Two talks on Mon Sept 8th at 12pm:

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1. "Getting real about rock glaciers"

Bob Anderson

Distinguished Professor, CU Boulder, INSTAAR and Geological Sciences

Summary - Colorado’s present alpine landscape, and in particular its icy bits, is dominated by bodies of ice that hide from view beneath a carapace of rock called rock glaciers.  I will report on three studies of Colorado rock glaciers in which we attempt to extract how fast they are moving, and  how they have responded to climate variations over the Holocene. We argue that the alpine cryosphere in Colorado transformed from one dominated by true glaciers in latest Pleistocene to Younger Dryas, to a rock glacier world in the Holocene, and that one can understand the modern length, thickness and speed structure of these features by honoring several pulses of activity through the Holocene.

Bio - I have now been at INSTAAR for 22 years, having taught for 15 years at UC Santa Cruz prior to coming here.  I am a geomorphologist, interested in the processes that govern the evolution of landscapes, and the history of climate written in them. I employ real-time measurements of process, establish timing in the landscape using cosmogenic radionuclides, and develop numerical models that bridge between short and long term.

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2. "The Next Ice Age began 2000 years ago but was terminated in 1960 CE by atmospheric heating from anthropogenic greenhouse gases"

Gifford Miller

Distinguished Professor, CU Boulder, INSTAAR and Geological Sciences

Summary - We’ve known for decades that Ice Age cycles dominated the past 2.5 Ma of Earth History, paced by orbitally driven changes in summer insolation across high Northern Latitudes. And we are currently in the most favorable insolation state for initiation of a new ice age.  Our work around the final remnant of the Laurentide Ice Sheet, largest of the Northern Hemisphere ice sheets, tracks ice recession across Baffin Island from 6000 until at least 3000 yr ago, followed by expansion at least 1000 and almost certainly 2000 years ago, heralding the onset of the Next Ice Age.  But warming summers stopped expansion in 1960 CE, leading to recession along all margins, terminating the Next Ice Age. The remnant Ice Age ice sheet is predicted to completely disappear in ~200 years.

Bio - I stumbled on INSTAAR after fieldwork on the glacial history of Yellowstone Park, and discovered that John Andrews was leading a field program on Baffin Island, Arctic Canada. I asked “take me with you” and he did, resulting in over 50 field seasons on Baffin, as well fieldwork on Iceland, Greenland, Svalbard, Franz Josef Land, and Alaska.  And Australia, but that’s another story.

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INSTAAR Seminar Series

All seminars are hybrid events, in person and via Zoom.

Audience: All are welcome

Location: Online and in SEEC S228. 4001 Discovery Drive, Boulder, CO.