Two weeks of U.N. climate talks are set to end with negotiators trimming a draft global climate pact, but leaving core sticking points to be untangled at later sessions before the December summit in Paris where the landmark agreement is meant to be adopted.

Frustrated by the pace of the talks in Bonn, some observers called it a squandered opportunity to capture the momentum of a declaration this week by leaders of the Group of Seven wealthy countries endorsing a long-term goal of decarbonizing the global economy.

Officials leading the talks called for patience, with co-chair Ahmed Djoghlaf telling reporters you can't craft a universal agreement to transform the world overnight.

He said Thursday that delegates worked so hard in Bonn they missed Saturday's Champions League soccer final in Berlin.