Rickaby Study Finds 10-40 Meter Sea-Level Band Drove 60 Million Years of Climate Regulation
Updated
Updated · SciTechDaily · Jul 25
Rickaby Study Finds 10-40 Meter Sea-Level Band Drove 60 Million Years of Climate Regulation
2 articles · Updated · SciTechDaily · Jul 25
Summary
A 10-to-40-meter sea-level window above today’s level produced the strongest organic carbon burial, giving Earth a long-running feedback that helped regulate temperature over the past 60 million years.
The mechanism ran through phosphate: high seas trapped the nutrient on flooded continental shelves, while lower seas released more phosphate to the open ocean, boosting marine growth, oxygen-poor waters and carbon burial that lowered atmospheric CO2.
Geological records and an iodine-to-calcium oxygen proxy were used to test the pattern across 60 million years, linking sea level, ocean oxygen and sediment carbon storage.
The Eocene, about 56 million to 34 million years ago, shows the feedback weakening when very high seas trapped phosphate on shelves, leaving less carbon buried and more CO2 in the atmosphere.
The study, published in PNAS, suggests this carbon-burial “sweet spot” narrowed over time as oxygen-minimum zones shifted deeper, making Earth’s climate system more resilient.