Volume 10 Issue 7, July 2017
For people and planet
The emerging field of geohealth links human well-being and ecosystem health. A deeper understanding of these linkages can help society mitigate the health costs of economic growth before they become crises.
Climate change narratives
Reconstructions of Earth's past are much more than benchmarks for climate models. They also help us comprehend risk by providing concrete narratives for diverse climates.
News & Views
Cleaner Chinese lakes
Phosphorus loading can cause eutrophication of lakes. Analyses of lake chemistry in China reveal that policies have led to lower phosphorus levels overall, but increasing trends in some lakes suggest that expanded policies may be needed.
The Atlantic's internal drum beat
The North Atlantic region experiences climate variability on a range of timescales. A climate reconstruction suggests that large-magnitude, multidecadal internal variability was a robust feature over the past 1,200 years.
The deep atmosphere of Venus and the possible role of density-driven separation of CO2 and N2
The only temperature profile of the lowermost Venusian atmosphere appears unstable. Compositional heterogeneity due to density-driven separation of N2 from CO2 gas in the lower atmosphere of Venus may be a viable explanation.
Causes of differences in model and satellite tropospheric warming rates
Over the early twenty-first century, model-derived warming trends exceeded observed warming. Analyses of global-mean tropospheric temperature suggest that these differences are likely to stem from missing external influences in the models.
Top-of-atmosphere radiative forcing affected by brown carbon in the upper troposphere
Brown carbon absorbs light, but its climate impacts in the upper troposphere are not well known. A series of aircraft observations in the US reveals that convection lofts brown carbon to high altitudes, causing greater warming than at lower altitudes.
Transition from high- to low-NOx control of night-time oxidation in the southeastern US
The influence of NOx levels at night on atmospheric oxidation is unclear. Analyses of aircraft observations suggest that night-time oxidation is transitioning from a high- to low-NOx regime in the southeast US due to declines in NOx levels.
Hotspots of soil N2O emission enhanced through water absorption by plant residue
Production of the greenhouse gas nitrous oxide occurs episodically in small soil volumes. Soil microcosm experiments reveal that water absorption by plant residue raises moisture levels and accelerates nitrous oxide production by microbial denitrification.
Substantial inorganic carbon sink in closed drainage basins globally
Dissolved inorganic carbon is buried in dryland basins that do not drain to the sea. Based on measurements of sediment chemistry in twelve of these sites, closed basins are estimated to store 0.15 Pg of dissolved inorganic carbon annually.
Decline in Chinese lake phosphorus concentration accompanied by shift in sources since 2006
Many lakes in China are subject to eutrophication. Water quality analyses on 862 Chinese lakes reveal that better sanitation has reduced phosphorus inputs in the most populated areas, but aquaculture and livestock offset improvements elsewhere.
Internal and external forcing of multidecadal Atlantic climate variability over the past 1,200 years
The North Atlantic region experiences climate variability on multidecadal timescales. An analysis of a tree-ring network shows this variability can be attributed to both internal and external forcing over the past 1,200 years.
Abrupt North Atlantic circulation changes in response to gradual CO2 forcing in a glacial climate state
During glacial climates, the strength of the Atlantic overturning circulation has changed abruptly. Climate model simulations show that gradual changes in atmospheric CO2 levels can trigger such events via atmospheric moisture transport.
Cumulate causes for the low contents of sulfide-loving elements in the continental crust
Earth’s continents are depleted in some economically important elements. Geochemical analysis reveals that some sulfide-loving elements are preferentially delaminated and recycled back into the mantle during subduction.
The roles of pyroxenite and peridotite in the mantle sources of oceanic basalts
Whether subducted oceanic crust is recycled via the mantle back into newly forming seafloor at mid-ocean ridges is unclear. Laboratory partitioning experiments now reveal that recycled material is not required to create oceanic lithosphere.