Valuing Carbon and Ecosystem Services to Guide Policy Decisions for the Transboundary Al-Hwezeh Marsh

Al-Hwezeh Marsh, a transboundary freshwater wetland in southeastern Iraq at the Iran border, is one of 40 UNESCO World Heritage sites globally designated for both cultural and natural value. Despite this status, the marsh has undergone severe degradation since the 1970s due to upstream regulation of the Tigris and Karkheh Rivers and local economic pressures from oil extraction and agriculture. Cross-border management efforts, coordinated by Bahr Al-Uloom Foundation, aim to promote sustainable restoration. This study supports these efforts by estimating the economic value of ecosystem services and carbon stock under different marsh area scenarios, integrating cultural, natural, and economic dimensions. Using the valuation framework of Costanza et al., ecosystem services were estimated at 31,462 USD ha-1 yr-1. Carbon stocks were assessed using IPCC Tier 1 and Tier 2 approaches and monetized through EU and UK Emissions Trading System (ETS) prices. Three marsh area scenarios were analyzed: historical (1970s), Ramsar site (2008), and current (2025). Total annual ecosystem service values ranged from ∼1.26 billion USD (current) to ∼7.15 billion USD (historical). Carbon storage (Tier 1) ranged between 10.8–61.2 million Mg, valued at ∼2.77–15.7 billion USD (EU ETS) and ∼2.26–12.8 billion USD (UK ETS). Tier 2 estimates were slightly lower. Initial integrated values reached ∼6.42 billion USD, combining annual services with stock assets, with subsequent years expected to transition to lower sequestration-driven rates. Our analysis indicates that long-term restoration yields higher cumulative economic value than short-term natural resource extractive activities. To the best of our knowledge, this study represents the first integrated macroeconomic valuation and IPCC-based multi-tier carbon asset assessment conducted for any ecosystem within Iraq.