[SLS Pre-Defense] Brynnydd Hamilton

“Amplified North Atlantic Little Ice Age Cooling Inferred from Inversion of Bottom-Dwelling Foraminiferal Records”

From the 1600s to 1900s, the Earth’s climate experienced one of the most sustained climate perturbations of the past 2000 years, called the Little Ice Age. Despite being one of the most intensively studied intervals of the past two millennia, the magnitude and timing of this cooling are heavily debated. The Little Ice Age is believed to have been strongest over the North Atlantic, but the records preserved by near-surface marine fauna are sparse, noisy, and biased, complicating inference of the climate signal. In this talk, I will discuss our new inverse methodology that enables the inference of surface temperature and δ¹⁸O_seawater from high-resolution δ¹⁸O_calcite records obtained from the shells of bottom-dwelling foraminifera. This methodology accounts for age model uncertainty, the opposing and covarying behavior of temperature and water oxygen isotopes, and, perhaps most importantly, the delayed transit time from surface to depth. We identify a high-latitude North Atlantic Little Ice Age sea surface temperature cooling of 0.38 ± 0.13 K, which reduces uncertainty in comparison to previous estimates from surface-dwelling foraminiferal records and exceeds the cooling exhibited in the Last Millennium Reanalysis. These results improve the detection of long-term climate signals and provide further insights into the spatial pattern of the Little Ice Age.

Sack Lunch Seminar Series —
Informal seminar series within PAOC (Program in Atmospheres, Oceans, and Climate) that focuses on more specialized topics than the PAOC Colloquium. The presentations are either given by an invited speaker or by a member of PAOC and can focus on new research or discussion of a paper of particular interest.

Contact: sacklunch-committee@mit.edu