Trends in the application of remote sensing in blue carbon science

Abstract

Blue carbon ecosystems (BCEs), such as mangroves, saltmarshes, and seagrasses, are increasingly recognized as natural climate solutions. Evaluating the current extent, losses, and gains of BCEs is crucial to estimating greenhouse gas emissions and supporting policymaking. Remote sensing approaches are uniquely suited to assess the factors driving BCEs dynamics and their impacts at various spatial and temporal scales. Here, we explored trends in the application of remote sensing in blue carbon science. We used bibliometric analysis to assess 2193 published papers for changes in research focus over time (1990 – June 2022). Over the past three decades, publications have steadily increased, with an annual growth rate of 16.9%. Most publications focused on mangrove ecosystems and used the optical spaceborne Landsat mission, presumably due to its long‐term, open‐access archives. Recent technologies such as LiDAR, UAVs, and acoustic sensors have enabled fine‐scale mapping and monitoring of BCEs. Dominant research topics were related to mapping and monitoring natural and human impacts on BCEs, estimating vegetation and biophysical parameters, machine and deep learning algorithms, management (including conservation and restoration), and climate research. Based on corresponding author affiliations, 80 countries contributed to the field, with United States (27.2%), China (15.0%), Australia (7.5%), and India (6.0%) holding leading positions. Overall, our results reveal the need to increase research efforts for seagrasses, saltmarshes, and macroalgae, integrate technologies, increase the use of remote sensing to support carbon accounting methodologies and crediting schemes, and strengthen collaboration and resource sharing among countries. Rapid advances in remote sensing technology and decreased image acquisition and processing costs will likely enhance research and management efforts focused on BCEs.

A blueprint for national assessments of the blue carbon capacity of kelp forests applied to Canada’s coastline

“…Yet whether kelp forests can provide viable NCS remains unclear due to the data gaps, process uncertainties, and the challenges associated with measuring kelp carbon sequestration at relevant scales for management (e.g., regional or national) 30 . Substantial stretches of temperate and sub-arctic coastlines are suitable habitats for kelp forests 18,19 , but the actual extent of kelp forests is not fully mapped in most countries 31 and is likely to exhibit seasonal and interannual variability in both extent and productivity 32 . Kelp-derived carbon stocks and fluxes (i.e., biomass, productivity, export, and sedimentary accumulation rates) leading to carbon sequestration are also uncertain because of natural variation and incomplete knowledge of their distribution, production, and POC and DOC fates.…”