I. Climate Change

1.Vetting New Models of Climate Responses to Geoengineering

The Seventh Meeting of the Geoengineering Model Intercomparison Project; Newry, Maine, 26 July 2017

https://eos.org/meeting-reports/vetting-new-models-of-climate-responses-to-geoengineering

2.Should AGU Have Fly-in Meetings Anymore?

Should members of the American Geophysical Union “walk their talk” by cutting carbon emissions related to meeting travel?

https://eos.org/opinions/should-agu-have-fly-in-meetings-anymore

3.Algae Reduce Reflectivity, Enhance Greenland Ice Sheet Melting

New research shows algae growing on the Greenland ice sheet significantly reduce the ice sheet’s surface reflectivity and contribute more to its melting than dust or black carbon.

https://eos.org/scientific-press/algae-reduce-reflectivity-enhance-greenland-ice-sheet-melting

II. Hydrology, Cryosphere & Earth Surface

1.Humans to Blame for Higher Drought Risk in Some Regions

New observations and analysis dispel remaining doubts that anthropogenic climate change is expanding dry areas in northern midlatitudes.

https://eos.org/research-spotlights/humans-to-blame-for-higher-drought-risk-in-some-regions

III. Space & Planets

1.Students Get Help from Weather Radar to Find Space Rock Remains

Teens helped by scientists and educators seek meteorites that plunged into Lake Michigan early this year. Weather radar guided the search for the projectiles.

https://eos.org/articles/students-get-help-from-weather-radar-to-find-space-rock-remains

IV. Biogeosciences

1.Why Mountainous Upland Forests Emit So Much Methane

New research suggests that moist tree heartwood produces methane and emits the greenhouse gas to the atmosphere.

https://eos.org/research-spotlights/why-mountainous-upland-forests-emit-so-much-methane

V. Geology & Geophysics

1.Brian Kennett Receives 2017 Inge Lehmann Medal

Brian Kennett was awarded the 2017 Inge Lehmann Medal at the American Geophysical Union Fall Meeting Honors Ceremony, held on 13 December 2017 in New Orleans, La. The medal is for “outstanding contributions to the understanding of the structure, composition, and dynamics of the Earth’s mantle and core.”

https://eos.org/agu-news/brian-kennett-receives-2017-inge-lehmann-medal

2.Exploring Methane Gas Seepage in the California Borderlands

Early-career scientists aboard the 2016 UNOLS Chief Scientist Training Cruise explored recently reactivated underwater methane seeps in the San Diego Trough.

https://eos.org/project-updates/exploring-methane-gas-seepage-in-the-california-borderlands

3.Roberta Rudnick Receives 2017 Harry H. Hess Medal

Roberta Rudnick was awarded the 2017 Harry H. Hess Medal at the American Geophysical Union Fall Meeting Honors Ceremony, held on 13 December 2017 in New Orleans, La. The medal is for “outstanding achievements in research on the constitution and evolution of the Earth and other planets.”

https://eos.org/agu-news/roberta-rudnick-receives-2017-harry-h-hess-medal

VI. Geophysical Research Letters

1. Genesis, Pathways, and Terminations of Intense Global Water Vapor Transport in Association with Large-Scale Climate Patterns

The CONNected objECT (CONNECT) algorithm is applied to global Integrated Water Vapor Transport data from the NASA's Modern-Era Retrospective Analysis for Research and Applications – Version 2 reanalysis product for the period of 1980 to 2016. The algorithm generates life-cycle records in time and space evolving strong vapor transport events. We show five regions, located in the midlatitudes, where events typically exist (off the coast of the southeast United States, eastern China, eastern South America, off the southern tip of South Africa, and in the southeastern Pacific Ocean). Global statistics show distinct genesis and termination regions and global seasonal peak frequency during Northern Hemisphere late fall/winter and Southern Hemisphere winter. In addition, the event frequency and geographical location are shown to be modulated by the Arctic Oscillation, Pacific North American Pattern, and the quasi-biennial oscillation. Moreover, a positive linear trend in the annual number of objects is reported, increasing by 3.58 objects year-over-year.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL075495/full

2. Sentinel-3A Views Ocean Variability More Accurately at Finer Resolution

This is the first multiplatform evaluation involving data from the new Sentinel-3A altimeter. An experiment was undertaken in the Algerian Basin, employing an ocean glider and a ship mission, along the same track and synchronous with an overpass of the Sentinel-3A mission. This provided three independent views of the ocean velocity field, along a section that encompassed three different oceanographic regimes. The results demonstrate the capacity of Sentinel-3A to retrieve fine-scale oceanographic features (~20 km). The intercomparison with in situ platforms showed a significant improvement, order 30% in resolution and 42% in velocity accuracy using a synthetic aperture radar mode with respect to lower-resolution mode of conventional altimetry. In addition, the three-platform view provided valuable insight into the variability of evolving oceanographic features, in an area of the Mediterranean that remains chronically under sampled.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL076244/full

