Abstract Climate change effects on large river basins, such as the Mekong River, are dramatic and unique given shared governance and watershed scale. In large rivers, socioeconomic sectors including agriculture, fisheries, transportation, human health, biodiversity, water supply, and livelihoods are interconnected and highly vulnerable to global change. The Mekong River is a transboundary river spanning six countries and is critical for food and economic security of >60 million people. But the Mekong River Basin has undergone extensive environmental changes due to agricultural expansion, deforestation, dam construction, urbanization, and population growth, and faces substantial confounding effects from climate change. In 2021, Thailand [...]