Going green could save the world a lot of money — about $17 trillion by 2050, according to a new New Climate Economy report.. The climate-focused project is an initiative from the Global Commission on the Economy and Climate, and the findings show that investing in public and low-emission transportation, building efficiency and waste management in cities could generate these big savings.

“U.S. $17 trillion in savings is actually a very conservative estimate, because it only looks at direct energy savings generated from investment, which are a small proportion of the wider social, economic and environmental benefits of these investments,” Nick Godfrey, head of policy and urban development at the New Climate Economy, said in a statement.

With even more aggressive policies and changes — including low-carbon innovation, reduced fossil fuel subsidies and carbon pricing — the savings could be as high as $22 trillion, and the world could erase a carbon footprint the size of India’s, according to the report, which offers ideas for how cities can get started.

The most immediate fix suggested: Greening transportation. The report points to bus rapid transit, which as I reported last week, is at an all-time high. It also calls for more bicycling, highlighting Copenhagen’s planned Cycle Super Highways, which are estimated to have an internal rate of return on investment of 19 percent annually.

“There is now increasing evidence that emissions can decrease while economies continue to grow,” said Seth Schultz, a researcher for the C40 Cities Climate Leadership Group who consulted on the report. “Becoming more sustainable and putting the world — specifically cities — on a low carbon trajectory is actually feasible and good economics.”

Former New York City Mayor Michael Bloomberg recently wrote an essay for Foreign Affairs titled, “Why Municipalities Are the Key to Fighting Climate Change.” In it, he points to urban policy as the catalyst for national and international shifts.

“Many of the most important new initiatives of this century — from the smoking ban adopted in New York City to the bus rapid transit system pioneered in Bogotá — have emerged from cities,” Bloomberg writes. “Mayors are turning their city halls into policy labs, conducting experiments on a grand scale and implementing large-scale ideas to address problems, such as climate change, that often divide and paralyze national governments.”