British policymakers now have detailed worst-case climate scenarios for the first time, including the possibility of a 6°C temperature plunge if Atlantic Ocean currents collapse or a scorching 4°C rise by the end of the century, according to research published Thursday in the journal Earth’s Future.
Scientists from the University of Reading have mapped out six long-term scenarios and multiple short-term extreme weather possibilities, filling a critical gap that left the UK unprepared for low-probability but high-impact climate outcomes. Until now, sea level rise was the only area where such extreme scenarios existed.
“The climate extremes we have mapped aren’t predictions, but they are plausible,” said Professor Nigel Arnell, lead author of the study. “The UK has been planning without the tools to test against worst-case scenarios. We’ve now given decision-makers what they need to prepare for climate outcomes they hope never happen, but can’t afford to ignore.
Six Long-Term Threats
The research, commissioned by the Met Office as part of the government’s climate resilience programme, outlines six scenarios through 2100. Global temperatures could rise well above 4°C if climate action collapses or feedback loops accelerate, bringing extreme heatwaves and droughts that would transform British summers.
A collapse of the Atlantic Meridional Overturning Circulation, one of the climate tipping points that most concerns scientists, could cause year-round cooling of 2.5°C to 6°C across the UK. “Agriculture would struggle enormously and water resources would be completely altered,” Arnell told The Guardian. “Our heat and energy system would be completely caught out by changing winter energy demand.”
Other scenarios include rapid sea level rises of 2.0 to 2.2 meters by 2100 if Greenland and Antarctic ice sheets collapse rapidly, a major volcanic eruption causing 2.5°C cooling for five years, and up to 0.75°C additional warming from sharp cuts to aerosol pollution.
Extreme Weather Anytime
The short-term scenarios describe extreme months or seasons that could occur at any time. Hot months could see temperatures soar 4°C to 6°C above average, while cold months could bring temperatures 4°C to 7°C below average. Wet months could deliver rainfall 2.5 to 3 times the average, while dry months could see rainfall drop to just 10% of normal levels. Wind speeds could spike 60% to 80% higher than average.
A government spokesperson said climate change is “at the heart of this government’s agenda” and emphasized the UK is investing £10.5 billion in flood defenses to protect nearly 900,000 properties by 2036.
Extreme Weather Anytime
The short-term scenarios describe extreme months or seasons that could occur at any time. Hot months could see temperatures soar 4°C to 6°C above average, while cold months could bring temperatures 4°C to 7°C below average. Wet months could deliver rainfall 2.5 to 3 times the average, while dry months could see rainfall drop to just 10% of normal levels. Wind speeds could spike 60% to 80% higher than average.
A government spokesperson said climate change is “at the heart of this government’s agenda” and emphasized the UK is investing £10.5 billion in flood defenses to protect nearly 900,000 properties by 2036.
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