When it comes to sustainable transportation, Michael Bloomberg is saving his strongest words for an international audience. While the mayor’s rhetoric on transportation now tends to focus on safety, when transportation is on his agenda at all, at a meeting of the C40 Cities Climate Leadership Group in São Paulo Bloomberg brought back some of his 2007-vintage language.

Said the mayor in his speech:

“The intense burning of fossil fuels in the world’s cities – where 70 percent of the world’s greenhouse gas emissions are produced – not only contributes to climate change, it also clogs the streets, pollutes the air, and shortens the lives of their millions of residents. How we as mayors respond to these challenges will strongly determine the fate of the entire world, now and for decades to come.”

Bloomberg, the current chair of the C40 project, was there to announce the release of two studies and a new partnership between the coalition of big-city mayors and the World Bank.

The first study created a shared greenhouse gas reporting system for the C40 cities, allowing high-quality comparisons for the first time. The 42 C40 cities that participated were responsible for 1.2 billion metric tons of CO2 equivalent emissions, it found, roughly equivalent to the emissions of Japan.

Numbers like that fed into what at times seemed to be a bit of urban policy triumphalism on the part of the mayors. “Because of our shared experiences in leading the world’s great cities, and because, more than anyone else, we grasp the urgency of the challenges we now face, no one can do more to produce good outcomes for the world than we, the mayors of great cities, can,” said Bloomberg.

While it’s true that many cities have shown real leadership on climate change and reduced their greenhouse gas emissions, in the United States, states have probably implemented the most effective new climate policies and no real solution to climate change seems imaginable absent national and international action.

That doesn’t mean that action at the city level isn’t critically necessary, and the second report lays out how much has already been done. In the 58 C40 cities, 4,734 climate change actions are in effect and another 1,465 are in the process of being implemented.

The report notes that transportation is one of the three areas where cities have the most direct ability to prevent climate change, along with energy use by buildings and waste management. Twenty-two of the C40 mayors have invested in new bike infrastructure, for a total of 9,370 km of new lanes, and ten have built bus rapid transit systems. Another nine are working to introduce electric or hybrid taxi fleets.

To ensure that progress on those fronts not only continues but speeds up, the World Bank announced a new partnership with the C40 cities. Though it normally works through national governments, the World Bank will create a new system for C40 cities to access its technical assistance and climate finance initiatives directly.