Climate change has thawed permafrost and increased rainfall in the Far North, producing sulfuric acid that is turning rivers and lakes yellow or rusty orange. Scientists are scrambling to parse the impacts on wildlife, fish, and the drinking water of Indigenous communities.

The pH levels in some rivers in Alaska and northern Canada have dropped to 2.3, comparable to the acidity of vinegar.

n Alaska, the most recent satellite imagery indicates that the affected rivers now cover an area more than 600 miles wide.