Mayors from more than 350 cities across Europe signed an EU climate change agreement Tuesday pledging to cut carbon dioxide emissions by more than 20 percent by 2020.
The pact covers urban areas across 23 EU countries and includes cities like London, Paris and Madrid.
European Commission President Jose Manuel Barroso called on the mayors to follow the famous slogan "think globally, act locally" by encouraging their city dwellers to reduce emissions further.
"Voluntary actions by citizens are crucial, changing our energy behavior, making intelligent investments, adopting smart mobility practices, these are actions that need to be motivated," Barroso during the signing ceremony.
EU Energy Commissioner Andris Piebalgs said the plan -- called the "Covenant of Mayors" -- will affect 80 million Europeans and will save around euro8 billion ($10.4 billion) in energy costs.
Under the pact, cities commit to "go beyond" a two-year agreement by EU national governments to cut greenhouse gas emissions by 20 percent, increase energy efficiency by 20 percent and to increase the use of renewable energy sources to 20 percent of all energy used by 2020.
Hamburg, for example, plans to reduce emissions by 40 percent by 2020, said Ole von Beust, the German city's mayor. Paris deputy mayor Denis Baupin said his city hopes to reduce emissions by 25 percent over the same period.
Budapest Mayor Gabor Demszky said he was confident the agreement "can actually become the new driving force behind the new European climate policy."
New York Mayor Michael Bloomberg told his European counterparts in a video message that his city would aim to reduce emissions by 30 percent by 2030 and backed the EU plan as well.
"We are committed to doing that even as our population grows to an expected 9 million people," Bloomberg said. "Those of us in city government can and must take a leading role."
Under the EU plan, cities must create their own energy efficiency plan, which will be updated and checked every two years by the EU. Those that fail to submit their plan within a year of signing the agreement or that do not meet the goals set out in those plans could lose possible EU aid.
EU lawmakers criticized the plan, however, after the commission last week scrapped euro500 million ($652 million) in funds meant to help cities meet their goals.