Category: Uncategorized

An in-depth read, ~15 min

TLDR/Summary

• Global systems theorist Thomas Homer-Dixon gave a webinar on Nov 6, 2025 in which he described the Cascade Institute’s breakthrough approach to modelling global systemic risk. You can watch the full video of his presentation on the ASRA YouTube channel.
• The Polycrisis Core Model (PCM) is a sophisticated analytical tool that not only maps the complex interactions driving today’s global crises but could help identify concrete pathways toward more hopeful futures.
• Moving beyond speculation: Previously, ideas about achieving positive global transformation were largely speculative. Now, based on 1,800 expert judgments and rigorous mathematical modelling, there’s a grounded, evidence-based approach to understanding how we might navigate out of today’s entangled crises.
• The PCM uses Cross Impact Balance (CIB) analysis to model 11 global subsystems (covering everything from economy and climate to food and governance), each with multiple possible states, generating over 4 million potential future scenarios for humanity by 2040.
• Only 11 scenarios are truly stable: Out of 4 million possibilities, the mathematics reveals just 11 “consistent” scenarios, or attractors in an 11-dimensional state space. Three major attractors emerge: Illiberal Decline, Mad Max, and Hope.
• The Hope attractor exists but is narrow: The good news is that a positive future is mathematically possible. The challenging news is that Hope attracts only about 100,000 scenarios compared to Mad Max’s 500,000, and it remains climatically “Hot” (high degrees of global warming), these facts mean resilience work against collapse remains a critical hedge.
• Democracy appears non-negotiable: The analysis reveals clear policy targets which most notably include maintaining democracy, this appears essential for any pathway to Hope. Without democratic systems, initial modelling suggests no viable route to positive outcomes.
• The work is actionable, not academic: The model identifies specific leverage points for interventions and provides a framework for understanding which policy moves might push us toward the edge of Hope’s basin of attraction, where natural system dynamics would pull us in to a positive future.

Introduction: Can We Model Our Way to Hope?

On November 6, 2025, Thomas Homer-Dixon presented findings from the Cascade Institute’s Polycrisis Core Model to a webinar hosted by the Accelerator for System Risk Assessment (ASRA). The presentation offered something rare in discussions of global catastrophic risk: not just a diagnosis of our predicament, but the potential for a mathematically grounded pathway through it.

This matters because, as Homer-Dixon emphasised, previously speculative ideas about reaching hopeful futures are now grounded in modelling and evidence. Based on approximately 1,800 expert judgments, the work demonstrates a concrete way to navigate toward hope, or at least to understand the terrain we must cross.

The timing is significant. As I reported in my recent blog on the ASRA Symposium, humanity faces accelerating, amplifying, and interacting crises across interconnected global systems. This polycrisis isn’t theoretical it is the world’s lived reality of pandemics, climate change, geopolitical conflict, economic instability, and democratic backsliding all reinforcing one another. For a New Zealand perspective on this see our recent paper on long-term resilience to global risk.

What the Cascade Institute’s new Polycrisis Core Model (PCM) offers is the potential for a way to move from acknowledging this complexity to actively navigating it.

The Cascade Institute’s Approach

The Cascade Institute has focused its work on identifying high-leverage interventions in global systemic risk. Their CORE initiative examines what pathways exist toward better futures through rigorous systems analysis.

The PCM represents the latest evolution of this work. As Homer-Dixon explained in the webinar linked above, it builds on the legacy of the “Limits to Growth” report (which Homer-Dixon called “the granddaddy of world models”) but employs more sophisticated methods suited to understanding social and political systems where relationships are inherently fuzzier than in physical or ecological models.

The CORE Model’s ambition is substantial: to create a “global system-of-systems” analysis projecting to 2040, capable of mapping millions of possible futures and identifying which are self-reinforcing (and therefore stable) and which policy interventions might shift humanity’s trajectory away from worse world states and into more hopeful ones.

Crucially, this isn’t just descriptive work. The model aims to identify plausible pathways to positive transformation, or what Homer-Dixon called finding the “self-reinforcing virtuous processes” that could move us toward flourishing world states rather than collapse.

The Technical Architecture: How the Model Works

For those comfortable with complexity science, the PCM employs Cross Impact Balance analysis (see below). But Homer-Dixon’s presentation makes the core methodology accessible to non-specialists.

The Building Blocks: 11 Subsystems, 45 States

The model divides global systems into 11 subsystems, split between social and material domains. Each descriptor can exist in one of 3-5 possible states across time. This creates the model’s vast scenario space:

Social subsystems (5):

• Economy (states: laissez-faire growth, guided growth, low growth, managed economic contraction, unmanaged economic failure)
• Polity Type (states: strong democracy, illiberal democracy, strong autocracy, weak autocracy, nonocracy)
• World Order (states: international fragmentation, multipolarity, consolidated blocs, multilateral rules-based order, thick global governance)
• Inequality (states: various combinations of low/high international and domestic inequality)
• Conflict & Security (states: low violence, widespread non-state violence, civil/proxy war, international war, great power war)

Material subsystems (6):

• Energy (states: fossil-fuel dependence, peak oil and gas, green-tech breakthrough, low-carbon energy contraction)
• Climate (states: increased global heating of <2.5°C in 2100, 2.5-4°C, >4°C)
• Health (states: high/medium/low burden of disease)
• Food (states: status-quo global industrial production, agri-tech breakthrough, agro-ecological production, variable regional production, failed global industrial production)
• Transportation (states: fit for the future, fit for now, fragmented and failing)
• Information technology (states: limited rollout, managed rollout, unmanaged rollout)

The Method: Cross Impact Balance Analysis

Cross Impact Balance (CIB) analysis was developed by Wolfgang Weimer-Jehle in a 2006 paper. This method is particularly powerful for social systems because it can integrate different types of data and expert judgment about fuzzy relationships.

The core of the approach involves creating a judgment matrix showing all descriptors (ie all global subsystems and their possible states) and their relationships to each other, including:

• Whether relationships are promoting or inhibiting
• The strength and confidence level of each relationship

A crucial methodological constraint disciplines the analysis: scores within each judgment group must sum to zero. This “balancing constraint” prevents arbitrary or unconstrained assessments and forces careful consideration of trade-offs.

The model required 110 separate judgment sections (eg, “effect of world order on economy”), resulting in approximately 1,800 individual expert judgments (across the 45 different states). These judgments are supported by 200 pages of research and rationale, allowing independent assessment of their validity. The judgment model and it’s calculation matrix, are completely transparent.

The Mathematical Core: Finding Consistency

With 45 possible states across 11 descriptors, the model theoretically encompasses 4,050,000 possible scenarios or “futures.”

The CIB mathematical framework determines which scenarios are “consistent”, which means they are self-reinforcing. A consistent scenario is one where the various system states mutually support each other, creating a stable configuration.

Think of it like this: some combinations of system states reinforce each other (eg, strong democracy + multilateral cooperation + managed technology rollout), while others create contradictions that make them unstable (eg, authoritarian regimes + thick global governance).

The Findings: Three Attractors and a Narrow Path to Hope

The mathematics reveals that out of 4 million possible states, only 11 are fully consistent. These function as attractors in the 11-dimensional state space. Attractors are stable configurations toward which the global system naturally tends.

