ISR Seminar Series

The ISR Seminar Series typically takes place on Thursdays at 10:30 a.m., in the ISR Conference Room, 202 Kenny Cottle Hall, 885 Centre St., Newton Campus of Boston College (click here for directions). Please join us for light refreshments at 10:15 a.m. To be added to the email announcements for the current series, contact Kathleen Kraemer.

November 14, 2019

SPECIAL TIME: 1 PM

Jeremy D. Shakun, Boston College Dept. of  Earth & Environmental Sciences

Arctic Permafrost Stability over the Past 1.5 Million Years Inferred from Cave Deposits

Arctic permafrost sequesters a substantial stock of perennially frozen organic carbon that could be released to the atmosphere as methane and carbon dioxide upon thawing. This thaw vulnerability of permafrost carbon represents a potentially powerful amplifier of climate change, but little is known about permafrost sensitivity and associated carbon cycling during past intervals of persistent climate warming. I will present a reconstruction of Canadian permafrost history during Pleistocene interglacials from 131 uranium-thorium ages on 74 speleothems, cave deposits that only accumulate during intervals of deep ground thaw. We infer that interglacial permafrost thaw was widespread ~0.5-1.5 million years ago, but deep permafrost persisted in much of Arctic and sub-Arctic North America through warm interglacials of the last ~500,000 years, with deep thaw likely limited to sub-Arctic discontinuous permafrost during the Marine Isotope Stage 11 “super-interglacial”. On Pleistocene timescales, interglacial CO2 concentrations remained within a narrow ~280 ± 20 ppm range and were insensitive to differences in the magnitude of interglacial permafrost thaw inferred here. This implies the existence of processes that attenuated the permafrost-carbon feedback during Pleistocene interglacials, including those when the magnitude of inferred permafrost thaw exceeded numerical model projections for extensive ground thaw over the next several centuries.

 

 

Fall 2019

PDF Schedule

September 26, 2019
Gregory Sloan, Space Telescope Science Institute
Organic Dust in the Interstellar Medium

October 10, 2019 (slides available here)
Vladym Paznukhov, Boston College Institute for Scientific Research
TID Climatologies in Antarctica and Europe Derived from HF and GNSS Observations

October 17, 2019
Majd Mayyasi, Boston University Center for Space Physics
Unraveling Present-day Mysteries of Mars using its Ionosphere

October 24, 2019
Sofia-Paraskevi Moschou, Harvard Smithsonian Center for Astrophysics
Stellar CMEs: What can We Learn from Historic Observations?

November 14, 2019 - 1 pm (NOTE SPECIAL TIME)
Jeremy Shakun, Boston College Dept. of  Earth & Environmental Sciences
Arctic Permafrost Stability over the Past 1.5 Million Years Inferred from Cave Deposits

November 21, 2019
Shu Lai, Boston College Institute for Scientific Research

December 5, 2019
BC/ISR Members
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