China's rivers and lakes defied a global oxygen crisis across 17 years, and nearly 1,300 sites, and the surprise is that it had nothing to do with slowing down climate change

Think of dissolved oxygen as freshwater's invisible lifeline. It keeps fish alive, cycles nutrients, and holds the whole aquatic food chain together. When the oxygen levels in a body of water get too low, it becomes hypoxic. When oxygen is completely absent, it is called anoxic: fish suffocate, toxic metals leach from sediments, and greenhouse gases such as methane begin to bubble up into the atmosphere.

Scientists who study rivers and lakes throughout the United States and Europe have documented and well established those declines for years. In the study ‘Widespread deoxygenation in warming rivers’ published in Nature Climate Change, Wei Zhi, Christoph Klingler, Jiangtao Liu, and Li Li reconstructed dissolved oxygen levels in 580 rivers across the United States and 216 rivers in Central Europe with deep learning models.