Guilt, self-promotion or genuine concern? These are just some of the motives suggested for Richard Branson's announcement that he will commit up to £1.6 billion ($3 billion) over the next 10 years to the fight against climate change. Branson's pledge to invest all profits from his Virgin travel firms to develop new renewable energy technologies has met with a considerable degree of cynicism. Never one to shun publicity, Branson was never the sort to make anonymous donations. But the phrase 'damned if you do and damned if you don't' springs to mind. Why should we care what his motives are? The struggle to reduce our dependence on fossil fuels is difficult enough and needs all the help it can get. His offer should be grabbed with both hands and encouragement should be offered to any other billionaires thinking of making similar investments, no matter what their motivation.