2026-10-11T16:03:24Z https://www.scidb.cn/oai

10.57760/sciencedb.43590 2026-08-28T10:44:23Z

2026-08-28 Neglecting diel dynamics underestimates Global lakes CO2 emissions by almost 20% doi:10.57760/sciencedb.43590 en Global lake CO2 emission estimates rely heavily on temporally sparse observations, yet the extent to which daytime sampling biases whole-day fluxes remains unresolved. Here we synthesize 616 high-frequency diel CO2 flux observations from 158 lakes worldwide to quantify this bias and identify its environmental controls. Nighttime fluxes were, on average, 27% higher than daytime fluxes, with 69% of lakes exhibiting a night-enhanced regime (NER) driven mainly by productive, shallow and low-latitude systems. Notably, 22% of lakes shifted from daytime CO2 uptake to nighttime emission, indicating potential misclassification of lake source-sink status. A contrasting day-enhanced regime (DER) occurred more frequently in dissolved organic carbon (DOC)-rich and higher-latitude lakes. The strength of diel asymmetry increased with chlorophyll-a (Chl-a) under low-to-moderate productivity but saturated under high trophic conditions. Incorporating diel variability increased global lake CO2 emissions from 357 to 439 Tg C yr−1, exposing a significant underestimation of 20% (82 Tg C yr−1). These findings reveal a previously under-resolved temporal bias in global lake carbon budgets and provide a regime-specific diel correction framework for improving lake CO2 emission estimates. lake; CO2; diel Lejun Zhao PUBLIC https://creativecommons.org/licenses/by/4.0/ dataset Science Data Bank