the US has recently passed a world-leading Global Catastrophic Risk Management Act, which mandates exactly this kind of systematic assessment of GCRs and x-risks, along with response plans to ensure basic necessities are available post-facto (we have blogged about this Act). There is no good reason why all countries can’t replicate this legislation or at least empower the United Nations to do it for all countries/regions (you can read a recent 2023 discussion of existential risks and the UN Office for Disaster Risk Reduction by the Simon Institute here). 

Example: Pandemics

Pandemics are an interesting case, and although we don’t dwell on them specifically in our paper, the Covid-19 pandemic illustrates the clear shortcomings of NRAs. We argue in our paper that national risks should not be presented in a risk matrix, but should be communicated quantitatively in ordinal fashion according to the consequence in expectation of agreed scenario types, across an agreed timeframe, under an agreed discount rate.

A standard national risk assessment presents the risk of pandemics something like this:

Figure 3: Human pandemic as a relatively likely & catastrophic risk (source: DPMC publication: ‘NZ’s National Security System’ Sept 2011).

However, Kohler points out that the Covid-19 pandemic has already exceeded the most severe pandemic scenario in most NRAs. This is even though it ‘only’ had an infection fatality ratio of less than 0.6%. Even the conservative official death toll from Covid-19 accounts for 95% of the deaths from disasters in the 21st Century. The other 5% include all deaths from the 2010 Haiti earthquake, plus the 2004 Indian Ocean tsunami, plus the 2008 Myanmar cyclone (about 200,000 deaths each). 

If the risk from human pandemics in the first two decades of the 21st Century were presented in a treemap chart (rather than a risk matrix) it might look something like this, thereby revealing the real salience of human pandemics:

Figure 4: Gestural treemap chart showing scale of pandemics in the 21st Century vs other major disasters

Indeed, Kohler found that only Switzerland and the Netherlands have chosen risk impact categories at the upper end that roughly correspond to the impact of Covid-19. And these categories would not discriminate between Covid-19 and a worse pandemic in the risk matrix. 

It has been our own experience that even using the Swiss method for NRA, applied in a workshop on the nuclear war/winter hazard risk to a non-combatant nation, that these upper impact categories are seriously inadequate. 

The reality is that if NRAs were actually presented as Treemap charts, or in some other form than risk matrices, and if the suite of GCRs and x-risks was included, then the picture of risk communicated would look very different. Over longer periods of time most (almost all?) expected disaster deaths come from a few worst case scenarios.

However, any presentation of a chart or graph is packed with foundational assumptions and can obscure uncertainties. 

Uncertainty and Assumption

We acknowledge that the probability of GCRs and x-risks is highly uncertain. But this appears to be the case with many risks already included in NRAs. For example Kohler reports that the likelihood of a -1600 nano-tesla (nT) solar storm was cited as 1:80 per annum in the 2015 Swiss NRA, but 1:1700 in the 2020 version of the same analysis. The explanation was that a mathematical analysis concluded that intensity of solar storms decreases with time since an event. Yet, research post-dating that analysis suggests that tree ring radiocarbon evidence might indicate large solar storms might be much more common than we have thought. More expert input appears to be needed. 

Similarly, for volcanic eruptions, the probability of a volcano affecting Switzerland was estimated at 1:70,000 whereas the UK’s analysis cited 1:20 to 1:4. Kohler notes an annualised baseline probability of 1:3000 for a Volcanic Explosivity Index (VEI) 6+ eruption in Europe. However, neither NRA mentions the 1:625 probability of a VEI 7 eruption somewhere else in the world, which like the Mt Tambora eruption of 1815 could have devastating consequences for global agriculture (we discuss the Mt Tambora eruption as it impacted potential island refuges in a separate paper in 2023).

In the present paper, our discussion then proceeds across other issues of uncertainty, including the problem that strength of knowledge poses (eg, equally likely risks but the strength of knowledge underpinning the data varies), the problem of dealing with different scenarios of a single hazard, the difficulty of probabilities that change across time, and how all these factors point towards the need for public engagement. 

