Changes in Mangrove Blue Carbon under Elevated Atmospheric CO2

While there is consensus that blue carbon ecosystems, such as mangroves, have an important role in mitigating some aspects of global climate change, little is known about mangrove carbon cycling under elevated atmospheric CO2 concentrations (eCO2). Here, we review studies in order to identify pathways for how eCO2might influence mangrove ecosystem carbon cycling. In general, eCO2 alters plant productivity, species community composition, carbon fluxes, and carbon deposition in ways that enhance mangrove carbon storage with eCO2. As a result, a negative feedback to climate change exists whereby eCO2 adds to mangrove's ability to sequester additional carbon, which in turn reduces the rate by which CO2 builds. Furthermore, eCO2 affects warming and sea-level rise (SLR) through alternate pathways, which coinfluence the mangrove response in both antagonistic (i.e., warming = greater carbon loss to decomposition) and synergistic (i.e., SLR = greater soil carbon burial) ways. eCO2 is projected to become a more prominent driver in the future before reaching a steady state. However, given the complexity of the interactions of biological and environmental factors with eCO2, long-term field observations and in situ simulation experiments can help to better understand the mechanisms for proper model initialization to predict future changes in mangrove carbon sequestration.