DelSontro et al.  assembled the largest global data set to date on emission rates from lakes of CO2, CH4 and N20 and found that they co-vary with lake size and trophic state. They estimated that moderate global increases in eutrophication of lakes could translate to 5-40% increases in the GHG effect in the atmosphere. Moreover, they estimated that GHG emissions from lakes and impoundments in past decades accounted for 1.25-2.30 PgCO2 yr1 , thus around 20% of global CO2 emissions from the burning of fossil fuels  .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report