Ultimately, NRAs are a social construction, built upon allegedly reasonable assumptions (about time frame of interest, discount rate, scenarios of choice, and decision rules), and including agreed choices about risk communication methods. All of this needs to be debated openly. 

Stakeholder Engagement

Most NRA processes involve little public consultation and in some instances overt secrecy. There is a documented lack of awareness of NRRs, even among local authorities to whom they are in part directed. This is despite the UN advocating for ‘increased access to risk information’ and that, ‘low risk awareness is one of the main challenges’. 

It is also unclear if citizens understand the foundational assumptions underpinning NRAs and whether they would authorise them if they did. 

In the paper we identify a range of arguments that would support wider public and expert engagement, including: risks of potential groupthink, politicisation, or uncertainty. 

We note that scrutiny must logically first be applied to the underlying process assumptions, then to the resulting empirical claims, and finally deliberative prioritisation (for prevention, mitigation or further research) can take place. We propose the development of a freely available, open-access, risk communication and engagement tool to facilitate discussions on NRAs. Aspects of such a tool could be tailored to experts and other aspects to the general public. 

In our paper we lay out the rationale for expert engagement, public engagement, and describe in some detail the sort of interactive online tool that could be deployed to support such engagement. 


In our paper we identified two shortcomings of National Risk Assessment (NRA) processes: lack of transparency around foundational assumptions, and exclusion of the largest scale risks. 

We discuss the importance of agreeing on key assumptions before conducting a NRA. The assumptions include methodological and normative choices that determine which risks are included, how they are characterised over time, and how uncertainties are expressed in risk communication.

A hypothetical demonstration set of risks is used to show how choices around time horizon, discount rate, and impact estimation affect risk characterisation. We highlighted the potentially dominating importance of global catastrophic and existential risks, which are often omitted from NRAs, and suggested using standard risk assessment and cost-effectiveness analyses to address them. 

Given the array of possible assumptions, uncertainties and inclusions, it is crucial that those undertaking NRA engage the public and a broad array of experts in the NRA process through a transparent and two-way risk communication process. This could help legitimise key assumptions, avoid omitting important risks, and provide robust critique of risk characterisations and the knowledge underpinning them.

A Historical Volcanic Winter & Future Sunlight-Blocking Catastrophes: New Study

Nick Wilson & Matt Boyd

Summary / TLDR:

  • Island nations may have potential long-term survival value for humanity in global catastrophes eg, during a “nuclear winter” or “volcanic winter”.
  • We studied a major historical eruption (Mt Tambora in 1815), and found that the “volcanic winter” impacts were less in the islands than on the continents (for latitudinally equivalent comparisons).
  • Out of the 31 islands studied, the smallest temperature drops were seen for islands in the Southern Hemisphere, the Indian Ocean, and in the tropics and subtropics of the Southern Hemisphere.
  • Island nations could work to enhance their resilience to sunlight-blocking catastrophes to help ensure humanity can survive such events.

Our Study of the 1815 Mt Tambora eruption

Catastrophes such as nuclear war and large magnitude volcanic eruptions could fill the stratosphere with sun-blocking material such as soot or sulphur dioxide. Island nations may have potential long-term survival value for humanity in such sun-blocking catastrophes. We aimed to explore this further by studying the impact on islands after the largest historically observed volcanic eruption: that of Mt Tambora in Indonesia in 1815.

In conjunction with colleagues from Switzerland and the UK, our just published study1 involved 31 large, populated islands for which we conducted literature searches for relevant historical and palaeoclimate studies. We also analysed results from a reconstruction (EKF400v2), which uses atmospheric-only general circulation model simulations with assimilated observational and proxy data.

How did islands fare in the “volcanic winter” after the eruption?

From the literature review, there was widespread evidence for weather/climate anomalies in the years 1815-1817 for these islands (29/29 for those with data; Figure 1, below). But missing data was an issue for other dimensions such as impaired food production (seen in 8 islands out of only 12 with data). Data on food insecurity or famines was also largely missing, but for the 12 islands with data, four definitely experienced such problems. These were all in the North Atlantic region ie, Great Britain, Ireland, Iceland and Newfoundland. In three of these there was also evidence of food riots or demonstrations (ie, all except Iceland). In Ireland there was also evidence of increased death rates from famine and/or famine-related disease.

