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Efficiency of short-lived halogens at influencing climate through depletion of stratospheric ozone

Research output: Contribution to journalJournal article

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  • R. Hossaini
  • M. P. Chipperfield
  • S. A. Montzka
  • A. Rap
  • S. Dhomse
  • W. Feng
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<mark>Journal publication date</mark>03/2015
<mark>Journal</mark>Nature Geoscience
Issue number3
Volume8
Number of pages5
Pages (from-to)186-190
Publication statusPublished
Early online date16/02/15
Original languageEnglish

Abstract

Halogens released from long-lived anthropogenic substances, such as chlorofluorocarbons, are the principal cause of recent depletion of stratospheric ozone, a greenhouse gas(1-3). Recent observations show that very short-lived substances, with lifetimes generally under six months, are also an important source of stratospheric halogens(4,5). Short-lived bromine substances are produced naturally by seaweed and phytoplankton, whereas short-lived chlorine substances are primarily anthropogenic. Here we used a chemical transport model to quantify the depletion of ozone in the lower stratosphere from short-lived halogen substances, and a radiative transfer model to quantify the radiative effects of that ozone depletion. According to our simulations, ozone loss from short-lived substances had a radiative effect nearly half that from long-lived halocarbons in 2011 and, since pre-industrial times, has contributed a total of about -0.02 W m(-2) to global radiative forcing. We find natural short-lived bromine substances exert a 3.6 times larger ozone radiative effect than long-lived halocarbons, normalized by halogen content, and show atmospheric levels of dichloromethane, a short-lived chlorine substance not controlled by the Montreal Protocol, are rapidly increasing. We conclude that potential further significant increases in the atmospheric abundance of short-lived halogen substances, through changing natural processes(6-8) or continued anthropogenic emissions(9), could be important for future climate.