(Bloomberg) — Cities, which are home to more than half the world's population, are stepping up efforts to slash pollution, often wresting the fight against climate change away from national governments. That's the conclusion of CDP, a non-profit group that pushes institutions to detail their greenhouse-gas emissions. Often able to move faster than their national counterparts, metropolitan authorities from London to Sydney and Boston are among a group of 15 setting out the most rigorous plans to achieve carbon or climate neutrality by 2050. The moves are evidence of ambition by local authorities to do their part in reining in global warming, almost two-thirds of global emissions come from cities. CDP wants to draw attention to their actions to encourage others to make similar commitments. "Cities are doing a lot of the work, but they can't get there alone," said Kyra Appleby, global director of cities, states and regions at CDP. "Businesses need to act, national governments need to act as well, people need to change their own behavior in order for us to limit carbon emissions." A smaller group consisting of five cities including Paris and San Francisco have set themselves 100% renewable energy targets. Reykjavik, population 123,000, says it already uses 100% renewable power. How fast other cities get to that point is largely down to the policies they enact. Paris gets 35% of its energy from clean sources, and San Francisco gets almost 60% of its power from renewables, CDP said. Almost 7% of the 625 cities that took part in the report were given the highest rating — joining the CDP "A-list." Among the top scoring, only 28 have set goals for carbon neutrality (balancing emissions of greenhouse gases), climate neutrality (designing wider policies to reduce the overall impact of human activity to the environment) or cutting emissions by half or more. Related: Local governments begin to confront climate change risk |

Cities are stepping up

More than 20 U.S. cities got the highest rating, showing how mayors and city level lawmakers can take the initiative on climate change in spite of a president who has repeatedly played down the effects of global warming. Since the 2015 Paris Agreement that committed the world to slowing down global warming, the narrative has shifted from a problem that the world faces in the future to an issue that exists today. That was sped up by a 2018 United Nations report that spelled out the need for rapid action to grapple with a warming planet — and what would happen to ecosystems if temperatures increased another half degree Celsius. Cities have formed alliances to share knowledge and push for change — like the C40 initiative that has 94 cities committed to implementing ambitious climate goals. Protests over the global warming have become more urgent with activists calling for climate emergencies to be declared. CDP gives an "A" rating to any city that reports publicly on its climate adaptation and action plans as well as reporting on emissions inventories and reduction targets. The worst performing cities are handed a "D", although CDP doesn't make those public. "Cities are real hot spots of innovation, business and human life on earth so it's crucial that cities are acting in order for us to meet the targets," Appleby said. Related: Insurers worry a financial crisis may come from climate risks

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