Glacial lakes are rapidly emerging in the Himalayas as glacier mass wastage rates in the region nearly doubled in recent times. Yet, the weathering-carbon feedbacks in the glacial lakes are poorly constrained limiting our ability to predict how these newly forming and expanding lakes will modulate atmospheric carbon dioxide levels. In this study, we quantify the sources and process of carbon cycling in small-sized (45% expansion in an area with a rapid expansion rate of +14.44 km2 yr- 1 be-tween 1976 and 2018, we conclude that CO2 emission from these smaller and newly developed Himalayan glacier-fed lakes and streams would be an important emerging component of carbon budgets in the glacierized Himalayan catchments, and its contribution will increase in future.Plain language summary: Glacial lakes are emerging worldwide in response to melting glaciers. However, their role in carbon cycling is still underexplored. The lack of direct observational datasets on carbon fluxes, as well as their CO2 feedback mechanisms in glacial catchments has made it challenging to determine the impact of glacier -weathering-carbon feedbacks on the concentration of atmospheric CO2. Here, we quantify the CO2 emitting potential of glacier-fed lakes and streams. By studying the carbon biogeochemistry of small (<= 0.4 km2) glacier -fed Himalayan lakes and streams, we show that small lakes are a significant emitter of atmospheric CO2 controlled by dissolved inorganic carbon. We suggest that CO2 emission from small glacial lakes is an emer-ging-and not an inert-component of the regional carbon budget.One-sentence summary: Small glacial-fed Himalayan lakes emit -0.1 Tg C yr- 1 to the atmosphere contributing to the annual carbon budget estimates of glacierized Himalayan catchments.
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