Three Major Attractors Emerge

Simplifying these results, Cascade Institute researchers identified three main types of attractors:

1. The Illiberal Democracy Attractor: A world of democratic backsliding and constrained freedoms
2. The Mad Max Attractor: Characterised by state failure, widespread violence, and collapsed governance, Homer-Dixon referenced Haiti as a current example
3. The Hope Attractor: A positive future with improved human wellbeing

The relative size of these attractors matters enormously:

• Mad Max is big: Attracting approximately 500,000 of the 4 million scenarios, this represents the largest basin of attraction. It appears frighteningly easy for the global system to slide into this catastrophic state.
• Illiberal Democracy and Autocracy: Significant individual attractors exist in this space as well, though collectively they appear to absorb more scenarios than Mad Max.
• Hope is narrow: Drawing in only about 100,000 scenarios, Hope has the smallest basin of attraction among the major outcomes

However, there’s important nuance here. Later analytical runs showed that Hope is a “relatively deep attractor”, meaning that once in its basin, the world systems tend to stay there. It’s a harder equilibrium to reach but stable once achieved.

Succession Analysis

Further research by the CORE Model team will employ a method known as succession analysis (which tracks how inconsistent scenarios migrate through state space toward the consistent scenarios), to deduce the lowest barrier pathways through the model from the world’s present system states to the nearest edge of the hope attractor. This approach leverages the idea of a kind of reverse tipping point, high leverage policy/intervention points that could set off a cascade of transformation into the hope attractor, the system’s natural dynamics would pull us in.

The temporal aspects of the model are complex. Succession analysis functions as “an analogue of time” rather than explicit temporal modelling. The model is essentially “instantaneous” (showing stable states) rather than fully dynamic (showing detailed trajectories through time).

This is both a limitation and a practical necessity as fully modelling the temporal dynamics of 11 coupled systems risks being computationally intractable and would require even more uncertain judgments about rates of change.

The real value of this work emerges in its policy implications. The model isn’t just descriptive, rather it’s designed to identify intervention points.

Hope’s Limitations

However, even the Hope attractor isn’t utopian. As Homer-Dixon emphasised, “Hope is still Hot”, by which he meant that even this positive scenario involves significant climate heating and its associated challenges. The model doesn’t promise a return to pre-industrial conditions or easy solutions, just significantly better outcomes than the alternatives.

Critical Policy Target: Democracy

The analysis has already revealed very clear policy targets. Most notably, according to Homer-Dixon, maintaining democracy appears essential, as without democratic governance, “there appears no way there”, ie, no viable pathway to the Hope attractor emerges in the model.

This finding aligns with the Cascade Institute’s broader work on global systemic stresses, which identifies ideological fragmentation, polarisation, and political-institutional decay as critical stressors undermining humanity’s capacity to respond to other challenges.

Methodological Considerations and Ongoing Work

Homer-Dixon was refreshingly candid about the model’s current status and limitations. He acknowledged the model is “somewhat crude” but argued it provides a foundation for mapping paths toward transformation. This honesty is important, the model isn’t claiming perfect foresight but offering structured insight into complex dynamics. Furthermore, it is fully transparent, so users could adjust the settings according to new evidence. The CORE Model lends itself to modelling interventions that change the present state of world subsystems and deducing likely future states.

Sensitivity Analysis and Refinement

The research team is conducting extensive sensitivity analysis and converging on the “right” approach through iterative refinement. The rules used for succession analysis, Homer-Dixon noted, are “very important and make a difference to outcomes.”

This ongoing refinement is crucial. Early versions of complex models often reveal more about the modellers’ assumptions than about reality. But through systematic testing and adjustment, such models can become increasingly useful.

The forthcoming release of 200 pages of research and rationale supporting the 1,800 expert judgments will provide important grounding. This documentation will allow others to assess the judgments’ correctness and validity.

Next Steps and Using This Work

Homer-Dixon indicated the work is being prepared for publication in Nature, suggesting it will soon face rigorous peer review. He also noted that slide decks, mathematical details, and video recordings will be made available through ASRA’s YouTube channel.

We note that for researchers, policymakers, and organisations working on global catastrophic risk, several opportunities emerge:

For Researchers

• Examine the detailed methodology when published
• Apply similar CIB approaches to regional or sectoral polycrises
• Contribute to refining the expert judgments as new evidence emerges
• Extend the model to explore specific intervention scenarios

For Policymakers

• Use the framework to identify high-leverage intervention points
• Prioritise policies that maintain democracy and international cooperation
• Assess whether current policies push toward Hope or away from it
• Design policies with an understanding of system-level interactions

For Organisations

• Apply polycrisis thinking to strategic planning
• Identify how organisational actions contribute to global system stresses or resilience
• Engage with the Cascade Institute’s broader work on global systemic stresses

Finally, such approaches and tools are exactly the kind of frameworks that we have previously argued are missing from a lot of national risk assessment, so there is much potential to incorporate these methods when addressing global catastrophic risk, see our call for more focus on these issues in our recent peer-reviewed paper on New Zealand’s long-term resilience to global risks.

Conclusion

What makes the Polycrisis Core Model significant isn’t that it predicts the future because it doesn’t and it can’t. What it does is transform our understanding of possibility space.

Before this work, discussions about achieving positive global transformation were largely speculative. We could point to things that needed to change such as carbon emissions, inequality, authoritarian governance, but we lacked a systematic understanding of how these elements interact and which changes might trigger virtuous rather than vicious cycles.

Now, based on the CORE Model’s 1,800 expert judgments and rigorous mathematical analysis, we have something more concrete. The model demonstrates that Hope is possible but narrow, that certain policy targets (especially democracy) appear non-negotiable, and that we need to find ways to push the global system toward that Hope attractor’s basin.

The work is also a further wake up call. Mad Max attracts far more scenarios than Hope. Our default trajectory, absent deliberate intervention, trends toward collapse not transformation. This is something we have also detailed when describing the ‘hard landing ahead’ in previous blogs. This likelihood also means that investment in resilience (to Mad Max) remains a critical hedge for decision-makers (for examples of resilience options see our previous “NZCat” work).

But unlike in previous work, and thanks to the Cascade Institute’s work, we now have tools to map this terrain. We can identify leverage points, evaluate interventions, and design policies with an understanding of system-level consequences. The question isn’t whether transformation is possible, the model shows it is. The question is whether we’ll implement the changes necessary to reach it.

As Ben Okri challenged myself and other attendees at the recent ASRA Symposium: “We have to find better alternatives to the current direction of history.” The Polycrisis Core Model provides not just warning but a roadmap for doing exactly that.

Whether we follow it remains to be seen.

Further Resources:

• Cascade Institute: https://cascadeinstitute.org/
• ASRA (Accelerator for System Risk Assessment): https://www.asranetwork.org/
• Lawrence et al. (2024). “Global polycrisis: the causal mechanisms of crisis entanglement.” Global Sustainability

The webinar recording and slide deck are available on ASRA’s YouTube channel.

New Zealand has a geographic advantage that could be a strategic liability. Our isolation protects us from many regional and global threats, but makes us uniquely vulnerable to the one consequence nearly all global catastrophes share: the collapse of international trade and supply chains.

This paradox sits at the heart of our new paper in peer-reviewed journal Policy Quarterly, which examines how New Zealand’s current approach to long-term resilience, while commendable in many ways, exemplifies broader blind spots that could leave this island country dangerously unprepared for 21st century risks. In this post we summarise the key points and recommendations from our research.

