Ocean sponges suggest Earth has warmed longer, more than thought; some scientists dubious

By SETH BORENSTEIN
AP Science Writer

A handful of centuries-old sponges from the Caribbean are causing some scientists to theorize that human-caused climate change began sooner and has warmed the world nearly a degree Fahrenheit more than most scientists previously thought. In Monday’s study, researchers figure that the world more than a decade ago blew past the internationally approved threshold of limiting global warming to 1.5 degrees Celsius since pre-industrial times and by 2020 had hit 1.7 degrees of added heat. They calculated the dramatic difference from scientific orthodoxy by examining six of these long-lived sponges for evidence of warming since 1700. Other scientists are skeptical of the study’s claims.