There is a long period during the Arctic fall, when much of the soil profile is suspended near 0°C. The investigators propose that this time of year may hold key information needed to better understand how Arctic ecosystems can be affected by climate change. The investigators hypothesize that there exist specialized cold-adapted microbes, which produce methane, a potent greenhouse gas, and that these microbes are active during this period when much of the soil column is at the freezing point. The investigators also argue that these specialized microbes may be responsible for a large fraction of the annual methane released from Arctic soils to the atmosphere. The study will test whether such specialized cold-adapted methane producing microbes are active during this period, and if so, how much they contribute to the annual soil flux of methane. To test this hypothesis, this study will bring to bear, field, laboratory, and computer model simulations.
This project aims to predict how the Arctic will respond to current and future climate change, and to better inform decision makers. This project will also continue a well-developed outreach program involving local communities and students from the North Slope of Alaska and San Diego.
Flux tower measurements have shown steady and significant methane emissions well into the Arctic fall, when the soil profile is nearly isothermal at zero degrees celsius. The investigators argue that this fall flux is maintained by specialized cold-adapted methanogenic microbial communities that live in the soil column. The study will test whether such specialized cold-adapted methanogenic communities are active during this period, and if so, how much they contribute to the annual soil efflux of methane. The proposed study includes field isotope work, laboratory incubations, methane flux monitoring, and modeling. The modeling aspect of the work was added as a response to suggestions from a previous panel.
