30 years of the iron hypothesis of ice ages
Stoll, Heather
<br>Thirty years ago this month, John Martin proposed a solution to one of the biggest mysteries of Earth's climate system: how was nearly one-third of the carbon dioxide in the atmosphere (about 200 gigatonnes of carbon) drawn into the ocean as the planet entered the most recent ice age, then stored for tens of thousands of years, and released again as the ice sheets melted? These large natural cycles in atmospheric CO2 levels (Fig. 1a) were revealed in 1987 by an analysis of ancient air bubbles trapped in the first long ice cores taken from the Antarctic ice sheet. Martin recognized that iron was a key ingredient that could have transformed the surface ocean during glacial times. His landmark iron hypothesis, published in Paleoceanography, described a feedback mechanism linking climatic changes to iron supply, ocean fertility and carbon storage in the deep ocean.<br></p>
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