Articles in 2010

The timing and origins of Alpine gorge formation are controversial. A high-resolution analysis of the inner gorges of the Swiss Alps suggests that these landforms were carved over successive interglacial periods, and survived the intervening glaciations.

Ocean drilling is the most successful long-standing international collaboration in the geosciences. The invaluable archive of samples and data that has been built underpins our understanding of the Earth, its surface environment and climate. Planning the next phase is at an advanced stage.

The sea floor is emerging as a source of carbon to the overlying ocean. Scientific exploration of the sea bed is essential for a full understanding of the global carbon budget and the safety of deep-sea carbon storage proposals.

The existence of a microbial community in the ocean crust has long been hypothesized. Isotopic evidence indicates that a deep biosphere of microbes both scrubs oceanic fluids of organic matter and produces new, yet old, organic carbon in situ.

Unusual wind patterns and the albedo feedback effect played crucial roles in the rapid reduction of Arctic sea-ice cover in recent years. Evidence is now building that a warmer ocean has also contributed to the thinning of Arctic ice.

Massimo Frezzotti and colleagues saw their 17-ton vehicle drop 10 m into an ice crevasse in their quest to recover the climatic history of East Antarctica.

Bromine facilitates the oxidation of elemental mercury in the lower atmosphere in polar and subpolar regions. Measurements over the Dead Sea suggest that bromine also generates large quantities of oxidized mercury in the mid-latitudes.

The mechanisms by which debris flows acquire mass and momentum as they entrain material are unclear. Large-scale experiments suggest that the pore pressure of wet bed sediment increases as the flow moves over the bed, leading to reduced friction and progressive scouring of the base.

Magma transports metals to the Earth’s surface to form ore deposits, but only sulphide-undersaturated magmas were thought to be capable of generating large amounts of ore. Laboratory experiments indicate that large volumes of gold ore can also be generated by sulphide-saturated magma, if the redox conditions of the magma are suitable.

Biogenic aerosol particles of terrestrial origin, including bacteria and pollen, trigger ice formation in the atmosphere. Laboratory experiments reveal that biogenic particles of marine origin also initiate ice formation under typical tropospheric conditions.

The amount of fluid delivered to subduction zones by the oceanic crust and penetrating sea water is not matched by that leaving through volcanic emissions or transfer to the deep mantle. Electromagnetic images of the Costa Rican subduction zone reveal an extra reservoir in the crust that may account for some of the missing fluid.

Climate models suggest that deficits in soil moisture can lead to more frequent and severe hot summer temperatures. Observations confirm this effect, but only for relatively dry regions, where evaporation is limited by available moisture.

The tropical African rainbelt is an important component of atmospheric circulation and the global hydrological cycle. Reconstructions of vegetation in tropical Africa over the past 23,000 years suggest that the rainbelt expanded and contracted in response to changes in high-latitude climate conditions.

Modelling studies have postulated a possible impact of soil-moisture deficit and drought on hot extremes. An analysis of observational indices from central and southeastern Europe confirms that summer hot extremes are linked to soil-moisture deficits in southeastern Europe but does not detect a similar effect in central Europe.

Deformation in the crust and mantle — measured using seismic anisotropy — is poorly constrained in the western United States because of inconsistencies in the existing data. A three-dimensional model that reconciles these discrepancies reveals that seismic anisotropy in the crust correlates with different geological provinces, but is unrelated to anisotropy in the underlying mantle.

During the last deglaciation, climate changes over Greenland and Antarctica on millennial timescales were asynchronous. A temperature record from the Talos Dome in Antarctica confirms this asynchrony and shows clear regional differences in deglacial warming between the Indo-Pacific and Atlantic sectors of Antarctica.

The origins of Alpine valleys are controversial. Topographic data from the Swiss Alps suggest that the valleys have been incised progressively during consecutive glacial–interglacial cycles.