Last month, I presented a paper at a United Nations conference in New York on what cities could do to make up for shortfalls in state-to-state cooperation.
States are often mistaken as the only actors in the international arena, even though cities are also at the forefront in fields such as climate change and human trafficking.
Tokyo, which launched the world's first urban "cap and trade" programme, assisted five Chinese cities in developing their own emissions trading schemes, despite tense Sino-Japanese relations. Hebron and Tel Aviv are working together with 44 other cities on an "Urban Food Policy Pact", which aims to build a global food system based on sustainability and social justice. Can we imagine such cooperation between Palestine and Israel?
A "sovereignty-free" cooperation model among cities has the potential to transcend political tensions on the state level. As the former New York mayor Fiorello La Guardia put it: "There is no Democratic or Republican way of fixing a sewer."
While states are still in debate, cities may have already taken concrete local actions that can empower global change. Just as 114 heads of state were pondering how sovereignty prevented them from taking bolder steps at the Copenhagen climate summit in 2009, more than 200 mayors agreed at a parallel summit on mutual cooperation through city-to-city networks like the C40 Climate Leadership Group, of which Hong Kong is a founding member.
Cities can learn from "best practices" around the world and exchange our policy experiences. As former chief executive Donald Tsang Yam-kuen said before 50 cities' officials at a C40 workshop in Hong Kong in 2010, cities share common goals, including jointly combating climate change. "Although there are many different views on the exact nature of the problems and solutions, there is a clear consensus that action is urgently needed," he said. Collaboration is essential.