Reviews & Analysis

Volcanic eruptions can release large amounts of climatically active gases. An emerging view stresses the role of the size and chemical composition of the plume, including its water content, in controlling the climatic effects of an eruption.

The Palaeocene–Eocene Thermal Maximum was associated with a massive release of carbon. Marine sediments suggest a temporary deepening of the calcite compensation depth, indicating extensive silicate weatheringin the aftermath of the event.

TEX₈₆-based records of sea surface temperature from the Early Eocene suggest polar warmth that is not seen in climate models. A reassessment of the TEX₈₆ proxy adjusts these temperatures, lending confidence to simulations of greenhouse climates.

Summer temperatures in Europe varied markedly over the past millennium. Climate models and palaeoclimate records indicate that changes in cloud cover related to storm tracks contributed to the variations — and may continue to do so in the future.

The two small satellites of Mars are thought to have accreted from a debris disk formed in a giant impact. Simulations suggest the moons were shepherded into formation by the dynamical influence of one or more short-lived massive inner moons.

Anomalously bright spots are seen on the dark cratered surface of the dwarf planet Ceres. The Dawn spacecraft's detection of sodium carbonates in bright areas is consistent with aqueous activity in an ice-poor and salty regolith.

At mid-ocean ridges, the directions in which plates spread and the underlying mantle flows were thought to broadly align. A synthesis of results from ridges that spread at a variety of rates reveals that instead there may be a systematic skew.

Conversion of Antarctic circumpolar upwelling waters to less dense water has mainly been attributed to surface heat fluxes. An analysis of water-mass transformation shows that the dominant process is the formation of sea ice near Antarctica and its melt offshore.

A weakening of the Atlantic meridional overturning circulation has emerged from noise after years of painstaking measurements. Three independent lines of evidence suggest that an anthropogenic influence on this overturning is not yet detectable.

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.

Soil carbon stocks depend on inputs from decomposing vegetation and return to the atmosphere as CO₂. Monitoring of carbon stocks in German alpine soils has shown large losses linked to climate change and a possible positive feedback loop.

Ethane emissions can lead to ozone pollution. Measurements at 49 sites show that long-declining atmospheric ethane concentrations started rising in 2010 in the Northern Hemisphere, largely due to greater oil and gas production in the USA.

Frequent storms on the young Sun would have ejected energetic particles and compressed Earth's magnetosphere. Simulations suggest that the particles penetrated the atmosphere and initiated reactions that warmed the planet and fertilized life.

Semivolatile organic compounds from fossil fuels or incomplete combustion are ubiquitous. A suite of circumglobal measurements of their oceanic and atmospheric concentrations reveals large carbon fluxes through the deposition of these compounds.

Atmospheric oxygen levels increased in two stages. This two-step rise of oxygen may be a natural consequence of lowered oxidative capacity caused by the emergence of felsic continents and the growth of a continental carbon reservoir.

Liquid water on Mars may be an agent of surface change, but it is unstable under the thin atmosphere. Experiments suggest water percolating though Martian hillslopes ejects sediment as it boils under the low pressure, and modifies the landscape.

Phosphorus is essential for food production, but it is also a key cause of eutrophication. Estimates of phosphorus flux for the past 40–70 years reveal that large river basins can experience phases of phosphorus accumulation and depletion.

Coastlines above subduction zones slowly emerge from the sea despite repeated drowning by great, shallow earthquakes. Analysis of the Chilean coast suggests that moderate-to-large, deeper earthquakes may be responsible for the net uplift.

Rockfall often seems to occur spontaneously without an obvious cause. Monitoring of a granitic cliff reveals that cyclical temperature variations can subtly act to slowly and incrementally damage hard rock until failure is inevitable.