Top climate change leaders from Europe to Africa are wondering if it's time to give up on the United States. Frustrated by the U.S. Senate's recent abandonment of climate legislation and baffled by Congress' seeming inability to cut emissions, several officials told ClimateWire that countries are uncertain about America's role in upcoming treaty negotiations. "Why is it that for the last 20 years the United States is unable to have a bill on climate change? What's happening? What's going on? It's very complicated to understand," said Brice Lalonde, France's top negotiator.