1. A Sea Change in Paleoceanography
The Editor-in-Chief of Paleoceanography explains that the journal is changing its name to Paleoceanography and Paleoclimatology to reflect the evolution of science in this field.
2. Why Is There So Much Carbon Dioxide in Rivers?
Observations of carbon dioxide oversaturation in the freshwater of the world led scientists to study its underlying causes at more than 100 field locations across the nation.
II. Geochemistry, Mineralogy, Volcanology
1. Better Tools for Tracing the Thermal History of Rocks
Thermo2016: The 15th International Conference on Thermochronology; Maresias, Brazil, 18–23 September 2016
III. Hazards & Disasters
1. Plastic Waste Knows No Bounds
Despite the vastness of Earth’s oceans, human plastic pollution overwhelms even remote corners.
2. Tornado Casualties Depend More on Storm Energy Than Population
National Weather Service data from nearly 900 tornadoes and a principle of economics reveal the relationship between storm energy, population, and casualty count.
IV. Hydrology, Cryosphere & Earth Surface
1. Rural Areas Becoming Less Water Efficient over Time
The first systematic evaluation of water use across the continental U.S. identifies areas that need the most help and highlights the types of action be best suited to help those areas.
V. Ocean Sciences
1. Deep Trouble! Common Problems for Ocean Observatories
Ocean Observing Infrastructure and Sensing – Technical Lessons Learned and Best Practices; Moss Landing, California, 23–25 September 2016
2. First Detailed Study of Circulation off Angola
New data give scientists insight into the eastern boundary current off Angola, helping them to evaluate and assess why simulations create sea surface temperature biases in the region.
VI. Space & Planets
1. Scientists, Policy Makers Push for Mars Exploration
At a recent forum, Sen. Ted Cruz also announced a Senate hearing to revisit the half-century-old Outer Space Treaty, and he warned about potential military threats to the nation’s satellites.
2. Starlike Brown Dwarf? Not Anymore
Because of a new, surprisingly smaller mass estimate for a much-studied, nearby brown dwarf, astronomers now regard the familiar object as merely planetlike.
VII. Geophysical Research Letters
1. The 2016 North Atlantic hurricane season: A season of extremes
The 2016 North Atlantic hurricane season had an early start with a rare and powerful storm for January impacting the Azores at hurricane force. Likewise, the end of season heralded Otto which was record breaking in location and intensity being a high-end Category 2 storm at landfall over southern central America in late November. We show that high precipitable water, positive relative vorticity, and low sea level pressure allowed for conducive conditions. During the season, few storms occurred in the main development region. While some environmental conditions were conducive for formation there (such as precipitable water, relative vorticity, and shear), the midlevel relative humidity was too low there for most of the season, presenting very dry conditions in that level of the atmosphere. We further find that the October peak in the accumulated cyclone energy was related to environmentally conducive conditions with positive relative humidity, precipitable water, relative humidity, and low values of sea level pressure. Overall 2016 was notable for a series of extremes, some rarely, and a few never before observed in the Atlantic basin, a potential harbinger of seasons to come in the face of ongoing global climate change.
2. Terrestrial glint seen from deep space: Oriented ice crystals detected from the Lagrangian point
The Deep Space Climate Observatory (DSCOVR) spacecraft resides at the first Lagrangian point about one million miles from Earth. A polychromatic imaging camera onboard delivers nearly hourly observations of the entire sunlit face of the Earth. Many images contain unexpected bright flashes of light over both ocean and land. We construct a yearlong time series of flash latitudes, scattering angles, and oxygen absorption to demonstrate conclusively that the flashes over land are specular reflections off tiny ice platelets floating in the air nearly horizontally. Such deep space detection of tropospheric ice can be used to constrain the likelihood of oriented crystals and their contribution to Earth albedo. These glint observations also support proposals for detecting starlight glints off faint companions in our search for habitable exoplanets.
3. Impact of oceanic warming on electromagnetic oceanic tidal signals: A CMIP5 climate model-based sensitivity study
In contrast to ocean circulation signals, ocean tides are already well detectable by electromagnetic measurements. Oceanic electric conductivities from the Coupled Model Intercomparison Project Phase 5 (CMIP5) climate simulations are combined with tidal currents of M2 and O1 to estimate electromagnetic tidal signals and their sensitivity to global warming. Ninety-four years of global warming leads to differences of ±0.3 nT in tidal magnetic amplitudes and ±0.1 mV/km in the tidal electric amplitudes at sea level. Locally, the climate-induced changes can be much higher, e.g., +1 nT in the North Atlantic. In general, all studied electromagnetic tidal amplitudes show large-scale climate-induced anomalies that are strongest in the Northern Hemisphere and amount to 30% of their actual values. Consequently, changes in oceanic electromagnetic tidal amplitudes should be detectable in electromagnetic records. Electric and magnetic signals, as well as tides of different frequencies, contain complementary regional information.
