Volume 1 Issue 12, December 2008

Volume 1 Issue 12

Global warming is likely to increase soil organic carbon decomposition, and thus CO2 release to the atmosphere, creating a positive feedback cycle. Inclusion of realistic estimates of soil black carbon in prediction models results in a decrease in soil CO2 emission in Australia by up to 24.4% following a 3 °C warming over 100 years, suggesting that black carbon reduces the strength of this feedback. The image shows a high-fuel-load, high-intensity savanna fire near Darwin, Northern Territory, Australia. (Image credit: R. D. Graetz.)

Editorial

  • Editorial |

    Destruction from earthquakes continues to threaten poor and wealthy nations alike. The Global Earthquake Model is a potentially important step towards providing risk information on a worldwide basis, using a unified standard.

Commentary

  • Commentary |

    The 2008 Atlantic hurricane season once again highlighted the challenges awaiting low-lying population centres close to the ocean. In the face of global sea-level rise, unconventional thinking is required to make urban coasts more resilient.

    • Torbjörn E. Törnqvist
    •  & Douglas J. Meffert

Research Highlights

News and Views

  • News & Views |

    Glaciologists have speculated that subglacial floods might lead to increased ice flow rates, altering Antarctica's mass balance and contribution to sea-level rise. Now, observations from Byrd Glacier in East Antarctica firmly link a subglacial flood to a 10% speed up of the glacier.

    • Helen Amanda Fricker
  • News & Views |

    The North Atlantic Oscillation has shown high variability over the past few decades. A two-hundred-year-long temperature reconstruction from a Bermuda coral suggests a link to recent climate warming.

    • Oliver Timm
  • News & Views |

    The Earth's known rock reservoirs contain more radiogenic lead than expected on average. Mantle-derived rocks with highly unradiogenic lead — as discovered in the Horoman massif — may bear witness to a previously unsampled, complementary reservoir.

    • Albrecht W. Hofmann
  • News & Views |

    The influence of climate on mountain building has long been debated. A reconstruction for the past 25 million years suggests coincidence of Himalayan erosion and monsoon intensification, hinting at a causal relationship.

    • A. Joshua West
  • News & Views |

    Two-thirds of terrestrial carbon is stored as organic matter in soils, but its response to warming has yet to be resolved. A soil warming experiment in a Canadian forest has revealed that the leaf-derived compound cutin is resistant to decomposition under elevated temperatures.

    • Cindy Prescott

Review

  • Review Article |

    The Snowball Earth concept envisages a fully frozen Earth for millions of years several times during the Neoproterzoic Era between 1,000 and 542 million years ago. However, the sedimentary evidence suggests that despite the severity of glaciation, some oceans must have remained ice-free.

    • Philip A. Allen
    •  & James L. Etienne

Letters

  • Letter |

    Large ice streams and outlet glaciers drain Greenland and Antarctica. An observed acceleration of ice velocity in one of these outlet glaciers, Byrd Glacier, East Antarctica coincides with a large water discharge from two subglacial lakes, allowing direct attribution of the change in glacier dynamics to the water drainage network beneath the ice.

    • Leigh A. Stearns
    • , Benjamin E. Smith
    •  & Gordon S. Hamilton
  • Letter |

    Global warming is likely to increase soil organic carbon decomposition, and thus CO2 release to the atmosphere, creating a positive feedback cycle. Inclusion of realistic estimates of soil black carbon in a climate model results in a decrease in soil CO2 emission in Australia by up to 24.4% following a 3 C warming over 100 years, suggesting that black carbon reduces the strength of this feedback.

    • Johannes Lehmann
    • , Jan Skjemstad
    • , Saran Sohi
    • , John Carter
    • , Michele Barson
    • , Pete Falloon
    • , Kevin Coleman
    • , Peter Woodbury
    •  & Evelyn Krull
  • Letter |

    Future climate warming is predicted to accelerate the decomposition of labile soil organic matter, but to have little impact on the degradation of biochemically resistant organic compounds such as leaf cuticles and lignin. However, 14 months of soil warming in a temperate mixed forest resulted in a build-up of leaf-cuticle-derived carbon and an increased decomposition of lignin in soils.

