Tree mortality is becoming increasingly widespread throughout the U.S. as a function of increasing temperature and drought. Large-scale tree die-off can feedback to affect climate through changes in water balance and surface reflectance (albedo). This project will use the Airborne Observation Platform (AOP) of the National Ecological Observatory Network (NEON) to study the effects of tree mortality on local climate, and link this information to earth system models to study "teleconnections" in which ecological changes in one area influence climate and associated ecological responses in another. The project will develop the first large-scale assessment of forest vulnerability to drought-induced tree mortality based on species-specific temperature response functions determined in previous experiments. These results will be combined with analysis of vegetation structure from NEON AOP data and modeling of climatic feedbacks. This activity will provide a prototype for a new approach to continental-scale science capable of quantifying ecoclimate teleconnections and risks of tree die-off across NEON Domains and which can be broadly applied to other major types of land transformation. The project will synthesize pre-existing climate and remotely sensed (LiDAR and hyperspectral) observations relating surface properties to fluxes (albedo, latent heat fluxes) to estimate how the changes in vegetation force the atmosphere. This information will be used to evaluate how this forcing impacts other NEON Domains through ecoclimate teleconnections. The approach initially focuses on forest die-off as a rapid ecological change with direct linkages to climate signals. It will develop the first large-scale assessment of drought-induced tree mortality based on experimentally determined temperature sensitivities, and will improve constraints on ecoclimate teleconnection predictions through incorporation of NEON AOP data. Deliverables include 1) a current assessment of the likelihood and magnitude of die-off by Domain; 2) quantification of impacts of tree die-off in one Domain on others via ecoclimate teleconnections using model experiments; and 3) estimation of associated Domain by Domain risks of die-off impacts from a given Domain. The project also provides professional development for post-docs and early career scientist and has a broad outreach component through an art-science collaboration and seminars at the Biosphere 2 that reach >100,000 visitors/year.