Global warming and ocean stratification: a potential result of large extraterrestrial impacts

Joshi, Manoj, von Glasow, Roland, Smith, Robin S., Paxton, Charles G. M., Maycock, Amanda C., Lunt, Daniel J., Loptson, Claire and Markwick, Paul (2017) Global warming and ocean stratification: a potential result of large extraterrestrial impacts. Geophysical Research Letters, 44 (8). 3841–3848. ISSN 0094-8276

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    Abstract

    The prevailing paradigm for the climatic effects of large asteroid or comet impacts is a reduction in sunlight and significant short-term cooling caused by atmospheric aerosol loading. Here we show, using global climate model experiments, that the large increases in stratospheric water vapor that can occur upon impact with the ocean, cause radiative forcings of over +20 Wm-2 in the case of 10-km sized bolides. The result of such a positive forcing is rapid climatic warming, increased upper-ocean stratification and potentially disruption of upper-ocean ecosystems. Since two thirds of the world’s surface is ocean, we suggest that some bolide impacts may actually warm climate overall. For impacts producing both stratospheric water vapor and aerosol loading, radiative forcing by water vapor can reduce or even cancel out aerosol-induced cooling, potentially causing 1-2 decades of increased temperatures in both the upper ocean and on the land surface. Such a response, which depends on the ratio of aerosol to water vapor radiative forcing, is distinct from many previous scenarios for the climatic effects of large bolide impacts, which mostly account for cooling from aerosol loading. Finally, we discuss how water vapor forcing from bolide impacts may have contributed to two well known phenomena: extinction across the Cretaceous/Paleogene boundary, and the deglaciation of the Neoproterozoic snowball Earth.

    Item Type: Article
    Uncontrolled Keywords: climate dynamics,asteroid impact,meteor impact,radiative forcing,k-pg boundary,neoproterozoic
    Faculty \ School: Faculty of Science > School of Environmental Sciences
    University of East Anglia > Faculty of Science > Research Centres > Tyndall Centre for Climate Change Research
    University of East Anglia > Faculty of Science > Research Groups > Climate, Ocean and Atmospheric Sciences
    University of East Anglia > Faculty of Science > Research Groups > Climatic Research Unit
    University of East Anglia > Faculty of Science > Research Groups > Marine and Atmospheric Sciences
    University of East Anglia > Faculty of Science > Research Groups > Meteorology, Oceanography and Climate Dynamics
    University of East Anglia > Faculty of Science > Research Groups > Volcanoes@UEA
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    Depositing User: Pure Connector
    Date Deposited: 12 Apr 2017 06:10
    Last Modified: 26 Jul 2018 15:39
    URI: https://ueaeprints.uea.ac.uk/id/eprint/63223
    DOI: 10.1002/2017GL073330

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