Based on the EKF400v2 reconstruction for temperature anomalies (compared to the relatively “non-volcanic” reference period of 1779 to 1808), the islands had lower temperature anomalies in the 1815-1818 period than latitudinally equivalent continental sites (at 100 km and 1000 km inland). This was statistically significant for the great majority of the comparisons for group analyses by hemisphere, oceans, and temperate/tropical zone.

Figure 1: Summarised evidence for impacts from the Tambora eruption on 31 islands in the 1815-1817 period (see the published article for additional details; Image produced using Ferret v7.63; Reproduced from Wilson et al 20231 (published under a Creative Commons Attribution 4.0 International License,

When considering just the islands, all but four showed statistically anomalous temperature reductions in the 1816-1817 period (for most p<0.00001; with Figure 2 (below) showing the pattern for 1816). In the peak impact year of 1816, the lowest anomalies were seen for islands in the Southern Hemisphere (p<0.0001), the Indian Ocean (p<0.0001), and in the tropics and subtropics of the Southern Hemisphere (p=0.0057). The latter included the islands of: Australia [a continental island], Java, Madagascar, Marajó (Brazil), New Britain (part of Papua New Guinea [PNG]), New Guinea (PNG) and Timor.

Figure 2: Reconstructed temperature anomalies in 1816 (“the year without a summer”) relative to the “non-volcanic” reference period (1779 to 1808) using monthly data from the reconstruction EKF400v2 (Image produced using Ferret v7.63; Reproduced from Wilson et al 20231 (published under a Creative Commons Attribution 4.0 International License,

Relevance to island refuges – for humanity to survive catastrophes

We might draw some provisional conclusions relevant to the concept of island refuges for humanity from this study. The findings do point to the likely benefits of island refuges in the Southern Hemisphere, the Indian Ocean and the tropics and subtropics of the Southern Hemisphere. Such islands may have features that advantage them in some catastrophes and could be considered for resilience building measures with the aim of ensuring humanity’s survival, especially in case much larger eruptions or nuclear war eventuate.

But other considerations for targeting resilience investments include the following:

  • The findings of simulation studies of the global climate impacts of nuclear war – which also favours Southern Hemisphere islands, including Aotearoa NZ (as we have studied here 2).
  • The risk of islands being directly attacked in a nuclear war (eg, those in military alliances with nuclear weapon states such as Australia, Iceland and Japan).
  • Capacity of islands to survive extreme pandemics (as we have studied here 3)
  • And the islands having the socio-economic and technological characteristics to potentially be a “node of persisting complexity” 4 from which more technologically advanced societies could be re-built.

Ideally a number of island nations could build up their resiliency to best survive such catastrophes, perhaps with initial focus on energy, food, transport and communications resilience. Well-placed islands might be provided with support to do so by the international community. But failing such international support – individual nations such as Australia and New Zealand should give consideration to doing this – for both themselves and the future of humanity.


1.         Wilson N, Valler V, Cassidy M, Boyd M, Mani L, Brönnimann S. Impact of the Tambora Volcanic Eruption of 1815 on Islands and Relevance to Future Sunlight-Blocking Catastrophesdair. Sci Rep. 2023;13:3649.

2.         Boyd M, Wilson N. Island refuges for surviving nuclear winter and other abrupt sunlight-reducing catastrophes. Risk Analysis. 2022.

3.         Boyd M, Wilson N. Optimizing island refuges against global catastrophic and existential biological threats: Priorities and preparations. Risk Analysis. 2021;41(12):2266-85.

4.         King N, Jones A. An Analysis of the Potential for the Formation of ‘Nodes of Persisting Complexity’. Sustainability. 2021;13(15):8161.

