I looked into it, and first, BP is taking proven reserves. Estimated reserves are 10% higher, but that's not very much. Coal has grown very much over the past two years (around 5%) due almost entirely to China, but the 10-year average is 2.5%.

So if we factor in that coal will have to gradually replace oil and gas as a source of electricity, 4% growth or higher is necessary, otherwise the growth rate it will be lower, I think.