Emergent Climatological Coupling of the Terrestrial Carbon Sink with Water and Energy Availability

Abstract:

The terrestrial carbon cycle acts as a control on the water and energy cycles through surface conductance of water from soils to the atmosphere, radiative partitioning, influences on soil characteristics, and roughness characteristics of the land-atmosphere interface. Simultaneously, but at longer time scales, the availability of water, energy, and habitable microclimate determine the viable density and composition of vegetation on a landscape. This leads to a coupling of the carbon, water, and energy cycles on successional time scales, which imposes limitations on what vegetation can co-occur with certain climatological states. Using surface micrometeorological data and satellite observations at continental scale, we present an emergent regime of carbon-climate coexistence, which provides specific bounds on landscape water use efficiency, driven to a large degree by water supply. We propose that this co-occurrence regime is the necessary result of spatial and temporal aggregation of heterogeneous landscape processes, and demonstrate that it holds over continental scales.