Taillardat et al. 2020
Although inland and coastal wetlands are highly efficient sinks of carbon dioxide, they also release methane – another carbon-containing greenhouse gas. Hence, wetlands can in some cases draw down carbon and yet have a net warming effect on the climate due to methane release. This means that restoration, protection and management of wetlands must be carefully planned in order to ensure an overall cooling effect on the climate. Currently, use of different metrics of greenhouse gas mitigation can show the same wetland to have a positive or negative effect on climate. This paper addresses this problem by using ‘switchover time’ (i.e. the age at which a wetland has a net cooling effect) to assess the effect of wetlands and their management on global temperatures.
The authors conduct a global meta-analysis of wetland carbon dynamics, showing that any wetland can have a net cooling effect, so long as it is maintained with stable emissions for a sufficient length of time. This time period is substantially shorter for coastal wetlands (median of 8.5 years) than inland wetlands (median of 263 years), leading to a need for different protection/restoration/management strategies for different wetland types.
The authors highlight three key policy-relevant findings:
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