Volume 3 Issue 12, December 2010

Sea-level rise is progressively changing coastlines. The legal implications for the seaward boundaries between neighbouring coastal states are neither straightforward nor foreseeable.

The Palaeocene–Eocene Thermal Maximum 55 million years ago was triggered by the sudden release of carbon to the ocean–atmosphere system. The carbon may have been removed almost as abruptly 100,000 years later, in the form of organic carbon.

Controversy has surrounded projections of tropical temperatures aloft in a changing climate. An analysis of sea surface temperatures and rainfall over the past decades suggests amplified warming in the upper atmosphere, consistent with theory and models.

Model projections of future climate are highly sensitive to the assumed response of organic matter decomposition to changes in temperature. Incubation experiments on North American soils suggest that the decisive factors lie at the molecular level.

Earth's topography is attributed to the interactions of the tectonic plates, but flow within the mantle also contributes to surface uplift and subsidence. An overview of recent research indicates that mantle-induced dynamic topography can be reconstructed by integrating the geological record with models of mantle flow.

The sulphur cycle plays fundamental roles in the chemistry and climate of Venus. Photochemical modelling suggests that the photolysis of sulphuric acid is a source of observed sulphur oxides in the Venusian mesosphere.

Extant or relict martian volcanic hydrothermal systems have been sought in the pursuit of evidence for habitable environments. Detection from orbit of hydrated silica deposits on the flanks of a volcanic cone in the martian Syrtis Major caldera complex suggests the possible preservation of a recent habitable microenvironment.

Deep convection in the tropics is observed generally above a threshold for sea surface temperatures of about 26–28 °C. An analysis of satellite observations of tropical rainfall shows that the threshold has varied in the past 30 years in parallel with tropical mean sea surface temperatures.

Skilful predictions of hurricane frequency have been limited to lead times of one season, and evidence for external forcing has been indirect. Simulations with nine variants of one global climate model show an influence of external forcing on hurricane frequency, and predictability on multi-year timescales.

Climate change could potentially destabilize marine ice sheets such as the West Antarctic ice sheet. A suite of predictions of sea-level change following grounding-line migration suggests that the gravitational effects of melting on local sea levels can exert a stabilizing influence on marine ice sheets on a reverse slope.

Soils comprise the largest terrestrial carbon store on the planet. Soil respiration measurements suggest that the more biogeochemically recalcitrant the soil organic matter, the greater the temperature sensitivity of soil respiration.

Archaea are prevalent in the deep sea, and comprise a major fraction of the biomass in marine sediments. ¹³C-labelling experiments on the sea floor suggest that benthic archaea use sedimentary organic compounds to construct their membranes.

Little is known about the source and residence time of sand in the Earth’s largest deserts. Burial ages obtained from cosmogenic nuclides in association with provenance data from geochronology indicate that the sand in the Namib Sand Sea has remained there for at least one million years.

The Palaeocene–Eocene Thermal Maximum warm event about 56 million years ago was caused by the release of large amounts of carbon to the ocean and atmosphere. Estimates of the rate of recovery from the event suggest that about 2,000 Pg of the carbon released was sequestered as organic carbon.

Northern South America experienced significant changes in drainage patterns during the opening of the South Atlantic. Numerical modelling of the influence of mantle processes on the South American continent indicates that mantle convection was partly responsible for the formation of the Amazon River, the largest river on Earth.

Pieter Vermeesch enjoyed training for a marathon in an empty two-dimensional space, with his eyes closed, in-between sampling aeolian dunes in the Namib Sand Sea.