OSLO, (Reuters) - The Amazon rainforest is less vulnerable to die off because of global warming than widely believed because the greenhouse gas carbon dioxide also acts as an airborne fertiliser, a study showed yesterday. The boost to growth from CO2, the main gas from burning fossil fuels blamed for causing climate change, was likely to exceed damaging effects of rising temperatures this century such as drought, it said. “I am no longer so worried about a catastrophic die-back due to CO2-induced climate change,” Professor Peter Cox of the University of Exeter in England told Reuters of the study he led in the journal Nature. “In that sense it’s good news.” Cox was also the main author of a much-quoted study in 2000 that projected that the Amazon rainforest might dry out from about 2050 and die off because of warming. Others have since suggested fires could transform much the forest into savannah.