MEGAN ROWLING TEN billion dollars - that's a lot of money for one person to invest in anything, especially in the space of just a decade. It's the staggering size of the Bezos Earth Fund, set up last year by the founder of online retailer Amazon.com, Jeff Bezos, to tackle climate change. That fund gets a new boss on Thursday: Andrew Steer. Announced in March, Steer's appointment went down well with experts in the climate world, following his respected stewardship of the World Resources Institute (WRI). Known as a straight talker, Steer brings decades of experience in international diplomacy and…