Chapter 13, Key Finding 2

North American terrestrial wetlands currently are a carbon dioxide sink of about 123 teragrams of carbon (Tg C) per year, with approximately 53% occurring in forested systems. However, North American terrestrial wetlands are a natural source of methane (CH₄), with mineral soil wetlands emitting 56% of the estimated total of 45 Tg C as CH₄ (CH₄ –C) per year (medium confidence, likely).