Volume 1 Issue 5, May 2008

Volume 1 Issue 5

On geological timescales, carbon dioxide enters the atmosphere through volcanism and oxidation of organic matter, and is removed through mineral weathering and carbonate burial. An analysis of ice-core CO2 records and marine carbonate chemistry indicates a tight coupling between these processes during the past 610,000 years, which suggests that a weathering feedback driven by atmospheric CO2 leads to a mass balance between carbon sources and sinks on long timescales. The cover image shows an eruption of Augustine Volcano, Alaska on 26 March 2006. Volcanic eruptions and outgassing release CO2, as well as ash and other gases, to the atmosphere.

Image credit: Cyrus Read.

Cover design by Karen Moore

Editorial

  • Editorial |

    The production of clean energy for transportation makes demands on resources that are already scarce. Biofuels can contribute to a solution, but only to a limited extent.

Correspondence

Commentary

  • Commentary |

    Power generation as well as the production of fuels for transportation requires water, and the supply of high-quality freshwater is energy intensive. A growing population and climate change will increase the pressure on both resources.

    • Carey W. King
    • , Ashlynn S. Holman
    •  & Michael E. Webber

Research Highlights

News and Views

  • News & Views |

    Atmospheric carbon dioxide levels greatly influence the Earth's climate. Evidence from ice cores and marine sediments suggests that over timescales beyond the glacial cycles, carbon fluxes are finely balanced and act to stabilize temperatures.

    • David Archer
  • News & Views |

    Late addition of meteoric material to the Earth's mantle could explain the presence of iron-loving elements that should have entered the Earth's core at its formation. But experiments at realistic conditions show that enough palladium could have remained in the mantle.

    • Bernard Marty
  • News & Views |

    In densely populated coastal areas, reactions of polluted air with sea salt aerosol from the ocean can lead to high surface ozone levels that affect air quality.

    • Roland von Glasow
  • News & Views |

    The generally warm and ice-free conditions of the Eocene epoch rapidly declined to the cold and glaciated state of the Oligocene epoch. Geochemical evidence from deep-sea sediments resolves in detail the climatic events surrounding this transition.

    • Katharina Billups
  • News & Views |

    Not only do plate boundary faults generate earthquakes, they also produce slow slip and non-volcanic tremor. New observations on these phenomena provide fresh insights into the conditions that dictate earthquake behaviour.

    • Michael R. Brudzinski

Review

  • Review Article |

    Subglacial water can significantly affect the velocity of ice streams and outlet glaciers of ice sheets. Depending on the geometry and capacity of the subglacial hydrologic system, increased surface melting in Greenland over the coming decades may influence the ice sheet's mass balance. Furthermore, subglacial lakes in Antarctica can modulate ice velocities and act as nucleation points for new fast-flowing ice streams.

    • Robin E. Bell

Letters

  • Letter |

    Tropospheric ozone contributes significantly to human-induced greenhouse warming. Calculations from satellite measurements of spectral radiance suggest that ozone in the upper troposphere caused an average reduction in clear-sky outgoing long-wave radiation over the oceans of 0.48±0.14 W m−2 for the year 2006 between 45 S and 45 N.

    • Helen M. Worden
    • , Kevin W. Bowman
    • , John R. Worden
    • , Annmarie Eldering
    •  & Reinhard Beer
  • Letter |

    On geological timescales, carbon dioxide enters the atmosphere through volcanism and organic matter oxidation and is removed through mineral weathering and carbonate burial. An analysis of ice-core CO2 records and marine carbonate chemistry indicates a tight coupling between these processes during the past 610,000 years, which suggests that a weathering feedback driven by atmospheric CO2 leads to a mass balance between CO2 sources and sinks on long timescales.

    • Richard E. Zeebe
    •  & Ken Caldeira
  • Letter |

    Temperature changes with depth do not appear to be a primary control for either slow slip or fault-locking processes at the Hikurangi margin, North Island, New Zealand. Both slow-slip events and the geodetically observed transition from fault locking to free slip at depth occur at temperatures as low as 100 C.

    • Robert McCaffrey
    • , Laura M. Wallace
    •  & John Beavan
  • Letter |

    Using experimental conditions approximating those of the early Earth, the partition coefficient for palladium was found to be sufficiently low to explain the palladium content of the Earth’s mantle in terms of an early equilibration of the mantle with core-forming metals, rather than requiring the addition of a ‘late veneer’ of chondritic material after core formation.

    • K. Righter
    • , M. Humayun
    •  & L. Danielson

Articles

  • Article |

    Nitryl chloride, an active halogen, can be produced through the night-time reaction of dinitrogen pentoxide with chloride-containing aerosol in the polluted marine boundary, and has been measured at levels that are sufficient to affect the photochemistry of oxidants off the southwestern US coast and near Houston, Texas.

    • Hans D. Osthoff
    • , James M. Roberts
    • , A. R. Ravishankara
    • , Eric J. Williams
    • , Brian M. Lerner
    • , Roberto Sommariva
    • , Timothy S. Bates
    • , Derek Coffman
    • , Patricia K. Quinn
    • , Jack E. Dibb
    • , Harald Stark
    • , James B. Burkholder
    • , Ranajit K. Talukdar
    • , James Meagher
    • , Fred C. Fehsenfeld
    •  & Steven S. Brown
  • Article |

    The Eocene–Oligocene transition is the largest global cooling in the Cenozoic period. A comparison of three independent proxies from the continental shelf and deep ocean reveals a three-step transition to cold glacial conditions, with ice sheets 25% larger than their present size.

    • Miriam E. Katz
    • , Kenneth G. Miller
    • , James D. Wright
    • , Bridget S. Wade
    • , James V. Browning
    • , Benjamin S. Cramer
    •  & Yair Rosenthal

Erratum

Backstory

  • Backstory |

    Willard Moore and his colleagues collected 200-litre samples of sea water from depths of up to 1,000 metres and stirred up the odd octopus in order to determine the input of submarine groundwater discharge into the Atlantic Ocean.

  • Backstory |

    Jim Roberts and colleagues inhaled petrochemical fumes and navigated between ships and oil platforms in order to understand halogen chemistry in the Houston area and along the Texas coast.