(snip) U.S. leadership is crucial. That is why I am encouraged by the spirit of compromise shown in the bipartisan initiative announced last week by John Kerry and Lindsey Graham. Here was a pair of U.S. senators — one Republican, the other Democratic — coming together to bridge their parties’ differences to address climate change in a spirit of genuine give-and-take. We cannot afford another period where the United States stands on the sidelines. An engaged United States can lead the world to seal a deal to combat climate change in Copenhagen. An indecisive or insufficiently engaged United States will...