TLDR/Summary

• The DPMC’s 2025 draft long-term insights briefing on hazard resilience represents a welcome shift toward anticipatory governance and long-term thinking
• However, current publicly facing frameworks tend to focus on familiar local natural hazards while systematically excluding global catastrophic risks like nuclear war, bioengineered pandemics, extreme volcanic eruptions, severe solar storms, and catastrophic AI failures
• For an island nation dependent on global trade, supply chain collapse represents our primary threat vector regardless of what triggers it
• Understanding global systemic risk and “polycrisis”, manifested through at least 14 global systemic stresses that interact to create cascading failures, is essential for effective resilience planning
• Moving forward requires transparent public engagement with comprehensive risk information, not technocratic approaches that limit disclosure for fear of “scaring the public”
• NZ needs publicly facing risk assessment work that facilitates informed democratic dialogue about resilience options and their costs – enabling citizens to make collective choices about investing in our shared future

Strengths and limitations of current thinking

We previously noted that discussion documents like the Department of the Prime Minister and Cabinet’s draft Long-Term Insights Briefing deserve credit for several important advances. Such work explicitly connects resilience with long-term prosperity, rejecting the false economy of austerity followed by repeated disaster-rebuild cycles. It acknowledges that hazards may have catastrophic consequences and that abrupt crises can occur. And crucially, it represents a fundamental shift from reactive emergency response toward proactive resilience-building.

These are genuine achievements that move New Zealand’s risk discourse in the right direction.

But the briefing, and much public sector risk thinking, remains trapped within frameworks addressing symptoms rather than systemic forces, focusing primarily on familiar natural hazards and incremental climate risks while missing an entire category of global catastrophic risks that could trigger the isolation and supply chain collapse we’re most vulnerable to.

Consider what’s systematically excluded from many current resilience frameworks:

• Nuclear war and electromagnetic pulse attacks causing global agricultural failures and cascading infrastructure collapse
• Bioengineered pandemics potentially far more severe than Covid-19
• Large volcanic eruptions comparable to Tambora 1815, particularly those affecting critical global supply chain pinch points or altering the climate
• Severe solar storms capable of disabling electrical grids for weeks or months across regions of the world
• Catastrophic AI failures in interconnected infrastructure
• Global food system failures from synchronous breadbasket failures severely impacting food supply and trade relations

These risks share critical characteristics that distinguish them from conventional hazards: they typically originate elsewhere yet spread via cascading impacts to cause global catastrophe; external assistance may be unavailable when needed most; and they could threaten global critical infrastructure destruction rather than mere disruption.

While individually unlikely in any given year, collectively these risks represent high-probability problems over decades, with some, like severe solar storms and large volcanic eruptions, being practically inevitable.

Understanding the polycrisis

Beyond discrete catastrophic events lies an even more fundamental challenge: the world faces rising systemic risk driven by interconnected global stresses.

Working with frameworks developed by institutions like the Cascade Institute, we identify at least 14 major chronic systemic stresses simultaneously pushing human systems toward dangerous disequilibrium. These range from great-power hegemonic transition and climate heating to ideological fragmentation, concentrated industrial food production, and the propagation of artificial intelligence.

These stresses interact through what researchers term the “stress-trigger-crisis” model. Any major trigger event – whether a volcanic eruption blanketing Southeast Asian ports with ash, catastrophic electricity loss disabling GPS and shipping, or nuclear conflict over Taiwan – could tip already-stressed global systems into cascading failure.

Our new peer reviewed paper illustrates how each of these global stresses creates specific vulnerabilities for New Zealand, from liquid fuel import disruption to digital payment system collapse to synchronous failure of global breadbaskets.

For New Zealand, this creates a stark reality: while our geography, natural resources and social systems position us relatively well to weather various global storms (think Covid-19), our greatest vulnerability lies precisely in trade and supply chain collapse – the downstream consequence of virtually all global catastrophic risk.

Breakdown in the supply of goods and services is both the cause and consequence of virtually all past civilisation collapse.

Need for improved risk and resilience tools

New Zealand’s approach to national risk assessment lacks analytical outputs that have become standard practice among comparable nations grappling with complex risk landscapes.

The United Kingdom maintains a detailed, publicly accessible National Risk Register, alongside comprehensive chronic risks analysis, substantial parliamentary inquiry reports, and a National Resilience Action Plan. The United States has commissioned RAND Corporation assessments of global catastrophic risks, enacted the Global Catastrophic Risk Management Act 2022, and established dedicated institutional frameworks for extreme risks.

Even when such comprehensive approaches exist, significant methodological problems persist. But at minimum, these nations have recognised that transparent, systematic assessment of the full spectrum of risks – including low-probability, high-impact events – represents a fundamental democratic necessity.

New Zealand’s current approach (both nationally and regionally) not only lacks this scope and transparency, but also exhibits the methodological shortcomings we identified in previous research including: insufficient justification of foundational assumptions, systematic omission of largest-scale risks, and limited stakeholder engagement to legitimise key choices.

The democratic imperative for transparency

This brings us to one of the most critical gaps: the absence of transparent, detailed, publicly-facing risk assessment that enables and can be used to stimulate informed democratic dialogue.

The 2021 UK House of Lords’ report on extreme risks included a presumption toward publication of security information, stating that “only through transparency and a healthy culture of challenge can we provide society with a reliable foundation to respond to emerging risks.”

The institutional aversion to “scaring the public” must be overcome. Citizens require access to comprehensive risk information spanning the full spectrum from conventional hazards to global catastrophic and systemic threats, supported by government-facilitated forums enabling structured public deliberation.

But more importantly, information sharing needs to be solutions-focused, including transparent information about resilience investment options, their costs, benefits and trade-offs across different time frames and scenarios.

This approach empowers rather than alarms populations. It enables discourse over the “tough decisions” the draft briefing acknowledges while ensuring democratic legitimacy for long-term resilience investments. And it recognizes that New Zealanders are adults capable of engaging with difficult realities and making informed choices about their collective future.

New Zealand’s strategic position

Here’s the opportunity: New Zealand possesses substantial advantages that current frameworks underutilise.

Our geographic isolation, low urban density, plentiful food production capacity, abundant renewable energy potential, relatively strong democratic institutions, and established social capital position us uniquely well – if properly leveraged through anticipatory planning.

Regional cooperation with Australia and Pacific neighbours offers additional strategic opportunities. Initiatives like shared vaccine manufacturing capacity, cooperation on shipping resilience, and coordinated resilience planning could strengthen collective preparedness for global catastrophic risks that are inherently cross-border in nature.

Research shows that egalitarian institutions and transparent governance structures demonstrate superior adaptive capacity compared with hierarchical alternatives. This suggests that democratic deepening through citizens’ assemblies and deliberative forums represents both a values commitment and a pragmatic resilience strategy.

Pathways forward

Our new paper outlines several concrete recommendations:

Expand hazard coverage to include global catastrophic risks that traditional frameworks systematically exclude. International precedents demonstrate this is slowly becoming standard practice among comparable nations.

Adopt systemic analytical frameworks that recognise interdependencies, cascade pathways, and stress-trigger-crisis dynamics rather than treating hazards as discrete events.

Strengthen resilience factors such as geographical advantages, institutions, and social capital through deliberate cultivation rather than focusing exclusively on risk drivers.

Implement institutional reforms including dedicated risk officers or a parliamentary commissioner for catastrophic risks, cross-sector collaboration mandates, and three-lines-of-defence approaches.

Ensure basic needs continuity through both strengthened existing systems and alternative “Plan B” infrastructure capable of functioning at a minimum when primary systems fail.

Finance using intergenerationally fair methods through approaches that avoid disadvantaging current populations while preventing unfair burden-shifting to future generations.

