Research discovers tropical winters in UK - only 26 million years ago

Tynemouth or the Costa del Sol?
-Credit: (Image: Newcastle Chronicle)


Had anyone been around in the UK 26m years ago, they could have dispensed with the heating in the winter.

Research at Northumbria University shows that then the average winter temperature in the UK and Ireland was more than 18°C, about the same as today’s average summer temperature. And such winter temperatures would classify the UK as tropical.

By reading layers of rocks, the university researchers were able to travel back in time. By studying the fossils which the rocks contain, it is possible to reconstruct past conditions in time periods before humans measured the weather and climate.

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The Northumbria study, involving associate professor Matthew Pound and PhD candidate Jessica McCoy, investigated the climates of the UK and Ireland from 33 to 20 million years ago. Back then, Antarctica had glaciers, but Greenland did not. As the Greenland ice sheet may collapse within this next century, reading the rocks of this time interval has relevance for what the climate would be like without the presence of Greenland ice.

The study used 25 locations to reconstruct the climate of this 13-million-year period from around the UK and Ireland by statistically analysing 82 collections of fossilised pollen from plants that had been frozen in time. As plants are intimately linked to climate, as they can’t simply move on when conditions become unfavourable, the pollen they leave behind in the fossil record provides a means to reconstruct past climates.

As this pollen changes through the sediment layers, it is possible to document the changing of climates through time. Using a statistical computer model, the Northumbria project reconstructed various different aspects of climate, such as mean annual temperature and mean annual precipitation, for each of the pollen assemblages.

The results showed that 26m years ago, the average winter temperature in the UK and Ireland was more than 18°C, which would classify the UK and Ireland then as tropical. Average summer temperature at this time was 25°C. These warmer temperatures were accompanied by 1,100–1,400mm of rain every year.

The study results show a substantially warmer and wetter climate could be reached by 2075 with greenhouse gases between current levels and those that could be reached in the next 50 years. But living in this kind of climate by 2075 would not be paradise, say the researchers.

If greenhouse gases continue to increase over the next 50 years, the ice in Greenland will melt. All this water will enter the world’s oceans leading to a global sea level rise of up to seven metres. This would expose millions of people across the world to coastal flooding. The Greenland ice is freshwater and adding this to the seas will affect ocean currents and create more unpredictable weather.

This would be bad news for food production. Between October 2022 and March 2024, almost 1.7m rain fell in the UK, badly affecting crops.

The Northumbria reconstructions suggest that it may be possible for rainfall rates to exceed 1.4m per year as a new norm. This would have massive implications for the future of food security in the UK and Ireland over the coming century.