noun

an event causing great and usually sudden damage or suffering; a disaster.

an environmental catastrophe

disaster,calamity,cataclysm,crisis,holocaust,ruin,ruination,tragedy,blow,shock,adversity,blight,trouble,trial,tribulation,mishap,misfortune,mischance,misadventure,accident,failure,reverse,woe,affliction,distress,meltdown,whammy,car crash,bale,mishanter