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 eCO₂ might 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.