🔗 Share this article

The gravest potential impacts of the climate crisis for the UK have been detailed by scientists, including a searing 4C increase in temperatures to a 2-metre increase in ocean levels. An alternative projection envisions a drop of 6C in temperature following the collapse of crucial Atlantic Ocean currents, which would severely impact food production and energy needs.

Credible Extremes, Not Guarantees

These effects, a number of which are associated with irreversible climate shifts, are considered as unlikely but plausible. The team stated that these scenarios filled a gap in forecasting that had rendered the UK not ready for extreme outcomes.

"The severe weather events we have detailed should not be seen as certainties, but they are credible," said the professor who oversaw the analysis. "Britain has been planning lacking the methods to assess worst-case scenarios. We've now provided planners what they need to get ready for future conditions they pray never occur, but must not overlook."

A Suite of Severe Conditions Scenarios

A second set of worst-case scenarios maps the possible scale of extreme weather between now and the year 2100. These indicate that thermometer readings could soar in particular seasons by up to 6C higher than the norm, while precipitation could be triple typical amounts.

The chance of the worst-case outcomes happening remains uncertain due to unknown factors about what action will be implemented to tackle climate change and how the planet's climate will respond. This research was compared to defence planning or stress tests for financial systems.

Critical Outcome Elements

• 4C Temperature Rise: Worldwide averages rising well above 4C by 2100 could occur if international cooperation fails or if vicious cycles such as the Amazon rainforest becoming a net carbon source emit its huge repository of carbon. This would lead to extreme and prolonged heatwaves and dry spells hitting the UK in summer.
• AMOC Shutdown: A key circulation system, the Atlantic meridional overturning circulation (Amoc), is slowing down and showing signs of collapse due to climate change. A full shutdown beginning in 2030 would lead to a 6C cooling in the UK. "Farming would struggle enormously and water supplies would be fundamentally reshaped," explained the professor.
• Sudden Ocean Inundation: A surge of 2.0-2.2 metres around the UK by 2100 could occur if polar ice in the polar regions disintegrate quickly, flooding seaside communities. In contrast to the other scenarios, this possibility is already recognized by coastal engineers.
• Pollution Paradox: Global averages could also be pushed higher by about 0.75C if industrial aerosols is drastically reduced. This unexpected result occurs because aerosol particles from industrial activity block sunlight from warming the ground.

Building Resilience Against the Extreme

The worst-case scenarios could be applied to guide the construction of critical national infrastructure, including housing developments, energy plants and water management networks. Knowledge about these future hazards could also speed the drive to slash fossil fuel emissions.

The research developed the severe projections using a blend of observed and historical experience, digital projections and established principles. These outcomes omit international cascading effects like the devastation of food supplies and increased conflict.

This work was commissioned as part of a national risk assessment framework. Earlier reports have warned that insufficient focus was being given to high-consequence, low-probability risks.

The government's climate advisors has said that the UK must "adapt to 2C" and assess the threats for 4C. Previous adaptation plans have been described as being "inadequate" by environmental groups.

An official statement commented: "The climate emergency is at the core of our national priorities, both adapting for the future and becoming a low-carbon economy. It is essential that the UK is resilient for the impacts."