Research articles

The origins of the non-mass-dependent oxygen isotope anomaly in planetary materials remain controversial. An analysis of the carbon and oxygen isotopes of organic matter from a carbonaceous chondrite suggests that the signature was acquired in the envelope of the protosolar nebula, triggered by the photodissociation of carbon monoxide.

The eruption of the Siberian Trap flood basalts resulted in the heating and combustion of coals and organic-rich sediments at the time of the Permian mass extinction. The presence of char in distant lake sediments linked to the eruption suggests that fly ash could have been generated by the coal combustion, and then dispersed globally, creating toxic marine conditions.

The Adula nappe, Central Alps, was thought to be a mélange of rock fragments, some of which were subducted and then exhumed from the mantle. Lu–Hf dating of two populations of garnets in one rock sample instead indicates that the nappe twice experienced subduction and exhumation as one coherent unit.

The present state and future evolution of Himalayan glaciers has been controversial. An analysis of remotely sensed frontal changes and surface velocities from glaciers in the greater Himalaya between 2000 and 2008 shows large regional variability in the responses of Himalayan glaciers to climate change.

The impact of external influences on European temperatures before 1900 has been thought to be negligible. An analysis of reconstructions of seasonal European land temperatures and simulations from three global climate models instead suggests that external forcing is responsible for a best guess of 75% of the observed winter warming since the late seventeenth century.

The extent of snow cover and sea ice in the Northern Hemisphere has declined since 1979, suggesting a positive feedback of surface reflectivity on climate. A synthesis of a variety of remote sensing and field measurements suggests that this albedo feedback from the Northern Hemisphere cryosphere falls between 0.3 and 1.1 W m⁻² K⁻¹.

Following a hypothesized complete cessation of carbon dioxide emissions, global climate models simulate approximately constant global mean temperatures for centuries. Long-term simulations with the Canadian Earth System Model suggest that, on these timescales, regional changes in temperature and precipitation are nevertheless significant, and that Southern Ocean warming at intermediate depths could affect the stability of Antarctic ice.

Manganese oxide minerals control numerous environmental processes, including the fate of contaminants. Laboratory experiments with a common species of marine bacteria reveal that bacterially generated superoxide can oxidize manganese ions, generating manganese oxides.

Water has been found in many lunar rock samples, but its sources are unknown. Isotopic analyses of Apollo samples of lunar mare basalts and highlands rocks suggest that a significant volume of water was delivered to the Moon by comets shortly after its formation by giant impact.

The contribution to sea-level rise from mountain glaciers and ice caps has grown over the past decades. A projection of their melting during the twenty-first century based on temperature and precipitation projections from ten climate models suggests that by 2100 these glaciers will lose about 21% of their total global volume.