Bundle up! These secrets are locked within 10,000 years of ice!
By Lola Gayle, Editor-at-large
The Scarisoara Ice Cave, located in the Apuseni Mountains of Romania, is considered to be one of Romania’s most iconic natural wonders. Despite its obvious appeal to tourists, this show cave — with its stunning towering ice formations — offers more than just sheer beauty for scientists. In fact, the icy cavern hidden deep in the heart of Transylvania is actually the oldest cave glacier in the world and among the most important scientific sites in Europe.
Why is that? According to a new study, funded by the National Science Foundation (NSF) and the Romanian Ministry of Education, ice cores drilled from the glacier cave can provide much-need insights into how the North Atlantic region’s winter weather and climate patterns may have fluctuated during the last 10,000 years — known as the Holocene period, the predecessor to the Anthropocene. NOTE: The North Atlantic region includes Europe and the United States.
Scarisoara Cave was formed during the Ice Age when the mountains in which it is nowadays situated were covered with snow and ice. But the cave is anything but dormant. Over the past 10,000 years, snow and rain steadily dripped into the depths of Scarisoara, eventually freezing into thin layers of ice.
It is those thin layers — which hold chemical evidence of past winter temperature changes — that are of particular interest to experts of ancient climate scenarios. Thankfully, all those layers have been preserved due to air currents formed by the cave’s single opening (60 m in diameter and 48 m in depth), which help keep the ice solid.
The problem with modeling ancient climate
According to Candace Major, program director in NSF’s Directorate for Geosciences, most of the region’s paleoclimate records are plant-based and track only the warm part of the year — the growing season. In fact, most reconstructions of the climate record have relied largely on summer conditions, charting fluctuations through vegetation-based samples, such as tree ring width, pollen and organisms that thrive in the warmer growing season.
That leaves a big gap in long-term climate reconstructions — specifically winter climate conditions. By filling in that gap, scientists can gain a better understanding of the complete climate picture. Indeed, according to Major, “the spectacular ice cave at Scarisoara fills a crucial piece of the puzzle of past climate change in recording what happens during winter.”
The ancient cave is estimated to be roughly 10,500 years old, based on radiocarbon dating of leaf and wood fragments preserved in the cave’s ice. Therefore, ice cores should contain winter climatic information for roughly the same time period. Also making the cave an ideal location to study climate and storm shifts is the fact that the cave receives precipitation from both the Atlantic Ocean and the Mediterranean Sea.
Warmer and wetter winters
After traveling down into the cave’s depths and collecting their ice core samples, the researchers were then able to chart the details of winter conditions growing warmer and wetter over time in Eastern and Central Europe. They found that temperatures reached a maximum during the mid-Holocene some 7,000 to 5,000 years ago and decreased afterward toward the Little Ice Age, 150 years ago.
The researchers also found that a major shift in atmospheric dynamics occurred during the mid-Holocene, when winter storm tracks switched and produced wetter and colder conditions in northwestern Europe, and the expansion of a Mediterranean-type climate toward southeastern Europe.
“Our reconstruction provides one of the very few winter climate reconstructions, filling in numerous gaps in our knowledge of past climate variability,” explains University of South Florida scientist Bogdan Onac.
Those warming temperatures then led to rapid environmental changes that allowed Neolithic farmers to expand northward toward mainland Europe, leading to the rapid population of the continent.
“Our data allow us to reconstruct the interplay between Atlantic and Mediterranean sources of moisture,” Onac said. “We can also draw conclusions about past atmospheric circulation patterns, with implications for future climate changes. Our research offers a long-term context to better understand these changes.”
The study, published this week in the journal Scientific Reports, was conducted by researchers from the University of South Florida, University of Belfast, University of Bremen and Stockholm University, Emil Racoviță Institute of Speleology in Cluj-Napoca, Romania, and other institutions.
The scientists are now continuing their cave study in an effort to extend the climate record back 13,000 years or more.
NOTE: The Holocene encompasses the growth and impacts of the human species worldwide, including all its written history, development of major civilizations, and overall significant transition toward urban living in the present. Human impacts on modern-era Earth and its ecosystems may be considered of global significance for future evolution of living species, including approximately synchronous lithospheric evidence, or more recently atmospheric evidence of human impacts. Given these, a new term, Anthropocene, is specifically proposed and used informally only for the very latest part of modern history involving significant human impact.