Reviews & Analysis

Carbon cycle–climate feedbacks are expected to diminish the size of the terrestrial carbon sink over the next century. Model simulations suggest that nitrogen availability is likely to play a key role in mediating this response.

Wildfires have been a natural part of the Earth system for millions of years. A new charcoal database for the past two millennia shows that human activity increased biomass burning after AD 1750 and suppressed it after AD 1870.

The tropics sustain strong coherent variations in wind and precipitation on intraseasonal timescales of 30–60 days. These variations pace the active and break cycles of the monsoons, exerting a direct control on the livelihoods of large populations dependent on rain-fed agriculture. Emerging evidence suggests that heat fluxes from ocean to atmosphere play a fundamental role in driving these intraseasonal oscillations.

Iron has been shown to stimulate productivity in certain areas of the modern ocean. However, it was not the primary driver of carbon burial in the equatorial Pacific Ocean for the past 10 million years.

A mantle plume origin for the Samoan hotspot has been contested because the ages along its putative trail did not seem to increase monotonically. New dates from the island of Savai'i resolve the controversy and favour a plume origin.

The causes of the catastrophic eruption of the Lusi mud volcano in Indonesia are hotly debated. Data from a nearby exploration well and a new look at the stress regime suggest that drilling operations, and not an earthquake set the eruption off.

The fate of dissolved organic carbon in the ocean interior is poorly constrained. Fluorescence measurements illuminate the relative roles of in situ production and riverine input of at least the coloured carbon fraction.

The vast Laurentide ice sheet once covered the northern reaches of the American continent. A combination of geological data and climate simulations suggests that it dwindled faster than has been projected for Greenland's ice over the next century.

Despite its potential importance in a warming world, the organic carbon content of Arctic soils has escaped robust quantification. A closer look at the North American sector suggests that much more carbon is stored in these high northern grounds than previously thought.

The ratio of magnesium to calcium in sea water is thought to have influenced the skeletal mineralogy of certain marine calcifiers throughout the Phanerozoic eon. A fresh look at old data suggests that mass extinctions may have also played a role.

Mud volcanoes often exhibit calderas, which are large circular depressions at their summit. Detailed mapping around the Caspian Sea suggests that caldera-forming mud volcanoes are dynamically similar to magmatic volcanoes.

Almost immediately after all the Earth's continents were amalgamated into the supercontinent Pangaea, rifting began to tear it apart. Subduction of the oceanic region of the Pangaean plate beneath its own continental margin may have been the trigger.

In the South Asian lowlands, high population density coincides with dangerous levels of arsenic in groundwater. Maps based on surface geology can help identify regions at risk of arsenic contamination.

The Waiho Loop moraine in New Zealand's southern Alps had long been viewed as a southern icon of a recent glacier response to cooling climate, possibly the Younger Dryas cold event. But a closer look has implicated a landslide in this particular glacial advance.

Cratons are ancient continental nuclei that have resisted significant fragmentation for almost two billion years. Yet, many cratons also experience phases of instability in the form of erosion and rejuvenation of their thick lithospheric mantle keels. Melting governed by redox processes as well as small-scale convection play a key role in triggering such instability.