🔗 Share this article

The most severe possible consequences of the climate crisis for the UK have been detailed by experts, including a blistering 4C rise in mean temperatures to a two-metre increase in ocean levels. A separate possibility envisions a decline of 6C in temperatures following the shutdown of critical Atlantic Ocean currents, which would severely impact agriculture and energy needs.

Possible Outcomes, Not Forecasts

These impacts, some of which are associated with climate tipping points, are considered as low probability but credible. The scientists explained that these projections plugged a hole in planning that had rendered the UK ill-prepared for catastrophic possibilities.

"The worst-case scenarios we have outlined aren’t predictions, but they are possible," commented the professor who led the study. "The nation has been making preparations lacking the tools to assess catastrophic outcomes. We've now given policymakers what they need to plan for future conditions they hope never happen, but must not overlook."

A Suite of Extreme Weather Scenarios

A second set of dire projections maps the potential extent of harsh climate between now and the close of the 2100s. These indicate that thermometer readings could soar in certain periods by up to 6C higher than average, while rainfall could be 300% of standard measurements.

The chance of the worst-case outcomes coming to pass cannot be precisely determined due to uncertainty about what steps will be taken to address climate change and how the planet's climate will respond. This analysis was compared to security threat evaluations or scenario planning for financial systems.

Key Possibility Highlights

• 4C Temperature Rise: Planetary heating exceeding 4C by 2100 could happen if emissions cuts breaks down or if powerful amplifying effects including the Amazon rainforest dying emit its vast reserves of carbon. This would cause extreme and prolonged heatwaves and dry spells affecting the UK in summer.
• Atlantic Current Collapse: A critical sea current, the AMOC, is losing strength and losing stability due to global heating. A full shutdown commencing by 2030 would lead to a 6C cooling in the UK. "Crop production would face immense difficulties and water resources would be completely altered," explained the professor.
• Sudden Ocean Inundation: A rise of 2.0-2.2 metres around the UK by 2100 could occur if ice sheets in the Arctic and Antarctic disintegrate quickly, flooding seaside communities. Differing from the other scenarios, this possibility is already understood by coastal engineers.
• Clean Air Warming: Temperatures could also be increased by about 0.75C if industrial aerosols is sharply cut. This paradoxical outcome occurs because tiny specks from burning coal scatter sunlight from reaching the ground.

Building Resilience Against the Worst

These dire projections could be applied to guide the development of major projects, such as new towns, energy plants and flood defences. Knowledge about these environmental threats could also speed the transition to reduce greenhouse gas emissions.

The research created the extreme models using a blend of observed and historical experience, climate models and climate physics. The scenarios exclude broader worldwide issues like the devastation of food supplies and geopolitical instability.

This work was commissioned as part of a government’s climate resilience programme. Earlier reports have cautioned that too little consideration was being paid to low‐likelihood but high‐impact risks.

The government's climate advisors has stated that the UK needs to "prepare for two degrees of warming" and assess the risks for 4C. Earlier government strategies have been described as being "very weak" by environmental groups.

An official statement commented: "Climate change is at the center of this government’s agenda, both building resilience and establishing itself as a low-carbon economy. It is crucial that the UK is prepared for the effects."