4. Skillful regional prediction of Arctic sea ice on seasonal timescales
Recent Arctic sea ice seasonal prediction efforts and forecast skill assessments have primarily focused on pan-Arctic sea ice extent (SIE). In this work, we move toward stakeholder-relevant spatial scales, investigating the regional forecast skill of Arctic sea ice in a Geophysical Fluid Dynamics Laboratory (GFDL) seasonal prediction system. Using a suite of retrospective initialized forecasts spanning 1981–2015 made with a coupled atmosphere-ocean-sea ice-land model, we show that predictions of detrended regional SIE are skillful at lead times up to 11 months. Regional prediction skill is highly region and target month dependent and generically exceeds the skill of an anomaly persistence forecast. We show for the first time that initializing the ocean subsurface in a seasonal prediction system can yield significant regional skill for winter SIE. Similarly, as suggested by previous work, we find that sea ice thickness initial conditions provide a crucial source of skill for regional summer SIE.
5. Multidecadal variability and climate shift in the North Atlantic Ocean
Decadal variability of ocean heat content (OHC) and temperature trends over ~60 years in the North Atlantic Ocean were analyzed using a new high-resolution ocean climatology based on quality-controlled historic in situ observations. Тwo ~30 year ocean climates of 1955–1984 and 1985–2012 were compared to evaluate the climate shift in this region. The spatial distribution of the OHC climate shift is highly inhomogeneous, with the climate shift being the strongest southeast of the Gulf Stream Extension. This may be caused by the Atlantic Meridional Overturning Circulation slowdown in conjunction with heaving of warm subtropical water. The 30 year climate shift shows higher OHC gain in the Gulf Stream region than reported in shorter timescale estimates. The OHC change is generally coherent with the Atlantic Multidecadal Oscillation index. This coherence suggests that quasi-cyclicity of the OHC may exist, with a period of 60 to 80 years, superimposed on the slow basin-wide warming trend.
6. Projected changes of the low-latitude north-western Pacific wind-driven circulation under global warming
Based on the outputs of 25 models participating in the Coupled Model Intercomparison Project Phase 5, the projected changes of the wind-driven circulation in the low-latitude north-western Pacific are evaluated. Results demonstrate that there will be a decrease in the mean transport of the North Equatorial Current (NEC), Mindanao Current, and Kuroshio Current in the east of the Philippines, accompanied by a northward shift of the NEC bifurcation Latitude (NBL) off the Philippine coast with over 30% increase in its seasonal south-north migration amplitude. Numerical simulations using a 1.5-layer nonlinear reduced-gravity ocean model show that the projected changes of the upper ocean circulation are predominantly determined by the robust weakening of the north-easterly trade winds and the associated wind stress curl under the El Niño-like warming pattern. The changes in the wind forcing and intensified upper ocean stratification are found equally important in amplifying the seasonal migration of the NBL.
VIII. AGU Blogs
1. Early Tanpopo mission results show microbes can survive in space
Clumps of microbes can survive in space for at least a year – and perhaps longer, according to Japanese researchers conducting an experiment on board the International Space Station (ISS).
2. New technique provides earthquake risk for major cities worldwide
Scientists have developed snapshots of the likelihood of major earthquakes occurring in megacities around the world using a new statistical approach for estimating earthquake risk. The new technique, called seismic nowcasting, estimates the progress of a defined seismically-active geographic region through its repetitive cycle of major earthquakes.
3. High levels of radioactive material migrating down into soil around Fukushima
High levels of radioactive cesium remain in the soil near the Fukushima Daiichi nuclear power plant and these radionuclides have migrated at least 5 centimeters down into the ground at several areas since the nuclear accident five years ago, according to preliminary results of a massive sampling project being presented at the JpGU-AGU joint meeting in Chiba, Japan.
4. Planting trees cannot replace cutting carbon dioxide emissions, study shows
Growing plants and then storing the carbon dioxide they have taken up from the atmosphere is not a viable option to counteract unmitigated emissions from fossil fuel burning, a new study shows. Plantations would need to be so large they would eliminate most natural ecosystems or reduce food production if implemented as a late-regret option in the case of substantial failure to reduce emissions, according to the study.
5. Researchers track groundwater loss during drought in California’s Central Valley
A new study from researchers at UCLA and the University of Houston reveals estimates of significant groundwater loss in California’s Central Valley during the recent drought and sparks questions of sustainability for the important agricultural area.
IX. AGU News
1. JPGU-AGU JOINT MEETING RESEARCH PRESENTATION HIGHLIGHTS
CHIBA, JAPAN — Discover the latest in Earth and space science research at the JpGU-AGU Joint Meeting 2017 taking place May 20-25 at the Makuhari Messe International Conference Hall in Chiba, Japan. The meeting will bring together researchers from theAmerican Geophysical Union and the Japan Geoscience Union.