Our recent research found majority public support (56-63%) across the political spectrum for institutional reforms to manage global catastrophic risk. New Zealanders are ready for this conversation.

Conclusion: An opportunity for leadership

Our critique extends far beyond the DPMC briefing toward establishing principles applicable across all public sector risk and resilience thinking.

By embedding systemic thinking, expanding considered hazards, ensuring transparency, and implementing institutional reforms oriented toward anticipatory governance, New Zealand can establish itself as a global leader in building resilience to 21st-century challenges through genuine democratic engagement.

The alternative of continuing reactive approaches that address symptoms while global stresses accumulate will ensure that risks will continue emerging faster than interventions can manage them.

The result of getting this right would benefit not just New Zealanders, but populations depending on our food exports and humanity generally, should catastrophe ever threaten global collapse. Our isolation could become our greatest strategic asset but only if we invest in resilience with eyes wide open to the full spectrum of threats we face.

The choice is ours: genuine anticipatory governance through transparent democratic engagement, or reactive crisis management that addresses symptoms while root causes remain unchanged.

***

Read the full paper: Boyd, M. and Wilson, N. (2025) “From Disaster Response to Anticipatory Governance: why Aotearoa New Zealand’s long-term resilience thinking must address global catastrophic risk and systemic vulnerabilities,” Policy Quarterly, 21(4), pp.61-71.

Read our original submission: Response to DPMC Draft Long-term Insights Briefing (PDF, 12 pages)

Consider donating

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Your support allows us to continue producing risk information and resilience options that could benefit New Zealand and the world.

By John Kerr, Matt Boyd, & Nick Wilson (Blog crossposted from PHCC ‘the Briefing‘)

TLDR/Summary:

There is increasing concern over catastrophic threats such as nuclear conflict, engineered pandemics, and emerging technologies including artificial intelligence. Our just published survey research shows New Zealanders want their government to take these risks seriously. Majority public support for planning and strategy on risks underscores the need to move beyond analysis and invest in practical preparedness. Yet Aotearoa New Zealand remains underprepared, with vulnerabilities in areas such as energy security and industrial inputs needed for food production.

Building resilience will require more than technical planning: trusted communication, cross-sector leadership, and public engagement are vital to maintain legitimacy and consensus. The findings highlight a need for policymakers to align with public expectations by developing a national strategy, strengthening institutions, and broadening the voices involved in planning for worst-case scenarios.

Introduction

Aotearoa New Zealand (NZ), like all nations, faces the possibility of extreme events that could cause global or civilisation-level disruption. These global catastrophic risks include nuclear conflict, bioengineered pandemics, major volcanic eruptions, severe space weather, and potentially runaway artificial intelligence (AI). While the probability of any one event is low in a given year, the potential consequences are so severe that preventive efforts and proactive planning are essential.^{1, 2}

Our survey of more than 1,000 New Zealanders provides evidence on how the public views government responsibility for these risks (Figure 1). The results, published in the journal Risk Analysis, show majority support for greater action – but also raise questions about gaps in trust, communication, and institutional readiness.³

Key Findings from the Survey

• Two-thirds of New Zealanders (66%) support government developing specific plans for catastrophic risks such as nuclear war or engineered pandemics.
• A clear majority (60%) also back establishing a dedicated commission or agency to monitor and report on these risks.
• Outright opposition is small (8–15%), but about a quarter of respondents are neutral or unsure, suggesting limited awareness or competing priorities.
• Support for government planning increases with age, education, income, and trust in scientists.
• Unlike many public health issues, there were no major differences in policy support across political orientation, gender, or ethnicity.

Overall, this suggests majority support across the political spectrum for government leadership on catastrophic risks. Trust in science stands out as the strongest predictor of support, highlighting both an opportunity and a vulnerability for building consensus.

Why this Matters Now

Although NZ has previously examined catastrophic risks – for instance, through work in the 1980s on nuclear war^{4, 5} – resilience has waned. Recent expert reviews conclude that Aotearoa remains poorly equipped to cope with global shocks, despite being relatively well placed geographically to weather them.^{6, 7}

The contrast between strong public support and limited government preparedness is striking. In a 2021 review, Sir Peter Gluckman and Dr Anne Bardsley highlighted major gaps in national planning for high-impact risks.⁸ More recent work has shown vulnerabilities such as reliance on imported fuel for food production, despite NZ’s apparent self-sufficiency in food supply.^{6, 9}

This new survey reinforces earlier evidence. The Department of the Prime Minister and Cabinet’s 2024 National Risks Public Survey found overwhelming support for government responsibility in managing threats from emerging technologies and critical infrastructure disruption.¹⁰ Our findings extend this picture, showing that the public also endorse forward planning for the very worst-case scenarios.

Understanding Ambivalence and Opposition

A significant minority of New Zealanders remain neutral or opposed to stronger government action. Possible reasons¹¹ include:

• Low awareness of catastrophic risks and their likelihood.
• Fatalism – a belief that little can be done to prepare.
• Distrust in government or science as credible actors.
• Competing priorities, with attention focused on more immediate social and economic concerns.

This points to the need for broader engagement beyond surveys. Deliberative methods such as citizens’ assemblies, public forums, and focus groups could help unpack how people weigh catastrophic risk planning against other policy demands, and identify framings that resonate across diverse groups.

Trust as a Foundation

The finding that trust in scientists is the single most consistent predictor of support is particularly important. While scientists are central to identifying and communicating extreme risks, they are not always the most effective messengers. For people with low trust in science, other credible voices – such as iwi leaders, community representatives, or political figures across the spectrum – may be more effective in building support.

This echoes lessons from public health communication during the Covid-19 pandemic, where trust was both an asset and a fault line. Building a coalition of trusted messengers will be vital for gaining broad consensus on preparedness.

Policy Implications

The survey adds to mounting evidence that NZ needs to go beyond the hazards it currently plans for (earthquakes, volcanic eruptions and severe space weather) to address all major  catastrophic risks. Several policy options merit urgent consideration:

1. Develop a national strategy for global catastrophic risks – building on the National Risk Framework but extending it to worst-case scenarios.⁸
2. Establish a dedicated agency or commission, either domestic or in partnership with Australia¹², to monitor, assess, and coordinate responses to these risks.
3. Invest in resilience measures that reduce vulnerabilities exposed in recent studies, such as energy security for ensuring food production.^{9, 13}
4. Engage the public through deliberative processes to deepen understanding of trade-offs and maintain legitimacy.
5. Broaden communication approaches, pairing scientific expertise with trusted community and political voices.^{14, 15}

Moving from Analysis to Action

As we noted in an earlier PHCC briefing on the NZ Government’s work on hazards¹⁶, progress has been made in recognising some major threats, but important gaps remain. 

NZ’s geographic position makes it one of the countries most likely to endure in certain global catastrophes. But survival advantage will only matter if we have invested in resilience and governance structures in advance. Public opinion is clear: most citizens want government to prepare for the unimaginable, before it is too late.

What is New in this Briefing?

• Risk scholars and other experts are increasingly concerned about the high-impact threats of global catastrophic risks such as severe engineered pandemics, nuclear war and rogue AI.
• The majority of New Zealanders support broad Government action to plan for global catastrophic risks.
• Few New Zealanders are actively opposed to policies addressing catastrophic risks, however a quarter (~25%) are unsure or ambivalent. 

Implications for Policy and Practice

• More in-depth research is desirable to understand why some people are unsure or opposed to Government action.
• Nevertheless, it is now over to policymakers to respond to the majority public support for better Government planning and infrastructure to identify and prepare for global catastrophic risks.

