Washington (AFP) – By the year 2300, life in the oceans faces a mass die-off rivaling the great extinctions of Earth’s deep past if humanity fails to curb greenhouse gas emissions, a study said Thursday. But limiting planetary warming to two degrees Celsius above pre-industrial levels will stave off such a catastrophe, said the paper’s authors, Justin Penn and Curtis Deutsch, both affiliated with the University of Washington and Princeton University. The authors used ecophysiological modeling to weigh species’ physical limits with projected marine temperatures and depletion of oxygen levels –…