Reuters: U.S. President Barack Obama on Tuesday touted new proposals from his administration to reduce carbon dioxide emissions from power plants and said the United States and Europe had to lead by example in fighting global warming. "This has to be a global effort," Obama said after a meeting with Polish Prime Minister Donald Tusk. "As we work to shape a strong global climate agreement ... it's important for the United States and the EU to set an example by committing to ambitious goals to reduce emissions...