Coastal ecosystems, including mangroves and fjords, play a significant role in either absorbing or releasing greenhouse gases. However, a comprehensive global study led by Australia’s Southern Cross University has revealed that, on a worldwide scale, these ecosystems serve as vital sinks for these gases.
The recent research, published in the journal Nature Climate Change, presents new insights into the coastal greenhouse gas balance, considering carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The study highlights that while CO2 is absorbed by coastal ecosystems, emissions of CH4 and N2O partially offset this absorption.
Coastlines across the globe, ranging from tropical lagoons to polar fjords, exhibit a diverse range of greenhouse gas sinks and emissions. Dr. Judith Rosentreter, Senior Research Fellow at Southern Cross University and lead researcher, emphasizes the importance of understanding the release and absorption of greenhouse gases in coastal ecosystems to implement effective climate mitigation strategies. She suggests that safeguarding and restoring habitats like mangrove and salt marsh ecosystems can enhance CO2 uptake in these coastal wetlands.
Additionally, reducing nutrient, organic matter, and wastewater inputs into coastal waterways can help minimize CH4 and N2O emissions into the atmosphere, thus curbing human impact.
The research team analyzed ten different regions worldwide, including North America, South America, Europe, Africa, Russia, West Asia, South Asia, East Asia, Southeast Asia, and Australasia. They discovered that Southeast Asia exhibited the strongest coastal greenhouse gas sink due to its extensive and productive tropical coastal wetlands that absorb CO2. North America, with its vast coastal wetlands and CO2-uptaking fjords, was identified as the second sink hotspot.
Professor Bradley Eyre, a co-author and Professor of Biogeochemistry at Southern Cross University, highlights the critical role played by fjords worldwide in capturing approximately 40% of the CO2 that would otherwise be released from tidal systems, deltas, and lagoons. Most of this CO2 uptake, about 86%, occurs in the North America region, particularly in Greenland.
Dr. Rosentreter also mentions that while certain coastal habitats act as sources of greenhouse gases, such as mangrove forests, coastal salt marshes, and seagrasses, they are still strong sinks for the atmosphere when considering the overall balance of all three greenhouse gases (CO2, CH4, N2O).
The findings of this study, which fill a gap in the greenhouse gas budgets of large regions across the globe, will contribute to the efforts of the Global Carbon Project’s RECCAP2.
Reference: “Coastal vegetation and estuaries are collectively a greenhouse gas sink” by Judith A. Rosentreter et al., Nature Climate Change, 22 May 2023, DOI: 10.1038/s41558-023-01682-9
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Frequently Asked Questions (FAQs) about coastal ecosystems, greenhouse gas sink
What did scientists discover about coastal ecosystems and greenhouse gases?
Scientists have discovered that coastal ecosystems, including mangroves and fjords, act as net greenhouse gas sinks. They absorb carbon dioxide (CO2) from the atmosphere, but they also emit methane (CH4) and nitrous oxide (N2O), which partially counterbalance the CO2 absorption.
How do coastal ecosystems contribute to greenhouse gas balance?
Coastal ecosystems play a crucial role in the global greenhouse gas balance. They absorb CO2, helping to reduce its concentration in the atmosphere. However, they also release CH4 and N2O, which contribute to greenhouse gas emissions. Overall, when considering the balance of all three gases, coastal ecosystems serve as net greenhouse gas sinks.
What can be done to strengthen CO2 uptake by coastal wetlands?
Protecting and restoring coastal wetland habitats like mangroves and salt marshes is a promising strategy to enhance CO2 uptake. By safeguarding these ecosystems, we can maximize their potential as carbon sinks and contribute to climate mitigation efforts.
Are there ways to reduce greenhouse gas emissions from coastal ecosystems?
Yes, reducing nutrients, organic matter, and wastewater inputs into coastal waterways can help minimize CH4 and N2O emissions from coastal ecosystems. By implementing measures to reduce human impact and pollution, we can effectively mitigate greenhouse gas releases from these areas.
Which regions exhibit the strongest coastal greenhouse gas sinks?
Southeast Asia, with its extensive tropical mangrove forests and seagrasses, was identified as the region with the strongest coastal greenhouse gas sink. North America also stands out due to its large coastal wetlands, including CO2-uptaking fjords. These regions play a significant role in absorbing CO2 and mitigating climate change.
More about coastal ecosystems, greenhouse gas sink
- Nature Climate Change – Journal where the research on coastal greenhouse gas sinks was published.
- Global Carbon Project – Initiative that conducted the research to establish greenhouse gas budgets for large regions globally.
- Southern Cross University – University leading the study on coastal ecosystems as greenhouse gas sinks.
- RECCAP2 – The Global Carbon Project’s initiative focusing on regional carbon budgets and processes.
