Magnitude and timing of permafrost C emission from the Arctic
We use field experiments, natural gradients, and laboratory studies to answer these questions:
- How vulnerable are permafrost soil C stocks to the rapidly changing climate (warming, wetting, changes in rain/snow)?
- How does greening (shrub expansion) impact the rate of surface permafrost thaw and C and N cycling? What are the mechanisms of shrub expansion?
- What are soil microbes decomposing during the winter?
Sources and fate of carbonaceous aerosols
In several projects, we are using isotopes to investigate the sources of carbonaceous aerosols and land use change. Study sites include Salt Lake City, UT, Interior Alaska (USA), Seoul (South Korea), Singapore, Alert (Canada), and the Arctic Ocean. The questions we ask include:
- What are the relative contributions of aerosol from fires/biomass burning and fossil fuel combustion to the total aerosol load?
- What are the sources of biomass burning (e.g. forests, grasslands, soil C pools)?