NEW HAVEN – In the here and now of climate change, it is easy to lose sight of important signs of progress. China, the world’s biggest emitter of greenhouse gases, is a case in point. By changing its economic model, shifting its sources of fuel, developing new transportation systems, and embracing eco-friendly urbanization, China’s sustainability strategy is an example of global leadership that the rest of the world should consider very carefully. In the rush to demonize China over trade, the West has missed this point altogether.