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4 Billion People Could be Dead in the Second Half of the 21st Century - UK Insurance Industry (2025)
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What's an acceptable number of deaths?

The number comes from the Institute and Faculty of Actuaries' Planetary Solvency report, which places mass death at over 4 billion in the worst-case risk category for 3°C of heating.

Some have objected to how we present it, insisting we say “illustrative scenario” and “risk of” rather than “prediction.” We use “predict” the way it’s actually used in everyday English, not the way it’s used inside a specific technical field.

A profession whose entire job is pricing risk conservatively for insurers, pension funds and governments, looked at the trajectory we’re on and put mass death in the billions into its worst-case band.

Focusing on whether the figure is “exact” is a way of avoiding what it actually makes us feel. You can win every argument about a figure and still have said nothing about the horror of what it refers to.

The fact is, we're on track towards mass death. We urgently need to stop what is happening.

Come along to our next public call, October 21st, 7pm BST, to find out what you can do. Link in bio: @4billiondead by @4billiondead

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5 days ago

You felt it this summer - the heat was relentless.

El Niño is coming, and it's only going to get worse. Approximately 546,000 people die as a result of extreme heat each year, and as temperatures continue to rise, so will the death toll.

Join Ruth Cerezo Mota and Roger Hallam on 21st October at our next international call to find out what you can do. Link in bio: @4billiondead by @4billiondead

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6 days ago

Will you be part of the next social movement?

4 billion people could die by the end of the century if things continue as they are.

Join Geneviéve Walker and Roger Hallam at our next public call next Monday, 7pm, to find out more. Link in bio: @4billiondead by @4billiondead

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23 days ago

At a moment of existential crisis, governments everywhere are retreating into a dreamworld, in which impossible contradictions are reconciled. You can send your legions to war with reality, but eventually we all lose.

Your life and the life of everyone you love is at stake.

Stop doomscrolling.

Join @4billiondead which has monthly international calls and actions because the UK security assessment warns ecosystem collapse could drive food shortages, mass migration, conflict and even nuclear escalation as soon as 2030.

The IFoA/University of Exeter Planetary Solvency report warns combined climate and ecosystem collapse could put billions of lives at risk, including over 4 billion deaths in an extreme 3°C scenario.
Join the @4billiondead public call on October 21. Register now at 4billiondead.org. by @4billiondead

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a day ago

Climate breakdown is not just about temperature records, atmospheric physics or lines on a graph. It is increasingly about irreversible damage, deadly heat and mass death.

Solomon et al. found that much of the climate change caused by carbon dioxide is effectively irreversible for at least 1,000 years after emissions stop, including persistent warming, rainfall disruption and continuing sea level rise.

Bressler estimated 83 million cumulative temperature related excess deaths by 2100 under a baseline pathway reaching about 4.1°C of warming. That estimate does not represent every way climate breakdown can kill people.

Kemp et al. warned in Climate Endgame that catastrophic climate scenarios involving mass mortality, societal collapse and cascading crises remain dangerously understudied.

Yet people consistently underestimate the danger to themselves.

A 2026 Nature Sustainability meta analysis covering 70,337 people across 17 countries found that in 81 of 83 datasets people perceived their own climate risk as lower than the risk faced by others.

Another 2026 study found that public perceptions of mortality from extreme heat, wildfire smoke, floods and droughts were poorly aligned with scientifically estimated death risks.

The science is increasingly describing a threat to human life on an enormous scale. Human perception is still struggling to treat that threat as personal.

With that said, your life and the life of everyone you love is at stake.

Stop doomscrolling.

Join @4billiondead which has monthly international calls and actions because the UK security assessment warns ecosystem collapse could drive food shortages, mass migration, conflict and even nuclear escalation as soon as 2030.

The IFoA/University of Exeter Planetary Solvency report warns combined climate and ecosystem collapse could put billions of lives at risk, including over 4 billion deaths in an extreme 3°C scenario.
Join the @4billiondead public call on October 21. Register now at 4billiondead.org. by @4billiondead

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2 days ago

HAPPENING NOW: Catastrophic flooding due to extreme rainfall hits Madrigueras in the province of Albacete in the region of Castile-La Mancha, Spain 🇪🇸

For every 1°C increase in atmospheric temperature, the air can hold approximately 7% more water vapour, according to the Clausius-Clapeyron relation. These floods will get worse until we stop burning fossil fuels.

Stop doomscrolling.

