三、 The rapid march of climate change up the global agenda has prompted a new, andoften poignant, conversation between the generations and, in public, among a selfappointedelite.          At its core, that conversation is about whether some of the first beneficiaries of thewonders developed during the past century — like electricity at the flick of a switch —have the means, or the will, to help their descendants with the consequences of burningvast quantities of fossil fuels.        The conversation also is playing itself out across the planet as leaders, industrialistsand citizens confront issues too costly for any single nation or generation to tackle alone.       For a group of 20th-century leaders called the Elders — whose members includeArchbishop Tutu of South Africa, former President Jimmy Carter and Mary Robinson, aformer Irish president — it also was a conversation with their families that they felt wouldbe most usefully conducted before the cameras.（25 分）