Vancouver Mayor Gregor Robertson has tweeted his arrival in Rome as he prepares for a two-day Vatican summit on the environment.

Gregor Robertson will join about 30 other representatives of big cities from Europe, Africa, Asia and the Americas for a two-day visit with Pope Francis in Vatican City on July 21. He will be the only Canadian representative in the delegation of global municipal leaders.

In his tweet, Robertson says anyone with ideas should send them to him before the meetings begin tomorrow.

He has already said he will encourage the Pope to ramp up pressure on national governments across the globe to take action on climate change. 

Robertson levelled harsh words for the current Canadian government, saying it has "been in the bad books globally" because of inaction on the environmental front. National governments in general have failed to deliver solutions on climate change, he said.

"But at a city level there's serious action and commitment and it's important that the rest of the world understands that,' Robertson said.

"I'll be sharing stories from our work in Vancouver and encouraging global cities and the Vatican to continue pressing for more urgent and aggressive action."

World leaders are slated to meet later this year in Paris for the United Nations Climate Change Conference.