When countries face complicated global issues —immigration, terrorism, climate change — progress is usually slow.

But often, those problems hit cities first, and mayors have to find solutions while national leaders (or political candidates) are still busy debating which policies to enact.

“There is a sense in which cities are beginning to assume a part of what was traditionally attributed to national sovereignty: the responsibility to secure the life, liberty and sustainability of citizens in a world where nobody else is doing it,” Benjamin Barber, a political theorist and the founder of the Global Parliament of Mayors, a new city-centric international governing body, tells Business Insider.

“I call it the devolution revolution. The fact is that authority is being devolved increasingly to cities.”

According to Barber, because of how interconnected our world has become and how much less significance geographic borders now hold, a coalition of city governments has the potential to get more done than any international accord. To explain why he believes it’s time for mayors to step up and take on the issues national governments are failing to solve, Barber gives two examples. Refugees and migrants struggle to jump off an overcrowded dinghy on the Greek island of Lesbos, after crossing in rough seas from the Turkish coast Thomson Reuters

Nation-states are supposed to control the flow of refugees and immigrants who enter a country, he says. But whether or not people enter legally, with the proper paperwork, city governments are often the ones who have to figure out what to do with these new residents — they’re the areas absorbing, housing, and employing undocumented immigrants.

“What happens is that cities have begun to develop programs to register and provide immigrants — legal or illegal — with their own so-called urban visas,” he says, citing New York’s NYC ID program, which allows any resident of the city with proof of residence (like an electricity bill, for example) to get a government-issued identification card. Citizens can use the card to get memberships at local cultural institutions, sign up for bank accounts, get access to public buildings, and more.

“The city in effect becomes the one that authorizes, controls, registers and oversees the immigrant population that has gotten into these places without the permission of the nation-states, which aren't in a position to control them and don’t,” Barber says.

Second, he says, climate change in another area in which cities are leading the way despite inaction from their national leaders. Citizens and lawmakers in New Orleans and New York know climate change is an imminent threat, he says, because they’ve already dealt with climate disasters. The leaders of those cities are now taking action to protect their residents, while the federal government remains stagnated by disagreement. A man puts his baby on top of his car as he and a woman abandon their car after it started to float after Hurricane Katrina hit the Treme area of New Orleans August 29, 2005. REUTERS/Rick Wilking

“We're already seeing bike share programs, electric vehicle programs for buses, above-ground rapid transit systems — those are all city-based solutions that address the problem of global climate warming through actions that cities can take,"Barber explains. "And if they take them together, they can have a tremendous impact on greenhouse gas emissions, even if nation-states don’t.”

Barber founded the Global Parliament of Mayors with the hope that by unifying the leaders of cities around the world, the group can address the complicated issues that national governments and the UN have thus far been too slow to deal with. The Parliament’s first meeting will take place in the Hague — the same birthplace as the League of Nations — in mid-September.

“This is an effort to establish a new global governance organization, different than any other urban network that currently exists,” he says, “that takes actions in common, that decides on common policies to address global issues of the kind that nation-states and international organizations are no longer able to or willing to address.”

Mayors Muriel Bowser of Washington, D.C. will join the inaugural convening of the Global Parliament of Mayors. Shutterstock/Orhan Cam

The list of attendees at the inaugural convening — including the mayors of Washington D.C, Paris, Cape Town, and Rio de Janeiro — suggests that many leaders are already onboard. Barber expects 70 to 80 cities to be represented. By next year, he predicts the membership will have doubled.

The topics of discussion at the meeting include how to integrate refugees, balance migration and security, and manage urban resources. By the end of the three days, Barber hopes mayors will have taken ownership of the organization, assumed leadership roles within it, and even planned their next gathering.

“Our new international is inter-urban,” he says.