Articles in 2008

The North Atlantic Oscillation controls winter climate variability in eastern North America and Europe. Coral-derived records of sea surface temperature in Bermuda suggest that multidecadal variability of the North Atlantic Oscillation has increased in the past few decades relative to the early nineteenth century.

Although the India–Eurasia collision initiated ∼50 Myr ago, major deformation and exhumation of the Himalaya did not begin until the early Neogene (∼23 Myr ago). This coincides with the increased intensity of the Asian monsoons, as indicated by weathering records from the South China Sea, Bay of Bengal and Arabian Sea, and hints at a dynamic coupling between climate and both erosion and deformation in the Himalaya.

Aaron Berger and colleagues leapt out of helicopters in the snow and fog in their quest to understand the effects of glacial erosion on mountain formation.

William Bowman and colleagues braved beverages of pig fat and vodka in their attempt to understand the impact of long-term nitrogen deposition on Slovakian soils.

Sustained nitrogen deposition has had a detrimental effect on ecosystems in Europe and North America. Now a grassland in Slovakia is showing symptoms of extreme soil acidification not previously observed in association with nitrogen deposition.

Understanding heat exchange in the Indian Ocean requires knowledge of the magnitudes and locations of both meridional deep-water transport and mixing. Observations from a fracture zone in the Southwest Indian Ridge quantify the flow through this narrow region to 20–30% of the total meridional overturning circulation in the Indian Ocean, and provide an example of elevated turbulence in a deep sheared flow.

The interactions between climate and tectonics in active mountain ranges are complex and important. Field and geophysical data from the St Elias Range of Alaska show that glacial erosion can influence the dynamics of the lithosphere in such settings.

Climate warming is not the only consequence of rising levels of atmospheric greenhouse gases. The only way to counter all effects, including those on rainfall and ocean acidity, is to remove carbon from the climate system.

Two chains of seamounts on the Pacific plate subduct beneath central Japan. In the process, a fragment of the Pacific slab has become wedged in the subduction zone and may be the source of recurring deep-thrust earthquakes beneath Tokyo.

Riverine transport of terrestrial organic carbon to the oceans exerts an important long-term control on atmospheric carbon dioxide levels. Tropical cyclones participate in this process by delivering recently fixed carbon to the sea.

Natural climate variability and limited observational records have made identifying human-influenced climate change at the poles difficult. But a human signature is now emerging in rising Arctic and Antarctic temperatures.

Polar temperatures have been warming significantly over the past few decades. A comparison between observational temperature records and model simulations shows that temperature changes in both the Arctic and Antarctic regions can be attributed to human activity.

Geo-engineering proposals for mitigating climate change continue to proliferate without being tested. It is time to select and assess the most promising ideas according to efficacy, cost, all aspects of risk and, importantly, their rate of mitigation.

The 2004 Sumatra earthquake was one of the largest events to occur in a subduction zone in the past 50 years. Seismic reflection data for this subduction zone reveal thrust faults cutting across the entire oceanic crust. This observation, coupled with the hypocentres of aftershocks, suggests that the megathrust—the interface between the Indo-Australian plate and the Sunda plate—currently lies in the oceanic mantle.

The quest to determine climate sensitivity has been going on for decades, with disturbingly little progress in narrowing the large uncertainty range. But fascinating new insights have been gained that will provide useful information for policy makers, even though the upper limit of climate sensitivity will probably remain uncertain for the near future.