Reuters: U.S. President Barack Obama is walking a tightrope on climate change — and so far appears to be achieving a delicate balance. At Obama’s urging, Congress is working on a bill to curb greenhouse gas emissions with a cap-and-trade system. The developed world is again looking to the United States to lead on the climate issue after eight years of Washington sitting on the sidelines. The president is balancing those moves with efforts to address concerns of U.S. business and win …