Volume 1 Issue 5, May 2008

Power generation as well as the production of fuels for transportation requires water, and the supply of high-quality freshwater is energy intensive. A growing population and climate change will increase the pressure on both resources.

Atmospheric carbon dioxide levels greatly influence the Earth's climate. Evidence from ice cores and marine sediments suggests that over timescales beyond the glacial cycles, carbon fluxes are finely balanced and act to stabilize temperatures.

Late addition of meteoric material to the Earth's mantle could explain the presence of iron-loving elements that should have entered the Earth's core at its formation. But experiments at realistic conditions show that enough palladium could have remained in the mantle.

In densely populated coastal areas, reactions of polluted air with sea salt aerosol from the ocean can lead to high surface ozone levels that affect air quality.

The generally warm and ice-free conditions of the Eocene epoch rapidly declined to the cold and glaciated state of the Oligocene epoch. Geochemical evidence from deep-sea sediments resolves in detail the climatic events surrounding this transition.

Not only do plate boundary faults generate earthquakes, they also produce slow slip and non-volcanic tremor. New observations on these phenomena provide fresh insights into the conditions that dictate earthquake behaviour.

Subglacial water can significantly affect the velocity of ice streams and outlet glaciers of ice sheets. Depending on the geometry and capacity of the subglacial hydrologic system, increased surface melting in Greenland over the coming decades may influence the ice sheet's mass balance. Furthermore, subglacial lakes in Antarctica can modulate ice velocities and act as nucleation points for new fast-flowing ice streams.

Tropospheric ozone contributes significantly to human-induced greenhouse warming. Calculations from satellite measurements of spectral radiance suggest that ozone in the upper troposphere caused an average reduction in clear-sky outgoing long-wave radiation over the oceans of 0.48±0.14 W m⁻² for the year 2006 between 45^∘ S and 45^∘ N.

Submarine groundwater discharge, estimated from a ²²⁸Ra inventory across the upper Atlantic Ocean, provides a flux of 2–4×10¹³ m³ yr⁻¹, equivalent to 80–160% of the influx from rivers into the Atlantic Ocean.

On geological timescales, carbon dioxide enters the atmosphere through volcanism and organic matter oxidation and is removed through mineral weathering and carbonate burial. An analysis of ice-core CO₂ records and marine carbonate chemistry indicates a tight coupling between these processes during the past 610,000 years, which suggests that a weathering feedback driven by atmospheric CO₂ leads to a mass balance between CO₂ sources and sinks on long timescales.

Temperature changes with depth do not appear to be a primary control for either slow slip or fault-locking processes at the Hikurangi margin, North Island, New Zealand. Both slow-slip events and the geodetically observed transition from fault locking to free slip at depth occur at temperatures as low as 100 ^∘C.

Using experimental conditions approximating those of the early Earth, the partition coefficient for palladium was found to be sufficiently low to explain the palladium content of the Earth’s mantle in terms of an early equilibration of the mantle with core-forming metals, rather than requiring the addition of a ‘late veneer’ of chondritic material after core formation.

Nitryl chloride, an active halogen, can be produced through the night-time reaction of dinitrogen pentoxide with chloride-containing aerosol in the polluted marine boundary, and has been measured at levels that are sufficient to affect the photochemistry of oxidants off the southwestern US coast and near Houston, Texas.

The Eocene–Oligocene transition is the largest global cooling in the Cenozoic period. A comparison of three independent proxies from the continental shelf and deep ocean reveals a three-step transition to cold glacial conditions, with ice sheets 25% larger than their present size.

Jim Roberts and colleagues inhaled petrochemical fumes and navigated between ships and oil platforms in order to understand halogen chemistry in the Houston area and along the Texas coast.

Willard Moore and his colleagues collected 200-litre samples of sea water from depths of up to 1,000 metres and stirred up the odd octopus in order to determine the input of submarine groundwater discharge into the Atlantic Ocean.