References

1. Mecklin J. (2025). Closer than ever: It is now 89 seconds to midnight – 2025 Doomsday Clock Statement. Bulletin of the Atomic Scientists. https://thebulletin.org/doomsday-clock/2025-statement/
2. World Economic Forum. (2025). The Global Risks Report 2025. https://www.weforum.org/publications/global-risks-report-2025/
3. Kerr J, Boyd M, & Wilson N. (2025). Public Attitudes to Responding to Global Catastrophic Risks: A New Zealand Case Study. Risk Analysis. https://doi.org/10.1111/risa.70096
4. Preddey G, Wilkins P, Wilson N, Kjellstrom T, & Williamson B. (1982). Nuclear Disaster: A Report to the Commission for the Future. https://www.mcguinnessinstitute.org/wp-content/uploads/2016/11/CFTF-March-1982-Future-Contingencies-4-Nuclear-Disaster-FULL.pdf
5. Green W, Cairns T, & Wright J. (1987). New Zealand After Nuclear War. New Zealand Planning Council.
6. Boyd M, Payne B, Ragnarsson S, & Wilson N. (2023). Aotearoa NZ, Global Catastrophe, and Resilience Options: Overcoming Vulnerability to Nuclear War and other Extreme Risks: Report by the Aotearoa NZ. Catastrophe Resilience Project (NZCat) [Report]. Reefton: Adapt Research Ltd. https://adaptresearchwriting.com/wp-content/uploads/2023/11/231117-v1-nzcat-resilience-nuclear-gcrs-1.pdf
7. Boyd M, & Wilson N. (2021). Anticipatory Governance for Preventing and Mitigating Catastrophic and Existential Risks. Policy Quarterly, 17(4), 20-31.
8. Gluckman P, & Bardsley A. (2021). Uncertain but inevitable: The expert-policy-political nexus and high-impact risks. https://informedfutures.org/high-impact-risks/
9. Wilson N, Prickett M, & Boyd M. (2023). Food security during nuclear winter: A preliminary agricultural sector analysis for Aotearoa New Zealand. The New Zealand Medical Journal (Online), 136(1574), 65-81.
10. Ipsos. (2024). National risks public survey: All threats and hazards (Commissioned by the Department of the Prime Minister and Cabinet). https://www.dpmc.govt.nz/our-programmes/risk-and-resilience/national-risk-framework/2024-national-risks-public-survey-report
11. Wiener JB. (2016). The Tragedy of the Uncommons: On the Politics of Apocalypse. Global Policy, 7(S1), 67-80. https://doi.org/10.1111/1758-5899.12319
12. Wilson N, Boyd M, Potter J, Mansoor O, Kvalsvig A, & Baker M. (2024). The case for a NZ-Australia Pandemic Cooperation Agreement. Public Health Expert Briefing. https://www.phcc.org.nz/briefing/case-nz-australia-pandemic-cooperation-agreement.
13. Boyd M, Ragnarsson S, Terry S, Payne B, & Wilson N. (2024). Mitigating imported fuel dependency in agricultural production: Case study of an island nation’s vulnerability to global catastrophic risks. Risk Analysis https://doi.org/10.1111/risa.14297.
14. Johns Hopkins University. (2019). Risk Communication Strategies for the Very Worst of Cases. https://centerforhealthsecurity.org/sites/default/files/2022-12/190304-risk-comm-strategies.pdf
15. Balog‐Way D, Mccomas K, & Besley J. (2020). The Evolving Field of Risk Communication. Risk Analysis, 40(S1), 2240-2262. https://doi.org/10.1111/risa.13615
16. Wilson N, Kerr J, & Boyd M. (2025). New government document on hazards: Good progress but gaps remain. Public Health Expert Briefing. https://www.phcc.org.nz/briefing/new-government-document-hazards-good-progress-gaps-remain 

The following is a transcript of our invited presentation to the Environment Canterbury regional council on 10 Sept 2025 as part of Council’s external speaker series and in support of a food resilience strategy.

You can click to watch the recorded version which is followed by Q&A with the councillors.

You can also access slides from a similar presentation Nick Wilson gave at the International Conference on Urban Health (Wellington, 18 Nov, 2025).

Introductory Remarks

Thank you for the opportunity to speak today.

I’m Matt Boyd, Executive Director of Islands for the Future of Humanity, a non-partisan NZ charity disseminating risk information. And I’d like to acknowledge the logos on this slide representing the contributions of various other people to our work.

This talk is about 16min and covers food system resilience.

In my work, that means ensuring the local population can eat enough to survive indefinitely, no matter what the circumstances.

First, I’d like to describe some relevant context, then we can address what can be done.

What is the Risk Context?

Disaster Risk Reduction efforts have advanced a lot.¹ However, these efforts focus almost exclusively on climate change and natural hazard risks.

Missing from disaster risk reduction frameworks are Global Catastrophic Risks—often overlooked because many of them are human-caused or because they originate elsewhere (probably outside NZ) and spread, through cascading impacts, to severely affect the entire world, beyond a point where response systems can cope.

Examples include:

• Extreme pandemics beyond Covid-19
• Months long electricity failures due to solar storms, electromagnetic pulses or cyberattacks
• Nuclear war or large magnitude volcanic eruptions that destroy critical global infrastructure or block the sun.

With such events, outside help may be unavailable. Critical systems could face destruction, not just disruption, preventing rapid recovery.

While unlikely in any given year, some of these risks are uncertain but inevitable.

We insure our houses against worst possible risks, despite low likelihood, because the harm would be unbearable. We need to apply this thinking to societal resilience.

But there’s more. Global human systems face failures because they are stressed by at least 14 rising global stresses: climate change is one, but there is also biodiversity loss, demographic changes, concentration of industrial food production, emerging AI risks, etc. We need to consider this portfolio.

Basically, we have stresses elevating all kinds of global systems into a precarious state, such that major triggers (eg global hazards, wars, policy changes) could tip stressed systems into crisis. The stress-trigger-crisis model,² represents this situation and provides tools for thinking about it.

Furthermore, our systems—food, energy, transport, communications—are densely interconnected, with stress in one causing feedback, potential amplification of problems, contagion across systems and cascading effects.

This creates continuous crisis—polycrisis—difficult to escape without addressing root causes:

• such as rivalry, inequality, exponential change, and unfettered resource extraction.

In the face of this, organisations like the ASRA network (whose symposium I was at in Paris in June) are developing tools that decision makers can use to apply systemic risk thinking to their risk management.

Why should NZ care about this?

Given this documented global context, NZ should be worried.

We need resilience to absorb these problems and public institutions play a critical role.

But NZ is also relatively well-placed to weather this storm.

For example, the figure on the left shows the expected global cooling following a regional nuclear war between India and Pakistan,³ you see agriculture would collapse in the Northern Hemisphere, but that islands suffer less. The same is true for global winter caused by very large volcanoes.

Additionally, islands with potential for strict border control are less susceptible to health effects of pandemics.

We have studied these various island resilience factors;⁴ The UK newspaper The Sun reports our work in the right figure – NZ could be one of the most resilient places given our geography, resources, and our social systems.

But islands like NZ need to organise themselves and actually harness their natural advantages, and this only works if we are smart about resilience to global risks and play a careful long game.

NZ is not most at risk from the Alpine Fault (though this is a severe problem)

NZ is most at risk from trade and supply collapse—a downstream consequence of basically all the global risks I’ve mentioned so far.

