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Ammonia is a significant atmospheric pollutant, accelerating the formation of particulate matter and damaging aquatic and terrestrial ecosystems. Infrared measurements of ammonia concentrations, obtained by the IASI/MetOp satellite, suggest that ammonia emissions in the Northern Hemisphere have been markedly underestimated.

Sea level has varied by over one hundred metres across glacial–interglacial cycles over the past 520,000 years. An extended sea-level reconstruction shows a strong coupling between these sea-level changes and Antarctic surface temperatures over the past five glacial cycles.

The mechanisms for localization of black-smoker systems at mid-ocean ridges remain to be fully understood. Seismic data for a segment of the Juan de Fuca ridge with long-lived black-smoker vents reveal ongoing magma recharge into the crustal magma chamber, thereby providing an explanation for the localization.

For the past few centuries, multidecadal climate variability in North Atlantic sea surface temperatures has been modulated by the Atlantic Multidecadal Oscillation (AMO). A coral-based temperature reconstruction reveals that the AMO is a transient climate feature that only became significant after AD 1730.

Over the past two decades, seasonal periods of rapid atmospheric mercury deposition over Antarctica have been described. Ice core records show that similar events have occurred during previous glacial periods, probably as a result of interactions between sea salts and mineral dust in the polar atmosphere.

The two main iron-bearing silicate phases in the mantle—ferroperovskite and ferropericlase—are expected to partition iron isotopes differently. Theoretical calculations suggest that the spin state of iron strongly influences the iron isotopic composition of ferropericlase, whereas the iron isotopic composition of ferroperovskite is almost independent of spin state.

Global mean sea-level change has increased from a few centimetres per century over recent millennia to a few tens of centimetres per century in recent decades. A review of the latest work shows that global mean sea-level rise is unlikely to exceed one metre over the twenty-first century, but regional departures from this global mean could reach several decimetres.

A widespread biotic turnover occurred around the time of the Sturtian glaciation. Microfossil analyses show that one regional extinction pre-dates the glacial advance, challenging the more severe models for glacial effects in the Neoproterozoic era.

Millions of people in southern Asia rely on arsenic-contaminated groundwater to live. Massive water withdrawals through wells may be increasing the problem by drawing arsenic-mobilizing substances into shallow aquifers and arsenic-contaminated shallow groundwaters into deeper aquifers.

In the world of Web 2.0, the variety of channels for communicating science is exploding. Technology can help to generate images that attract attention, but there is much more to reaching the public than pretty pictures.

Ice clouds significantly affect the Earth's radiative forcing, but which particles lie at the core of the ice crystals is a matter of debate. In-flight spectroscopy suggests that biogenic materials contribute to ice formation in clouds.

The lack of strong splitting of seismic shear waves below central Nevada is in marked contrast to the surrounding region. Seismic data and numerical experiments suggest that a skinny, cylindrical drip of lithosphere may be to blame.

The complex three-dimensional structure of the Earth's solid inner core reveals how it has grown through time. Numerical simulations of the solidification process suggest that part of this structure has resulted from recent tectonic activity.

Remnants of the Laurentide ice sheet lasted until about 7,000 years ago. Climate simulations show that they caused the multimillennial delay between maximum early Holocene solar radiation and temperatures evident in Northern Hemisphere proxy records.