Small lakes are bad news for greenhouse gas emissions
This mechanism causes lakes to act like greenhouse gas factories. In fact, freshwater lakes probably account for 20% of all global CO2 fossil fuel emissions into Earth’s atmosphere. Forecasts suggest that climate change will cause lakes to emit an ever-greater share of greenhouse gases in the future. This is just one of the reasons why it is important to know how many and how big these lakes are, as well as how they develop. Until now, this information was unknown. Researchers have now prepared a more accurate and detailed map of the world’s lakes than has ever existed. The researchers mapped 3.4 million lakes and their evolution over the past four decades using high-resolution satellite imagery combined with artificial intelligence. According to the study’s calculations, the annual increase of CO2 emissions from lakes during the period is 4.8 teragrams (10^12, trillion) of carbon - which equals to the CO2 emission increase of the United Kingdom in 2012. While small lakes account for just 15% of total lake area, they account for 25% of CO2 and 37% of methane emissions. Furthermore, they also contribute to 45% and 59% of the net increases of the lake CO2 and CH4 emissions, respectively, over the period 1984-2019.