Research Highlights
Nature Reports Climate Change
Published online: 2 July 2008 | doi:10.1038/climate.2008.67
A natural detox
Alicia Newton
JAMES MCQUAID
Naturally occurring chemicals are destroying greenhouse gases in the lower atmosphere over the tropical Atlantic much faster than previously thought. The amount of ozone being depleted by halogens is 50 per cent greater than assumed in state-of-the-art chemistry models. The breakdown of ozone, a greenhouse gas, also cleanses the atmosphere of another powerful heat-trapping gas, methane.
Lucy Carpenter at the University of York and colleagues used records of greenhouse gases from the new Ocean–Atmosphere Observatory in the Cape Verde islands and supplemented these data with airborne measurements to assess ozone trends in the region. They found that ozone was being depleted much more rapidly than expected from chemistry models, even though the models simulated other atmospheric gases accurately. The researchers link depletion of the greenhouse gas to the presence of the halogens bromine and iodine, produced by sea spray and phytoplankton, which destroy ozone and prevent its formation.
Although the study suggests that tropical ocean regions are a larger ozone sink than once thought, whether this applies to the global ocean is yet unknown. The results highlight the need to include halogen chemistry in future climate models.
