CBC: Rising food prices could cause political instability worldwide, the UN’s top humanitarian official said Tuesday, as clashes over food costs in Haiti and Egypt continued for a second day. Pointing to a 40 per cent average rise in food costs worldwide since mid-2007, John Holmes, the United Nations under-secretary-general for humanitarian affairs and emergency relief co-ordinator, said the trend is likely to exacerbate both the incidence and depth of food insecurity …