Scientists have outlined a range of worst-case climate scenarios for the UK, including potential temperature increases of 4C and sea level rises of up to 2 metres by 2100. Another scenario details a possible 6C plunge in temperatures should key Atlantic Ocean currents collapse, with significant consequences for agriculture and energy supplies.
Understanding the Scenarios
These impacts, linked in some cases to climate tipping points, are considered plausible, though not necessarily probable. Researchers emphasize the need to prepare for outcomes that, until now, have not been fully accounted for in UK forecasting.
Beyond long-term projections, the analysis also considers extreme weather events that could occur between now and the end of the century. These scenarios suggest temperatures could rise by as much as 6C above average in certain months, accompanied by rainfall three times higher than normal levels.
Preparing for the Unexpected
“The climate extremes we have mapped aren’t predictions, but they are plausible,” explained Nigel Arnell, a University of Reading professor who led the study. “The UK has been planning without the tools to test against worst-case scenarios. We’ve now given decision-makers what they need to prepare for climate outcomes they hope never happen, but can’t afford to ignore.”
The study acknowledges that calculating the probability of these scenarios is difficult due to uncertainties surrounding future climate action and the climate system’s response. Arnell likened this to national security risk assessments, where probabilities are often unknown but potential consequences are evaluated.
These scenarios could inform the development of long-term infrastructure projects, including new towns, nuclear power stations, and improved urban drainage systems. Increased awareness of these risks may also accelerate efforts to reduce fossil fuel emissions.
Potential Impacts in Detail
A significant temperature rise exceeding 4C by 2100 could occur if climate action falters or if feedback loops, such as the death of the Amazon rainforest and subsequent carbon release, are triggered. This would likely result in prolonged heatwaves and droughts. Thousands of early deaths have already been linked to heatwaves in England with only a 1.3C increase in global temperatures.
Conversely, a reduction in industrial pollution could lead to a 0.75C temperature increase, as aerosol particles from burning fuels currently block sunlight. The Atlantic meridional overturning circulation (Amoc), a critical ocean current, is weakening and could collapse as early as 2030, potentially causing a 6C cooling in the UK.
According to Arnell, a collapse of Amoc would “struggle enormously” impact agriculture and alter water resources, while also disrupting the UK’s heat and energy systems. Even a partial collapse of Amoc’s sub-polar gyre could reduce UK temperatures by 2.5C.
Finally, a 2.0-2.2 metre rise in sea levels around the UK by 2100 is possible if glaciers in Greenland and Antarctica collapse rapidly, potentially flooding coastal areas. This scenario is already considered in some planning efforts.
Frequently Asked Questions
What is the Atlantic Meridional Overturning Circulation (Amoc)?
Amoc is a major ocean current that is weakening due to global heating. A collapse of Amoc could lead to significant cooling in the UK, potentially by 6C if the entire current collapses, or 2.5C if only a part of it collapses.
Are these scenarios predictions of what will happen?
No, according to Nigel Arnell, the scenarios are not predictions, but rather plausible outcomes. They are designed to help decision-makers prepare for a range of possibilities, even those they hope will not occur.
What is the government doing to prepare for these risks?
The government spokesperson stated that climate change is a priority, with efforts focused on adaptation and becoming a “clean energy superpower.” They are investing £10.5bn in flood defences to protect nearly 900,000 properties by 2036 and have commissioned an evidence review of climate risks from the Climate Change Committee.
Given these potential, far-reaching consequences, how should communities and governments balance the need for immediate economic development with the long-term investments required for climate resilience?
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