Workshop on Nuclear War/Winter & NZ: Wellbeing of millions and $1 trillion plus at risk, strategic resilience must become bread & butter NZ policy

Matt Boyd, Ben Payne, Nick Wilson

Photo by Rod Long on Unsplash


  • We held a workshop on the risk of nuclear war/nuclear winter and implications for Aotearoa/NZ on 9 February 2023.
  • The workshop was attended by 20 experts representing organisations in the public and private sector, and academia.
  • Attendees discussed our new NZ Nuclear War Hazard Profile * and deemed the key scenario to be both ‘quite plausible’ and ‘catastrophic’.
  • Elicitation and sharing of key knowledge underscored the severe and wide-ranging impact of a Northern Hemisphere nuclear war for an isolated non-combatant nation like NZ.
  • Resilience measures are likely to be possible, but research to understand the cascading impacts through NZ industry and society is needed.
  • Also needed is a long-term big-picture strategic view of how resilience measures can improve wellbeing now and mitigate a wide class of risks including extreme weather or future severe pandemics.
  • Next possible steps for better understanding NZ’s resilience and vulnerabilities were identified (see bullet points and numbered list at end).

*Note: some readers report this hyperlink not working, the url is:

Resilience: NZ’s Bread & Butter

Global catastrophic risks such as nuclear war could result in long-term harm on a global scale, with profound disruption to our way of life in Aotearoa New Zealand (NZ). Other global risks including extreme pandemics, supervolcano eruptions, catastrophic solar flares, abrupt climate change, and many others are named in the new US Global Catastrophic Risk Management Act which requires analysis and planning for major impacts. Resilience to such risks to protect people now and ensure flourishing of future generations requires more than ‘stacks of tuna cans.’ Wise strategy, investment in risk analysis, planning, quality infrastructure, resilience, and cooperation can help optimise the path forward. This should be bread and butter policy in the 21st century.

New Zealanders have seen first hand the impact of catastrophe in recent weeks. Severe flooding and cyclone damage reveal what happens when regions are cut-off and government response is stretched thin. In a global catastrophe, all of NZ could be isolated making response difficult. We need to ensure that as a nation we can get through such catastrophe by developing national and local resilience ahead of time.

Aotearoa NZ Catastrophe Resilience Project

Using nuclear war as a representative global catastrophe, the Aotearoa NZ Catastrophe Resilience Project seeks to understand NZ’s vulnerability and resilience factors and recommend initiatives to mitigate global catastrophic risk.

The Aotearoa NZ Catastrophe Resilience Project Plan

Hazard Profile

The first step in building resilience to global catastrophe is to analyse the hazards. Using the methodology of national risk assessment, we developed a Nuclear War/Winter Hazard Profile for Aotearoa/NZ.

The profile describes ‘significant’, ‘major’ and ‘extreme’ nuclear war scenarios. The ‘major’ scenario is then analysed in depth.

Major Nuclear War Scenario

In the ‘Major’ scenario 250–500 nuclear weapons of 10–100kT are detonated, many on cities. This results in 10–30 teragrams (megatonnes) of soot rising into the stratosphere. This soot blocks the sun and causes -4.0 C of mean global cooling. Simultaneous conventional attacks mean mass destruction of Northern Hemisphere infrastructure. 30–75 million people are killed immediately. Weeks of chaos follow as radiation disperses, deaths mount, normal business and trade functions halt, and communications are destroyed. The global temperature drop lasts into the following years. Food production in North America, Europe, and Russia falls 60-90% in the second year.As regional famines take hold, countries turn inwards, hoard commodities, and global trade is severely disrupted. NZ suffers from massive trade disruption and some modest impact on crop production (from cooler temperatures and reduced sunlight).  The Hazard Profile accounts for 12 key impacts and two plausibility factors (based on a Swiss methodology). Together these allow this hazard to be plotted on a likelihood vs consequences diagram (see below).

February 9 Workshop

We ran a workshop on 9 February 2023 to help validate the nuclear war/winter hazard profile for NZ. The workshop included a pre-workshop activity to estimate the impact and plausibility of the ‘major’ scenario. Expert elicitation activities on the day allowed us to gather and aggregate informed input to refine the Hazard Profile.

