Research articles

Zinc is a marine nutrient that may have been limited in the early oceans. Estimates of marine zinc availability through time suggest that values were instead near-modern during the Proterozoic eon.

The West Antarctic Ice Sheet is contributing to sea-level rise, but temperature trends in the region have remained uncertain. A complete temperature record for Byrd Station in central West Antarctica, spanning from 1958 to 2010, establishes West Antarctica as one of the fastest-warming regions globally.

Wind power inputs at the surface ocean are dissipated through smaller-scale processes in the ocean interior and turbulent boundary layer. Simulations suggest that seafloor topography enhances turbulent mixing and energy dissipation in the ocean interior.

The recovery from the end-Permian mass extinction was slow and prolonged. A temperature reconstruction shows that further biotic crises during the recovery were associated with extreme warmth.

The tropical Atlantic Ocean shows sea surface temperature variability on interannual timescales. Observational and model data suggest that some of this variability can be attributed to the advection of anomalously warm northern subtropical waters toward the Equator.

Tropospheric thunderstorms have been reported to disturb the lower ionosphere, at altitudes of 65–90 km. The use of lightning signals from a distant mesoscale storm to probe the lower ionosphere above a small tropospheric thunderstorm reveals a reduction in ionospheric electron density in response to lightning discharges in the small storm.

Every year, thousands of mesoscale storms (termed polar lows) cross the climatically sensitive subpolar North Atlantic Ocean. High-resolution numerical simulations of the ocean circulation, taking into account the effect of these storms on deep-water formation, suggest that polar lows significantly affect the global ocean circulation.

The recurrence times of great Himalayan earthquakes are difficult to assess because they rarely rupture the surface. Field mapping and ¹⁴C dating of offset fluvial deposits are used to identify two great Himalayan quakes that ruptured the surface along the main plate boundary fault in AD 1255 and 1934.

Changes in continental water storage have been difficult to constrain from space-borne gravity data in regions experiencing both ice melting and glacial isostatic adjustment. Separation of the hydrologic and isostatic signals reveals increases in water storage in both North America and Scandinavia over the past decade.

Sulphate concentrations in the ocean prior to 2.4 Gyr ago were lower than today. The sulphur isotope systematics of 2.7-Gyr-old sulphide deposits suggests that these low concentrations were maintained by a balance between hydrothermal sources and microbial sulphate reduction.

Over 90% of marine species were lost during the end-Permian extinction. Fossil data show that the crisis in China was marked by two distinct phases of marine extinction separated by a 180,000-year recovery period.

A pulse of sulphur dioxide in Venus’s upper atmosphere was observed by the Pioneer Venus spacecraft in the 1970s and 1980s and attributed to volcanism. Recent sulphur dioxide measurements from Venus Express indicate decadal-scale fluctuations in sulphur dioxide above Venus’s cloud tops in an atmosphere that is more dynamic than expected.

As a result of ocean acidification, aragonite may become undersaturated by 2050 in the upper layers of the Southern Ocean. Analyses of sea snail specimens, extracted live from the Southern Ocean in January and February 2008, show that the shells of these organisms are already dissolving.

The current mountain pine beetle infestation in forests in British Columbia ranks among the largest ecological disturbances recorded to date. An analysis of remote sensing data suggests that the resultant forest loss has led to a 1 °C rise in summertime surface temperatures.

The West Antarctic Ice Sheet is sensitive to ocean warming and contains enough ice to significantly raise sea level. Direct oceanographic measurements in the Amundsen Sea during 2010 show continuous inflow of warm water towards the thinning ice shelves in West Antarctica.

The mantle plume beneath Hawai’i shifted southwards by about 15° between 80 and 50 million years ago. Palaeomagnetic inclination data from four South Pacific seamounts along with Ar/Ar dating reveal that by contrast the Louisville hotspot—Hawai’i’s southern hemisphere counterpart—remained within 3° of its present latitude between 70 and 50 million years ago.

Diatoms—unicellular algae that form substantial blooms in cold, nutrient-rich waters—are thought to be responsible for the export of marine silica to depth. An analysis of the elemental composition of marine cyanobacteria suggests that picocyanobacteria also accumulate significant quantities of silicon.

The efficiency with which the oceans take up heat has a significant influence on the rate of global warming. An analysis of observations of heat uptake into the deep North Atlantic shows that the propagation of density-compensated temperature anomalies is an important mechanism for this heat uptake, and depends on high salinity in the subpolar gyre.

Considerable climatic variability on decadal to millennial timescales has been documented for the Holocene epoch. A reappraisal of estuarine and coastal sediment records reveals five periods of enhanced storminess during the past 6,500 years, at a frequency of approximately every 1,500 years and unrelated to solar irradiance variations.

In contrast to the dramatic decline of Arctic sea ice, Antarctic sea ice has increased over recent decades. A 19-year satellite record of sea-ice motion shows that winds are driving decadal trends in Antarctic ice concentrations.