1. By David Battisti (University of Washington)
    Professor of Atmospheric Sciences, and
    Tamaki Endowed Chair

    Abstract: Cave deposits from India and China have been widely used to infer past strength of the Indian and East Asian summer monsoons, as the isotopic composition of oxygen (d18O) in stalagmites is primarily controlled by the d18O of precipitation. These stalagmites show spatially and temporally coherent variability in oxygen isotopes throughout the ice age. Here we use a climate model with an embedded module for oxygen isotopes to show that a sudden increase in North Atlantic sea ice extent during the last glacial period cools the Northern Hemisphere, reduces precipitation over the Indian basin and weakens the Indian monsoon. In turn, the precipitation weighted d18O is increased over India and isotopically heavier vapor is exported to China. The model broadly reproduces the proxy evidence of abrupt climate changes associated with an archetypal Heinrich event and the abrupt changes in d18O seen in stalagmites across China, which are tape recorders for the strength of the Indian monsoon and not the East Asian monsoon, as previously thought. The implication of our results for Dansgaard-Oeschger events and precessional cycle variations seen in these cave records will be discussed.

    # vimeo.com/22893832 Uploaded 177 Plays 0 Comments
  2. With Prof. Göran Ekström, Lamont Doherty Earth Observatory

    Application of a new technique based on array processing of long-period data from the Global Seismographic Network has recently led to the discovery of hundreds of previously unreported earthquakes in the magnitude-5 range, many of which have unusual characteristics. The most surprising group of new earthquakes so far is spatially associated with rapidly moving glaciers and may represent sudden sliding or rapid internal deformation of the glaciers. Other "new" events may represent subaereal and submarine gravitational sliding, volcanic collapse, and perhaps even slow earthquakes on regular faults.

    # vimeo.com/14586954 Uploaded 38 Plays 0 Comments

Earth Science Colloquium Series

Lamont Doherty Plus

The Earth Science Colloquium Series is sponsored by the Lamont-Doherty Earth Observatory and the Columbia University Department of Earth and Environmental Sciences (DEES). This series provides a lively forum for discussing a wide variety of topics within…


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The Earth Science Colloquium Series is sponsored by the Lamont-Doherty Earth Observatory and the Columbia University Department of Earth and Environmental Sciences (DEES). This series provides a lively forum for discussing a wide variety of topics within the earth sciences and related fields.

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