Members of the U.S. Climate Alliance, a coalition of 24 states committed to achieving the emissions reductions outlined in the 2015 Paris Agreement, are considering policy options for inclusion of forest carbon in climate mitigation plans. Required forest carbon data consist of integrated: (1) baseline mapping of contemporary carbon stocks, (2) projections of future carbon stocks for planning, and (3) annual monitoring for assessment. Previously, we developed high-resolution mapping of contemporary carbon stocks and 300-yr projections of annual carbon sequestration potential (CSP) for Maryland at 90m resolution by integrating airborne LiDAR with mechanistic ecosystem modeling (Ecosystem Demography (ED) model). Here we extend this work to Delaware and present the first consistent, annual monitoring results for both states (Maryland and Delaware). For monitoring, we intersect annual carbon stock estimates with 30m Landsat-derived changes in forest area to compute realized carbon gains and losses over the period 2011—2019. Moving forward, we expect to extend this pilot system developed for Maryland and Delaware to an additional 9 U.S. states. As the framework is flexible, developing a nationwide or global system is increasingly feasible, particularly with the recent availability of GEDI LiDAR observations from space.

Climate mitigation and forest management require accurate information on carbon stocks, fluxes, and potential future sequestration potential. Previous large-scale estimates have substantial uncertainties arising from lack of data, heterogeneity of forest structure, and modeling limitations. However, recent local-to-regional studies suggest that combination of lidar-derived canopy height with an advanced 3-D ecosystem model that explicitly tracks vegetation height (i.e. Ecosystem Demography, ED) can reduce uncertainties and provide mapped estimates of these quantities at high-spatial resolution over policy relevant domains. Extending this approach to the global scale requires both a source of global lidar data height data and a global height structured ecosystem model. The NASA GEDI mission provides precise measurements of forest canopy height and vertical structure with great potential for global carbon cycle modelling. Here we present recent development and calibration of ED-global (v1.0) and its evaluation simulations against heterogeneous sources of satellite observations and field measurements. ED-global estimates of vegetation carbon stocks and fluxes, vegetation distribution and structure will be examined across various temporal and spatial scales from seasonal to inter-annual and also from grid cell to biome. The developed ED-global will serve as base model of NASA’s GEDI mission to answer the key science questions: What is the carbon balance of Earth’s forests? And how will the land surface mitigate atmospheric CO2 in the future?

Climate mitigation planning requires accurate information on forest carbon dynamics. Forest carbon monitoring and modeling systems need to step beyond the traditional Monitoring, Reporting, and Verification (MRV) framework of current forest cover and carbon stock. They should be able to project potential future carbon stocks with high accuracy and high spatial resolution over large policy-relevant spatial domains. Previous efforts have demonstrated the possibility and value of combining a process-based ecosystem model (Ecosystem Demography, ED), high-resolution (1-meter) lidar and NAIP data, field inventory data, and meteorology and soil properties in a prototype carbon monitoring and modeling system developed for the state of Maryland. Here we present recent work on expanding the Maryland prototype to a 10x larger domain, namely the Regional Greenhouse Gas Initiative (RGGI+) domain consisting of the states of Maryland, Delaware, Pennsylvania, New York, New Jersey, Rhode Island, Connecticut, Massachusetts, Vermont, New Hampshire, and Maine. The system expansion includes an updated version of the ED ecosystem model, improved initialization strategy, and expanded Cal/val approach. High-resolution wall-to-wall maps of current aboveground carbon, carbon sequestration potential, carbon sequestration potential gap, and time to reach sequestration potential are provided at 90m resolution across the RGGI+ domain. Total forest aboveground carbon sequestration potential gap is estimated to be over 2,300 Tg C for the RGGI+ region, about 1.5 times of contemporary aboveground carbon stock. States and counties exhibit variations in carbon sequestration potential gap, implying different policy planning for future afforestation/reforestation and forest conservation activities. Here we present the details of this new carbon monitoring and modeling system as well as regional results, including evaluations of our estimates against USFS Forest Inventory and Analysis (FIA) data, multiple wall-to-wall AGB maps, and state-wide and county-wide future carbon sequestration potential over time.

In support of the American College & University Presidents’ Climate Leadership Commitments, the University of Maryland College Park (UMD) has established a goal to become climate neutral by 2050. While much progress has been made to lower the University’s carbon footprint across multiple emissions sectors, tree conservation or restoration has traditionally been excluded due to concerns about the reliability and consistency of the science. For the past several years, faculty and students in UMD’s Department of Geographical Sciences have been working with state governments across the region to inform climate action planning with advanced forest carbon science. However, with student support and leadership, we identified an opportunity to retool this same science to help UMD “walk the walk” and advance our own forest climate goals in parallel with Maryland and other U.S. Climate Alliance states. By partnering with the Office of Sustainability and other land management entities, we have been able to directly inform the campus climate action plan with robust forest carbon estimates as well as influence and support the carbon budgeting process of all universities that have pledged support for the “Carbon Commitment.” Unlike state governments, the university’s approach to sustainability broadly follows that of a corporation, requiring enhanced collaboration to ensure the science is provided in user-relevant formats while remaining consistent with science approaches utilized by state partners. Our experience during the first year of this project underscores the value of building out scientific approaches that meet specific stakeholder needs while remaining poised to adapt these tools in support of new partnerships and collaborations.

International frameworks for climate mitigation that build from national actions have been developed under the United National Framework Convention on Climate Change and advanced most recently through the Paris Climate Agreement. In parallel, sub-national actors have set greenhouse gas (GHG) reduction goals and developed corresponding climate mitigation plans. Within the U.S., multi-state coalitions have formed to facilitate coordination of related science and policy. Here, utilizing the forum of the NASA Carbon Monitoring System’s Multi-State Working Group (MSWG), we collected and reviewed climate mitigation plans for 11 states in the Regional Greenhouse Gas Initiative (RGGI) region of the Eastern U.S. For each state we reviewed the 1) policy framework for climate mitigation, 2) GHG reduction goals, 3) inclusion of forest carbon in the state’s climate action plan, 4) existing science used to estimate forest carbon, and 5) stated needs for carbon monitoring science. Across the region, we found important differences across all categories. While all states have GHG reduction goals and framework documents, nearly three-quarters of all states do not account for forest carbon when planning GHG reductions; those that do account for forest carbon use a variety of scientific methods with various levels of planning detail and guidance. We suggest that a common, efficient, standardized forest carbon monitoring system would provide important benefits to states and the geographic region as a whole. In addition, such a system would allow for more effective transparency and progress tracking to support state, national, and international efforts to increase ambition and implementation of climate goals.