Evaluating the carbon payback period of nature-based solutions: A life cycle assessment approach

Nature-based Solutions (NbS) have emerged as a promising strategy for mitigating climate change while providing additional benefits such as biodiversity enhancement and improved ecosystem services. Despite growing interest, most NbS assessments focus on cumulative carbon sequestration, often neglecting the temporal aspects of GHG sequestration. This study introduces the Carbon Payback Period (CPP)—the time required for NbS to offset their life cycle GHG emissions—and applies it as a novel indicator to evaluate the temporal climate effectiveness of NbS through Life Cycle Assessment (LCA). Employing a LCA framework, we assessed the CPP of two NbS types with distinct implementation approaches—forest-type and wetland-type—in the Hangang River Basin, South Korea. Results show that the forest-type NbS emitted 8.37 tCO 2 -eq and sequestered 53.57 tCO 2 by 2050, with a CPP of approximately 7 years. The wetland-type emitted 4.06 tCO 2 -eq and sequestered 13.21 tCO 2 , with a CPP of about 10 years. These findings underscore the importance of incorporating temporal metrics in NbS evaluations. By introducing CPP as a decision-making tool, this research provides a methodological foundation for prioritizing NbS projects based on their temporal carbon performance, ultimately supporting more efficient, resilient, and strategically timed climate actions.