The intensification of Northern Hemisphere glaciation 2.7 million years ago marked the growth of northern continental ice sheets. It also spurred the delivery of dust to the North Atlantic Ocean, according to an analysis of marine sediments.
David Naafs of the Alfred Wegner Institute for Polar and Marine Research, Germany, and colleagues measured the accumulation of leaf waxes, a constituent of continental dust, in marine sediments from the middle of the North Atlantic. They found a marked increase in accumulation associated with the onset of glaciation, coincident with a rise in dust delivery across the planet. Numerical simulations give no indication that changes in the atmospheric circulation were responsible for the rise in dustiness. Instead, the team suggests glacier activity, which tends to grind rock and sediments into an easily blown flour, as the cause.
Dust accumulation in marine sediments varies with the obliquity of the Earth's orbit, suggesting that this orbital parameter drove Northern Hemisphere ice-sheet growth at the onset of glaciation.
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Newton, A. Dusty transition. Nature Geosci 5, 91 (2012). https://doi.org/10.1038/ngeo1399
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DOI: https://doi.org/10.1038/ngeo1399
