American Geophysical Union 2019: Key Events from Lamont-Doherty Earth Observatory

December 2, 2019

By Kevin Krajick

Here is a chronological guide for journalists to key talks and other events at the Dec. 9-13 American Geophysical Union meeting in San Francisco, from Lamont-Doherty Earth Observatory. Reporters may contact scientists directly. More info: science news editor Kevin Krajick, 917-361-7766.

Sailing Rocks, Ice and Dinosaurs Paul Olsen
“Sailing stones”—boulders that mysteriously traverse flat landscape, leaving tracks—are known from Death Valley and a handful of other locations. One explanation: winds propel them during freezing episodes that create a slick surface. Paleontologist Olsen looks at a startling new example of such a track, contained in an already well-known 200-million-year-old piece of Connecticut sandstone that contains a dinosaur footprint. Olsen has now also identified the tracks of a small hopping mammal that came along first, and the track of the sailing rock, which the dinosaur apparently stepped in. The sequence, which could have occurred within hours, could provide evidence that certain dinosaurs survived a severe winter snap caused by a volcanic eruption or some other cause. Olsen will participate in a press conference featuring a grab bag of other weird geological discoveries.
Press Conference: Monday Dec. 9, 3:30pm, Press Conference Room
Poster: Tuesday Dec. 10, 1:40-6:00pm, Moscone South Poster Hall EP23C-2277

The 1930s Dust Bowl and the Corn Belt’s Future Mingfang Ting, Michael Puma, Center for Climate Systems Research
Ting projects that warming temperatures will lead to reduced precipitation plus increased evaporation of soil moisture in the U.S. Midwest corn belt—a climatic double whammy. Much of the precipitation that previously reached this region will instead be exported northward to the currently drier Great Plains, he says. In a related study, Puma projects that warmer temperatures will increase the likelihood of events similar to the 1930s Dust Bowl—an event briefly mirrored in the powerful 2012-13 U.S. drought. He projects that crop losses could greatly exceed 2012-13, and that shocks could cascade through the world food system.
Puma: Monday Dec. 9, 1:40pm-6:00pm, Moscone South Poster Hall GC13G-1232
Ting: Tuesday Dec. 10, 5:00-5:15pm, Moscone West 3002-L3 A24J-05

Lamont-Doherty Earth Observatory Reunion Party
Traditionally on Tuesday night at AGU, staff and alumni of Lamont-Doherty Earth Observatory from around the world gather for a reunion. Journalists covering AGU are welcome—a great chance to make contacts, hear the buzz about new work, and have fun.
Tuesday Dec. 10, 6:30-8:30pm, Marriott Union Square, 480 Sutter St.

Extraterrestrial Impact Preserved Deep in Ice? Dallas Abbott
In 535-536 AD, and again several years later, the world underwent a brief but intense cooling and dimming of the sun, along with famines, civil upheavals and unexplained astronomical phenomena. The episodes are commonly attributed to major volcanic eruptions, but Abbott proposes another possibility: an extraterrestrial impact. Within Greenland’s GISP2 ice core, she has detected evidence of marine microfossils that apparently were ejected into the atmosphere and settled on the ice during these years. The discovery adds to earlier evidence she has found of possibly impact-related spherules in the ice from this same time.
Wednesday Dec. 11, 8:00am-12:20pm, Moscone South Poster Hall V31C-0127

Another Reason Not to Eat the Snow: Microplastics Laurel Zaima
Microplastics have become ubiquitous in rivers, oceans and other environments. It turns out they are also in the air, and can be transported to land by snow, as far away as the Arctic. A citizen-scientist project starting in January 2020 will employ volunteers to collect, examine and report snow-deposited microplastics, and send samples for lab analysis. The project will start in New York state, but is expected to expand. It aims at tracking down the sources, and possible ramifications for crops and water supplies. It is an outgrowth of the X-Snow Project, which has recruited volunteers to study how climate may be affecting the distribution of snowfall itself, and the structures of individual snowflakes.
Wednesday Dec. 11, 1:40-6:00pm, Moscone South Poster Hall ED33B-1015
X-Snow website | Columbia Magazine article on the project

Implications of Greenland’s Last Melt Season Marco Tedesco, Shujie Wang
Tedesco explores how exceptional melting in Greenland this summer may have wrought changes in the surface structure of the ice sheet that will set the stage for future accelerated melting. Among other things, he says that this summer’s events have probably altered drainage systems within the ice and left large areas of surface bare of reflective snow cover. Wang describes advances in satellite imagery analysis that are enabling scientists to map the rapid growth of algae over wide areas, and quantify how they are decreasing the reflectivity of the ice.
Tedesco: Wednesday Dec. 11, 1:40-1:55pm, Moscone West 2008, L2 C33A-01
Wang: Wednesday Dec. 11, 5:30-5:45pm, Moscone West 2008, L2 C34A-07
Story, video on Tedesco’s work on the Greenland ice

