2014 Annual Science Report
VPL at University of Washington Reporting | SEP 2013 – DEC 2014
Coupled Energy Balance Ecosystem-Atmosphere Modeling of Thermodynamically-Constrained Biogenic Gas Fluxes Project
The thermodynamically-constrained fluxes of gases to and from a biosphere has profound, planet-wide consequences. These fluxes can directly control the redox state of the surface environment, the atmospheric composition, and the concentration of nutrients and metals in the oceans. Through these direct effects, they also create strong forcings on the climate, the redox state of the interior of the planet, and the detectability of the biosphere by remote observations. This is a theoretical modeling study to constrain biomass, productivity, and biogenic gas fluxes given a range of geologic parameters.
We have begun modeling chemosynthetic-based biospheres by coupling together two models: one model codifies a thermodynamic energy balance concept for habitability (Hoehler, 2009); the other model predicts a planet’s atmospheric composition and climate while balancing the redox state of the surface environment (Domagal-Goldman et al., 2014). These models are now coupled together, and we are benchmarking their results against prior work on chemosynthetic-based biospheres on Archean Earth (e.g., Kharecha et al., 2005).
The result of this coupling is the calculation of a self-consistent planetary surface environment, that treats the ecosystem as one system component that is coupled to atmospheric, oceanic, and subsurface system components. We willl be able to predict the standing biomass size, net biological productivity, and resulting gas fluxes to and from a biosphere with a given set of volcanic and hydrothermal inputs to the planetary surface. This will also enable predictions of the secondary effects life has on its environment, including controls on climate and the long-term evolution of the redox state of the planet’s surface and near-surface. Finally, this will aid us in predicting the strength of biosignatures for remote observations and ultimately help us interpret spectra from extrasolar planets.
PROJECT MEMBERS:Shawn Domagal-Goldman
RELATED OBJECTIVES:Objective 1.1
Formation and evolution of habitable planets.
Indirect and direct astronomical observations of extrasolar habitable planets.
Co-evolution of microbial communities
Biochemical adaptation to extreme environments
Effects of environmental changes on microbial ecosystems
Biosignatures to be sought in nearby planetary systems