🔗 Share this article

The gravest potential impacts of the climate emergency for the UK have been outlined by scientists, encompassing a scorching 4C jump in temperatures to a two-metre increase in sea levels. Another scenario envisions a plunge of 6C in temperatures following the shutdown of key Atlantic Ocean currents, which would profoundly upset farming and energy demand.

Possible Outcomes, Not Guarantees

These impacts, certain ones are linked to climate tipping points, are considered as unlikely but plausible. The researchers said that these models addressed a shortfall in risk assessment that had rendered the UK unprepared for catastrophic possibilities.

"The worst-case scenarios we have outlined aren’t predictions, but they are credible," stated Nigel Arnell who led the research. "The UK has been making preparations lacking the frameworks to assess catastrophic outcomes. We've now provided decision-makers what they need to prepare for climate outcomes they pray never occur, but can’t afford to ignore."

A Suite of Extreme Weather Scenarios

A second set of severe models maps the potential extent of extreme weather between now and the close of the 2100s. These suggest that thermometer readings could soar in certain periods by up to 6C above average, while precipitation could be 300% of standard measurements.

The likelihood of the extreme scenarios occurring remains uncertain due to a lack of certainty about what steps will be taken to combat global heating and how the Earth's systems will respond. This research was compared to national security risk assessments or scenario planning for financial systems.

Key Scenario Highlights

• Severe Heating: Global temperatures rising well above 4C by 2100 could occur if international cooperation fails or if strong feedback loops such as the Amazon rainforest perishing unleash its vast reserves of carbon. This would lead to severe and lengthy heat domes and dry spells hitting the UK in summer.
• Atlantic Current Collapse: A key circulation system, the AMOC, is slowing down 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. "Crop production would struggle enormously and water supplies would be drastically changed," said the professor.
• Rapid Sea Level Rise: A surge of 2.0-2.2 metres around the UK by 2100 could happen if glaciers in the polar regions melt abruptly, flooding coastal cities and towns. Differing from the other scenarios, this possibility is already known by coastal engineers.
• Pollution Paradox: Global averages could also be increased by about 0.75C if pollution from industry is rapidly cleaned up. This counterintuitive effect occurs because tiny specks from industrial activity block solar radiation from warming the ground.

Planning for the Worst

The worst-case scenarios could be used to inform the building of critical national infrastructure, such as expanded cities, nuclear power stations and flood defences. Knowledge about these climate risks could also accelerate the transition to cut fossil fuel emissions.

The research created the worst-case scenarios using a blend of past data and records, digital projections and scientific theory. These outcomes omit broader worldwide issues like the devastation of food supplies and increased conflict.

The research was requested as part of a government’s risk assessment framework. Previous assessments have stated that insufficient focus was being given to high-consequence, low-probability risks.

The government's climate advisors has recommended that the UK must "become resilient to moderate heating" and evaluate the threats for four degrees. Past policy documents have been labeled being "very weak" by some observers.

An official statement noted: "Climate change is at the heart of this government’s agenda, both building resilience and becoming a renewable energy leader. It is vital that the UK is prepared for the consequences."