Volume 8 Issue 7, July 2015

The history of attempts to spread scientific know-how beyond western centres of excellence is littered with failures. Capacity building needs long-term commitment, a critical mass of trainees, and a supportive home environment.

Earth's crust was thought to deform uniformly over most of the seismic cycle. Analysis of two centuries of nautical surveys from Chile reveals temporal variability that complicates our view of time-dependent seismic hazards.

Saturn's poles exhibit giant swirling cyclones, whereas Jupiter's poles may not. Simulations of giant planet atmospheres suggest that just the right balance of convective storm energy and poleward drift of cyclones may explain Saturn's vortices.

The ocean is an important source of the potent greenhouse gas N₂O. Measurements in the tropical South Pacific have revealed a massive efflux of N₂O from the coastal upwelling zone.

The continents are archives of Earth's evolution. Analysis of the isotopic signature of continental crust globally suggests that buoyant, silicic continents began to form 3 billion years ago, possibly linked to the onset of plate tectonics.

The continents have a puzzling structure — a transition occurs at mid-lithospheric depths. A synthesis of geological data indicates that stress-induced sliding along crystal grain boundaries may be responsible forforthe transition.

The solar wind, cometary ices, and inner Solar System bodies exhibit distinct nitrogen isotopic compositions. A synthesis of these analyses suggests that these distinct reservoirs may be the result of early fractionation processes.

Strong vortices have been observed at Saturn’s poles. Simulations suggest that tropospheric polar flows on giant planets are driven by moist convection, and that, while vortices can develop on Saturn, similar cyclones are not expected on Jupiter.

The response of rain and storm dynamics to climate warming is unclear. An analysis of high-resolution rainfall records from 79 Australian stations suggests that rain intensity rises and falls more steeply within a storm at warmer temperatures.

Oceans emit a third of the natural emissions of nitrous oxide. High-resolution measurements suggest that the Peruvian coast is a hotspot of nitrous oxide fluxes, representing 5–22% of global ocean emissions from previous estimates.

The factors leading to the full retreat of ice sheets during deglaciation are debated. Numerical modelling suggests that the Laurentide ice sheet retreated only after a threshold for warming and radiative forcing was passed in the Holocene.

The effect of glacial–interglacial cycles on surface weathering rates has been unclear. A beryllium-based proxy for weathering shows minimal variations in the input of silicate weathering products to the oceans for the past two million years.

Continental rifting is thought to occur in particularly hydrous plates. Magnetotelluric images of the East African Rift, however, reveal that the rift is anhydrous, implying that hydrogen content is not a primary control on plate strength.

Records of complete earthquake cycles are rare. Analysis of historical nautical charts and modern GPS data that record a full earthquake cycle in Chile show that great earthquakes can create small amounts of permanent uplift.

The continental crust provides a record of Earth’s evolution. Analysis of the geochemical signature of continental crust formed since the Hadean points to the initiation of plate tectonics about 3 billion years ago.

The composition of the Earth’s lower mantle is not well constrained. First-principles calculations support a pyrolitic composition containing ferric iron, suggesting that the upper and lower mantles are geochemically uniform.

The climate-model mean response of the summertime mid-latitude circulation to global warming is weak. Model experiments reveal that a tug of war between the influences of radiative forcing and surface warming is the reason.

The controls on plant functional diversity are unclear. Analysis of spectral data from the tree canopy in the Amazonian lowlands implies that plant functional traits are influenced by nutrient supply, which in turn varies with topography.