SHANGHAI, May 29 (Xinhua) -- Mayors and representatives of 26 cities across 22 countries have gathered in Shanghai for the ongoing Global Mayors Dialogue and the 2025 Shanghai International Friendship Cities Cooperation Forum, which kicked off on Wednesday.

Sub-forums are themed "Green and low-carbon empowerment for sustainable urban development" and "Inspiring youth vitality for city innovation in the future." The forum runs until Saturday.

While developing sister-city relationships against "a complicated and ever-changing international backdrop," cities need to deepen pragmatic cooperation, solidify longstanding friendships based on equality, mutual trust and joint consultation, and share development opportunities, all with the aim of promoting prosperity and stability, Shanghai's Mayor Gong Zheng noted.

Haris Doukas, mayor of Athens, Greece, stressed the role of city diplomacy in tackling the climate crisis. "City diplomacy has allowed cities to lead the way, to achieve important partnerships for prevention, to share knowledge, to set brave and specific goals through participation in international networks and forums, and to reduce the burdens of the climate crisis," Doukas said. Shanghai and Athens established a sister-city relationship in January.

"Climate change is the defining challenge facing our shared world today," said Dan Boyle, lord mayor of Cork, Ireland, adding that "the spirit of international cooperation, which informs gatherings like today, can give us some optimism that this challenge facing all of humanity will be met."