A recent study conducted by an international team of researchers, led by Australia’s Southern Cross University, has shed light on the complex dynamics of greenhouse gas (GHG) sinks and emissions in coastal ecosystems worldwide. The researchers emphasized the significance of understanding the sources and sinks of greenhouse gases in these ecosystems as a crucial first step towards implementing effective climate mitigation strategies.
The study revealed that coastal ecosystems globally act as net sinks for carbon dioxide (CO2), effectively absorbing this greenhouse gas from the atmosphere. However, the positive effect of CO2 uptake is partially offset by the emissions of methane (CH4) and nitrous oxide (N2O) from these ecosystems.
The researchers examined ten different world regions, including North America, South America, Europe, Africa, Russia, West Asia, South Asia, East Asia, Southeast Asia, and Australasia. They found that when considering all three greenhouse gases (CO2 + CH4 + N2O), eight out of the ten regions exhibited a net greenhouse gas sink.
Southeast Asia emerged as the strongest greenhouse gas sink due to its vast and productive tropical coastal wetlands, which effectively absorb CO2. North America, with its extensive coastal wetlands and CO2-uptaking fjords, was identified as another prominent sink hotspot. Fjords worldwide were found to account for approximately 40 percent of the CO2 uptake that would otherwise be released from tidal systems, deltas, and lagoons. Notably, a significant portion (86 percent) of this CO2 uptake was attributed to the North America region, particularly Greenland.
While coastal wetlands such as mangrove forests, salt marshes, and seagrasses were identified as sources of CH4 emissions, they also exhibited strong CO2 uptake and, in some cases, absorbed N2O. Consequently, when considering the overall balance of all three greenhouse gases, these coastal wetlands acted as net sinks for the atmosphere, earning them the designation of “blue carbon” wetlands.
The study emphasized the importance of protecting and restoring coastal habitats, such as mangrove and salt marsh ecosystems, to enhance CO2 uptake by these valuable coastal wetlands. Furthermore, reducing nutrient inputs, organic matter, and wastewater discharge into coastal waterways could help mitigate the release of CH4 and N2O into the atmosphere.
The findings of this research provide valuable insights for policymakers and environmental practitioners in developing targeted strategies for climate change mitigation. By focusing on preserving and rehabilitating coastal ecosystems, we can leverage their potential as crucial allies in the global fight against greenhouse gas emissions. Ultimately, a comprehensive understanding of the greenhouse gas dynamics in coastal regions will contribute to more effective and sustainable climate mitigation efforts.