Vancouver's mayor is getting a higher profile as a climate crusader with an invitation to discuss the issue with United States Secretary of State John Kerry this week alongside a select handful of global city leaders.

Gregor Robertson was invited to attend the Our Cities, Our Climate initiative in Washington, D.C., to help advise Kerry in the lead up to the United Nations Climate Change Conference in Paris later this year.

Robertson's environmental advocacy -- including his pledge to convert Vancouver to 100 per cent renewable energy -- earned him an audience with Pope Francis earlier this year, where he encouraged the Catholic leader to ramp up pressure on national governments for more commitment to combat climate change.

Robertson attributed his emergence as a vocal campaigner and internationally recognized point person on climate action in part to a dearth of initiative at the federal level.

"When there's a void of leadership on climate change and the green economy with the Canadian government, it's necessary for mayors and business leaders and community leaders to step up and make sure that Canada is represented," Robertson said in an interview.

"It's important, when Canada is being tarnished on the world stage by battling against meaningful climate commitments, that we show leadership in our cities."

Robertson described a stark contrast between Canada's approach to climate change action compared to that of its neighbour to the south.

"Secretary Kerry will be the key negotiator in Paris for the U.S. and part of his prep is gathering mayors from his country and leading cities globally and broadening his understanding and commitment to climate action," he said.

"We've seen nothing like that from Canada. That's a great disappointment."

 Robertson was the only Canadian mayor invited to attend the event, which will involve 19 mayors, 10 of whom are from the U.S.

He described the upcoming meeting as an opportunity both to share best practices and success stories from across the globe, but also to make a united call for leadership at the national level.

He anticipated sharing the story of Vancouver's quest to attract investment in green business opportunities, which he described as essential to being able to compete in the global economy.

"Going green is great for business," said Robertson. "There's a very compelling economic case to adopting renewables and eliminating waste ... and we're seeing cities pick up the pace."

Besides Kerry, the Our Cities, Our Climate summit will be headed by the U.N.'s special envoy for cities and climate change: former New York City mayor Michael Bloomberg.

The meeting of global mayors will mark the culmination of the event, which is characterized by organizers as a "historic initiative."

Mayors will participate in two days of site visits, working sessions and a State Department-hosted luncheon, in addition to taking part in discussions and meetings with senior U.S. government officials.