Halving of the northern wetland CH 4 source by a large Icelandic volcanic eruption

• Published in: Journal of Geophysical Research
• Main Authors: Gauci, Vincent, Blake, Stephen, Stevenson, David S., Highwood, Eleanor J.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2008
• Subjects: Laki; ice core
• Online Access: https://oro.open.ac.uk/25569/; https://oro.open.ac.uk/25569/1/d78193.pdf; https://doi.org/10.1029/2007JG000499

Northern temperate and high-latitude wetlands are a major source of the greenhouse gas methane (CH 4 ). Here, we estimate the sensitivity in the strength of this source to the effects of large Icelandic volcanic eruptions such as the Laki eruption of 1783-1784. We applied spatially explicit modeled sulfate aerosol and S deposition fields from a Laki eruption simulation to a climate-sensitive model of CH 4 emissions from wetlands. We estimate that the combined influence on climate and S deposition from the Laki eruption halved the output of CH 4 from wetlands north of 30°N for the first 12 months following the eruption. The largest short-term component responsible for the CH 4 suppression is the aerosol-influenced surface cooling, although the effect of large-scale S deposition on CH 4 emissions provides a longer-term suppressive effect on emissions. Together, we estimate this combination of processes to result in an annual suppression of ~20 Tg CH 4 in the year of the eruption and two subsequent years. Further, the impact of the eruption on atmospheric CH 4 concentration extends beyond the likely duration of suppressed emission. The modeled effect of this large Icelandic eruption is consistent with ice core records of atmospheric CH 4 concentrations at the time and is equivalent, in size, to the current estimated suppressive effect of industrially derived S pollution on the global wetland CH 4 source.