• A major volcanic eruption in Indonesia could blanket Asian ports with metres of ash.
• Catastrophic electricity loss or cyber-attack could disable GPS and shipping portside operations.
• Nuclear war over Taiwan would cause far more supply harm than one stuck ship in the Suez canal.

NZCat

Our multidisciplinary NZCat research project studied these problems through 2023.⁵

We created hazard profiles, conducted workshops, a survey, interview study, document reviews, technical research, and hosted a webinar. We spelled out these risks and identified resilience options.

This included food.

We found that our food system’s operation depends on the world. Without imported liquid fuel, fertiliser, agrichemicals, seed, expertise, machinery, spare parts, functioning electricity and internet, NZ’s food production, processing and distribution grinds to halt in its current state.

It is even worse if yields are reduced due to smoke in the atmosphere in a nuclear or volcanic winter.

This is bad for NZers and bad for export recipients depending on NZ food.

It is worst for economically disadvantaged people unable to afford scarcity pricing or source alternatives.

Good risk governance and risk management is key.

Risks need to be visible to the community and discussed.

Sometimes we think we’re already resilient, but local research shows many cases of supposedly redundant NZ systems susceptible to the same risks as primary systems. For example: parallel buried gas pipelines in Taranaki often run through the same topographic corridors being vulnerable to the same volcanic lahars.

For a full presentation of the NZCat project work you can watch the Korero on Catastrophe we held with diverse experts in 2023.

Turning to Food Security: What can be done?

I’ve deliberately spent half this talk NOT discussing food because the context I’ve just outlined needs to be better understood by the public and decision-makers.

This context of: Ordinary disaster risk, global catastrophic risk, global systemic risk, polycrisis, and dependence on trade and supply, is critical to food security.

Export foods, crop choices & liquid fuel

Growers require industrial inputs, crops must thrive despite climate, food must be transported to processing and consumption, sustainably, at levels feeding the local population indefinitely.

So, we need systems in place that can easily pivot export food to the local market if needed.

Some have already argued for a two-track New Zealand food system, with product from the farmgate going directly to the local market as well as to export processing.

We may need frost-resilient crops like wheat and carrots to sustain yields in potential volcanic or nuclear winter.

Most importantly: we need to ensure supply of inputs like liquid fuel.

MBIE has raised this issue with a Draft NZ Fuel Plan proposing increased tankerage, domestic fuel storage, and small-scale refining options.

Our research shows how much difference crop choices can make and how much locally produced liquid biofuel might be needed in a trade collapse. Let’s take a look:

In our paper on mitigating imported fuel dependency,⁶ we noted that New Zealanders collectively need 4 trillion kcal per year and 150,000 tonnes of protein. So what does that look like?

This square represents the entire scope of NZ land used for dairy farming (1.7 million hectares). This is how much wheat we grow, and this is potatoes.

If you wanted to supply all that protein and food energy using just dairy, you’d need a supply of industrial inputs to farm this much land (640k ha in the figure). If you grew only wheat, this much (117k ha), and only potatoes, this much (84k ha).

Now if you needed to produce liquid fuel locally for the machinery, you’d need 32,000 ha of a feedstock like canola seed to do the dairy farming. You’d need 10,000 ha for potatoes, and only 4.5k hectares for wheat.

The choice of what is produced has massive implications for inputs like fuel. Any resilience programme should consider these factors.

We can drive home the point on this next slide:

This shows how much liquid fuel is needed to conduct the agriculture to feed NZ depending on whether we do dairy, grow potatoes, or wheat, and whether produce is transported 20, 50, or 100km. And whether the skies are darkened by nuclear or volcanic winter or not. You can see it makes a huge difference to certain logistics.

Let’s look at urban agriculture.

Urban and near-urban agriculture

Urban agriculture brings production near to the population, eliminating transport fuel, and some off-road fuel. We analysed Palmerston North (chosen as a median sized city)⁷ and I’ll talk you through that:

This blue circle represents the built urban area, to scale, at 3400 hectares. If you planted every available green space, parks, gardens, golf courses, for urban agriculture (730 ha) with highest yield crops, you can meet the full food needs of up to 20% of the city.

But you only need a relatively small amount, about 1000 hectares in the case of Palmerston North, of city adjacent land, with high yield industrial cultivation (eg potatoes, wheat) to make up the shortfall.

And a relatively small 100 hectares of a biofuel feedstock could provide the liquid fuel needed. The near urban growing could follow a transport route such as an electric railway.

The main point is this: feeding a city or region doesn’t require much land or fuel if done cleverly. But each region needs to understand its minimum needs and secure this minimum before any catastrophes, assuming no imports.

Of course, urban and near-urban agriculture raise land use and zoning issues.

Urban and near-urban agriculture also require productive soils, which could be prepared in anticipation through green waste to compost schemes.

What can ECan do?

ECan could commission a formal study mapping these problems and generating local resilience options, including analysis of who would be worst affected.

This could form the basis for serious public consultation on options and trade-offs via citizen’s assemblies/citizen juries.

For context, our Palmerston North analysis cost ~NZ$30k—not bank-breaking stuff when it can spark such important conversations.

Our national NZCat analysis included a suggested national Food Security Plan for nuclear war/winter. Here’s some key points:

Ideally, resilient food production could occur throughout a weeks- or months-long electricity loss (a possible consequence of solar storms flagged by NEMA in their new Space Weather Plan). We have provided a free webinar, expert interview, and panel discussion on Managing the Risk of Catastrophic Electricity Loss.

But overall, to help ensure basic food needs can be met, no matter what happens, ECan could champion something like this 12-point plan:

• Include global catastrophic risks in local risk planning and governance
• Advocate for central government responsibility for basic needs during catastrophes
• Facilitate public discussion on catastrophic risks and resilience
• Promote 10-day household food storage (vs. current 3-day standard)
• Convene cross-sector working groups for contingency planning
• Plan low-fuel food production with frost-resistant crops post-catastrophe
• Protect near-urban land for high-yield crop production
• Support urban agriculture and community food knowledge
• Prepare to redirect export food to domestic markets
• Plan food transport without liquid fuels through electrification
• Develop compost from urban waste for soil improvement
• Incentivize high-yield farming near cities over energy-intensive production

Food Resilience

So the objective is: everyone eats, no matter what

The strategy is: increase food system resilience to GCR

And the tactics are: near-urban agriculture, crop selection, local fuel supply…

I’m very happy to take questions and point you to websites with all the research work I have talked about.

Thank you again for this opportunity to speak.

