Nature paper on short-lived halogens
We have co-authored a new Nature review paper on short-lived halogens (SLHs).
Observations have demonstrated the ubiquity of SLHs - defined as organic and inorganic chlorine, bromine and iodine compounds with an overall atmospheric lifetime of less than 6 months - in the global atmosphere. They are primarily emitted naturally from the ocean, cryosphere, volcanoes, salt lakes and the biosphere. However, unregulated anthropogenic sources are increasingly contributing to their atmospheric loading. Some of their natural emissions have increased over time due to anthropogenic pollution, for example, the increased oceanic emissions of iodine compounds due to the deposition of ozone on the sea surface. SLHs affect chemical processes, such as ozone and methane chemistry, and therefore influence air quality and climate. Nevertheless, some of their sources and chemistry are not included in air-quality and climate models used in international assessment reports.
The paper describes in detail the various impacts of SLHs on air quality and climate, and argues for the inclusion of more comprehensive SLH chemistry in future atmospheric, air-quality and climate assessments. The paper also identifies gaps in our knowledge of SLH emissions, chemistry, and environmental and climate impacts..