California’s Weather Whiplash: The Climate Connection
Park Williams, Jonathan Nichols
California has recently veered year to year from very wet to very dry, but it has not been clear whether this is part of a new pattern caused by warming climate. Two new studies suggest that it is. In a tree-ring reconstruction going back to 800 AD, Park Williams shows that cold-season precipitation in the Sierra Nevada has undergone increasingly extreme and frequent swings, with most of both the wettest and driest years occurring since 2000. Separately, Nichols and colleagues have analyzed 130,000 years of pollen in ocean sediments. They find a similar pattern of increasingly extreme seasonal swings taking place in northern California. Nichols: Wednesday Dec. 11, 8:00am-12:20pm, Moscone South Poster Hall PP31D-1658
Williams: Thursday Dec. 12, 10:50-11:05am, Moscone West, 2004, L2 PP42B-03

A New Consensus (and Warning) on Past CO2 Bärbel Hönisch
Reconstructions of past CO2 levels are needed to project the effects of current human emissions, but some previous estimates are now no longer considered sound, because of subsequent discoveries about how to interpret data. For the past three years, Hönisch has spearheaded a global network of paleo-CO2 researchers from some 50 institutions to assemble a comprehensive new consensus on CO2 over the past 65 million years, and their correlations with climate swings. At AGU, they will launch a website that makes the timeline and data easily viewable for public, policymakers and scientists. Bottom line: Some past very warm times appear linked to much smaller increases in CO2 than previously thought.
Thursday, Dec. 12, 11:20-11:35am, Moscone West 2002-L2 PP42A-05
Paleo-CO2 website (Site will go live during AGU)

Connecting the Science of Cryosphere and Coastlines Robin Bell
AGU president Bell will discuss the need for a convergent workforce of physical and social scientists, engineers and policymakers to understand and plan for coastline changes that wasting ice sheets and glaciers are expected to cause. She cites key discoveries made about Antarctica’s Ross Ice Shelf by the interdisciplinary ROSETTA-Ice team as a model first step. Continuing studies of ice dynamics will need to be joined with work on oceans, changing land levels and coastal dynamics to plan for future land use and infrastructure, she says.
Thursday Dec. 12, 4:00-4:15, Moscone South 201-202, L2 C44A-01

Coupled Megadrought Risk in North and South America Nathan Steiger
Paleoclimate researchers have extensively documented prehistoric North American droughts dwarfing anything seen in modern times, but much less is known about past droughts in South America, and whether they might be connected to the north. Analyzing existing data from tree rings, lake sediments and other sources, Steiger has discovered that droughts indeed have hit both continents at roughly the same time. The El Niño-Southern Oscillation appears to be the dominant influence in most cases. The finding suggests a significant risk of simultaneous crop failures in both regions.
Friday Dec. 13, 9:30-9:45am, Moscone West 201-L2 GC51A-07

First Discovery of an Ice-Shelf Estuary Alexandra Boghosian
Boghosian presents satellite imagery revealing the existence of a seasonal estuary penetrating Greenland’s Petermann Ice Shelf—probably the first time such a feature has been identified anywhere. The shelf is penetrated by a meltwater river that appears to start at the shelf’s grounding line, some 50 kilometers from the terminus; and it appears that ocean tides are sloshing in and out at the mouth, up a kilometer in. Boghosian suspects that the feature could destabilize the ice in a number of ways; and, if such features appear in other ice shelves, they could also be destabilized. She and colleagues hope to visit in person in the near future.
Friday Dec. 13, 10:50-11:05am, Moscone West 2008-L2 C52B-03

Tsunami Potential Off North Carolina Will Fortin
Off North Carolina, geologists have long eyed the remains of past giant submarine landslides off the steep continental slope. Many believe that if repeated now, such events could cause tsunamis. The slides are thought to be triggered in part by the buildup of gases within sediments. Fortin has analyzed pore-pressure data collected on a recent research cruise, and will offer the latest estimate of slide danger around the Cape Fear and Currituck slides, which together cover about 175 square kilometers. Big movements there are thought to have occurred repeatedly over the last 30,000 to 50,000 years.
Friday Dec. 13, 8am-12:20pm, Moscone South Poster Hall OS51C-1506

AGU Cinema
Two short Lamont films will be screened as part of the yearly AGU Cinema. Or, see them online any time:
How High Could Oceans Rise? (filmed in Barbados)
The Greenland Ice Sheet: A Waking Giant
AGU Cinema: 2001 Moscone West. Mon/Wed/Thurs 8-10am; Tues 8-9am; Fri 8am-12pm


Lamont-Doherty Earth Observatory seeks fundamental knowledge about the origin, evolution and future of the natural world. Its scientists study the planet from its deepest interior to the outer reaches of its atmosphere, on every continent and in every ocean.

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Kevin Krajick
(212) 854-9729