The workshop consisted of diverse representatives across public and private sectors, as well as academia. Attendees included experts on global catastrophe, nuclear war, emergency management, and societal systems. The workshop included presentations on national risk assessment and nuclear war, as well as discussion of impacts, plausibility and knowledge gaps.

A lot of brainstorming and expert input took place both in the room and in the Zoom chat.


Overall, the original ‘Major’ scenario was considered relatively conservative. Outcomes could be worse due to the logic of escalation in a nuclear conflict, likely targeting of industrial capabilities, loss of cloud/digital systems and cascading impacts across all industries.

The likely scenario could result in many fatalities in NZ due to a range of mechanisms including shortages of imported medication. There could be widespread illnesses, including mental health issues, and widespread societal impacts.

The anchor points for economic harms experienced by NZ used in national risk assessment were seen as too conservative (designed for floods, earthquakes, etc). The reality could far exceed NZ$1 trillion in monetised equivalent value loss irrespective of impact on factors such as environment or culture. The potential for electromagnetic pulse (EMP) as a strategic warfare method should not be discounted. Although NZ has held a longstanding anti-nuclear stance, the nascent space industry and existing formal military alliance with Australia (and more informal military links with the US), may be seen as a threat and could lead to NZ being targeted (albeit some participants thought this very unlikely). It was also considered necessary to build a ‘reasonable’ timeframe into the scenario, as a reference point to calibrate thinking on impacts.

Participants rated the impacts the ‘major’ nuclear war scenario would have on NZ using a 0–8 scale anchored with descriptors, where each point increase represents a 3x magnitude increase in impact. The following graph summarises the participants thinking on impact levels, and the table quantifies this scale in concrete harms and monetised value (again using the Swiss methodology). A separate table provides a high-level summary of key contributions.

12 Impacts of a Northern Hemisphere nuclear war on NZ

The 12 impacts quantified (mean of expert estimates, n=14)

The NZ$1 trillion plus risk

When the diverse impacts of the ‘major’ scenario are converted to monetary terms (a necessarily highly speculative activity) to allow comparison with other risks, the harm to NZ from a Northern Hemisphere nuclear war would likely exceed NZ$1 trillion. But this ‘mean’ total value doesn’t capture the distribution – with some expert respondents suggesting that the impacts would be very much higher than the top of the scale in multiple domains.


Agential or unprecedented risks, which lack a historical data set or depend on fluctuating willingness to act, such as nuclear war, can be classified according to the plausibility of the specific scenario being considered (ie, the ‘Major’ scenario outlined above). 

In this case, plausibility was construed by combining estimates of the degree of intent and ability possessed by likely perpetrators of nuclear war, with the technical and operational feasibility of the scenario. Following discussion, independent estimates were aggregated and the scenario was estimated to be ‘quite plausible’ at a mean of 3.39 on a 1–5 scale with 0.5 point increments.

Key to the plausibility assessment was the fact that a wide range of nuclear risk variables are trending in the wrong direction, these include: the number of weapons, modernisation of systems, increasing conflict, cyber threat, intermixing of command and control systems, terrorist threats, the desire to acquire weapons, plus the existence of historical near misses.

The resulting plausibility of the ‘major’ scenario is mapped to the estimated impact in the following risk diagram.

Figure Legend: The figure displays the plausibility assessment for the ‘major’ scenario mapped against the impact assessment (using an established Swiss methodology). The circle indicates the mean of independent assessments of diverse experts (n=14) conducting a pre-workshop activity. The arrow indicates that the assessment moved towards a higher impact category (~$1 trillion plus monetised harm) following workshop interactions with diverse other experts (n=12).


Workshop participants indicated that several of the impact categories in the Hazard Profile were hard to quantify. There was some suggestion that quantification is not necessary if the scenario is clearly in the ‘upper right’ section of the risk diagram (ie, plausible and highly damaging). However, some quantification seems useful as a first step to place it in the upper right part of the risk diagram and therefore to distinguish it from more minor hazards.

