A Closer Look at the Effects of Lake Area, Aquatic Vegetation, and Double‐Counted Wetlands on Pan‐Arctic Lake Methane Emissions Estimates

Abstract

AbstractLake methane emissions are commonly upscaled from lake area, with recognition that smaller, non‐inventoried lakes emit more per unit area. There is also growing awareness of the importance of lake aquatic vegetation and potential “double‐counting” with wetlands, but lack of consensus on which is most impactful. Here, we combine high‐resolution data with the comprehensive lake inventory HydroLAKES to rank these three variables based on emissions sensitivity. Including non‐inventoried small lakes <0.1 km2 (+30 [range: 9.0 to 82]% change) is greatest, followed by double‐counting (−20 [−11 to −34]%) and lake aquatic vegetation (+14 [2.7 to 43]%). Significantly, emissions from non‐inventoried lakes contribute far less than the ∼40% previously determined globally through statistical area extrapolation. We produce a first pan‐Arctic estimate of lake aquatic vegetation in 1.37 million km2 of lakes, but after correcting for persistent double‐counting, its net effect is to decrease emissions estimates by 9%. Thus, previous global emissions estimates are likely too high.