Reviews & Analysis

The last deglaciation was punctuated by several millennial-scale climate changes. In the Gulf of California, the cold stages were marked by decreased upwelling, opposite to the changes expected if these shifts were analogous to modern seasonal variability.

Mercury concentrations in the Arctic atmosphere exhibit a pronounced peak during summer. Model simulations suggest that this can be explained only if boreal rivers deliver large quantities of mercury to the Arctic Ocean.

Lichens, cyanobacteria, mosses and algae coat many terrestrial surfaces. These biological covers turn out to play an important role in the global cycling of carbon and nitrogen.

The growth of the smallest atmospheric particles to sizes at which they may act as seeds for cloud droplets is a key step linking aerosols to clouds and climate. A synthesis of research indicates that the mechanisms controlling this growth depend on the size of the growing particle.

Most volcanism on Earth takes place under water, yet little is known about submarine eruptions. Monitoring of two volcanic seamounts beneath the Pacific Ocean reveals the pulsed nature of their eruption cycles.

Earthquakes may trigger or retard quakes on nearby faults, but such relationships are difficult to verify. Observations showing that the Landers earthquake in California shut down aftershocks from a preceding event validate such relationships.

Greenland's glaciers have lost significant amounts of ice over the past decade. Rediscovered historical images of the ice margin show a record of southeast Greenland's response to the last major warming event in the 1930s.

Over 90% of species were lost during the end-Permian mass extinction. A review of the fossil record shows that the rate of recovery was highly variable between different groups of organisms as a result of complex biotic interactions and repeated environmental perturbations.

Methane emissions from natural gas reservoirs have long been largely overlooked. The discovery of abundant geological gas seeps in areas of cryosphere degradation highlights the relevance of these emissions to the greenhouse gas budget.

Of the West Antarctic ice shelves, those in the Amundsen Sea sector have given the most cause for concern. Ocean modelling of the Weddell Sea region, together with a detailed survey of the ice bed morphology, indicates that this region, too, may change soon.

The hothouse climate of the early Eocene epoch was punctuated by a series of transient warming events linked to massive carbon release. Detailed terrestrial records for three of these events indicate that they were caused by similar underlying mechanisms.

The prediction of marine microbial responses to ocean acidification is a key challenge for marine biologists. Experimental evolution offers a powerful tool for understanding the forces that will shape tomorrow's microbial communities under global change.

Faults break under the stress of plate tectonic forces, but the processes immediately preceding rupture are enigmatic. Monitoring of a remote oceanic fault that breaks regularly indicates that rupture is controlled by physical properties of the fault zone.

The fate of glaciers in the greater Himalaya is widely discussed, but poorly known. A new measurement in the central Karakoram mountain range suggests that glacier mass change in this region contributes to sea-level rise nearly 0.05 mm per year less than has been thought.

Earth's crust is formed where tectonic plates rift apart and upwelling magma solidifies. Disparate observations from rifts beneath the oceans and on land provide insights into the dynamics of rifting and opportunities for synthesis.

The supply of magma to Kīlauea Volcano was relatively stable for 50 years. But between 2003 and 2007, the volcano experienced a surge in the supply of magma from the mantle that implies short-term changes in the underlying Hawaiian hotspot.