Seashells in Scotland Warn of Rapid Climate Change in Post-Ice Age Europe

A new study of seashells excavated from ancient glacial deposits in Scotland indicate that the region’s glaciers melted over a relatively short period of time–a period spanning only a few decades, and possibly as short as a matter of years–illustrating the abruptness of past climate change events, and how those events could serve as a warning as to how quickly our modern environment could also take an abrupt turn.

The study, conducted by The National University of Ireland Galway and the University of Maine in the US, collected carbon-14 dating data from ancient seashells excavated from glacial deposits in Scotland to construct a timeline of when the creatures lived in the area following the retreat of the region’s ice sheets. The timeline of the shells’ presence painted a picture of cold winters during the onset of the modern Holocene era, but also the growth of increasingly warm summers as the climate warmed. And instead of the gradual increase in average temperatures that was commonly assumed, Scotland warmed up far more abruptly at the end of the Pleistocene 11,700 years ago, resulting in a correspondingly abrupt melt of the region’s glaciers.

"There’s a lot of geologic evidence of these former glaciers, including deposits of rubble bulldozed up by the ice, but their age has not been well established," explains study lead Dr. Gordon Bromley, with NUI Galway’s School of Geography and Archaeology.

"It has largely been assumed that these glaciers existed during the cold Younger Dryas period [12,900 to 11,700 years ago], since other climate records give the impression that it was a cold time."

"Our new radiocarbon data crucially shows that the glaciers existed before the Younger Dryas and that they were melting rapidly and disappeared during that period," Bromley adds.

"We found that despite the cold winters, summers had to be warm as it is the intensity of the summer melt season that dictates glacier ‘health’. This is controversial and if we are correct, it rewrites our understanding of how abrupt climate change impacts our maritime region, both in the past and potentially into the future."

Indeed, this study’s aim was to further science’s understanding of the impact of climactic conditions in the North Atlantic, and how these changes impacted the climate in Europe, especially in light of how the geologic record illustrates that "Earth is capable of abrupt, high-magnitude changes in both temperature and precipitation that can occur well within a human lifespan."