Chicago Tribune: Earlier this week, Energy Secretary Steven Chu caused a stir in the Golden State – and many circles across the country – with his warnings that global warming could spell the demise of California agriculture by century’s end. Chu isn’t a climate scientist – he’s a Nobel-winning physicist – but he’s served on several climate-change commissions, and in his position, will be one of President Obama’s point men on the climate issue. His comments came in a 40-minute interview, his first …