Volume 12 Issue 4, April 2019

Thinning and retreat of Jakobshavn Isbræ has reversed in 2016, in tandem with regional ocean cooling.

The distribution of two distinct geologic units on Mars’s moon Phobos – red and blue units – can be explained by surface grain motion triggered by orbital variations in slope steepness, according to dynamical analyses and numerical simulations.

Observations and heat-flow modelling suggest that briny groundwater surfacing from fractures forms recurring slope lineae on Mars.

Near-Earth rubble-pile asteroid Bennu has an unexpectedly old surface, with numerous candidate impact craters and morphologically diverse boulders, according to early observations by the OSIRIS-REx mission.

Near-Earth asteroid Bennu has a top-like shape with longitudinal ridges, macroporosity, prominent boulders and surface mass wasting, suggesting that it is a stiff rubble pile, according to early observations by the OSIRIS-REx mission.

Dusts from glaciers may contribute significantly to ice nucleation in Arctic low-level clouds, according to analyses of glacial outwash sediments in Svalbard.

Bubble-mediated gas exchange in high-energy streams accelerates faster as energy dissipation intensifies than does turbulent-diffusion-driven gas exchange in low-energy streams, according to an analysis of new measurements and published data.

Soil moisture effects can substantially reduce photosynthesis and amplify the impacts of extreme events on primary production, potentially leading to biases in satellite-based estimates of photosynthesis, suggests an analysis of ground-based measurements.

Many lakes that currently mix once or twice a year may become permanently stratified or mix only once in a warming climate, suggest numerical simulations of lake mixing regimes. Mixing regimes are most affected by ice-cover duration and surface temperatures.

Jakobshavn Isbrae, the largest source of ice mass loss from the Greenland Ice Sheet, has been re-advancing since 2016 after a decades-long retreat, reveals an analysis of airborne altimetry and satellite data. The advance coincides with regional ocean cooling.

A delayed increase of landslide activity occurred about two to six years after two volcanic eruptions in Chile in 2008 and 2011, according to remote-sensing data. The time lag is consistent with decaying tree roots in areas covered by tephra.

During deglacial warming at Termination II, about 130,000 years ago, the Indian summer monsoon helped convey heat northwards as deglaciation progressed from the Southern to the Northern Hemisphere, according to sediment records from the Bay of Bengal.

Oxidative weathering supplied a crucial flux of nutrients to the late Archaean oceans that sustained methanogenesis and kept the Archaean atmosphere in a methane sweet-spot, according to analyses of nickel isotopes from glacial deposits.

Lower-mantle anisotropy is present beneath all subduction zones, indicating that dislocation creep is active in the lower mantle, according to analysis of 3D global seismic tomography images.