Massive Disruption Forecasted: UK's Worst-Case Climate Emergency Possibilities Laid Bare by Experts

The gravest projected effects of the climate emergency for the UK have been outlined by scientists, ranging from a searing 4C increase in average temperatures to a 2-metre increase in ocean levels. An alternative projection predicts a drop of 6C in temperatures following the collapse of critical Atlantic Ocean currents, which would profoundly upset food production and power requirements.

Plausible Extremes, Not Predictions

These effects, a number of which are linked to climate tipping points, are seen as low probability but credible. The researchers said that these scenarios plugged a hole in forecasting that had rendered the UK unprepared for worst-case results.

"The worst-case scenarios we have mapped aren’t predictions, but they are possible," commented Nigel Arnell who oversaw the study. "The UK has been formulating policy without the tools to test against extreme possibilities. We've now provided policymakers what they need to plan for future conditions they pray never occur, but dare not dismiss."

A Suite of Harsh Climate Possibilities

A second set of severe models sets out the potential extent of severe conditions between now and the close of the 2100s. These show that thermometer readings could soar in some months by up to 6C above historical levels, while precipitation could be 300% of standard measurements.

The likelihood of the worst-case outcomes happening could not be calculated due to a lack of certainty about what measures will be taken to combat climate change and how the Earth's systems will behave. This analysis was compared to security threat evaluations or stress tests for the banking sector.

Key Outcome Details

• Four-Degree Warming: Worldwide averages rising well above 4C by 2100 could happen if emissions cuts breaks down or if vicious cycles like the Amazon rainforest dying unleash its vast reserves of carbon. This would result in intense and enduring heatwaves and droughts affecting the UK in summer.
• Ocean Circulation Failure: A major ocean current, the AMOC, is slowing down and showing signs of collapse due to ocean warming. A full shutdown commencing by 2030 would lead to a 6C cooling in the UK. "Agriculture would face immense difficulties and freshwater availability would be fundamentally reshaped," said the professor.
• Rapid Sea Level Rise: A rise of 2.0-2.2 metres around the UK by 2100 could occur if ice sheets in the polar regions collapse rapidly, submerging low-lying areas. Unlike the other scenarios, this threat is already recognized by infrastructure experts.
• Aerosol Effect: Global averages could also be pushed higher by about 0.75C if pollution from industry is drastically reduced. This counterintuitive effect occurs because pollution particles from fossil fuel combustion reflect sunlight from reaching the ground.

Planning for the Extreme

These dire projections could be utilized in planning the development of critical national infrastructure, for example expanded cities, energy plants and flood defences. Awareness of these climate risks could also hasten the drive to slash carbon pollution.

The analysis developed the worst-case scenarios using a mix of observed and historical experience, climate models and established principles. The scenarios exclude potential global problems including the devastation of food supplies and geopolitical instability.

The project was commissioned as part of a official adaptation planning initiative. Earlier reports have stated that insufficient focus was being allocated to catastrophic yet improbable risks.

Official experts has stated that the UK needs to "prepare for two degrees of warming" and evaluate the dangers for four degrees. Past policy documents have been labeled being "very weak" by environmental groups.

A national response said: "Global warming is at the heart of this government’s agenda, both building resilience and establishing itself as a low-carbon economy. It is essential that the UK is prepared for the effects."