Half of global methane emissions come from highly variable aquatic ecosystem sources

Nature Geoscience
By: , and 

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Abstract

Atmospheric methane is a potent greenhouse gas that plays a major role in controlling the Earth’s climate. The causes of the renewed increase of methane concentration since 2007 are uncertain given the multiple sources and complex biogeochemistry. Here, we present a metadata analysis of methane fluxes from all major natural, impacted and human-made aquatic ecosystems. Our revised bottom-up global aquatic methane emissions combine diffusive, ebullitive and/or plant-mediated fluxes from 15 aquatic ecosystems. We emphasize the high variability of methane fluxes within and between aquatic ecosystems and a positively skewed distribution of empirical data, making global estimates sensitive to statistical assumptions and sampling design. We find aquatic ecosystems contribute (median) 41% or (mean) 53% of total global methane emissions from anthropogenic and natural sources. We show that methane emissions increase from natural to impacted aquatic ecosystems and from coastal to freshwater ecosystems. We argue that aquatic emissions will probably increase due to urbanization, eutrophication and positive climate feedbacks and suggest changes in land-use management as potential mitigation strategies to reduce aquatic methane emissions.

Publication type Article
Publication Subtype Journal Article
Title Half of global methane emissions come from highly variable aquatic ecosystem sources
Series title Nature Geoscience
DOI 10.1038/s41561-021-00715-2
Volume 14
Year Published 2021
Language English
Publisher Nature Research
Contributing office(s) Southwest Biological Science Center
Description 6 p.
First page 225
Last page 230
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