Ice-melt period dominates annual carbon dioxide evasion from clear-water Arctic lakes

Current estimates of carbon dioxide (CO₂) evasion from Arctic lakes are highly uncertain because few studies integrate seasonal variability, specifically evasion during spring ice-melt. We quantified annual CO₂ evasion for 14 clear-water Arctic lakes in Northern Sweden through mass balance (ice-melt period) and high-frequency loggers (open-water period). On average, 80% (SD: ± 18) of annual CO₂ evasion occurred within 10 d following ice-melt. The contribution of the ice-melt period to annual CO₂ evasion was high compared to earlier studies of Arctic lakes (47% ± 32%). Across all lakes, the proportion of ice-melt : annual CO₂ evasion was negatively related to the dissolved organic carbon concentration and positively related to the mean depth of the lakes. The results emphasize the need for measurements of CO₂ exchange at ice-melt to accurately quantify CO₂ evasion from Arctic lakes.