Reviews & Analysis

Subducting oceanic crust is sometimes observed to stagnate in the lower mantle. Laboratory experiments show that high pressures in the deep Earth may strengthen mantle rocks, increasing their viscosity and halting the sinking slabs.

Ice shelves in West Antarctica have been shown to melt where warm circumpolar deep water enters a sub-shelf cavity. A bathymetric reconstruction of Totten Glacier in East Antarctica suggests that the same process may be at work there.

Deep abyssal clay sediments in organic-poor regions of the ocean present challenging conditions for life. Techniques for identifying cells at extremely low concentrations demonstrate that aerobic microbes are found throughout these deep clays in as much of 37% of the global ocean.

Flowing water shapes most of Earth's canyons, obscuring the contributions of other erosional mechanisms. A comparison of adjacent canyons with and without wind shielding shows that wind can amplify canyon incision on windblown Earth and Mars.

Pinpointing when Earth's core formed depends on the extent of metal–silicate equilibration in the mantle. Vaporization and recondensation of impacting planetesimal cores during accretion may reconcile disparate lines of evidence.

Metals often accumulate in the crust beneath volcanoes. Laboratory experiments and observations reveal important roles for magmatic vapours and brines in transporting and concentrating the metals into deposits worth targeting for extraction.

The hydrology of the North American west looked very different at the Last Glacial Maximum to today. A model–data comparison suggests the observed precipitation patterns are best explained if the storm track was squeezed and steered by high-pressure systems.

Beneath the fresh and cold surface water in the Arctic Ocean resides more saline and warmer water of Atlantic origin. Pan-Arctic measurements of turbulent mixing suggest that tidal mixing is bringing up substantial amounts of heat in some areas.

Instrumental records have hinted that aerosol emissions may be shifting rainfall over Central America southwards. A 450-year-long precipitation reconstruction indicates that this shift began shortly after the Industrial Revolution.

The Witwatersrand Basin in South Africa contains extraordinary amounts of gold. Thermodynamic calculations suggest that the gold may have accumulated there in response to a perfect storm of conditions available only during the Archaean.

Boreal forest fires tend to be more intense and lethal in North America than Eurasia. Differences in tree species composition explain these differences in fire regime, and lead to contrasting feedbacks to climate.

The Sahara was more humid and habitable thousands of years ago. Reconstructions of North African hydroclimate show that the onset of aridity started in the north, with the monsoon rains weakening progressively later at lower latitudes.

Glaciers and polar ice sheets store and release a small but important pool of organic carbon. The changing climate is making glaciers an increasingly important driver of carbon dynamics in aquatic ecosystems.