Other ‘upper right’ quadrant risks

It is interesting to compare the location of the ‘major’ nuclear war scenario in the upper right (ie, quite plausible and extremely damaging) region of the risk diagram to the glaringly obvious ‘upper right’ risk identified in a NZ national risk assessment that pre-dated the Covid-19 pandemic and the Cyclone Gabrielle disaster (but post-dated the Christchurch Earthquakes and the 1918 pandemic – the highest impact natural hazard in NZ’s history where over 8000 NZ citizens died).

A historical NZ national risk assessment

Source: DPMC NZ’s National Security System Sept 2011

Some key themes of workshop discussion

The following represent just some of the key insights that workshop participants contributed and which the Aotearoa NZ Catastrophe Resilience Project will be following up.

  • Compared to findings of previous 1980s work on nuclear war impact and NZ, the impact of damage to the internet, overseas-based cloud data, and digital communications featured prominently. It is unclear to what degree the internet, cloud data, and digital communications would be operational in the ‘major’ scenario. This is a key area for research and interviews with experts as it has serious implications for the operational potential of government, industry, and personal life.
  • The risk to NZ’s territorial integrity is very uncertain. It is possible that refugees, non-state actors, hostile state actors, or powerful individuals attempt to reach NZ (just prior to or after such a nuclear war). It is also possible that there are insurmountable difficulties of doing this under the conditions of the ‘major’ scenario. This is another key area for further analysis.
  • The possible collapse of the financial system and likely shortages including transport/fuel, might mean that a key response to the ‘major’ scenario may be quick transfer of power/agency to local government and local communities. However, planning to ensure that such agencies/groups have access to the raw materials and knowledge required to ensure food supply, alternative energy supply, and communications may be needed. A detailed analysis of these requirements would probably be useful.
  • Several workshop attendees emphasised the need for a NZ narrative around resilience to major global catastrophe, fostering public discussion of these risks, with emphasis on the need for cooperation to achieve strategic resilience. Fostering such a narrative could be a very worthwhile government action if it focuses on opportunities for enhanced wellbeing now, as well as building resilience against other hazards (eg, severe storms associated with climate change).
  • The principles of Te Tiriti o Waitangi and the knowledge and perspectives of Māori are likely to aid strategic resiliency to major global catastrophes and to strengthen local level resilience for a wide range of other hazards.
  • Further analysis of the ‘major’ scenario and other global hazards would not cost much in comparison to large infrastructure projects such as Transmission Gully and could form part of an expanded National Science Challenge on resilience to hazards, or a new national science ‘mission’.

Additional decision-relevant information

Our nuclear war/winter Hazard Profile notes that nuclear war is a representative risk and other global catastrophes could produce conditions with functionally similar impacts on NZ, perhaps requiring common resilience measures. These hazards should also be assessed and include:

  • Solar flares (that threaten nearly all electronic infrastructure)
  • Major volcanic eruptions (that cause volcanic winter)
  • Asteroid/comet impacts (that cause global sunlight blocking)
  • Conventional Great Power conflicts
  • Extreme pandemics (eg, from bioweapons)

There is a plausible risk of collapse of both technological and industrial society following a major global catastrophe. Prospects for recovery following such collapse are unclear and societies could stagnate at low technological levels with chronically low levels of wellbeing. This possibility increases the salience of these risks.  

NZ is plausibly one of the countries in the world most resistant to the physical and climatic impacts of nuclear war (see our recent publication on this). This privileged position is reason for NZ to ensure resilience to the likely impacts, thereby maintaining a hub of functioning industrial/social complexity for the sake of humanity. Our country could have an inspirational ‘out of the ashes’ story to tell.  

Next Steps

This workshop took place in the context of recent global research on the public’s increasingly hawkish views on nuclear conflict. A recent study found that support for the use of nuclear weapons under certain circumstances has risen in the Netherlands and Germany from before to after the Russian invasion of Ukraine. Similarly, another study from the Cambridge Centre for the Study of Existential Risk published in 2023 found that informing people about the possible devastating impacts of nuclear winter reduced their support for nuclear weapon use. There appears to be a role for open discussion about the implications of nuclear war and the use of opinion polls on global catastrophe and resilience, especially in a NZ election year.

