Seminar: Anna Michalak

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September 28, 2020 11:30 am - 12:20 pm

Leveraging atmospheric observations to constrain regional controls on carbon fluxes

Climate change is driven primarily by anthropogenic emissions of greenhouse gases, chief among them carbon dioxide and methane. One of the most fundamental challenges in carbon cycle science is to anticipate how the “natural” oceanic and terrestrial components of the carbon cycle will act to mitigate or to amplify the impact of human emissions. Because the atmosphere preserves signatures of emissions and uptake (a.k.a. fluxes) of greenhouse gases at the earth’s surface, spatiotemporal variability in observations of atmospheric concentrations of greenhouse gases can be used to tackle this challenge. While the majority of studies using atmospheric observations primarily aim to quantify biospheric and oceanic carbon fluxes for various regions and at various spatiotemporal scales, the search for a net flux is only a steppingstone towards the process-based understanding that is critical to constraining projections of carbon balance under changing climate conditions. Given the increasing awareness of challenges posed by equifinality in mechanistic modeling, getting the right “number” for a snapshot in time is also not sufficient to anticipate responses to changing conditions. This talk will present examples of recent studies that attempt to more directly constrain terrestrial carbon flux responses to climatic variability at synoptic to interannual scales. These include the use of remote sensing observations of solar induced fluorescence, the diagnosis of the geographic and meteorological drivers of interannual variability in the North American carbon sink, the role of synoptic-scale meteorological variability in controlling net carbon uptake, and the particular challenge of constraining ecosystem respiration.