Review Articles

Size, morphology, silica content and life cycle of diatoms affect their contribution to the export of carbon to the deep ocean, suggests a literature review.

Climate sensitivity, the long-term warming due to doubled atmospheric CO₂ levels, is estimated in the range of 1.5 °C to 4.5 °C. A synthesis of work reveals that whether the value falls at the high or low end, future emissions will have to be strongly limited.

Microbial metabolisms depend on enzymes that contain trace metals. A synthesis of molecular and geochemical data shows that these metabolic pathways evolved alongside changing marine availability of trace metals during the Precambrian.

River deltas are shaped by interactions between fluvial and tidal processes. Tides act to stabilize delta morphology, but sediment depletion due to human activities disrupts the balance and leads to erosion and scour.

Extratropical storms contribute to precipitation, wind and temperature extremes. A synthesis of the influences of a changing climate on storm tracks reveals competing effects on meridional temperature gradients, which make projections difficult.

Two large zones through which seismic waves travel unusually slowly are found at the base of Earth's mantle. These zones are thermally and chemically distinct from the surrounding mantle and may be a source for mantle plumes.

The formation of Earth's continents is unclear. A review of the geochemical composition of crust formed above subduction zones across the globe suggests that subduction and relamination of buoyant magmatic rocks play an important role.

Lakes are sources of the greenhouse gas methane. A synthesis of measurements of methane emissions reveals that lakes and ponds above 50 °N emit 16.5 Tg methane annually, and emissions may increase by 20 to 50% with longer ice-free seasons.

The material properties of the Earth’s core have been better constrained by recent technical and computational advances. The properties imply that the core was once hot, but is cooling quickly, and the inner core is young.

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.

The atmospheric layer that lies above Earth's weather systems can exert a strong downward influence. A review of this influence on storm tracks and surface weather suggests that the dynamical links between the layers hold across timescales.

In order to limit climate warming, CO₂ emissions must remain below fixed quota. An evaluation of past emissions suggests that at 2014 emissions rates, the total quota will probably be exhausted within the next 30 years.

The Arctic has warmed more than twice as fast as the global average. A literature synthesis discusses mechanisms how the associated decline in sea ice and snow cover could potentially alter mid-latitude weather, but uncertainties are profound.

The discovery of water in lunar samples in 2008 challenged the notion that the Moon's interior had lost all its volatiles. Since then, analyses of the water concentrations and isotopic compositions in lunar samples taken together suggest that the Moon is heterogeneously wet, which may lend clues to its origin.

The oxygenation of the Earth's deep oceans is often thought to have triggered the evolution of simple animals. A review article proposes that instead, the evolution of animal life set off a series of biogeochemical feedbacks that promoted the oxygenation of the deep sea.

Feedbacks between the terrestrial carbon cycle and climate change could affect many ecosystem functions and services. A synthesis of global air temperature data reveals non-uniform rates of climate warming on diurnal and seasonal timescales, and heterogeneous impacts on ecosystem carbon cycling.

The Indian Ocean Dipole is a key mode of interannual climate variability influencing much of Asia and Australia. A Review suggests that in response to greenhouse warming, mean conditions of the Indian Ocean will shift toward a positive dipole state, but with no overall shift in the frequency of positive and negative events as defined relative to the mean climate state.

Porphyry ore deposits supply much of the copper, molybdenum, gold and silver used by humans. A review of the main processes that trigger porphyry ore formation suggests that sulphide saturation of the magmas that supply the metals could be the overriding mechanism that helps control the temporal and spatial distribution of the ore deposits.

Methane is an important greenhouse gas, responsible for about 20% of the warming induced by long-lived greenhouse gases since pre-industrial times. A compilation of observations and results from chemical transport, ecosystem and climate chemistry models suggests that a rise in wetland and fossil fuel emissions probably accounts for the renewed increase in global methane levels after 2006.

The Arctic is warming faster than any other region in the world. The resultant large-scale shift in sea ice cover could increase oceanic emissions of dimethylsulphide, a climate-relevant trace gas generated by ice algae and phytoplankton.