Volume 6 Issue 2, February 2013

Extrasolar planet research is booming. We welcome submissions with links to the geosciences.

The dawn of exoplanet discovery has unearthed a rich tapestry of planets different from anything encountered in the Solar System. Geoscientists can and should be in the vanguard of investigating what is out there in the Universe.

At the end of the Eocene epoch, permanent ice cover developed over Antarctica as the Earth began to cool from greenhouse warmth. Sediment records off the Antarctic coast show spikes in weathering rate at the onset of ice growth that may indicate synchronous consumption of atmospheric carbon dioxide.

The Antarctic Peninsula has long been thought to be the only part of Antarctica that has warmed in recent decades. Careful detective work confirms that West Antarctica is also warming rapidly.

The molten-iron alloy of the core meets the mantle's silicate rock at Earth's core–mantle boundary. Seismological images reveal hummocks of iron-enriched material above the boundary, highlighting the heterogeneous nature of the mantle.

About 8,200 years ago, the overturning circulation in the Atlantic Ocean slowed and the Northern Hemisphere cooled. A speleothem record from China reveals a period of drying that occurred almost simultaneously with the cooling recorded by the Greenland ice cores.

Diogenite meteorites are thought to represent mantle rocks that formed as cumulates in magma chambers on 4 Vesta or a similar differentiated asteroid. Microstructural analysis of olivine grains from a diogenite meteorite show that the preferred orientation of their crystal lattice was formed through plastic deformation, indicating dynamic, planet-like processes in its parent body.

Advances in seasonal forecasting have brought widespread socio-economic benefits. A modelling study suggests that tropospheric forecast skill is enhanced when the forecast model is initialized at the onset of a stratospheric sudden warming event.

Anammox, anaerobic ammonium oxidation, accounts for over 50% of nitrogen loss in marine ecosystems. A field study in north China reveals hotspots of anammox activity in sediments sampled from land–lake interfaces.

Naturally occurring bromine- and iodine-containing compounds substantially reduce regional, and possibly global, tropospheric ozone levels. Experimental and model results suggest that the reaction of ozone with iodide could account for around 75% of observed iodine oxide levels over the tropical Atlantic Ocean.

The El Niño/Southern Oscillation in the Pacific Ocean influences temperature in other tropical ocean basins. Reanalysis data and model simulations suggest that temperature anomalies in the north tropical Atlantic may also influence the development of La Niña events.

A period of cooling in the North Atlantic region 8,200 years ago affected climate throughout the Northern Hemisphere. A speleothem record from central China indicates that a dry period lasting 150 years was associated with the 8,200 year event.

During the Eocene–Oligocene transition, a permanent ice sheet was established on Antarctica. Marine sediment geochemistry indicates a period of intense weathering associated with the inception of the ice sheet.

Zinc is a marine nutrient that may have been limited in the early oceans. Estimates of marine zinc availability through time suggest that values were instead near-modern during the Proterozoic eon.

Deposits of highly vesicular pumice that blanket submarine volcanoes are often attributed to explosive eruptions. Density and textural analysis of clasts dredged from the submarine Macauley Volcano, southwest Pacific Ocean, however, reveal an eruptive style that is neither explosive nor effusive, with clasts instead forming from buoyant detachment of a magma foam.

The subsurface of Mars could potentially have contained a vast microbial biosphere. An evaluation of the possibility of groundwater upwelling, which might provide clues to subsurface habitability, reveals evidence in the deep McLaughlin crater for clays and carbonates that probably formed in an alkaline, groundwater-fed lacustrine setting.

The West Antarctic Ice Sheet is contributing to sea-level rise, but temperature trends in the region have remained uncertain. A complete temperature record for Byrd Station in central West Antarctica, spanning from 1958 to 2010, establishes West Antarctica as one of the fastest-warming regions globally.

Uptake of atmospheric carbon dioxide in the subpolar North Atlantic Ocean declined rapidly between 1990 and 2006. An analysis of oceanographic data suggests that the slowdown of the meridional overturning circulation was largely responsible.