The UK's warmest year (for now)
And introducing a ‘causal chain’ for changes in extreme UK heat
2025 was a year of climate records for the UK.
It was the warmest spring, summer and calendar year in the Met Office official records which go back to 1884. It was also the warmest spring, summer and year for Central England, in a dataset which goes back to 1659. And it was the UK’s sunniest year (records back to 1910) and the year with most burnt area by wildfires (but records only back to 2012).
2025 was also one of the three warmest years for the globe, in records back to 1850 (or even 1790). Why do these records matter?
Human actions have emitted over 2750Gt of CO₂ into the atmosphere, mainly due to burning fossil fuels and deforestation, enhancing the greenhouse effect and warming the planet. The UK is responsible for around 3% of those total cumulative emissions (~76 GtCO₂ directly, and a bit more indirectly).
As a result of these global emissions the world has warmed by around 1.4°C and the UK by about 1.7°C. What is notable is that the hottest day of the year in Central England has warmed more than 2x faster than the annual average and is now around 3.5°C hotter than in the late 19th century.
A global warming of “just” 1°C does not imply that every day is 1°C hotter everywhere. For the UK, and many other regions, the very hot extremes are warming much faster than the mean. This matters because it is those hottest days which often cause the worst impacts on health, ecosystems and infrastructure, and even wildfires.
The ‘causal chain’ approach illustrated above is a potentially useful tool to show how global actions and decisions can be directly linked to harmful consequences locally.
Of course, many of these heat-related records are likely to be broken again soon and 2025 will, like previous record years, end up being a relatively cool year when looking back from the future.
Our choices today matter for determining how much warmer that future will be.