India, May 17 -- Global warming is causing rivers to slowly lose oxygen, threatening fish and other lives in the waterways, a new study shows.

Researchers in China used satellites and artificial intelligence to track and analyse oxygen levels in more than 21,000 rivers across the globe since 1985.

They found oxygen levels have dropped an average of 2.1 per cent since 1985, according to a study published Friday in Science Advances. That doesn't seem like much but it adds up and if it continues or accelerates, rivers in the Eastern United States, India and across the tropics could lose enough oxygen by the end of the century to suffocate some fish and create dead zones, the study said.

Basic chemistry and physics dictate that warmer wate...