WASHINGTON – There’s an unexpected method governments can use to reduce poverty, improve public health and reduce greenhouse gas emissions, top world leaders said Friday.

Their idea: Make transportation in the world’s megacities more available and sustainable to reduce congestion and benefit populations — and economies — that are projected to boom in the coming decades.

Jim Yong Kim, president of the World Bank, said Friday at a global transportation conference that working on sustainable transportation is part of the bank’s moral responsibility and will be a major focus of its lending in the coming years. Lifting people out of poverty is the bank’s chief mission, Kim said. But climate change caused by global warming threatens that mission, he said, particularly for future generations.

The bank recently issued a report that outlines what the world could be like if temperatures rise by 7 degrees Fahrenheit by 2060. It’s sometimes difficult for people to understand that, Kim said, but he offered the example of his own 3-year-old son.

“When he’s my age, he’ll be living in a world where the oceans will be 150 percent more acidic … (and) fisheries would have been completely disturbed,” he said, adding that there will be struggles every day for food and water. “The world that I’m literally handing over to him as an adult will be one that does not exist today. For me it’s very real.”

Cities are uniquely positioned to thwart such dire consequences, said New York City Mayor Michael Bloomberg, who has been a vocal advocate for aggressive action on climate change. The mayor is one of the leaders of the C40 Cities Climate Leadership Group, a partnership of the world’s largest cities that have decided to take action on climate change in the absence of movement by national governments.

It’s vital they do so, Bloomberg said. The World Bank estimates that 60 percent of all people will live in cities by 2030. He warned that national or federal governments can throw up obstacles, but cities can solve transportation and climate change-related problems.

“They talk a good game,” Bloomberg said of the national governments. “They vote fictitious funds for projects that never get done. But whether you are tackling the environment or crime or education or transportation, they are basically done at the local, city level.”