people 's ability to fight climate change . `` The challenge for national governments is that while they can sometimes reach agreement they do n't know how to act collectively , '' Miller continued . `` For cities , that 's easier . We all have climate strategies , but can make our actions work better and make the partnerships to do that . '' The Seoul summit is the third conference by cities held to discuss responses to climate change . The C40 group was established in London in 2005 . A second summit was held in New York in 2007 . Watch efforts to make New York 's Empire State Building more eco-friendly '' Much of the talk at this week 's conference was how major urban centers could work toward adhering to the Kyoto Protocol , the existing environmental treaty that sets targets for nations to reduce greenhouse gas concentrations . Adopted in December 1997 , the Kyoto Protocol entered into force in February 2005 . In countries that did not sign up to the Kyoto agreement , cities took it upon themselves to reduce their carbon footprint . While the United States did not sign Kyoto
SEOUL , South Korea -LRB- CNN -RRB- -- Former U.S. President Bill Clinton on Tuesday urged urban leaders and policymakers they need to take the lead now in fighting climate change . Bill Clinton to urban leaders in Seoul : What will you do about climate change ? `` What are you going to do and how much are you going to spend ? '' Clinton asked leaders from the world 's biggest cities at a climate summit being held in South Korea 's capital , Seoul . Officials from the world 's 40 biggest cities plus 17 affiliate municipalities are attending the C40 Large Cities Climate Summit , which ends on Thursday . Waiting for nations to take the lead with a new climate protocol in Copenhagen in December is not an option , said David Miller , mayor of Toronto and chairman of the C40 Cities Leadership Group . `` If governments talk about reducing CO2 -LRB- carbon dioxide -RRB- , cities are the ones that show how it 's done , '' Miller said . `` The point is that cities act , and working together we have a scale and a size that we dramatically increase