But the Trump administration failed to support the plan, and on Thursday city officials presided over a much smaller gathering of 20 US mayors and four officials from cities in other countries, including China.

Two years ago, with great fanfare, then-Secretary of State John F. Kerry announced in Beijing that Boston would host an international climate summit that would bring together thousands of urban and business leaders from cities across the United States and China, the world’s two largest producers of greenhouse gases. It would have been the third such conference.

In introducing a panel at Boston University that included Kerry, Mayor Martin J. Walsh acknowledged how politics narrowed the scope of the event.


“We were thrilled” after Kerry’s initial announcement, Walsh said. “Then the election of 2016 happened. The new administration was not supportive of our plans. In fact, they tried to prevent the summit from happening at all.”

“But one thing Boston and John Kerry have in common is that we don’t back down from a fight,” Walsh added.

Indeed, Kerry was unsparing in his criticism of President Trump, who has called climate change a hoax and last year announced that the United States would withdraw from the landmark Paris climate accord, which Kerry negotiated and 195 other nations agreed to.

“I’m so tired and sick of the absence of real leadership to say, ‘Here’s what we got to do,’ ” he said. “Nothing is happening today.”

Kerry accused Trump of “misleading” Americans about the nature of the Paris accord, in which each country pledged to meet specific goals for reducing carbon emissions with the goal of curbing the rise of global temperatures.

The pledges, by design, were not binding.

“There is no burden placed on us by any other nation or by Paris itself,” Kerry said. “We are only agreed to do what we decide, what all of our experts said we could accomplish in the United States, without hurting our economy.”


Kerry noted that the Paris agreement doesn’t let the United States withdraw until after the next presidential election.

“So, if we do the right thing in 2020, we’ll solve the problem and be back in 30 days later,” Kerry said.

And while the federal government may no longer be abiding by the accord, the majority of the nation’s cities and states are working to reduce emissions, Kerry said.

“While Donald Trump may have said he’s out of Paris, the American people have stated unequivocally that they’re in Paris,” Kerry said.

Kerry acknowledged that the Paris accord alone will not solve the problem of global warming. But he said it was designed to unleash market forces that could help reduce the rising amount of carbon dioxide and other emissions that trap heat in the atmosphere.

He pointed to research by scientists and technologies produced by private companies, which he said are indispensable to addressing the problem. He pointed to the work of his copanelist, Anne Finucane, the vice chairman of Bank of America, who said she sees action on climate change as a “market opportunity” for big businesses.

“You take the top 20 market cap companies in the country, I’d say that most of them are focused on this because we see huge risk and big opportunity,” she said. “We are full-on doing this. It’s a business for us.”


Earlier in the day, Walsh announced an effort to team up with cities around the country to buy renewable energy, with the goal of pooling their buying power to lower costs.

“Our effort on renewable energy will not only help cities cut carbon emissions and get us closer to the goals of the Paris climate agreement, it will help power our cities and create more clean energy jobs,” Walsh said in a statement. “We can do more than just address the problem of climate change, we can build a healthy, thriving future by working together.”

Not everyone was sold on Walsh’s words. Some environmental groups have accused Walsh of failing to match his rhetoric on climate change with concrete action.

The groups planned to project an image on the Copley Marriott parking garage Thursday night, urging the mayor to do more. Their message: “Mayor Marty Walsh: #Walkthetalkonclimate.”

The groups were planning a protest Friday in the Back Bay to coincide with the nearby US Conference of Mayors’ annual meeting.

“While this new announcement [on renewable energy] is promising, the Walsh administration is still approving millions of square feet of new development without mandating climate mitigation or resiliency, and approving massive, new fracked gas infrastructure to luxury apartment buildings,” said Deb Pasternak, chair of the Massachusetts Sierra Club.

David Abel can be reached at dabel@globe.com.