The carbon emissions reduction targets of a group of the biggest listed companies are too weak collectively, meaning they are failing to play their part in preventing the most devastating impacts of global warming, a report on Tuesday showed. A study of 51 companies by the non-profit NewClimate Institute and Carbon Market Watch found they had committed to reducing their emissions by 30% by 2030, on average, against the 43% needed to limit global warming to 1.5 degrees Celsius (2.7 Fahrenheit) by 2050. "Four years into the critical decade for action on climate change, some companies have...