3. Observation-Based Trends of the Southern Ocean Carbon Sink

The Southern Ocean (SO) carbon sink has strengthened substantially since the year 2000, following a decade of a weakening trend. However, the surface ocean pCO2data underlying this trend reversal are sparse, requiring a substantial amount of extrapolation to map the data. Here we use nine different pCO2 mapping products to investigate the SO trends and their sensitivity to the mapping procedure. We find a robust temporal coherence for the entire SO, with eight of the nine products agreeing on the sign of the decadal trends, that is, a weakening CO2 sink trend in the 1990s (on average 0.22 ± 0.24 pg C yr−1 decade−1), and a strengthening sink trend during the 2000s (−0.35 ± 0.23 pg C yr−1 decade−1). Spatially, the multiproduct mean reveals rather uniform trends, but the confidence is limited, given the small number of statistically significant trends from the individual products, particularly during the data-sparse 1990–1999 period.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL074837/full

4. Attributable Human-Induced Changes in the Likelihood and Magnitude of the Observed Extreme Precipitation during Hurricane Harvey

Record rainfall amounts were recorded during Hurricane Harvey in the Houston, Texas, area, leading to widespread flooding. We analyze observed precipitation from the Global Historical Climatology Network with a covariate-based extreme value statistical analysis, accounting for both the external influence of global warming and the internal influence of El Niño–Southern Oscillation. We find that human-induced climate change likely increased the chances of the observed precipitation accumulations during Hurricane Harvey in the most affected areas of Houston by a factor of at least 3.5. Further, precipitation accumulations in these areas were likely increased by at least 18.8% (best estimate of 37.7%), which is larger than the 6–7% associated with an attributable warming of 1°C in the Gulf of Mexico and Clausius-Clapeyron scaling. In a Granger causality sense, these statements provide lower bounds on the impact of climate change and motivate further attribution studies using dynamical climate models.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL075888/full

5. Enrichment of Extracellular Carbonic Anhydrase in the Sea Surface Microlayer and Its Effect on Air-Sea CO2 Exchange

This paper describes the quantification of extracellular carbonic anhydrase (eCA) concentrations in the sea surface microlayer (SML), the boundary layer between the ocean and the atmosphere of the Indo-West Pacific. We demonstrated that the SML is enriched with eCA by 1.5 ± 0.7 compared to the mixed underlying water. Enrichment remains up to a wind speed of 7 m s−1 (i.e., under typical oceanic conditions). As eCA catalyzes the interconversion of HCO3− and CO2, it has been hypothesized that its enrichment in the SML enhances the air-sea CO2 exchange. We detected concentrations in the range of 0.12 to 0.76 nM, which can enhance the exchange by up to 15% based on the model approach described in the literature.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL075797/full

VII. AGU Blogs

1.Scientists engineer microbes to form ‘memories’ of their environment

Microbes like bacteria aren’t conscious enough to form memories, but a group of scientists in Texas developed a new way for them to do so at the genetic level. Researchers report they’ve successfully engineered microbes to report on their environments and form genetic “memories” of the event. It’s a tool that could help scientists better understand chemical cycling on Earth and how microbes share information like antibiotic resistance with one another, according to the researchers.

https://blogs.agu.org/geospace/2017/12/22/scientists-engineer-microbes-form-memories-environmental-conditions/

2.Promising new wildfire behavior model may aid fire managers in near real-time

Wildfires continue to scar California beyond the normal fire season in what’s been a particularly catastrophic year for natural disasters across the U.S. But a new big-data solution for predicting wildfire spread is also heating up, and it may become a useful tool in the firefighters’ arsenal, according to wildfire researchers attending the 2017 American Geophysical Union Fall Meeting.

https://blogs.agu.org/geospace/2017/12/22/promising-new-wildfire-behavior-model-may-aid-fire-managers-near-real-time/

3.Organic aerosols in remote areas have shorter lives than scientists assumed

Scientists find the lifetime of organic aerosols in the upper atmosphere is on the order of 10 days, far shorter than scientists previously assumed.

https://blogs.agu.org/geospace/2017/12/21/organic-aerosols-remote-areas-shorter-lives-scientists-assumed/

4.Queulat Norte Glacier, Chile Retreat Creates Two Lakes

Nevado Queulat, Chile is the centerpiece of the Queulat National Park in the Aysen Region. The largest glacier draining the substantial ice cap on this mountain flows north draining into Lago Rosselot and then the Rio Palena. Here we examine 1987 to 2016 Landsat imagery to identify changes in this glacier. Paul and Molg (2014) observed a rapid retreat in general of 25% total area lost from glaciers in the Palena district of northern Patagonia from 1985-2011.

https://blogs.agu.org/fromaglaciersperspective/2017/12/21/queulat-norte-glacier-chile-retreat-creates-two-lakes/