Volume 10 Issue 2, February 2017

Groundwater resources are directly affected by climate variability via precipitation, evapotranspiration and recharge. Analyses of US and India trends reveal that climate-induced pumping indirectly influences groundwater depletion as well.

The twin isotopic signatures of the Moon and Earth are difficult to explain by a single giant impact. Impact simulations suggest that making the Moon by a combination of multiple, smaller moonlet-forming impacts may work better.

The dynamics of polar marine ecosystems are poorly understood. A laser-based space-borne sensor captures annual cycles of phytoplankton biomass in seasonally ice-free polar waters, and provides clues on how growth drives these cycles.

Atmospheric oxygen was maintained at low levels throughout huge swathes of Earth's early history. Estimates of phosphorus availability through time suggest that scavenging from anoxic, iron-rich oceans stabilized this low-oxygen world.

The climatic response to the eruption of the Samalas Volcano in 1257 has been elusive. Medieval archives tell of a spatially variable reaction, with Europe and Japan experiencing severe cold compared to relative warmth in North America.

The net carbon flux on land comprises emissions from land-use change and uptake by vegetation. An evaluation of vegetation models suggests that emissions from land-use change, and thus the terrestrial sink, may be substantially underestimated.

The upper atmosphere of Venus rotates much faster than the planet itself. An anomalous stationary structure observed by the Akatsuki mission at the cloud tops of Venus could be an atmospheric gravity wave induced by mountain topography below.

A giant impact has been proposed as being responsible for forming the Moon, but scenarios that match existing constraints are improbable. Numerical modelling now suggests that instead a series of smaller and more common impacts can explain the Earth–Moon system.

Glaciers have been retreating almost globally over the past century. An analysis using signal-to-noise ratio as a metric of individual glacier change reveals that glacier retreat constitutes categorical evidence for regional climate change.

Soils have the capacity to store water at the land–atmosphere interface. Analysis of global satellite data suggests that significant precipitation can be retained by soils, leading to even less groundwater storage in water-starved regions.

Drought affects deep groundwater through changes in natural recharge with a multi-year time lag. Rapid changes in US groundwater storage in response to climate variability reflect the human response to drought through groundwater pumping.

Groundwater storage has declined in northern India and increased in southern India over the past decade. Trend analysis shows that much of this variability can be explained by changes in irrigation in response to monsoon precipitation.

Phytoplankton productivity is high in the polar oceans. Lidar observations from 2006–2015 reveal that phytoplankton biomass was characterized by annual cycles influenced by sea-ice extent in the Antarctic and ecological processes in the Arctic.

The climatic response to the 1257 Samalas eruption is unclear. Analyses of proxy data and medieval archives suggest that the eruption triggered some of the coldest summers of the past millennium, but only in some Northern Hemisphere regions.

The Toarcian anoxic event was linked to a massive release of carbon to the atmosphere. Geochemical data suggest that organic carbon burial in large lacustrine systems was key to the recovery of the carbon cycle.

Large iron deposits formed episodically in the Archaean oceans. Experimental data and geochemical modelling suggest that green rust was an important contributor to the formation of these deposits and the Archaean iron cycle in general.

The brittle–ductile transition is thought to control crustal permeability. Laboratory experiments and model simulations show that permeability is also stress dependent and ductile granitic rocks may have enough permeability to host geothermal resources.

Large earthquakes are often assumed to reset the seismic hazard of a region. Analysis of recent and historical seismicity in Ecuador suggests that this region may experience clusters of large earthquakes and extended periods of high seismic hazard.

Pressure during subduction is thought to reduce porosity and restrict water escape from the slab. Thermodynamic modelling shows that channel networks, which grow around local chemical heterogeneities, can help drain the subducting plate.