Volume 8 Issue 9, September 2015

Volume 8 Issue 9

Faults are unlocked by earthquakes. Analysis of seismic data from the 2015 Nepal earthquake shows that only part of the Main Himalayan Thrust fault was unzipped by the quake, leaving much of the fault locked and ready to slip in a future event. The image shows the Swayambhunath temple in Kathmandu basin eight days after the M w 7.8, Gorkha earthquake of April 2015.

Letter p708

IMAGE: CLAUDETTE RIBARDIÈRE

COVER DESIGN: DAVID SHAND

Editorial

  • Editorial |

    During several intervals in Earth's history, ice sheets expanded to cover the globe. These glaciations may be intricately linked to the evolution of life.

Correspondence

Feature

  • Feature |

    The Earth underwent two snowball glaciation events between 720 and 635 million years ago. The preceding expansion of eukaryotic algae and a consequent rise in emissions of organic cloud condensation nuclei may have contributed to the dramatic cooling.

    • Georg Feulner
    • , Christian Hallmann
    •  & Hendrik Kienert

News and Views

  • News & Views |

    Braided channels are rare on ocean floors, but abundant on land. Experiments and theory suggest that deeper flows and rapid overbank deposition restrict braiding in underwater rivers relative to their terrestrial counterparts.

    • Jeff Peakall
  • News & Views |

    Tropospheric ozone is generated from precursor pollutants, but can be blown far afield. Satellite observations show rising ozone levels over China — and almost stable levels over western North America despite stricter regulations.

    • Ruth M. Doherty
  • News & Views |

    Saturn's F ring is chaperoned on both sides by the tiny moons Prometheus and Pandora. Numerical simulations show that this celestial ballet can result from the collision of two aggregates that evolved out of Saturn's main rings.

    • Aurélien Crida
  • News & Views |

    Evidence for a Neoproterozoic Snowball Earth in the sedimentary record has been controversial. A weathered horizon preserved in sedimentary rocks from Svalbard may provide a rare signature of prolonged global glaciation.

    • Philip Allen

Progress Article

  • Progress Article |

    Sea surface temperatures have varied over the past 2,000 years. A synthesis of surface-temperature reconstructions shows ocean surface cooling from ad 1 to 1800, with much of the trend from 800 to 1800 driven by volcanic eruptions.

    • Helen V. McGregor
    • , Michael N. Evans
    • , Hugues Goosse
    • , Guillaume Leduc
    • , Belen Martrat
    • , Jason A. Addison
    • , P. Graham Mortyn
    • , Delia W. Oppo
    • , Marit-Solveig Seidenkrantz
    • , Marie-Alexandrine Sicre
    • , Steven J. Phipps
    • , Kandasamy Selvaraj
    • , Kaustubh Thirumalai
    • , Helena L. Filipsson
    •  & Vasile Ersek

    Collection:

Review

Letters

  • Letter |

    Tropospheric levels of ozone and its precursors have risen in Asia since 2000. Satellite observations and chemistry–transport simulations suggest that transport of these pollutants to North America partly offsets benefits from stricter regulation.

    • Willem W. Verstraeten
    • , Jessica L. Neu
    • , Jason E. Williams
    • , Kevin W. Bowman
    • , John R. Worden
    •  & K. Folkert Boersma
  • Letter |

    Rivers and streams are key sources of CO2. Estimated emissions and aquatic productivity from across the US show that small streams predominantly emit CO2 produced in soils, but the contribution from aquatic metabolism increases with river size.

    • E. R. Hotchkiss
    • , R. O. Hall Jr
    • , R. A. Sponseller
    • , D. Butman
    • , J. Klaminder
    • , H. Laudon
    • , M. Rosvall
    •  & J. Karlsson
  • Letter |

    Braided channels are rare in submarine environments, yet common in fluvial systems. Laboratory experiments suggest that the formation mechanisms are the same, but submarine channels are typically not wide enough to promote braiding.

    • Brady Z. Foreman
    • , Steven Y. J. Lai
    • , Yuhei Komatsu
    •  & Chris Paola
  • Letter |

    The presence of dynamic ice sheets during Snowball Earth glaciations is controversial. Geological evidence and ice sheet modelling suggest that ice sheets may have responded to orbital forcing when pCO2 reached a certain threshold.

    • Douglas I. Benn
    • , Guillaume Le Hir
    • , Huiming Bao
    • , Yannick Donnadieu
    • , Christophe Dumas
    • , Edward J. Fleming
    • , Michael J. Hambrey
    • , Emily A. McMillan
    • , Michael S. Petronis
    • , Gilles Ramstein
    • , Carl T. E. Stevenson
    • , Peter M. Wynn
    •  & Ian J. Fairchild
  • Letter |

    Faults are unlocked by earthquakes. Analysis of seismic data from the 2015 Nepal earthquake shows that only part of the Main Himalayan Thrust fault was unzipped by the quake, leaving much of the fault locked and ready to slip in a future event.

    • Jean-Philippe Avouac
    • , Lingsen Meng
    • , Shengji Wei
    • , Teng Wang
    •  & Jean-Paul Ampuero

Articles

  • Article |

    Long-term changes of the mountain glaciers in the Tien Shan, Central Asia, are not well constrained. Remote sensing data and glaciological models reveal a 27% decline of glacier mass from 1961 to 2012, linked to increased summer melting.

    • Daniel Farinotti
    • , Laurent Longuevergne
    • , Geir Moholdt
    • , Doris Duethmann
    • , Thomas Mölg
    • , Tobias Bolch
    • , Sergiy Vorogushyn
    •  & Andreas Güntner
  • Article |

    Ammonium levels in Greenland ice cores track changes in soil emissions and wildfires, primarily in North America. Ice-core ammonium records show abrupt increases in wildfire activity during brief warmings in the last glacial period.

    • Hubertus Fischer
    • , Simon Schüpbach
    • , Gideon Gfeller
    • , Matthias Bigler
    • , Regine Röthlisberger
    • , Tobias Erhardt
    • , Thomas F. Stocker
    • , Robert Mulvaney
    •  & Eric W. Wolff
  • Article |

    How plate tectonic subduction is initiated is unclear. Analysis of sediments and rock cores taken from the Izu–Bonin–Mariana subduction zone trench suggests subduction started spontaneously in this region around 50 million years ago.

    • Richard J. Arculus
    • , Osamu Ishizuka
    • , Kara A. Bogus
    • , Michael Gurnis
    • , Rosemary Hickey-Vargas
    • , Mohammed H. Aljahdali
    • , Alexandre N. Bandini-Maeder
    • , Andrew P. Barth
    • , Philipp A. Brandl
    • , Laureen Drab
    • , Rodrigo do Monte Guerra
    • , Morihisa Hamada
    • , Fuqing Jiang
    • , Kyoko Kanayama
    • , Sev Kender
    • , Yuki Kusano
    • , He Li
    • , Lorne C. Loudin
    • , Marco Maffione
    • , Kathleen M. Marsaglia
    • , Anders McCarthy
    • , Sebastién Meffre
    • , Antony Morris
    • , Martin Neuhaus
    • , Ivan P. Savov
    • , Clara Sena
    • , Frank J. Tepley III
    • , Cees van der Land
    • , Gene M. Yogodzinski
    •  & Zhaohui Zhang