Ma Shizhou, Creed Irena F, Badiou Pascal
School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK Canada.
Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, ON Canada.
NPJ Clim Atmos Sci. 2024;7(1):222. doi: 10.1038/s41612-024-00778-z. Epub 2024 Sep 28.
There is debate about the use of wetlands as natural climate solutions due to their ability to act as a "double-edged sword" with respect to climate impacts by both sequestering CO while emitting CH. Here, we used a process-based greenhouse gas (GHG) perturbation model to simulate wetland radiative forcing and temperature change associated with wetland state conversion over 500 years based on empirical carbon flux measurements, and CO-equivalent (CO-e.q.) metrics to assess the net flux of GHGs from wetlands on a comparable basis. Three CO-e.q. metrics were used to describe the relative radiative impact of CO and CH-the conventional global warming potential (GWP) that looks at pulse GHG emissions over a fixed timeframe, the sustained-flux GWP (SGWP) that looks at sustained GHG emissions over a fixed timeframe, and GWP* that explicitly accounts for changes in the radiative forcing of CH over time (initially more potent but then diminishing after about a decade)-against model-derived mean temperature profiles. GWP* most closely estimated the mean temperature profiles associated with net wetland GHG emissions. Using the GWP*, intact wetlands serve as net CO-e.q. carbon sinks and deliver net cooling effects on the climate. Prioritizing the conservation of intact wetlands is a cost-effective approach with immediate climate benefits that align with the Paris Agreement and the Intergovernmental Panel on Climate Change timeline of net-zero GHG emissions by 2050. Restoration of wetlands also has immediate climate benefits (reduced warming), but with the majority of climate benefits (cooling) occurring over longer timescales, making it an effective short and long-term natural climate solution with additional co-benefits.
由于湿地在封存二氧化碳的同时会排放甲烷，在气候影响方面犹如一把“双刃剑”，因此对于将湿地用作自然气候解决方案存在争议。在此，我们基于经验性碳通量测量数据，使用了一个基于过程的温室气体（GHG）扰动模型来模拟500年间与湿地状态转变相关的湿地辐射强迫和温度变化，并使用二氧化碳当量（CO-e.q.）指标在可比基础上评估湿地温室气体的净通量。我们使用了三种CO-e.q.指标来描述二氧化碳和甲烷的相对辐射影响——传统的全球变暖潜能值（GWP），它关注固定时间范围内的脉冲式温室气体排放；持续通量GWP（SGWP），它关注固定时间范围内的持续温室气体排放；以及GWP*，它明确考虑了甲烷辐射强迫随时间的变化（最初更强，但大约十年后逐渐减弱）——并与模型得出的平均温度剖面进行对比。GWP最接近地估计了与湿地温室气体净排放相关的平均温度剖面。使用GWP，完整的湿地充当净CO-e.q.碳汇，并对气候产生净降温效应。优先保护完整的湿地是一种具有成本效益的方法，能立即带来气候效益，符合《巴黎协定》以及政府间气候变化专门委员会到2050年实现温室气体净零排放的时间表。湿地恢复也能立即带来气候效益（减少变暖），但大部分气候效益（降温）在更长的时间尺度上才会显现，这使其成为一种有效的短期和长期自然气候解决方案，还具有额外的协同效益。
