|Paper title||Remote sensing monitoring system to trigger payments for environmental services via CO2 offsetting|
|Form of presentation||Poster|
The rise in atmospheric CO2 due to anthropogenic emissions is the leading cause of climate change. In order to avoid reaching tipping points in the Earth System, efforts to cut down emissions and compensate for existing atmospheric CO2 are pursued. Within this context, nature-based solutions such as reforestation, afforestation and agroforestry favour the potential of carbon sequestration through tree growth and health. Though, the kick-off of planting activities is insufficient for these initiatives to present a substantial impact. Routine field maintenance and restoring the ecosystems are capital. Since several decades are necessary before observing the positive impacts of such initiatives, long-run investments become indispensable, and with them, monitoring and metrics. Current methods that measure carbon storage in forests and their evolution are based regionally on Forest National Inventories and globally on products derived from satellite imagery at coarse resolution. These solutions frequently lack the temporal and spatial coverage to ensure traceability and transparency to monitor most interventions.
In order to follow the evolution of local and regional scale nature-based projects effectively, a monitoring strategy relying on remote sensing is presented, covering the needs of new afforested sites and reforestation and agroforestry management in existing forested areas. The methodology revolves around skilled monitoring of Above-Ground Biomass (AGB) -one of the most reliable means to assess natural carbon sinks. The proposed monitoring system covers regional stakeholders' needs to trigger payments for the environmental services implemented by over a thousand local farmers.
At high resolution, several reforestation efforts in the Sahel area in Africa are being monitored using Very High Resolution (VHR) imagery from Airbus' Pleiades mission. The detection of individual trees is possible thanks to the mission's pan-sharpened resolution of 0.5m. A monitoring system for larger-scale regional projects using medium-resolution imagery of 20m pixels is also presented. For the latter, data sources include Copernicus Sentinel-1 and Sentinel-2 missions for Synthetic Aperture Radar (SAR) and Multi-Spectral imagery, respectively, LiDAR-based AGB data provided by the Global Ecosystem Dynamics Investigation (GEDI) mission on board of the International Space Station (ISS), Land Cover maps and Digital Elevation Models (DEM).
In order to train, test and validate regression methods that predict the evolution of carbon stored in individual trees, reliable and standardised measurements at tree level are necessary. A dedicated in-situ survey strategy has been designed collaboratively with local communities and field experts in the Sahel to overcome the limitations of horizontal GNSS resolution and obtain reliable measurements at the tree level.
While the in-situ surveying is not taking place due to security constraints in West Africa, a preliminary study is carried out in Catalunya, Spain, benefiting from an AGB dataset obtained from the Spanish 4th National Forest Inventory (NFI-4). This proof of concept shows the correlations of the individual data sources with field biomass and the combined use of all the datasets in the methodology to address biomass assessment. The study over the region of Catalunya serves as a basis to transfer the methodology to the Sahel region, where the aforementioned nature-based projects are taking place.
Further to the CO2 sequestration potential, the beneficial side-effects of nature-based solutions include improved soil quality, increased crop yield, ground temperature and biodiversity recovery, and positive socio-economic impacts, which are rarely quantified. Additional metrics are presented as valuable information to the overall Key Performance Indicators to add a comprehensive vision of the reforestation and afforestation activities on the local communities involved.
The presented approach is developed within the JESAC project (https://www.jesac-project.com), integrating a virtual monitoring platform. Payments for Environmental Services (PES) will be triggered once the trees have stored a certain amount of carbon. These payments cover in-field activities for land restoration and voluntary carbon offsetting, which is traced transparently through blockchain technology.