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

Manoj Joshi, Roland von Glasow, Robin S Smith, C.G.M. Paxton, Amanda C Maycock, Daniel J. Lunt, Claire A Loptson, Paul Markwick

Research output: Contribution to journalArticle (Academic Journal)

5 Citations (Scopus)
416 Downloads (Pure)

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.
Original languageEnglish
Pages (from-to)3841-3848
Number of pages8
JournalGeophysical Research Letters
Volume44
Issue number8
Early online date24 Apr 2017
DOIs
Publication statusPublished - 19 May 2017

Keywords

  • Climate dynamics
  • Asteroid impact
  • Meteor impact
  • Radiative forcing
  • K-Pg boundary
  • Neoproterozoic

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