Guardian: A “perfect storm” of food shortages, scarce water and insufficient energy resources threaten to unleash public unrest, cross-border conflicts and mass migration as people flee from the worst-affected regions, the UK government’s chief scientist will warn tomorrow. In a major speech to environmental groups and politicians, Professor John Beddington, who took up the position of chief scientific adviser last year, will say that the world is heading for major upheavals which are due to …