Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Increasing concentrations of carbon dioxide in sea water are driving a progressive acidification of the ocean, with as yet unclear impacts on marine calcifying organisms. Simulations with an Earth system model suggest that future changes in the marine environment could be more severe than those experienced during the Palaeocene–Eocene thermal maximum, both in the deep ocean and near the surface.
Widespread glacier acceleration has been observed in Greenland in the past few years. Oceanographic observations taken in summer 2008 show that ocean waters melted a substantial fraction of ice along the calving fronts of three West Greenland glaciers, indicating that submarine melting has a profound influence on grounding-line stability.
The recent rapid increase in mass loss from the Greenland ice sheet is primarily attributed to an acceleration of outlet glaciers. Oceanographic data obtained in summer 2008 show that subtropical waters that reside year-round in the shelf ocean off Greenland continuously enter a large glacial fjord in East Greenland and contribute to melting at the glacier terminus.
Ninety-four million years ago, during Ocean Anoxic Event 2, there was a marked increase in the burial of organic carbon in marine sediments. Measurements of stomata in fossil leaves show that the two main pulses of carbon burial were associated with a decline in atmospheric CO2 levels of up to 26%.
The southwest corner of Western Australia has been subject to a serious drought in recent decades, whose ultimate cause remains unclear. A comparison of precipitation records in the area of drought and an ice core from East Antarctica reveal a significant inverse correlation between precipitation in the two locations, and suggest that the current drought may be highly unusual compared with the past 750 years of variability.
Reducing tropical deforestation is at present considered a cost-effective option for mitigating climate change. Satellite-based estimates of forest loss suggest that urban population growth and urban and international demand for agricultural products are key drivers of deforestation in the tropics.
In the Arctic spring, sunlight-induced reactions convert gaseous elemental mercury into compounds that are rapidly deposited on the snowpack. Analysis of the isotopic composition of mercury in snow samples collected during an atmospheric mercury depletion event suggests that sunlight triggers the re-emission of mercury from the snowpack.
In the North Atlantic region, six massive iceberg discharge events marked the last glacial period. A numerical model now links these events to ocean temperatures and ice-shelf conditions.
The south pole of Saturn's icy moon Enceladus is anomalously warm, geologically youthful and cryovolcanically active. Episodic convective overturn explains how the moon's modest sources of internal heat can be channelled into intense geological activity.
Indonesia's tsunami-warning system is scheduled to enter full operational mode by March 2010. The sooner it runs, the better: the threat of a tsunamigenic earthquake in the region is still imminent.
Hydrologists have thought of soil as a kind of giant sponge that soaks up precipitation and slowly releases it to streams. But according to new evidence the soil water used by vegetation may be largely decoupled from the water that flows through soils to streams.
Several periods of global ocean anoxia punctuated the Cretaceous period. Marine-sediment chemistry indicates that extensive volcanism at the beginning of Oceanic Anoxic Event 2 released sulphur to the oceans, triggering a biogeochemical cascade that led to enhanced surface productivity and depletion of oxygen in the underlying waters.
The rise in atmospheric carbon dioxide at the end of the Last Glacial Maximum has been attributed to the release of carbon dioxide from the deep Southern Ocean. However, reconstructions of the radiocarbon signature of Chilean margin intermediate waters during the glacial termination do not reflect the influence of such a release.
Jupiter’s large moons Ganymede and Callisto are similar in size and composition, but different in surface and interior characteristics. Simulations with geophysical models of core formation indicate that the difference in impact energy received by the two satellites during the period of late heavy bombardment can explain the dichotomy.
