Volume 8 Issue 7 July 2015

Volume 8 Issue 7

Strong vortices have been observed at Saturn's poles. Simulations suggest that tropospheric polar flows on giant planets are driven by moist convection, and that although vortices can develop on Saturn, similar cyclones are not expected on Jupiter. The image shows the spinning vortex of Saturn's north polar storm in a false-colour image from NASA's Cassini spacecraft, taken on 27 November, 2012.

Letter p523; News & Views p503

IMAGE: NASA/JPL-CALTECH/SSI

COVER DESIGN: DAVID SHAND

Editorial

  • Editorial |

    Developing countries lag far behind, in terms of scientific — including geoscience — output. Failing to spread the know-how means that the world is missing out on great intellectual potential.

Correspondence

Commentary

  • Commentary |

    The history of attempts to spread scientific know-how beyond western centres of excellence is littered with failures. Capacity building needs long-term commitment, a critical mass of trainees, and a supportive home environment.

    • Bruce Hewitson

News and Views

  • News & Views |

    Earth's crust was thought to deform uniformly over most of the seismic cycle. Analysis of two centuries of nautical surveys from Chile reveals temporal variability that complicates our view of time-dependent seismic hazards.

    • Aron J. Meltzner
  • News & Views |

    Saturn's poles exhibit giant swirling cyclones, whereas Jupiter's poles may not. Simulations of giant planet atmospheres suggest that just the right balance of convective storm energy and poleward drift of cyclones may explain Saturn's vortices.

    • Leigh N. Fletcher
  • News & Views |

    The ocean is an important source of the potent greenhouse gas N2O. Measurements in the tropical South Pacific have revealed a massive efflux of N2O from the coastal upwelling zone.

    • Imke Grefe
  • News & Views |

    The continents are archives of Earth's evolution. Analysis of the isotopic signature of continental crust globally suggests that buoyant, silicic continents began to form 3 billion years ago, possibly linked to the onset of plate tectonics.

    • Cin-Ty A. Lee
    •  & N. Ryan McKenzie

Perspective

Review

  • Review |

    The solar wind, cometary ices, and inner Solar System bodies exhibit distinct nitrogen isotopic compositions. A synthesis of these analyses suggests that these distinct reservoirs may be the result of early fractionation processes.

    • Evelyn Füri
    •  & Bernard Marty

Letters

  • Letter |

    Strong vortices have been observed at Saturn’s poles. Simulations suggest that tropospheric polar flows on giant planets are driven by moist convection, and that, while vortices can develop on Saturn, similar cyclones are not expected on Jupiter.

    • Morgan E O’Neill
    • , Kerry A. Emanuel
    •  & Glenn R. Flierl
  • Letter |

    Oceans emit a third of the natural emissions of nitrous oxide. High-resolution measurements suggest that the Peruvian coast is a hotspot of nitrous oxide fluxes, representing 5–22% of global ocean emissions from previous estimates.

    • D. L. Arévalo-Martínez
    • , A. Kock
    • , C. R. Löscher
    • , R. A. Schmitz
    •  & H. W. Bange
  • Letter |

    The factors leading to the full retreat of ice sheets during deglaciation are debated. Numerical modelling suggests that the Laurentide ice sheet retreated only after a threshold for warming and radiative forcing was passed in the Holocene.

    • David J. Ullman
    • , Anders E. Carlson
    • , Faron S. Anslow
    • , Allegra N. LeGrande
    •  & Joseph M. Licciardi
  • Letter |

    The effect of glacial–interglacial cycles on surface weathering rates has been unclear. A beryllium-based proxy for weathering shows minimal variations in the input of silicate weathering products to the oceans for the past two million years.

    • Friedhelm von Blanckenburg
    • , Julien Bouchez
    • , Daniel E. Ibarra
    •  & Kate Maher
  • Letter |

    Records of complete earthquake cycles are rare. Analysis of historical nautical charts and modern GPS data that record a full earthquake cycle in Chile show that great earthquakes can create small amounts of permanent uplift.

    • Robert L. Wesson
    • , Daniel Melnick
    • , Marco Cisternas
    • , Marcos Moreno
    •  & Lisa L. Ely
  • Letter |

    The continental crust provides a record of Earth’s evolution. Analysis of the geochemical signature of continental crust formed since the Hadean points to the initiation of plate tectonics about 3 billion years ago.

    • Bruno Dhuime
    • , Andreas Wuestefeld
    •  & Chris J. Hawkesworth
  • Letter |

    The composition of the Earth’s lower mantle is not well constrained. First-principles calculations support a pyrolitic composition containing ferric iron, suggesting that the upper and lower mantles are geochemically uniform.

    • Xianlong Wang
    • , Taku Tsuchiya
    •  & Atsushi Hase

Articles

Erratum