The Hazard Profile we have produced should now be connected to a capabilities assessment. This is an assessment of how, specifically, the conditions resulting from a ‘major’ nuclear war would have downstream impacts on NZ sectors and way of life, and how domestic activity could be adapted to preserve systemic functions. 

Next, we move into a survey and interview phase of our research to address these questions. We plan to hold additional workshops once results of these studies have been compiled. These discussions will form a foundation for policy recommendations and resilience options that central government, local government, communities, and private industry could consider.

In the meanwhile, there are concrete actions that central government could take to reduce NZ’s risk to major catastrophe in the longer term. Indications at our workshop were that participants felt these actions are “bread and butter policy” and functions that citizens expect of government. Some examples are that central government could:

  1. Work to combine existing narratives in government work on food system security, energy security, communications security, etc, into an overarching narrative of building resilience across interlinked systems to mitigate both catastrophic risks and increasingly routine risks.
  2. Develop and provide information about major risks such as nuclear war/winter and other global catastrophes to the public and decision makers. This is because such information has an impact on people’s beliefs and actions and could aid wise decision making. Our workshop showed that when experts shared information the group’s average assessment of risk rose.
  3. Reframe the upcoming draft NZ National Security Strategy so that it focuses less explicitly on ‘malicious threats’ and more on ‘resilience and vulnerability’ to both catastrophic risks and more routine risks (eg, large storms).
  4. Allocate resources to research and analyse specifically the issue of territorial integrity following a major global catastrophe and a plan to manage likely situations (both aiding refugees in need and protecting the wellbeing of NZ’s citizens).
  5. Allocate resources to research and analyse specifically the issue of whether and how government and the financial system could continue to operate in a context of no internet, no access to cloud data, and no digital communications. What are the required resiliency measures needed to minimise cascading degradation in governance and financial security?  

Our 9 February 2023 workshop on the nuclear war/nuclear winter hazard and Aotearoa NZ has provided a fascinating and practical foundation for the next phases of our Aotearoa NZ Catastrophe resilience project. We again thank all the workshop participants and welcome any further feedback on this blog post and the work to date.

US takes action to avert human existential catastrophe: The Global Catastrophic Risk Management Act (2022)

Photo by Joshua Sukoff on Unsplash


  • Global catastrophic risks (GCRs) include those events or incidents consequential enough to significantly harm or set back human civilization at the global scale (including: severe global pandemics, nuclear war, asteroid and comet impacts, supervolcanoes, sudden and severe changes to the climate, and intentional or accidental threats arising from the use and development of emerging technologies).
  • Recognising the potentially unbearable impact of global catastrophic risks, the US has just passed the Global Catastrophic Risk Management Act.
  • The Act requires the Secretary of Homeland Security and the Administrator of the Federal Emergency Management Agency to coordinate an assessment of GCRs within one year, and every ten years thereafter.
  • The report must be coordinated with senior officials from 16 other specified national agencies.
  • Each Federal Interagency Operational Plan will then be updated to include an annex containing a strategy to ensure basic needs are met in the aftermath of global catastrophe.
  • Aotearoa NZ should replicate this Act, with the National Security Group and NEMA coordinating the report. The upcoming shake-up of NZ’s research sector could include a National Science Challenge on Mitigating GCRs.

Global Catastrophic Risks

Global catastrophic risks (GCRs) could inflict serious damage to human wellbeing on a global scale, exceeding humanity’s collective ability to respond, potentially killing billions of people. Existential catastrophes are those GCRs that would either cause human extinction or prevent a full recovery. The significance of such events is potentially very great, superseding the salience of many day-to-day issues when assessed according to likelihood, consequences, neglectedness, and cost-benefit of action.

The US GCR Management Act

Lawmakers in the United States appear to have recently recognised the importance of these risks for people here and now, as well as those living in the future, and the US has recently passed the US Global Catastrophic Risk Management Act.

The Act was folded into the National Defence Authority Act, on the strength of a broad coalition of interest among stakeholders each concerned with various risks.

The Act defines global catastrophes as well as existential risks to human civilisation. These risks include many that have concerned scholars of existential risk for years, namely: severe global pandemics, nuclear war, asteroid and comet impacts, supervolcanoes, sudden and severe changes to the climate, and intentional or accidental threats arising from the use and development of emerging technologies.

