Tiny fossils, big climate change: how ocean life responded to the onset of Antarctic ice sheets ~34 million years ago
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Double blast from the past: Did large asteroid impacts in the late Eocene affect Earth's climate?

Claudia Agnini

Tiny fossils, big climate change: how ocean life responded to the onset of Antarctic ice sheets ~34 million years ago

About 34 million years ago, Earth’s climate changed dramatically. The planet shifted from a warm, ice-free world to a colder climate, when large ice sheets began to form on Antarctica. For a long time, scientists believed that microscopic marine algae called calcareous nannoplankton were only weakly affected by this major climate transition. This presentation tells a different story. By examining tiny fossil remains preserved in ocean sediments from the Indian, Pacific, and Atlantic oceans, we identified a clear and simultaneous global change. Around the time Antarctic ice sheets began to form, these microorganisms became both larger and more abundant. This signal is observed worldwide and can be recognized even where fossil preservation is poor. We suggest that this global response was linked to changes in ocean chemistry and food availability, particularly higher carbonate saturation and increased marine productivity.