    • Xiaojuan Feng
    • , André J. Simpson
    • , Kevin P. Wilson
    • , D. Dudley Williams
    •  & Myrna J. Simpson
  • Letter |

    Pacific salmon deliver substantial quantities of nutrients to freshwater streams when they spawn. Experiments with a recirculation flume support the idea that bacterially mediated aggregation of salmon organic matter, as well as inorganic particulate matter, is responsible for nutrient delivery to these stream beds.

    • John F. Rex
    •  & Ellen L. Petticrew
  • Letter |

    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.

    • Nathalie F. Goodkin
    • , Konrad A. Hughen
    • , Scott C. Doney
    •  & William B. Curry
  • Letter |

    Coral records from a range of sites extend the index of the Indian Ocean Dipole back to 1846. Indian Ocean Dipole events increased in strength and frequency in the twentieth century, coincident with the development of direct feedbacks with the Asian Monsoon.

    • Nerilie J. Abram
    • , Michael K. Gagan
    • , Julia E. Cole
    • , Wahyoe S. Hantoro
    •  & Manfred Mudelsee
  • Letter |

    During the early stages in the formation of divergent margins, the lithosphere experiences large changes in temperature that can determine its strength and influence magma generation. Heat-flow data from the Eastern Gulf of Aden indicate a thermal anomaly that has persisted after continental break-up. This anomaly may have been caused by small-scale convection that occurred during and after rifting.

    • Francis Lucazeau
    • , Sylvie Leroy
    • , Alain Bonneville
    • , Bruno Goutorbe
    • , Frédérique Rolandone
    • , Elia d’Acremont
    • , Louise Watremez
    • , Doga Düsünur
    • , Patrick Tuchais
    • , Philippe Huchon
    • , Nicolas Bellahsen
    •  & Khalfan Al-Toubi
  • Letter |

    Peridotites from the Horoman massif have the least radiogenic lead isotope ratios reported from any mantle material, and unlike any inferred from the compositions of mid-ocean ridge basalts. These data hint at the existence of ancient mantle domains that are not sampled by mid-ocean ridge basalts.

    • Sanjeewa P. K. Malaviarachchi
    • , Akio Makishima
    • , Masaaki Tanimoto
    • , Takeshi Kuritani
    •  & Eizo Nakamura

Articles

  • Article |

    The response of ocean circulation in the Southern Ocean to changes in wind stress and surface buoyancy fluxes is under debate. An analysis of Argo data and historical measurements suggests that transport in the Antarctic Circumpolar Current and the meridional overturning circulation in the Southern Ocean are insensitive to decadal changes in wind stress.

    • C. W. Böning
    • , A. Dispert
    • , M. Visbeck
    • , S. R. Rintoul
    •  & F. U. Schwarzkopf
  • Article |

    The formation and circulation of Antarctic Intermediate Water has varied over glacial–interglacial timescales. A neodymium record from the Atlantic Ocean basin suggests that changes in circulation may have been driven by changes both in Antarctic Intermediate Water formation in the Southern Ocean and in the strength of North Atlantic meridional overturning.

    • Katharina Pahnke
    • , Steven L. Goldstein
    •  & Sidney R. Hemming
  • Article |

    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.

    • Peter D. Clift
    • , Kip V. Hodges
    • , David Heslop
    • , Robyn Hannigan
    • , Hoang Van Long
    •  & Gerome Calves

Backstory

  • Backstory |

    Nathalie Goodkin and colleagues dug deep into coral geochemistry and wrestled with waves for a 200-year record of the North Atlantic Oscillation.

  • Backstory |

    Deep-sea drilling was the order of the day for Peter Clift and colleagues on their expedition to the South China Sea.

  • Backstory |

    Stephen Rintoul and an international team of oceanographers headed south on the Australian icebreaker, Aurora Australis, to discover how Southern Ocean currents influence climate and biodiversity.