A group of environmental organizations have accused Shell of being the most carbon-intensive oil company in the world. In a report issued today, to coincide with the company’s annual shareholder meeting, Shell is criticized for its reliance on Nigerian crude oil, which is associated with huge levels of gas flaring; liquefied natural gas, which is highly energy-intensive; and oil from Canada’s tar sands. Shell revealed to investors last year that 30 percent of its total resources are tar sands.