Join @4billiondead which has monthly international calls and actions because actuaries are now warning that at 3C or more of heating by 2050, there could be more than 4 billion deaths, significant sociopolitical fragmentation worldwide, failure of states (with resulting rapid, enduring, and significant loss of capital), and extinction events. If it's 2C by 2050 (guaranteed) that's 2 billion deaths.

Both scenarios are 20-40 times worse than both world wars combined, respectively. See https://global-tipping-points.org/planetary-solvency/ by @4billiondead

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5 days ago

Climate scientist Bill McGuire says the public is still being shielded from the full scale of the climate emergency.

The UCL professor emeritus warned that Earth is undergoing an extraordinarily rapid heating episode, driven by an equally extraordinary surge in greenhouse gases.

“We’re experiencing, in our lifetimes, a heating episode that is probably unique in the last 4.6 billion years.”

“What’s happening to our world scares the hell out of me,” he wrote.

McGuire argues that calling people “doomers” for discussing catastrophic climate risks can become another form of delay: downplaying the severity of the crisis reduces the perceived urgency to act.

The evidence does not support the simplistic claim that frightening people automatically paralyses them. Research has found climate anxiety can motivate action, particularly when people believe meaningful collective action is still possible.

His point is simple: people have a right to know what the science says, even when the facts are terrifying.

We cannot respond rationally to a planetary emergency while sanitising the scale of the threat.

Source: Bill McGuire, CNN Opinion, March 8, 2024. by @4billiondead

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6 days ago

Listen to this short clip of @rogerhallamcs21 talking at the Hackney public meeting earlier this month.

The British Insurance Industry has predicted 4 billion people could die this century. There are no words.

Sign up for our next online public call, October 21st, with Roger Hallam and Ruth Cerezo Mota. Link in bio: @4billiondead by @4billiondead

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7 days ago

The quiet comprehending of the ending of it all.

Your life and the life of everyone you love is at stake.

Stop doomscrolling.

Join @4billiondead which has monthly international calls and actions because the UK security assessment warns ecosystem collapse could drive food shortages, mass migration, conflict and even nuclear escalation as soon as 2030.

The IFoA/University of Exeter Planetary Solvency report warns combined climate and ecosystem collapse could put billions of lives at risk, including over 4 billion deaths in an extreme 3°C scenario.
Join the @4billiondead public call on October 21. Register now at 4billiondead.org. by @4billiondead

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7 days ago

A catastrophic landslide in Nepal 🇳🇵following severe prolonged rainfall.

For every 1°C increase in atmospheric temperature, the air can hold approximately 7% more water vapour, according to the Clausius-Clapeyron relation. These floods will get worse until we stop burning fossil fuels.

Stop doomscrolling.

Join @4billiondead which has monthly international calls and actions because actuaries are now warning that at 3C or more of heating by 2050, there could be more than 4 billion deaths, significant sociopolitical fragmentation worldwide, failure of states (with resulting rapid, enduring, and significant loss of capital), and extinction events. If it's 2C by 2050 (guaranteed) that's 2 billion deaths.

Both scenarios are 20-40 times worse than both world wars combined, respectively. See https://global-tipping-points.org/planetary-solvency/ by @4billiondead

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9 days ago

A massive landslide following days of heavy rainfall demolished houses in Chame, Manang, Nepal 🇳🇵

For every 1°C increase in atmospheric temperature, the air can hold approximately 7% more water vapour, according to the Clausius-Clapeyron relation. These extreme events will get worse until we stop burning fossil fuels.

Stop doomscrolling.

Join @4billiondead which has monthly international calls and actions because actuaries are now warning that at 3C or more of heating by 2050, there could be more than 4 billion deaths, significant sociopolitical fragmentation worldwide, failure of states (with resulting rapid, enduring, and significant loss of capital), and extinction events. If it's 2C by 2050 (guaranteed) that's 2 billion deaths.

Both scenarios are 20-40 times worse than both world wars combined, respectively. See https://global-tipping-points.org/planetary-solvency/ by @4billiondead

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9 days ago

Your life and the life of everyone you love is at stake.

Stop doomscrolling.

Join @4billiondead which has monthly international calls and actions because the UK security assessment warns ecosystem collapse could drive food shortages, mass migration, conflict and even nuclear escalation as soon as 2030.

The IFoA/University of Exeter Planetary Solvency report warns combined climate and ecosystem collapse could put billions of lives at risk, including around 4 billion deaths in a severe 3°C scenario.

Join the @4billiondead public call on October 21. Register now at 4billiondead.org. by @4billiondead

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13 days ago