Has the planet warmed more than we thought? Ocean sponges might be telling us something

A handful of centuries-old sponges from deep in the Caribbean are causing some scientists to think human-caused climate change began sooner and has heated the world more than they thought.

They calculate that the world has already gone past the internationally approved target of limiting global warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) since pre-industrial times, hitting 1.7 degrees (3.1 degrees Fahrenheit) as of 2020. They analyzed six of the long-lived sponges — simple animals that filter water — for growth records that document changes in water temperature, acidity and carbon dioxide levels in the air, according to a study in Monday’s journal Nature Climate Change.