Benthic δ18O records Earth’s energy imbalance
In: Nature Geoscience. Nature Publishing Group: London. ISSN 1752-0894; e-ISSN 1752-0908, more
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| Authors | | Top |
- Shackleton, S.
- Seltzer, A.
- Baggenstos, D.
- Lisiecki, L.E.
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| Abstract |
Oxygen isotope ratios (δ18O) of foraminifera in marine sediment records have fundamentally shaped our understanding of the ice ages and global climate change. Interpretation of these records has, however, been challenging because they reflect contributions from both ocean temperature and ice volume. Here, instead of disentangling, we reconstruct global benthic foraminiferal δ18O across the last deglaciation (18–11.5 ka) with ice volume constraints from fossil corals and ocean temperature constraints from ice core noble gases. We demonstrate that, while ocean temperature and ice volume histories are distinct, their summed contributions to δ18O agree remarkably well with benthic δ18O records. Given the agreement between predicted and observed δ18O, we further build upon recent insight into global energy fluxes and introduce a framework to quantitively reconstruct top-of-atmosphere net radiative imbalance, or Earth’s energy imbalance, from δ18O. Finally, we reconstruct 150,000 years of energy imbalance, which broadly follows Northern Hemisphere summer insolation but shows millennial-scale energy gain during the cold intervals surrounding Heinrich events. This suggests that, in addition to external forcing, internal variability plays an important role in modifying the global energy budget on long (millennial-plus) timescales. |
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