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.

Diplomatic tensions over global warming will take center stage at the G20 summit in Brazil this week, as negotiators at U.N. talks in Azerbaijan hit an impasse on climate finance that they hope leaders of the world's 20 major economies can break.

As Brazil gears up to host the G20 leaders summit, here are 5 things that will be at the top of the South American nation’s agenda