🔗 Share this article

The direst possible consequences of the climate crisis for the UK have been mapped by experts, encompassing a scorching 4C increase in average temperatures to a 6.5-foot rise in sea levels. A separate possibility predicts a plunge of 6C in temperatures following the shutdown of crucial Atlantic Ocean currents, which would severely impact food production and energy needs.

Credible Extremes, Not Guarantees

These consequences, a number of which are linked to critical climate thresholds, are viewed as unlikely but credible. The team stated that these scenarios filled a gap in forecasting that had rendered the UK ill-prepared for catastrophic possibilities.

"The worst-case scenarios we have detailed should not be seen as certainties, but they are plausible," said the lead researcher who oversaw the study. "Britain has been planning without the frameworks to plan for worst-case scenarios. We've now provided decision-makers what they need to get ready for climate outcomes they hope never happen, but can’t afford to ignore."

A Range of Harsh Climate Scenarios

A second set of dire projections details the projected severity of harsh climate between now and the end of the century. These show that temperatures could soar in certain periods by up to 6C above historical levels, while precipitation could be triple typical amounts.

The probability of the catastrophic events happening cannot be precisely determined due to uncertainty about what action will be implemented to tackle global heating and how the climate system will react. This approach was compared to defence planning or resilience checks for financial systems.

Critical Scenario Elements

• 4C Temperature Rise: Worldwide averages rising well above 4C by 2100 could happen if emissions cuts collapses or if strong feedback loops like the Amazon rainforest becoming a net carbon source release its huge repository of carbon. This would cause severe and lengthy heat domes and droughts hitting the UK in summer.
• Ocean Circulation Failure: A major ocean current, the North Atlantic current, is losing strength and losing stability due to ocean warming. A collapse beginning in 2030 would lead to a drastic cooling in the UK. "Farming would face immense difficulties and water resources would be drastically changed," explained the professor.
• Rapid Sea Level Rise: A rise of 2.0-2.2 metres around the UK by 2100 could happen if glaciers in the polar regions disintegrate quickly, inundating low-lying areas. Differing from the other scenarios, this threat is already understood by coastal engineers.
• Aerosol Effect: Global averages could also be driven up by about 0.75C if airborne particulates is drastically reduced. This counterintuitive effect occurs because pollution particles from industrial activity scatter solar radiation from reaching the ground.

Building Resilience Against the Unthinkable

The severe models could be used to inform the construction of critical national infrastructure, for example expanded cities, energy plants and flood defences. Knowledge about these environmental threats could also hasten the push to cut greenhouse gas emissions.

The research created the severe projections using a mix of observed and historical experience, climate models and scientific theory. The scenarios exclude broader worldwide issues like the devastation of food supplies and geopolitical instability.

This work was requested as part of a national adaptation planning initiative. Independent analyses have cautioned that too little consideration was being allocated to low‐likelihood but high‐impact risks.

Official experts has recommended that the UK must "become resilient to moderate heating" and evaluate the threats for severe warming. Previous adaptation plans have been described as being "very weak" by some observers.

An official statement said: "Global warming is at the center of the country's focus, both preparing for impacts and transitioning to a renewable energy leader. It is vital that the UK is ready for the effects."