The immediate horror of nuclear weapon explosions, the blinding flash, crushing blast wave and radioactive inferno, is well documented.
But what nuclear-armed nations either do not grasp or will not admit, is far more chilling: how their weapons could devastate even countries thousands of kilometres from any mushroom clouds.
The collapse of global supply chains, widespread power failures and a nuclear winter that could plunge temperatures below freezing for years could create a catastrophe that respects no borders.
The world's lack of preparedness for Covid-19's second-order effects showed how vulnerable we are to cascading global disasters, and a nuclear war's impact would be incomparably worse.
Last month, Russian president Vladimir Putin signed a law permitting a nuclear response if Russia was attacked by Western long-range missiles, even conventional missiles.
Fortunately, the world's nations have just voted 144 to three in November to progress a United Nations resolution on "Nuclear War Effects and Scientific Research", sponsored by Ireland and New Zealand and co-sponsored by 30 countries.
France, Russia and the United Kingdom voted against progressing the resolution.
While the United Kingdom Foreign Office claims we do not need an independent scientific panel to understand nuclear war's devastating consequences, there is a shortage of official publications that explain the downstream implications for non-combatant nations like New Zealand, Argentina or Madagascar.
The New Zealand Planning Council's own 1980s Nuclear War Impacts Study showed the effects of trade disruption and a lack of planning would wreak untold catastrophe in this country.
Our research group has also written at length on these issues, with far-reaching likely impacts including lack of diesel for agricultural equipment, breakdown in shipping, transport and food distribution, failed communications, no digital payments and mass unemployment.
The planning council's study was commissioned before the world wide web even existed and has not been updated by the government.
As a nation that has shown leadership in nuclear-free policy, we must now lead in understanding and preparing for these risks.
Prime Minister Christopher Luxon, coming from aviation's rigorous risk management culture, understands the importance of operational ownership of risk, chief risk officers and independent oversight.
These private sector risk management practices must now be applied by government to understand and mitigate the consequences of nuclear war and other global catastrophes.
Critical human systems are interconnected and susceptible to a range of hazards.
A scientific study of the global effects of nuclear war would likely reveal insights pertinent to other global catastrophic risks, such as volcanic winter, asteroid or comet strikes, industry-disabling cyber-attacks and massive solar storms, all of which would severely impact infrastructure and global connections.
The United States National Academies of Science, Engineering, and Medicine concluded in 2023 that the US military and policymakers lack key knowledge about the effects of nuclear war.
Recognising that our understanding in the 1980s was incomplete, the New Zealand Planning Council recommended a phase II study, which was shelved for unknown reasons.
There remains uncertainty around some physical effects of multiple nuclear explosions, including fires, the impact on modern urban environments, potentially continent disabling effects of high-altitude electromagnetic pulses and climatic effects, such as nuclear winter. This is before even considering the psychological, societal and political consequences.
The need to study the downstream effects of global catastrophes, including nuclear war, was strongly recommended by Rand Corporation in a report prepared this year for the US government under the Global Catastrophic Risk Management Act.
Key recommendations included global co-operation to mitigate the impact of these threats, so this UN resolution is timely. It would task an independent scientific panel with a two-year study examining the local, regional and planetary physical effects and societal consequences of a nuclear war. The 21-member panel would publish a comprehensive report.
Scientists such as Alan Robock, who researches the effects of nuclear explosions on the climate, argue the report could help accelerate the complete elimination of nuclear weapons worldwide by speeding up the adoption of the UN Treaty on the Prohibition of Nuclear Weapons.
However, a detailed report on the likely consequences of nuclear war could also help non-combatant nations, who have no say in whether nuclear war is fought or not, ensure that they are prepared to protect their populations from cascading catastrophe far from the explosions.
The deteriorating global situation, with rising tensions among nuclear-armed nations and an emerging climate crisis, heightens nuclear war risk.
Competition for dwindling resources only adds to this powder keg.
Scientific understanding is not just desirable, it is essential for evidence-based policy and collective survival. New Zealand, with its nuclear-free legacy, should ensure its scientists are represented on the 21-member panel.
Every year without this study leaves us blind to the full scope of nuclear war's devastation.
While nuclear-armed nations focus on the immediate blast zones, the flash and fire and radiation, we must understand the deeper truth: in our interconnected world, no nation is likely to escape the darkness that follows.
The choice between knowledge and ignorance could mean the difference between survival and catastrophe for countries that never chose this fight. - Newsroom
Nick Wilson is a professor of public health at the University of Otago; Matt Boyd is an independent global catastrophic risk researcher.
