Volume 8 Issue 2, February 2015

Volume 8 Issue 2

Holocene temperature trends in the Arctic are unclear. An isotope record from ice wedges in Siberia suggests that winters have warmed since the mid-Holocene, whereas summer temperatures have cooled. The image shows a Pleistocene ice wedge on Muostakh Island, North Siberia, in August 2012.

Letter p122

IMAGE: THOMAS OPEL

COVER DESIGN: DAVID SHAND

Editorial

  • Editorial |

    Humans have altered their environment ever since they first appeared. Updates on three frameworks of thinking about the scale of twenty-first-century human influence on the Earth are invigorating the global change debate.

Correspondence

News and Views

  • News & Views |

    Soil contains aged organic carbon that can be hundreds or thousands of years old. Human disturbance in small and large watersheds is mobilizing some of this fossil carbon from soils to aquatic systems.

    • Chris Evans
  • News & Views |

    The Sahara was more humid and habitable thousands of years ago. Reconstructions of North African hydroclimate show that the onset of aridity started in the north, with the monsoon rains weakening progressively later at lower latitudes.

    • Peter B. de Menocal
  • News & Views |

    In the first decades of the twentieth century, the Earth warmed rapidly. A coral-based climate proxy record of westerly winds over the equatorial Pacific suggests that wind strength and warming rate were linked, as they are today.

    • Stefan Brönnimann

Progress Article

Letters

Articles

  • Article |

    The spatial pattern of climate change is uncertain. Analyses of a simple model suggest that uncertainty in tropical feedbacks induces a global response, but the impact of uncertainty in polar feedbacks tends to be limited to the region.

    • Gerard H. Roe
    • , Nicole Feldl
    • , Kyle C. Armour
    • , Yen-Ting Hwang
    •  & Dargan M. W. Frierson
  • Article |

    During the early to mid-Holocene, Africa was more humid than today. Precipitation reconstructions from across Africa suggest that the termination of humidity was spatially variable, moving towards progressively lower latitudes.

    • Timothy M. Shanahan
    • , Nicholas P. McKay
    • , Konrad A. Hughen
    • , Jonathan T. Overpeck
    • , Bette Otto-Bliesner
    • , Clifford W. Heil
    • , John King
    • , Christopher A. Scholz
    •  & John Peck

Addenda

Addenda