Story highlights Michael R. Bloomberg and Maroš Šefčovič: Cities will bear brunt of climate change

Leaders must collaborate to help spread solutions to cities around world, they say

Michael R. Bloomberg and Maroš Šefčovič are co-chairs of the Global Covenant of Mayors for Climate & Energy. Bloomberg is the former mayor of New York and founder, CEO and owner of Bloomberg LP, a global financial data and media company. Šefčovič is a current vice president for the Energy Union for the European Commission. The opinions expressed in this commentary are solely theirs.

(CNN) While longstanding partnerships between nations are being tested by shifting politics on both sides of the Atlantic, the world's cities are working together more closely than ever to address shared challenges. No issue better demonstrates this than the global effort to confront climate change -- and in the wake of the US withdrawal from the Paris climate agreement, cooperation among US and global cities will be even more important.

Maroš Šefčovič

Michael Bloomberg

Through the Global Covenant of Mayors for Climate & Energy, more than 7,400 cities worldwide have united in a coordinated effort to address the causes and impacts of climate change. These cities have pledged to meet ambitious targets for reducing carbon emissions, adapt to climate change and increase local access to clean and affordable energy, all while holding themselves accountable for planning and reporting their progress transparently and consistently.

This mirrors what nations have agreed to do under the Paris Agreement but with one critical difference: City leaders are often setting higher goals than their national counterparts and acting faster and closer to citizens to reach them.

Mayors helped to raise the ambition of the Paris Agreement by showing national governments how much progress was possible. Working together, cities are leading the charge to implement the agreement and help nations reach their goals. That includes the more than 200 US mayors and 1,500 business leaders who have signed a pledge committing to actions that will help the United States reach the goal it set in Paris in 2015 despite the federal government's decision to withdraw from the agreement.

The reason so many mayors, from all regions of the world, have come forward to join the pledge is simple: They recognize the same steps that are most effective in reducing carbon emissions while increasing access to clean energy and protecting people and assets also improve people's lives and spur economic growth.

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