Newswise — According to a study conducted by climate researchers, geoscientists, and environmental physicists, the intensity of summer insolation during past ice ages had a significant impact on the occurrence of warm and cold periods. The research, which involved scientists from Germany, Austria, and Switzerland, was led by researchers from Heidelberg University and the GFZ German Research Centre for Geosciences Potsdam.
By analyzing stalagmites in the European Alps, the researchers were able to demonstrate that warm phases predominantly occurred when the summer insolation reached its highest levels in the Northern Hemisphere. This finding suggests that the variations in summer sunlight played a crucial role in triggering abrupt climate changes during those historical periods.
During past ice ages in the Northern Hemisphere, there were notable and rapid shifts between cold and warm phases, each lasting for thousands of years. The exact reasons behind these fluctuations remain unresolved, but research indicates that the size of continental ice sheets may have played a significant role. Greenland ice records reveal 25 such warm-cold cycles that occurred between 115,400 and 14,700 years ago.
In a pioneering study, scientists conducted investigations on stalagmites within the Melchsee-Frutt cave system in the Swiss Alps. This research provided, for the first time and with remarkable precision, insights into 16 fluctuations that occurred during the penultimate glacial period, approximately 185,000 to 130,000 years ago. The findings from this study shed light on the climatic variability during that ancient time period.
In climate research, stalagmites found in caves play a crucial role as valuable archives that provide insights into temperature variations, precipitation patterns, and changes in vegetation cover. Professor Dr. Norbert Frank from the Institute of Environmental Physics at Heidelberg University explains that by accurately determining their age and analyzing oxygen isotope values, researchers can study the chronological sequence of abrupt climate fluctuations during ice ages.
The study, led by Dr. Jens Fohlmeister, who completed his doctorate in environmental physics at Heidelberg University and was affiliated with the GFZ German Research Centre for Geosciences Potsdam and the Potsdam Institute for Climate Impact Research, focuses on investigating whether the abrupt climate changes were influenced not only by changes in ice volumes in the Northern Hemisphere but also by orbitally driven alterations in the global distribution of insolation. By combining these insights, the researchers aim to gain a deeper understanding of the factors that contributed to past climatic variations.
By examining stalagmites from the Melchsee-Frutt cave system, the researchers conducted a detailed analysis of the warm-cold cycles during the penultimate ice age. They determined the age and oxygen isotope composition of the stalagmites to gain insights into past climate variations.
The newly acquired data revealed a significant finding: warm phases predominantly occurred during the peak phase of summer insolation in the Northern Hemisphere, even when the sea level, influenced by the volume of continental ice sheets, remained near its minimum during peak glacial periods. Dr. Fohlmeister emphasized the importance of this discovery in understanding how warm periods were triggered during these historical ice age transitions.
To validate their findings, the researchers conducted model simulations, which confirmed the results obtained from the cave system data. These simulations accurately predicted both the frequency and duration of warm phases based on the corresponding sea levels and existing insolation patterns. This convergence between the research data and simulations strengthens the understanding of the interplay between orbital variations, climate changes, and sea levels during the penultimate ice age
The study involved collaboration among scientists from various esteemed institutions, including the Potsdam Institute for Climate Impact Research, the GFZ German Research Centre for Geosciences Potsdam, Heidelberg University, the University of Innsbruck (Austria), the Swiss Institute for Speleology and Karst Studies, and the Karst and Caves Natural Heritage Foundation Obwalden (Switzerland). The research project received funding support from the German Research Foundation.
The noteworthy findings resulting from this study were published in the scientific journal "Communications Earth & Environment," further contributing to the collective knowledge in the field of climate research and its implications for understanding past climate fluctuations.
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