When microbes ruled the Earth

Biological signatures from microbes that lived billions of years ago may help resolve the long-standing debate regarding the earliest life on Earth, according to a study published online in Nature Geoscience. Traces of the microbes have been detected in ancient rocks using nanoscale spectroscopic techniques.

Kevin Lepot and colleagues studied layered rocks called stromatolites from the interior of Australia, which were formed 2.7 billion years ago. Although stromatolites are often considered evidence of early life, some can have a non-biological origin. However, the team identified molecules and microscopic structures, including the oldest crystals of the mineral aragonite found to date, that proved these rocks were associated with microbes.

Applied to older, more controversial stromatolites, the technique should permit the detection of the oldest life on Earth.

Microbially influenced formation of 2,724-million-year-old stromatolites

Kevin Lepot (Institut de Physique du Globe de Paris, France)

Published online: 27 January 2008 | doi 10.1038/ngeo107

Abstract | Full text

Making waves in the ionosphere

Lightning in the tropics produces radiowaves that can disturb the Earth's ionosphere, according to satellite observations published online this week in Nature Geoscience. The findings suggest a previously unknown influence of thunderstorms on this uppermost part of the atmosphere, which stretches between 80 and 1,000 km above the surface of the Earth.

Jean-Jacques Berthelier and colleagues analysed measurements of the DEMETER satellite that is stationed in a polar orbit at 600 km altitude and was designed originally in the hope of detecting earthquake precursor signals. The researchers observed spatial bunching of plasma waves along with an acceleration of ions where the radiowaves from lightning hit.

Lightning-induced plasma turbulence and ion heating in equatorial ionospheric depletions

Jean-Jacques Berthelier (Centre National de la Recherche Scientifique, Saint Maur des Fosses, France)

Published online: 27 January 2008 | doi 10.1038/ngeo109

Abstract | Full text

Other papers from Nature Geoscience to be published online at the same time and with the same embargo:

Importance of post-seismic viscous relaxation in southern Iceland

Sigurjón Jónsson (Institute of Geophysics, ETH Zurich, Switzerland)

Published online: 27 January 2008 | doi 10.1038/ngeo105

Abstract | Full text

Volcanoes under ice

A newly identified volcano underneath the West Antarctic ice sheet has been described in a study published online in Nature Geoscience this week.

The Hudson Mountains Subglacial Volcano last erupted 2,300 years ago, and probably affected regional ice flow at the time. This discovery has important consequences for our understanding of past, present and future stability of the West Antarctic ice sheet.

Hugh Corr and David Vaughan used radar data collected from flights over Antarctica to identify a large layer of volcanic ash buried in the ice. The increased heat from this eruption is thought to have led to local and regional melting of the surrounding and overlying ice, which would have increased the flow rate of other nearby glaciers as well.

A recent volcanic eruption beneath the West Antarctic ice sheet

Hugh Corr (British Antarctic Survey, Cambridge, UK)

Published online: 20 January 2008 | doi 10.1038/ngeo106

Abstract | Full text

Other papers from Nature Geoscience to be published online at the same time and with the same embargo:

Towards forecasting volcanic eruptions using seismic noise

Florent Brenguier (Univ. Joseph Fourier, Grenoble, France)

Published online: 20 January 2008 | doi 10.1038/ngeo104

Abstract | Full text

Biophysical controls on dissolved organic carbon in fluvial networks

Tom J. Battin (University of Vienna, Vienna, Austria.)

Published online: 20 January 2008 | doi 10.1038/ngeo101

Abstract | Full text

Nitrogen transfer from sea to land via commercial fisheries

R. Maranger (Université de Montréal, Montréal, Canada)

Published online: 20 January 2008 | doi 10.1038/ngeo108

Abstract | Full text

Antarctic ice losses

Increasing amounts of ice mass have been lost from West Antarctica and the Antarctic peninsula over the past ten years, according to research published online this week in Nature Geoscience.

Meanwhile the ice mass has been roughly stable in East Antarctica, with neither loss nor accumulation over the past decade.

Eric Rignot and colleagues estimated the flux of ice from the ice sheet into the ocean from satellite data that cover 85% of Antarctica's coastline, which they compared with simulations of snow accumulation over the same period, obtained using a regional climate model. They arrived at a best estimate of a loss of 132 billion tonnes of ice in 2006 from West Antarctica – up from about 83 billion tonnes in 1996 – and a loss of about 60 billion tonnes in 2006 from the Antarctic Peninsula. The ice loss is concentrated at narrow glacier outlets with accelerating ice flow, which suggests that glacier flow is important for the mass balance of the entire ice sheet.

Recent Antarctic ice mass loss from radar interferometry and regional climate modelling

Eric Rignot (Jet Propulsion Laboratory, California, USA)

Published online: 13 January 2008 | doi 10.1038/ngeo102

Abstract | Full text

Other papers from Nature Geoscience to be published online at the same time and with the same embargo:

Importance of pre-impact crustal structure for the asymmetry of the Chicxulub impact crater

Sean P. S. Gulick (Institute for Geophysics, Texas, USA)

Published online: 13 January 2008 | doi 10.1038/ngeo103

Abstract | Full text