Atmospheric 14CO2 Constraints on and Modeling of Net Carbon Fluxes 06-ERD-031. An LLNL Exploratory Research in the Directorate's Final Report

摘要

A critical scientific question is: what are the present day sources and sinks of carbon dioxide (CO2) in the natural environment, and how will these sinks evolve under rising CO2 concentrations and expected climate change and ecosystem response. Sources and sinks of carbon dioxide impart their signature on the distribution, concentration, and isotopic composition of CO2. Spatial and temporal trends (variability) provide information on the net surface (atmosphere to ocean, atmosphere to terrestrial biosphere) fluxes. The need to establish more reliable estimates of sources and sinks of CO2 has lead to an expansion of CO2 measurement programs over the past decade and the development of new methodologies for tracing carbon flows. These methodologies include high-precison pCO2, a13CO2, and (O2/N2) measurements on atmospheric constituents that, when combined, have allowed estimates of the net terrestrial and oceanic fluxes at decadal timescales. Major gaps in our understanding remain however, and resulting flux estimates have large errors and are comparatively unconstrained.