Volume 5 Issue 5, May 2012

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.

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.

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 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.

In contrast to those in other regions, the North Atlantic storm track responds to anthropogenic greenhouse-gas forcing by strengthening and extending farther east. A regression analysis of an ensemble of coupled climate model simulations shows that this response is, to a large part, shaped by the interaction between ocean and atmosphere.

Uncertainty in the future atmospheric burden of methane—a potent greenhouse gas—represents an important challenge to the development of realistic climate projections. Airborne observations of methane suggest that the remote Arctic Ocean could prove to be a potentially important methane source.

The mass balance of Hindu-Kush–Karakoram–Himalaya glaciers has been debated, partly because of a severe lack of observations from the region. An analysis of the regional mass balance of Karakoram glaciers by comparison of digital elevation models from 1999 to 2008 reveals a small glacier mass gain in the area.

The Earth’s climate between 60 and 50 million years ago was punctuated by several abrupt warming events, the largest of these being the Palaeocene–Eocene Thermal Maximum. Carbon isotope records from the Bighorn Basin, Wyoming, document these events in the terrestrial realm, and show a consistent scaling between marine and terrestrial records across the three main events.

The transition between the weak lithosphere of the Tibetan plateau and the surrounding rigid crustal blocks has a key role in the ongoing collision between India and Asia. A reanalysis of existing magnetotelluric data suggests that crustal melt penetrates north from the Tibetan plateau beyond the Kunlun Fault, and weakens the crust beneath the Kunlun Shan.

Mid-ocean ridge transform faults experience more foreshocks than continental faults, yet the mainshock rarely ruptures the entire fault. Analysis of seismic data from the Gofar transform fault at the East Pacific Rise indicates that the foreshock region has different material properties from the mainshock region, and acts as a barrier to rupture propagation.

The Chilean subduction zone, where the oceanic Nazca plate subducts beneath the continental South American plates, is a very active convergent margin. Wide-angle seismic refraction and reflection data, combined with records of aftershocks following the 2007 Tocopilla earthquake, document an abrupt change in the dip of the subducting plate from less than 10° to about 22°.

Ocean acidification may seriously impair marine calcifying organisms. Emiliania huxleyi, the world’s single most important calcifying organism, may be able to evolve in response to ocean acidification conditions, according to laboratory selection experiments.

Carbon capture and geological storage represents a potential means of managing atmospheric carbon dioxide levels. An analysis of a 135,000 palaeorecord shows that pulses of carbon dioxide leakage from a natural reservoir in Utah are associated with episodes of glacial unloading.

Before the rise of oxygen, the atmosphere of the early Earth may have consisted of an organic haze. Geochemical data and modelling suggest that from 2.65 to 2.5 Gyr ago, several transitions between hazy and haze-free atmospheric conditions occurred, potentially linked to variations in biogenic methane production.