Warnock Publishes With Colleagues on Atmospheric Variability over Last 1.5 Million Years

Posted on 4/26/22 11:30 AM

Jonathan Warnock and colleagues published a record of the relationship between ice age cycles, nutrient input to the oceans, and atmospheric carbon dioxide in their new paper, "Antiphased dust deposition and productivity in the Antarctic Zone over 1.5 million years," in Nature Communications. The record, spanning 1.5 million years, is the longest detailed record of such changes, effectively doubling the available record.

The paper finds that during cold glacial periods, iron in dust delivered to the ocean is 10 times higher than during a warm interglacial stage. This iron fertilizes the Southern Ocean, causing it to draw down carbon dioxide. During warm interglacial periods, a reduction in sea ice allowed for increased nutrients in surface water, also fueling biological productivity and pulling down carbon dioxide (CO2) from the atmosphere. This change in the relationship between nutrients, the Southern Ocean, and carbon is responsible for the variability in CO2 in the atmosphere between glacial and interglacial periods, with the Southern Ocean acting to remove CO2 from the atmosphere in warm and cold stages. The results provide a significant warning for increased global CO2 levels in light of recent reductions in Southern Ocean biological activity.

Weber, M.E., Bailey, I., Hemming, S.R. et al. Antiphased dust deposition and productivity in the Antarctic Zone over 1.5 million years. Nat Commun 13, 2044 (2022).