Volume 9 Issue 10, October 2016

The composition of Earth's crust depends on the style of plate tectonics and of the melting regimes in the mantle. Analyses of the oldest identified rocks suggest that these styles and the resulting crust have changed over Earth's history.

Increasing groundwater extraction supports hundreds of millions of people across the Indo-Gangetic Basin. Data suggests that despite the increase in withdrawals, groundwater depletion is localized and the most widespread threat is contamination.

There is potential evidence for a stratified layer at the top of the Earth's core, but its origin is not well understood. Laboratory experiments suggest that the stratified layer could be a sunken remnant of the giant impact that formed the Moon.

Marine macroalgae are dominant primary producers in coastal zones. A review of the published literature suggests that macroalgae may play an important role in carbon sequestration.

The planet Mercury has contracted over its history. The identification of small thrust fault scarps suggests the occurrence of tectonic activity on Mercury within the past 50 million years and thus a slow-cooling planetary interior.

Convective precipitation may change in a changing climate. Large eddy simulations of convection with a realistic diurnal cycle suggest that interactions between convective systems and precipitation extremes are influenced by temperature.

Landfalling typhoons can cause great damage in East and Southeast Asian countries. An analysis of bias-corrected data sets reveals that the proportion of the strongest landfalling typhoons has at least doubled over the past decades.

Aquatic CO₂ emissions are expected to increase if warming reduces photosynthesis relative to respiration. An analysis of streams across a 41 °C temperature gradient reveals that the thermal responses of respiration and photosynthesis are similar.

Increasing groundwater abstraction in the Indo-Gangetic Basin poses a threat to groundwater supplies. In situ observations reveal that sustainable groundwater in much of the region is limited more by contamination than depletion.

The internal dynamics of pyroclastic density currents are not easily observed. Experiments reveal how the underflow and turbulent ash-cloud regimes within pyroclastic flows are dynamically coupled through a zone of intermediate turbulence.

The composition of subduction zone lavas varies systematically. Numerical simulations and geochemical analysis of lavas from the Chilean Southern Volcanic Zone suggest that the thermal structure of the mantle wedge controls lava composition.

Little is known about the character of the Hadean crust. Geochemical analyses of the 4-billion-year-old Acasta Gneiss from Canada suggest Earth’s earliest crust formed from a mafic reservoir, similar to the formation of oceanic crust today.

The carbon abundance in the Earth’s mantle is enhanced relative to sulfur. Experiments suggest that the accretion of a differentiated planetary body to the growing Earth could explain the silicate Earth’s carbon and sulfur budgets.

The Earth’s outermost core is thought to be stratified. Turbulent mixing experiments suggest that merging between the cores of projectile and planet following the Moon-forming giant impact could have produced the stratification.

International trade links regions of production and consumption. Analyses with a multiregional input–output model based on trade data reveal that much of East Asia’s aerosol radiative forcing is tied to consumption in developed countries.