This set includes measurements of the carbon flux during the growing season and the full analysis process from the Arctic wetlands near Trail Valley Creek (Northwest Territories, Canada). These were collected during fieldwork in late June, July 2022, 2023, and 2024. The measurements include methane (CH₄) and carbon dioxide (CO₂). Other measurements include environmental drivers (soil temperature at different depths, soil moisture, how deep the active layer is, air temperature, photosynthetically active radiation), and vegetation characteristics (the amount of each plant species, the make-up of each plant group, how many different types of vascular plant there are). Each observation is linked to one of six microtopographic wetland elements: trench, polygon, transitional zone, degraded centre, gully, or upland tundra. The repository also includes the R analysis script that reproduces all statistical analyses and figures from the associated manuscript. These cover random-forest variable importance, general vs. element-specific modelling, bootstrapped predictor-selection curves, and radar/quality plots. Format: .xlsx (data) and .R (analysis); Units: CH₄ in mg m⁻² h⁻¹; CO₂ fluxes in g m⁻² h⁻¹