References

1. UN Office for Disaster Risk Reduction. (2025). Global Assessment Report 2025: Resilience Pays: Investing and financing for our future. United Nations. https://www.undrr.org/gar/gar2025
2. Lawrence M, Homer-Dixon T, Janzwood S, Rockstöm J, Renn O, Donges JF. Global polycrisis: the causal mechanisms of crisis entanglement. Global Sustainability. 2024;7:e6. doi:10.1017/sus.2024.1
3. Mills, M. J., O. B. Toon, J. Lee-Taylor, and A. Robock (2014), Multidecadal global cooling and unprecedented ozone loss following a regional nuclear conflict, Earth’s Future, 2, doi:10.1002/2013EF000205.
4. Boyd, M., & Wilson, N. (2023). Island refuges for surviving nuclear winter and other abrupt sunlight-reducing catastrophes. Risk Analysis, 43, 1824–1842. https://doi.org/10.1111/risa.14072
5. Boyd M, Payne B, Ragnarsson S, Wilson N. (2023). Aotearoa NZ, Global Catastrophe, and Resilience Options: Overcoming Vulnerability to Nuclear War and other Extreme Risks: Report by the Aotearoa NZ Catastrophe Resilience Project (NZCat). Reefton: Adapt Research Ltd
6. Boyd, M., Ragnarsson, S., Terry, S., Payne, B., & Wilson, N. (2024). Mitigating imported fuel dependency in agricultural production: Case study of an island nation’s vulnerability to global catastrophic risks. Risk Analysis, 44, 2360–2376. https://doi.org/10.1111/risa.14297
7. Boyd M, Wilson N (2025) Resilience to abrupt global catastrophic risks disrupting trade: Combining urban and near-urban agriculture in a quantified case study of a globally median-sized city. PLoS One 20(5): e0321203. https://doi.org/10.1371/journal. pone.0321203

[Media Release by University of Otago]

This blog cross-posts a University of Otago media release about our recent research:

Many former leaders of the world’s nine nuclear-armed nations were impaired by health conditions while in office, raising concerns over their decision-making abilities while they had access to nuclear weapon launch codes, a study from the University of Otago, New Zealand, has found.

The study analysed the health information of 51 deceased leaders of nuclear-armed countries: China, France, India, Israel, North Korea, Pakistan, Russia, the United Kingdom and the United States. Eight of the leaders died from chronic disease while still in office, five from heart attacks or strokes. Many of the leaders had multiple serious health issues while in office, including dementia, personality disorders, depression and drug and alcohol abuse.

The research was led by Professor Nick Wilson, from the Department of Public Health at the University of Otago, Wellington – Ōtākou Whakaihu Waka, Pōneke, with Associate Professor George Thomson and independent researcher Dr Matt Boyd.

Professor Wilson says that of the leaders who left office while still alive, 15 had confirmed or possible health issues which likely hastened their departure.

“Probably all of this group of 15 leaders had their performance in office impaired by their health conditions. In some cases, the degree of impairment was profound, such as in the case of two former Israeli Prime Ministers: Ariel Sharon, who became comatose after suffering a stroke in office, and Menachem Begin, whose depression was so severe he spent his last year as leader isolated in his home. Impairment during crises was also seen in the case of Richard Nixon’s bouts of heavy drinking – including during a nuclear crisis involving the Middle East.

“There have also been occasions where health information about leaders has been kept secret at the time.”

This was the case for multiple US presidents, including Dwight D Eisenhower, whose doctor described his 1955 heart attack as a digestive upset; John F Kennedy, whose aides lied about him having Addison’s disease, a serious, chronic condition; and Ronald Reagan, whose administration hid the extent of his injuries after he was shot in 1981, and the likely signs of his dementia near the end of his term.

Professor Wilson says Kennedy was in poor health during his first two years in office in 1961 and 1962, with his performance likely impaired from Addison’s disease, back pain, and his use of anabolic steroids and amphetamines. It was in 1961 that he authorised the failed CIA-backed Bay of Pigs invasion of Cuba and that his poor performance at a Cold War summit with Soviet leader Nikita Khrushchev in Vienna was noted. In turn, Khrushchev’s poor mental health probably contributed to him triggering both the Berlin Crisis and the Cuban Missile Crisis.

In France, long-serving President François Mitterrand clung onto power until the end of his term in 1995, despite keeping secret his advanced prostate cancer and after his doctor had concluded in late 1994 that he was no longer capable of carrying out his duties.

This latest study follows previous research involving Professor Wilson on the health of former New Zealand Prime Ministers. It found the performance of at least four of the leaders was impaired, in three cases by poor health, and, in the case of Robert Muldoon, by his heavy drinking.

Professor Wilson says with the rise in international instability following the Russian invasion of Ukraine in 2022 it has become even more important to ensure there is good leadership and governance in those countries with nuclear weapons.

“This is particularly the case for the United States, where a leader can in principle authorise the release of nuclear weapons on their own, a situation referred to as a ‘nuclear monarchy’.”

He says there are a range of measures which could reduce global security risks from leaders whose judgement is in question. They include removing nuclear weapons from ‘high alert’ status, adopting ‘no first use’ policies where nations refrain from using nuclear weapons except as a retaliatory second strike, ensuring any weapon launches need authorisation by multiple people, and progressing nuclear disarmament treaties.

Professor Wilson says democracies could consider introducing term limits for their leaders, as well as recall systems, so voters could petition for politicians to step down. Requirements for medical and psychological assessments could be introduced for leaders before they take office, and during their terms.

“Maintaining a strong media with investigative journalists can also help expose impairment in leaders.”

Professor Wilson says politicians in general are exposed to high levels of stress, which can affect their mental wellbeing. A study of UK Members of Parliament has found they were 34 per cent more likely to experience mental health problems than other high-income earners.

“Finding ways to reduce stress on politicians and better address their mental health needs is another way global security risks can be reduced.”

Notes to editors:

The research paper, ‘The Frequently Impaired Health of Leaders of Nuclear Weapon States: An Analysis of 51 Deceased Leaders’ is published in BMC Research Notes and is fully available online: https://doi.org/10.1186/s13104-025-07351-8
The associated recent study of impaired New Zealand Prime Ministers is detailed in this University of Otago media release: https://www.otago.ac.nz/news/newsroom/nz-needs-options-to-remove-ill-or-infirm-leaders,-researchers-say

For more information, contact:

Professor Nick Wilson
Department of Public Health
University of Otago, Wellington – Ōtākou Whakaihu Waka, Pōneke

Email: nick.wilson@otago.ac.nz

Mobile: + 64 21 204 5523

Cheryl Norrie
Communications Adviser

University of Otago, Wellington – Ōtākou Whakaihu Waka, Pōneke

Email: cheryl.norrie@otago.ac.nz
Mob: + 64 21 249 6787

New US National Academy of Sciences Report reveals the complex web of societal vulnerabilities that could amplify nuclear war’s devastating impact

TLDR/Summary

• The US National Academy of Sciences has just released a comprehensive report on the “Environmental Effects of Nuclear War”. This work extends analysis beyond physical damage to examine impacts on human social and economic systems.
• Chapter 7 reveals that nuclear war’s most severe consequences may come through cascading societal failures rather than direct blast effects, with global interconnections creating “societal teleconnections” that could spread impacts worldwide.
• Global crop yields could suffer 3–16% reductions from nuclear winter cooling, while marine fisheries could decline by 30–70%, threatening global food security.
• The report identifies fundamental gaps in our understanding of how complex human systems respond to nuclear shocks, calling for unprecedented interagency coordination and advanced modelling.
• While acknowledging massive uncertainties, the evidence suggests even regional nuclear conflicts could trigger global disruptions through interconnected trade, financial, and supply chain networks.
• Key recommendations call for coordinated US Government assessment, advanced predictive modelling, comprehensive research programmes, health system preparedness, and community resilience initiatives.
• We have previously made similar recommendations about the need for post-nuclear-war trade and supply modelling, the need for New Zealand to build resilience and how, and lessons from past volcanic winters.

A System of Systems Under Stress

The National Academy of Sciences’ (NAS) latest report on nuclear war represents a critical evolution in how we understand catastrophic risks. Unlike Cold War-era studies focused primarily on blast radius and fallout, this analysis treats nuclear conflict as a “system of systems” problem, where cascading failures through interconnected human networks may prove more devastating than the initial explosions. I watched with interest the 25 June webinar presentation by the NAS authors, which summarised the findings. Chapters deal in turn with:

• Nuclear weapon scenarios and weapon effects
• Fire dynamics
• Effects of plumes, aerosols, and chemistry
• Physical Earth system impacts
• Ecosystem impacts
• Societal and economic impacts

Although the report inexplicably omits study of the effects of radiation and radioactive fallout, as per their directive from the US Congress, particularly relevant is Chapter 7, which examines the societal and economic impacts of nuclear war.

