By Jake Spring and Lisandra Paraguassu RIO DE JANEIRO (Reuters) -Diplomatic tensions over global warming spilled over into the G20 summit negotiations in Brazil this week, with sources saying the 20 major economies reached a fragile consensus on climate finance that had eluded U.

With leaders from the world's biggest economies converging on Rio de Janeiro for a two-day G20 summit starting Monday, the usually relaxed seaside city is under a tight security blanket.