The Act requires a broad assessment of all such risks within one year and every ten years thereafter. These reports will be coordinated by the Secretary for Homeland Security and the Administrator of the Federal Emergency Management Agency. These individuals are to coordinate with senior officials from 16 other national agencies, as follows:

  • Assistant to the President for National Security Affairs
  • Director of the Office of Science and Technology Policy
  • Secretary of State and the Under Secretary of State for Arms Control and International Security
  • Attorney General and the Director of the Federal Bureau of Investigation
  • The Secretary of Energy, the Under Secretary of Energy for Nuclear Security, and the Director of Science
  • Secretary of Health and Human Services, the Assistant Secretary for Preparedness and Response, and the Assistant Secretary of Global Affairs
  • Secretary of Commerce, the Under Secretary of Commerce for Oceans and Atmosphere, and the Under Secretary of Commerce for Standards and Technology
  • Secretary of the Interior and the Director of the United States Geological Survey
  • Administrator of the Environmental Protection Agency and the Assistant Administrator for Water
  • Administrator of the National Aeronautics and Space Administration
  • Director of the National Science Foundation
  • Secretary of the Treasury
  • Secretary of Defense, the Assistant Secretary of the Army for Civil Works, and the Chief of Engineers and Commanding General of the Army Corps of Engineers
  • Chairman of the Joint Chiefs of Staff
  • Administrator of the United States Agency for International Development
  • Secretary of Transportation

Reports on GCRs now mandated by law

The report must include expert estimates of cumulative risk across 30 years, analysis of the most concerning risks, technical assessments, an explanation of uncertainties, whether risk is likely to increase across 10 years, and various recommendations for action.

The Act also requires a supplement to each Federal Interagency Operational Plan that includes a strategy to ensure the health, safety, and general welfare of the civilian population affected by catastrophic incidents. This strategy is to assume the military is otherwise engaged and not able to assist. Plans for critical sectors should include: transportation, communications, energy, healthcare and public health, and water/wastewater.

Finally, the strategies developed above must be validated through exercises.

Increasing global action in the face of catastrophic risk

Global awareness of the risk of major catastrophe has been growing in recent years. We have seen ‘existential risk’ mentioned in the UN Secretary General’s Report ‘Our Common Agenda’. We have experienced the warning shots of the Covid-19 pandemic, Russian invasion of Ukraine, and impactful new weather patterns.

Drawing in part of a House of Lords report on ‘Preparing for Extreme Risks’ the new (Dec 2022) UK Government Resilience Framework takes an explicit focus on value for money, and the cost-effectiveness of resilience planning. They note that every £1 spent advising on flood risk matters saved £12 in future flood damages. Analysis already exists showing that investments to mitigate GCRs might have even more favourable business cases. It is now time for action to systematically determine this. In Australia a new Disaster Ready Fund will provide up to $200 million every year over five years to disaster resilience and mitigation projects across Australia.

New Zealand needs to act

GCRs would affect every country and it is time for Aotearoa New Zealand to get on board and contribute with local analysis, and New Zealand-specific action plans. No country can mitigate the suite of GCRs on their own. New Zealand needs to pivot to a focus on broad resilience rather than merely maximising sector profits. This need was stated clearly by Simon Upton, the Parliamentary Commissioner for the Environment, in his letter to the Minister of Energy (Dec 2022) about energy security.

The new US GCR Management Act has lain the gauntlet. There is no reason why NZ’s National Security Group in conjunction with NEMA can’t lead a similar assessment to that now required in the US. They just need appropriate resourcing, perhaps equivalent to the per capita sum Australia is investing in resilience projects. Indeed, the benefits are likely to be economically positive. NZ Research, Science and Innovation Minister Ayesha Verrall plans an upcoming shake-up of the NZ research sector. Now would be an opportune time to include a National Science Challenge on ‘Mitigating Extreme Risks’ as one of New Zealand’s new science missions. Political Parties in NZ should state where they stand on these possibilities during the present election year.

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.

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