It’s long been said you can reduce emissions and keep your economy growing. The latest report from the world’s top body of climate scientists confirms that 18 countries have done just that, sustaining emissions reductions “for at least a decade,” and growing at the same time. But they are mainly developed nations, whose economies are already fully built out. Some, including the United States, Germany, Japan and the United Kingdom, are among the largest contributors to historical carbon emissions, with perhaps the greatest responsibility to reduce emissions.