Reviews & Analysis

The generally warm and ice-free conditions of the Eocene epoch rapidly declined to the cold and glaciated state of the Oligocene epoch. Geochemical evidence from deep-sea sediments resolves in detail the climatic events surrounding this transition.

Late addition of meteoric material to the Earth's mantle could explain the presence of iron-loving elements that should have entered the Earth's core at its formation. But experiments at realistic conditions show that enough palladium could have remained in the mantle.

In densely populated coastal areas, reactions of polluted air with sea salt aerosol from the ocean can lead to high surface ozone levels that affect air quality.

Atmospheric carbon dioxide levels greatly influence the Earth's climate. Evidence from ice cores and marine sediments suggests that over timescales beyond the glacial cycles, carbon fluxes are finely balanced and act to stabilize temperatures.

Not only do plate boundary faults generate earthquakes, they also produce slow slip and non-volcanic tremor. New observations on these phenomena provide fresh insights into the conditions that dictate earthquake behaviour.

Subglacial water can significantly affect the velocity of ice streams and outlet glaciers of ice sheets. Depending on the geometry and capacity of the subglacial hydrologic system, increased surface melting in Greenland over the coming decades may influence the ice sheet's mass balance. Furthermore, subglacial lakes in Antarctica can modulate ice velocities and act as nucleation points for new fast-flowing ice streams.

Extraction of the continental crust has left the Earth's mantle depleted in certain elements. Some rocks from the Arctic Ocean floor suggest that the extent of depletion and heterogeneity in the Earth's mantle may be greater than we thought.

Violent uplift of western Crete in AD 365 generated a Mediterranean-wide tsunami that tossed boats onto house-tops in Alexandria, Egypt. Although a similar earthquake may not recur for 5,000 years, contiguous fault segments could rupture sooner.

Because of difficulties in creating a radiocarbon calibration that covers the end of the last glaciation, defining the timing and duration of the Younger Dryas cold event has been a challenge. Linking related cosmogenic isotopes in tree rings and ice cores may provide new insights into abrupt climate changes.

All organisms require elements to live, grow and reproduce, but some of these are hard to find or take up. Nitrogen-fixing bacteria solve the problem by secreting compounds that allow them to acquire the metals they need.

Electrical discharges from thunderstorms include bolts-from-the-blue, blue jets and gigantic jets along with the more common intracloud and cloud-to-ground lightning. All these phenomena can be understood in a single framework.

Black carbon in soot is an efficient absorbing agent of solar irradiation that is preferentially emitted in the tropics and can form atmospheric brown clouds in mixture with other aerosols. These factors combine to make black carbon emissions the second most important contribution to anthropogenic climate warming, after carbon dioxide emissions.

Whether convection in the Earth's mantle extends through its entire depth or if the mantle is layered has long been debated. Recent research suggests that spatially and temporally intermittent or partial layering is the most likely solution.

Earthquake data seem to reveal a huge sausage-shaped slab of material detaching itself from the material subducting as two plates meet beneath the Hindu Kush. This largest-ever 'boudin' could tell us more about what happens when continents collide.

Numerous long, wall-like ridges can be observed in the Valles Marineris region of Mars. They probably represent fault zones cemented by water-deposited minerals and are indicative of ancient groundwater flow.

Deltas are among the most valuable coastal ecosystems, but they are very dynamic and the factors that influence their health are complex. The rate of compaction of underlying sediments might be a more significant factor than was thought.