This Chapter has much in common with our own NZCat Main Report from 2023 on New Zealand’s vulnerability and resilience options to Northern Hemisphere nuclear war (summarised in recent journalistic reporting here).

Chapter 7 provides a sobering assessment of how nuclear war would ripple through the complex web of modern civilisation. The findings reveal that while humanity has grown adept at modelling the physics of nuclear explosions, we remain dangerously ignorant about how human societies collapse and recover under such extreme stress.

When Food Systems Fail

The agricultural impacts alone paint a grim picture. The report concludes that nuclear winter effects from atmospheric soot could reduce global crop yields by 3–16%, with temperate regions above 30°N—including the United States, China, and Europe—facing the greatest impacts.

The cause of this precipitous drop in yield is the 5–12 teragrams (Tg) of soot that would be thrown high in the atmosphere, blocking the sun.

The large-scale scenario described in Section 2.2.2 could inject 5 to 12.5 Tg of submicron particles in the stratosphere (p.42).

These findings align our own reporting for New Zealand (NZCat Main Report), based on 10–30 Tg of soot, with even further reductions in yield due to cascading shortages of industrial agricultural inputs like imported fuel, fertiliser, seed, and agrichemicals.

Marine ecosystems would suffer as well. The NAS report projects 30% declines in global fisheries catches after a major nuclear conflict, potentially reaching 70% if fisheries are already overfished. These aren’t abstract statistics—they represent the potential collapse of food systems that sustain billions of people.

As the report notes:

Nuclear winter may be one of the most far-reaching public health crisis scenarios, with effects including threats to global food security. Secondary impacts would disrupt transport, food, water, trade, energy, finance, and communication to the detriment of public health efforts (p.169).

The Cascade Effect: When Everything is Connected

Perhaps most concerning is the report’s analysis of “societal teleconnections” (p.155), how disruptions cascade through today’s hyperconnected global systems. Historical examples demonstrate this vulnerability: oil crises, natural disasters, and regional conflicts have repeatedly triggered worldwide food price spikes and economic instability. Nevertheless, the report possibly understates these connection risks, given advancing research in global systemic risk, such as the interaction of algorithms and the potential for deleterious algorithmic collisions in unforeseen circumstances.

In a nuclear conflict scenario, these connections become transmission vectors for catastrophe. Trade networks, supply chains, and financial systems that normally distribute prosperity could instead spread economic collapse. The scale could surpass Covid-19 pandemic disruptions (p.169), with the added challenge that recovery infrastructure might itself be compromised. As we’ve written before, the world needs specific ‘resilience’ infrastructure to call on when business-as-usual has ceased functioning, not merely ‘resilient’ infrastructure.

The NAS report notes that the human toll extends far beyond immediate casualties. Direct health consequences include blast injuries, thermal burns, radiation exposure, and severe mental health trauma. Studies of atomic bomb survivors show increased suicide rates, PTSD, and intergenerational psychological effects that persist for decades. Mass displacement would overwhelm shelter, healthcare, food, and water provision, while psychological impacts could trigger panic, hoarding, and breakdown of civil order. Additionally the webinar panel was explicit that:

It’s difficult to understate the importance of the economic disruptions.

That said, the geographic particulars, and type and number of weapons employed, as well as the targets struck, will all interact to determine the effects of any particular nuclear conflict.

The Knowledge Gap Crisis

The report’s most troubling finding may be how little we actually know. As the authors acknowledge:

There is a fundamental lack of data, process understanding, and modelling capabilities that prevents researchers and analysts from quantitatively linking specific nuclear war scenarios to precise societal outcomes (p.152).

Current climate models “are not well suited for evaluating the consequences of sudden shocks such as nuclear war” as they focus on gradual changes rather than abrupt disruptions. We lack understanding of ecosystem recovery thresholds, low-dose radiation effects, complex human behavioural responses, and cascading infrastructure failures.

We have noted these shortcomings before and highlighted the need for modelling the potential cascading consequences to trade and supply chain of major catastrophes like nuclear war. Our paper ‘Resilience Reconsidered: The need for modelling resilience in food distribution and trade relations in post nuclear war recovery’, is forthcoming in a Special Issue on Polycrisis and Systemic Risk in the International Journal of Disaster Risk Science. You can read a preprint here.

Without understanding how societies collapse and recover, we cannot effectively prepare for or prevent these catastrophes.

Building Resilience in an Uncertain World

Despite massive uncertainties, the report doesn’t counsel despair. Community resilience, social capital, and preparedness can significantly influence outcomes. Strong governance, robust infrastructure, and social cohesion enable better recovery.

These are investments that benefit society whether or not nuclear war can be prevented. This finding echoes our own mention of a four capitals approach to building resilience to global catastrophic risk, see our report Aotearoa New Zealand, Global Catastrophe, and Resilience Options.

While the prevention of nuclear war must remain a high priority of all governments, countries not contributing to the nuclear arms race (like New Zealand) should consider improving their survival chances. The NAS report’s key recommendations around societal and economic consequences of nuclear war provide a roadmap for action:

• Interagency coordination: Major government agencies must develop coordinated assessments of how nuclear war would affect food, water, health, and economic systems.
• Advanced modelling: Investment in sophisticated capabilities that integrate climate, agricultural, and economic factors to help policymakers develop contingency plans.
• Comprehensive research: Transdisciplinary collaboration to understand climate impacts, ecosystem recovery, and community resilience.
• Health system preparedness: Strengthening hospital capacity, public health workforce, and strategic stockpiles.
• Community resilience: Research on how social inequities would influence nuclear impacts, with emphasis on local collaboration.

The evidence is strongest for direct agricultural and health impacts, moderate for broader economic disruptions based on historical precedents, and weakest for complex cascading social effects.

But even the moderate-confidence findings paint a picture of civilisational disruption that demands preparation, and preparing to survive nuclear war would benefit preparations for other major global catastrophes too.

Wider Global Context

This US NAS report joins a growing body of work examining the likely impacts of nuclear war, including:

• The UN’s recent call for nominations for a scientific panel being established to assess the impacts of nuclear war
• Upcoming WHO health impact studies
• Our own NZCat analysis of New Zealand’s vulnerability to Northern Hemisphere nuclear war.

Together, these efforts represent recognition that nuclear threats require serious, coordinated analysis and mitigation options.

As geopolitical tensions rise in 2025, the NAS report’s timing proves prescient. We face an era of increasing instability where nuclear risks intersect with other global catastrophic threats, such as pandemics, climate change, and technological disruption (eg, from artificial intelligence).

Finally, it is a shame that the NAS was so cautious in their assessment of the quality of evidence available. The report seemed to demand very high levels of certainty, yet what we need to know to act is that there is a reasonable chance of major famines and social collapse, and that seems to be that case. The report shied away from using evidence from past volcanic eruptions as any kind of analogue for the climate impacts of nuclear war, yet both events are sun-blocking. Our own work describing impacts and lessons from the 1815 Tambora eruption are examples of this.

Sometimes it is important to acknowledge what we don’t know, but act on “good enough evidence”, rather than wait for perfect understanding. Irrespective of the state of knowledge, we should begin acting now, so we are not too late.