🔗 Share this article

The most severe potential impacts of the climate emergency for the UK have been mapped by scientists, including a scorching 4C rise in mean temperatures to a 2-metre surge in sea levels. An alternative projection predicts a drop of 6C in temperatures following the collapse of key Atlantic Ocean currents, which would severely impact farming and energy needs.

Possible Extremes, Not Forecasts

These effects, certain ones are linked to irreversible climate shifts, are viewed as unlikely but plausible. The scientists explained that these scenarios plugged a hole in forecasting that had left the UK ill-prepared for extreme outcomes.

"The climate extremes we have detailed should not be seen as certainties, but they are plausible," said Nigel Arnell who directed the study. "The nation has been making preparations without the methods to plan for worst-case scenarios. We've now provided policymakers what they need to get ready for environmental results they wish to avoid, but can’t afford to ignore."

A Spectrum of Severe Conditions Projections

A further series of worst-case scenarios maps the projected severity of severe conditions between now and the year 2100. These indicate that thermometer readings could rocket in some months by up to 6C above average, while rainfall could be triple typical amounts.

The probability of the catastrophic events happening cannot be precisely determined due to uncertainty about what steps will be implemented to address climate change and how the climate system will respond. This approach was likened to national security risk assessments or resilience checks for financial systems.

Critical Possibility Details

• Severe Heating: Worldwide averages soaring past 4C by 2100 could occur if climate action fails or if powerful amplifying effects like the tropical forests dying release its enormous store of carbon. This would lead to extreme and prolonged heat domes and dry spells affecting the UK in summer.
• Ocean Circulation Failure: A major ocean current, the North Atlantic current, is losing strength and showing signs of collapse due to ocean warming. A full shutdown starting around 2030 would lead to a six-degree temperature drop in the UK. "Agriculture would be severely challenged and water supplies would be fundamentally reshaped," said the lead researcher.
• Rapid Sea Level Rise: A surge of 2.0-2.2 metres around the UK by 2100 could happen if ice sheets in the Arctic and Antarctic melt abruptly, flooding coastal cities and towns. Differing from the other scenarios, this risk is already understood by infrastructure experts.
• Clean Air Warming: Temperatures could also be increased by about 0.75C if airborne particulates is sharply cut. This counterintuitive effect occurs because tiny specks from burning coal scatter solar radiation from reaching the ground.

Planning for the Extreme

The worst-case scenarios could be used to inform the development of major projects, such as housing developments, nuclear power stations and flood defences. Understanding these climate risks could also speed the push to slash carbon pollution.

The analysis developed the extreme models using a mix of real-world events, computer simulations and established principles. These outcomes do not take into account broader worldwide issues including the agricultural collapse and resource wars.

The project was initiated as part of a official risk assessment framework. Independent analyses have cautioned that insufficient focus was being allocated to low‐likelihood but high‐impact risks.

Official experts has said that the UK must "adapt to 2C" and examine the threats for 4C. Previous adaptation plans have been criticised as being "inadequate" by environmental groups.

A national response commented: "Climate change is at the heart of this government’s agenda, both preparing for impacts and transitioning to a renewable energy leader. It is crucial that the UK is prepared for the effects."