Reviews & Analysis

Most of the world's surface oceans are oversaturated with respect to atmospheric methane and emit large quantities of this greenhouse gas. Aerobic decomposition of phosphorus-containing organic compounds may be responsible.

The uneven distribution of biological nitrogen fixation in terrestrial ecosystems has yet to be explained. Latitudinal gradients in temperature and phosphorus may hold the answer.

Ninety-five million years ago, ocean bottom waters were much warmer than at present. Some of this warmth could have come from the proto-North Atlantic's continental shelves after the balmy surface waters became increasingly salty through evaporation.

European forests are intensively exploited for wood products, yet they are also a potential sink for carbon. European forest inventories combined with timber harvest statistics from sixteen European countries show that between 1950 and 2000 forest biomass increased faster than the amount of timber harvests. Silviculture, which has developed over the past 50 years, can efficiently sequester carbon on timescales of decades, while maintaining forests that meet the demand for wood.

Land and ocean carbon sinks play a critical role in determining atmospheric carbon dioxide levels. Nitrogen-induced increases in land and ocean sink strength are unlikely to keep pace with future increases in carbon dioxide.

Archaean and early Proterozoic rocks reveal that the Earth's magnetic field two billion years ago behaved differently than over most of the past 200 million years. Do these changes relate to the growth of the inner core?

Two overlapping oceanic plates are sinking into the mantle underneath central Japan where they dehydrate, releasing water-rich fluids that enhance mantle melting. Geochemical work helps determine the relative contribution of each plate to the overall fluid budget.

The Nili Fossae region on Mars is one of the places earmarked for the search of evidence for life. A combination of geomorphological and mineralogical data from the area suggest ideal conditions for the burial of organic matter.

The termination of the Marinoan glaciation 635 million years ago is one of the most spectacular climate change events ever recorded. Methane release from equatorial permafrost might have triggered this global meltdown.

Uncertainty over tropical tropospheric temperature change has loomed large over the last two decades. Use of wind data to infer temperature change offers a new avenue of investigation.

Stunning images of fjords are familiar to geologists, but their origins are less well known. A simple model suggests that topographic steering of ice and erosion proportional to ice discharge are sufficient to explain fjord formation during the Quaternary period.

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.