COPENHAGEN (Reuters) -Global warming is crossing dangerous thresholds sooner than expected with the world’s coral reefs now in an almost irreversible die-off, marking what scientists on Monday described as the first “tipping point” in climate-driven ecosystem collapse. The warning in the Global Tipping Points report by 160 researchers worldwide, which synthesizes groundbreaking science to estimate points of no return, comes just weeks ahead of this year's COP30 climate summit being held at the edge of the Amazon rainforest in Brazil. That same rainforest system is now at risk of collapsing once the average global temperature warms beyond just 1.5 degrees Celsius based on deforestation rates, the report said, revising down the estimated threshold for the Amazon.