As the 2009 global climate summit in Copenhagen approached, the European Union raced to announce an ambitious target for reducing greenhouse gas emissions. The bloc’s leaders worked to smooth over the competing interests of more than two dozen members, settling on a three-part plan that it promised to meet by 2020, nicknamed the 20-20-20 Pledge: The bloc would reduce its emissions by 20 percent from 1990 levels, increase renewable energy to 20 percent of electricity use, and increase energy efficiency by 20 percent. By the 2020 deadline, the European Union had achieved two of its three goals — an example of a major emitter achieving a climate pledge. Overall emissions were 24 percent lower than in 1990, by the bloc’s accounting, and renewable energy was about 20 percent of its electricity use. But many climate scientists and others involved in the process question the European Union’s accounting.