Evidence for a Northern Hemispheric trigger of the 100,000-y glacial cyclicity

What is it about?

Nearly a million years ago, the cyclicity of ice ages underwent fundamental changes from ~41,000 to 100,000 years, and ice ages became more intense. As the astronomical cycles didn't change, the transition must be explained by internal climatic mechanisms. For this reason the causes of the shift have been a matter of intense scientific debate involving geochemists, climate modelers, paleoceanographers, glaciologists, and others, all questioning where (for example, the northern vs southern hemisphere) and when and how was the cyclicity shift initiated. Our work documents the importance of the northern hemisphere as the trigger for this shift, and shows that the tipping point was associated with the continental ice sheet reaching an important stability threshold that led to a near collapse of the global ocean circulation and the onset of the 100 kyr cyclicity.

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Photo by Jennifer Latuperisa-Andresen on Unsplash

Photo by Jennifer Latuperisa-Andresen on Unsplash

Why is it important?

Nearly a million years ago, the cyclicity of ice ages underwent fundamental changes from ~41,000 to 100,000 years, and ice ages became more intense. As the astronomical cycles didn't change, the transition must be explained by internal climatic mechanisms. For this reason the causes of the shift have been a matter of intense scientific debate involving geochemists, climate modelers, paleoceanographers, glaciologists, and others, all questioning where (for example, the northern vs southern hemisphere) and when and how was the cyclicity shift initiated. Our work documents the importance of the northern hemisphere as the trigger for this shift, and shows that the tipping point was associated with the continental ice sheet reaching an important stability threshold that led to a near collapse of the global ocean circulation and the onset of the 100 kyr cyclicity.