The direst projected effects of the global heating for the UK have been outlined by scientists, including a searing 4C jump in mean temperatures to a 2-metre surge in ocean levels. An alternative projection predicts a drop of 6C in temperature following the collapse of crucial Atlantic Ocean currents, which would massively disrupt agriculture and power requirements.
Credible Extremes, Not Guarantees
These impacts, a number of which are linked to irreversible climate shifts, are viewed as improbable but plausible. The scientists stated that these models plugged a hole in forecasting that had rendered the UK ill-prepared for worst-case results.
"The worst-case scenarios we have detailed aren’t predictions, but they are possible," stated the professor who directed the analysis. "The UK has been planning in the absence of the tools to test against catastrophic outcomes. We've now supplied policymakers what they need to plan for future conditions they wish to avoid, but dare not dismiss."
A Range of Severe Conditions Possibilities
A further series of dire projections details the potential extent of harsh climate between now and the year 2100. These indicate that thermometer readings could soar in some months by up to 6C above historical levels, while rainfall could be 300% of normal levels.
The probability of the extreme scenarios occurring remains uncertain due to a lack of certainty about what steps will be taken to combat climate change and how the climate system will react. This research was described as similar to national security risk assessments or scenario planning for the banking sector.
Critical Possibility Highlights
- Severe Heating: Global temperatures soaring past 4C by 2100 could happen if international cooperation breaks down or if powerful amplifying effects such as the Amazon rainforest perishing release its vast reserves of carbon. This would lead to severe and lengthy heatwaves and droughts plaguing the UK in summer.
- Ocean Circulation Failure: A key circulation system, the Atlantic meridional overturning circulation (Amoc), is losing strength and becoming unstable due to global heating. A collapse beginning in 2030 would lead to a drastic cooling in the UK. "Farming would be severely challenged and freshwater availability would be drastically changed," explained Arnell.
- Accelerated Coastal Flooding: A increase of 2.0-2.2 metres around the UK by 2100 could take place if glaciers in the polar regions disintegrate quickly, flooding coastal cities and towns. Differing from the other scenarios, this threat is already known by coastal engineers.
- Pollution Paradox: Global averages could also be pushed higher by about 0.75C if airborne particulates is rapidly cleaned up. This counterintuitive effect occurs because aerosol particles from burning coal scatter solar radiation from reaching the ground.
Building Resilience Against the Worst
The worst-case scenarios could be utilized in planning the development of critical national infrastructure, for example new towns, energy plants and flood defences. Understanding these environmental threats could also accelerate the drive to cut fossil fuel emissions.
The research developed the worst-case scenarios using a combination of observed and historical experience, computer simulations and scientific theory. The scenarios do not take into account international cascading effects including the global food shortages and resource wars.
The project was initiated as part of a government’s risk assessment framework. Independent analyses have stated that insufficient focus was being allocated to low‐likelihood but high‐impact risks.
An independent advisory body has said that the UK must "adapt to 2C" and evaluate the threats for four degrees. Previous adaptation plans have been criticised as being "insufficient" by environmental groups.
An official statement commented: "Climate change is at the heart of the country's focus, both building resilience and establishing itself as a low-carbon economy. It is essential that the UK is ready for the impacts."
