2023-05-16 17:07:09
MADRID, 16 May. (EUROPA PRESS) –
700,000 years ago, a “warm ice age” changed Earth’s weather cycles, an exceptionally warm and wet period, in which the polar glaciers expanded enormously.
A European research team including Earth scientists from the University of Heidelberg used recently acquired geological data in combination with computer simulations to identify this seemingly paradoxical connection.
According to the researchers, this profound change in Earth’s climate was responsible for the change in climate cycles, representing a critical step in the subsequent climate evolution of our planet. Their study is published in the journal Nature Communications.
Geologic ice ages, called glacial periods, are characterized by the development of large ice sheets in the northern hemisphere. In the past 700,000 years, the phases have switched between distinct warm and glacial periods every 100,000 years. Before then, however, Earth’s climate was governed by 40,000-year cycles with shorter and weaker glacial periods. The change in climate cycles occurred in the Middle Pleistocene Transition period, which began about 1.2 million years ago and ended about 670,000 years ago.
“The mechanisms responsible for this critical change in the global climatic rhythm remain largely unknown. They cannot be attributed to variations in the orbital parameters that govern the Earth’s climate,” he explains. it’s a statement Associate Professor Dr. André Bahr from the Institute of Earth Sciences at the University of Heidelberg. “But the recently identified ‘warm ice age’, which caused excess continental ice to build up, played a pivotal role.”
For their investigations, the researchers used new climate records from a drill core off the coast of Portugal and loess records from the Chinese Plateau. The data was then fed into computer simulations. The models show a long-term warming and wetting trend in both subtropics over the past 800,000 to 670,000 years.
Contemporaneously with this last ice age in the mid-Pleistocene transition period, sea surface temperatures in the North Atlantic and tropical North Pacific were warmer than in the previous interglacial, the phase between the two ice ages. This led to increased moisture and precipitation production in southwestern Europe, expansion of Mediterranean forests, and an increase in the summer monsoon in eastern Asia. The moisture also reached the polar regions where it contributed to the expansion of the northern Eurasian ice sheets.
“They persisted for some time and heralded the long-range, sustained glaciation phase of the ice age that lasted until the late Pleistocene. Such expansion of continental glaciers was necessary to trigger the shift from the 40,000-year to 100,000-year cycles. “that we experience today, which was critical to Earth’s subsequent climate evolution“, says André Bahr.
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