Leaders from the world’s top economies will try to bridge deep differences with U.S. President Donald Trump on climate change and trade on Friday as a Group of 20 summit gets underway in Germany amid the threat of violent protests. The meeting in the port city of Hamburg comes at a time of tectonic shifts in the global geo-political landscape, with Trump’s “America First” policies pushing Europe and China closer together. Trump will meet Russia’s Vladimir Putin for the first…