Lamont Weekly Report, May 8, 2020

    For all of us who have been sheltering in place since late March, we should have spent more time outside. The European Union’s Copernicus Climate Change Service reported this week that last month was tied for the warmest April on record. Two weeks earlier, NOAA had announced that there is a 75% chance that 2020 will be the warmest year since 1880, when instrument records began. This past weekend, the daily mean atmospheric carbon dioxide concentration on Mauna Loa exceeded 418 ppm. Neither the coronavirus pandemic nor climate change, however, has markedly altered the pace of overall scientific progress at Lamont.

    Late last week, Marco Tedesco and Tri Datta learned that their paper, “The effect of foehn-induced surface melt on firn evolution over the northeast Antarctic Peninsula,” was ranked on the basis of number of downloads among the top 10 percent of papers published in Geophysical Research Letters during 2018-2019. In their April 2019 paper, Tri, Marco, and their colleagues showed from regional climate models and satellite passive microwave data that since 2015 there had been a substantial increase in surface melting on the glaciers and ice shelves of the region late in each melting season as a result of foehns, warm downslope winds on the lee sides of mountain ranges. The enhanced surface melting produces an increase in the density of near-surface ice and, over time, may affect the stability of the Larson C ice shelf.

    Last week also saw the online publication in Geology of a paper by Suzanne Carbotte, Marc Spiegelman, Michelle Lee, and their collaborators on the deep seismic structure of Axial Seamount, a submarine volcano on the Juan de Fuca Ridge that hosted seafloor volcanic eruptions in 1998, 2011, and 2015. Suzanne and her colleagues applied a recent data processing procedure to multi-channel seismic reflection data collected in the region by the R/V Maurice Ewing in 2002 to reveal that the shallowest and thickest section of the upper-crustal magma reservoir is underlain by a conduit, 3–5 km wide, of vertically stacked melt sills. The sills are separated by 300–450 m in depth and extend downward to an inferred zone of melt-crystal mush in the mid-to-lower crust. The regularly spaced melt lenses are interpreted as signatures of solitary porosity waves of melt migrating upward within the conduit.

    On Monday, Scientific Reports published a paper by Joaquim Goes, Hongzhen Tian, Helga Gomes, O. Roger Anderson, Doug Martinson, and colleagues that proposed an explanation for the recent emergence of the green dinoflagellate Noctiluca scintillans as the dominant wintertime bloom-forming organism in the Arabian Sea. Joaquim and his colleagues argued that a climate-change-induced decline in the extent of snow cover in the Himalayas and Tibetan Plateau has altered wintertime wind patterns and reduced the convective mixing in the Arabian Sea that brings nutrient-rich deeper waters to shallow levels. Along with a sharp loss in marine inorganic nitrate – likely the result of an expansion of the permanent oxygen minimum zone – the conditions have favored Noctiluca over native phytoplankton, including the previously dominant diatoms, the base of the marine food web in the region. A Marie Aronsohn press release on the paper’s findings was posted Monday, and the story was carried by The Science Times and other media.

    The R/V Marcus Langseth completed its transit from the South Pacific this week and docked on Tuesday at Oregon State University’s Mark Hatfield Marine Science Center in Newport, Oregon. The vessel will remain in port until at least early July. Sean Higgins reported this morning, “The ship cleared customs on Tuesday evening, and demobilization on Wednesday and Thursday morning went well. The first contingent of crew and staff are departing today; we rented two minivans and are taking people directly to the Portland airport ourselves. There have been no issues with disembarking or moving people around. Travel protocols are in place for personal protective equipment for everyone traveling. We’re following OSU, Oregon State, and our own safety protocols, as a stay-at-home order is in effect in Oregon, so people still aboard are largely restricted to the vessel. The first contingent of returning crew won’t arrive until May 14; those individuals have been self-quarantining at home for 2 weeks.”

    Also on Tuesday, Earth Institute Faculty held their annual meeting on the Lamont campus, albeit virtually. The bulk of the meeting was devoted to presentations on scientific projects and priorities at the Observatory, organized by Mo Raymo. Terry Plank spoke on “Forecasting volcanic eruptions, saving lives;” Jacky Austermann gave a presentation on “Changing ice, changing coastlines;” Lex van Geen summarized work of the recently formed group designing “Solutions for pollutions;” Christine McCarthy spoke on “Solid Earth and the Rock and Ice Mechanics Lab at Lamont;” and Mo gave a virtual tour of facilities for “Paleoclimate studies at Lamont.”

    Our web site gained a Kevin Krajick story Tuesday on how to take photos while working in the field. Generously illustrated, the essay includes photos taken during fieldwork by Jacky Austermann, Natalie Boelman, Conny Class, Billy D’Andrea, Nicole Davi, Steve Goldstein, Yael Kiro, Chris Lepre, Einat Lev, Javier Martin Fernandez, Paul Olsen, Mo Raymo, Marco Tedesco, and Beizhan Yan.

    On Wednesday, the May issue of Lamont’s monthly newsletter was broadly circulated. Under the banner headline “Scientific Progress during the COVID-19 Pandemic,” the issue includes links to 11 stories on Lamont-led science from last month, a link to the EI Live videos to be aired this month, a story from Lamont’s Education and Outreach team on a geoscience career panel event held on Earth Day 2020, and links to 32 media stories from April about Lamont science or with commentary by Lamont scientists.

    Yesterday, Nature Communications published a paper coauthored by Ben Bostick, Rajib Mozumder, Peter Schlosser, Martin Stute, and Lex van Geen on the role of bounding clay layers in arsenic contamination of aquifers in Bangladesh. In contrast to the prevailing view that an overlying low-permeability clay layer protects an aquifer from the downward intrusion of contaminants, the authors – led by Lamont and Department of Earth and Environmental Sciences alumnus Ivan Mihajlov, now at Geosyntec Consultants – combined results from drilling, groundwater dating, and chemical monitoring to argue that an increase in arsenic contamination at a village well near Dhaka was the result of chemical changes in the source aquifer enabled by release of organic carbon from the clay layer that caps the aquifer. The group concluded further that expulsion of carbon from the clay layer was the result of compaction of the layer driven by high levels of groundwater pumping in the Dhaka region. A press release on the paper’s findings was posted yesterday as well.

    As a weekend respite from global warming records, cold weather and snow are forecast for New York and New England this evening and tomorrow, yet another reason to shelter in place.