Last autumn, a UK government report warned that climate-driven ecosystem collapse could lead to food shortages, mass migration, political extremism and even nuclear conflict. The report was never officially launched.

Commissioned by Defra – the Department for Environment Food and Rural Affairs – and informed by intelligence agencies including MI5 and MI6, the briefing assessed how environmental degradation could affect UK national security.

At the last minute the launch was cancelled, reportedly blocked by Number 10. Thanks to pressure from campaigners and a freedom of information request, a 14-page version of the report was snuck out (no launch, not even a press release) on January 22.

That report says: “Critical ecosystems that support major food production areas and impact global climate, water and weather cycles” are already under stress and represent a national security risk. If they failed, the consequences would be severe: water insecurity, severely reduced crop yields, loss of arable land, fisheries collapse, changes to global weather patterns, release of trapped carbon exacerbating climate change, novel zoonotic disease and loss of pharmaceutical resources.

In plainer terms: the UK would face hunger, thirst, disease and increasingly violent weather.

An unredacted version of the report, seen by the Times, goes further. It warns that the degradation of the Congo rainforest and the drying up of rivers fed by the Himalayas could drive people to flee to Europe (Britain’s large south Asian diaspora would make it “an attractive destination”), leading to “more polarised and populist politics” and putting more pressure on national infrastructure.

The Times describes a “reasonable worst case scenario” in the report, where many ecosystems were “so stressed that they could soon pass the point where they could be protected”. Declining Himalayan water supplies would “almost certainly escalate tensions” between China, India and Pakistan, potentially leading to nuclear conflict. Britain, which imports 40% of its food, would struggle to feed itself, the unredacted report says.

The report isn’t an outlier, and these concerns are not confined to classified briefings. A 2024 report by the University of Exeter and think-tank IPPR warned that cascading climate impacts and tipping points threaten national security – exactly the risk outlined in the Defra report.

The government has not publicly explained why the launch was cancelled. In response to the Times article, a Department for Environment, Food and Rural Affairs spokesperson said: “Nature underpins our security, prosperity and resilience, and understanding the threats we face from biodiversity loss is crucial to meeting them head on. The findings of this report will inform the action we take to prepare for the future.”

Perhaps there are mundane reasons to be cautious about a report linked to the intelligence services that warns of global instability. But the absence of any formal briefing or ministerial comment is itself revealing – climate risks appear to be treated differently from other risks to national security. It’s hard to imagine a report warning of national security risks from AI, China or ocean piracy getting the same treatment.

This episode is not even especially unusual, historically. Governments have been receiving warnings about climate change – and downplaying or delaying responses – for decades.

Decades of warnings

In January 1957, the Otago Daily Times reported a speech by New Zealand scientist Athol Rafter under the headline “Polar Ice Caps May Melt With Industrialisation”. And Rafter was merely repeating concerns already circulating internationally, including by a Canadian physicist whose similar warning went around the world in May 1953. Climate change first went viral more than seven decades ago.

By the early 1960s, scientists were holding meetings explicitly focused on the implications of carbon dioxide build-up. In 1965, a report to the US president’s Science Advisory Council warned that “marked changes in climate, not controllable though local or even national efforts, could occur”.

Senior figures in the UK government were aware of these discussions by the late 1960s, while the very first environment white paper, in May 1970, mentions carbon dioxide build-up as a possible problem.

But the story we see today was the same. Reports are commissioned, urgent warnings are issued – and action is deferred. When climate change gained renewed momentum in the mid-1980s, following the discovery of the ozone hole and the effects of greenhouse gases besides carbon dioxide, the message sharpened: global warming will come quicker and hit harder than expected.

Margaret Thatcher finally acknowledged the threat in a landmark 1988 speech to the Royal Society. But when green groups tried to get her to make specific commitments, they had little success.

Since about 1990, the briefings have barely changed. Act now, or suffer severe consequences later. Those consequences, however, are no longer theoretical.

Why does nothing happen?

Partly, it’s down to inertia. We have built societies in which carbon-intensive systems are locked in. Once you’ve built infrastructure around, say, the private petrol-powered automobile, it’s hard for competitors to offer an alternative. There’s also a mental intertia: it’s hard to let go of assumptions you grew up with in a more stable era.

Secrecy plays a role too. As the Defra report illustrates, uncomfortable assessments are often softened, delayed or buried. Then, if you do accept the need for action, you are then up against the problem of responsibility being fragmented across sectors and institutions, making it hard to know where to aim your efforts. Meanwhile, social movements fighting for climate action find it hard to sustain momentum for more than three years.

Here’s the final irony. Conspiracy theorists and climate deniers insist governments are exaggerating the threat. In reality, the evidence increasingly suggests the opposite. Official assessments tend to lag behind scientific warnings, and the most pessimistic scenarios are often confined to technical or classified documents.

The situation is not better than we are told. It’s actually far worse.

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Marc Hudson was employed as a post-doctoral researcher on various industrial decarbonisation projects. He runs a climate histories website called All Our Yesterdays. http://allouryesterdays.info