Rivers, streams, lakes, and reservoirs aren’t just scenic parts of our landscape—they’re also vital engines for life on Earth. These inland waters “breathe” oxygen, just like we do. But a new study led by Utrecht University researchers shows that we’ve been suffocating them during the last century, an era also known as the Anthropocene. The research, published today in Science Advances, reveals that the way oxygen is produced and used in inland waters has dramatically changed since 1900. The culprit? Human activities.