Politicians and journalists tend to be jaded about international agreements aimed at improving society. And already too many commentators are saying the global climate summit that begins December 7 in Copenhagen will not produce tangible instruments that limit greenhouse gas emissions. Disgusted by the pessimism, the global advertising industry has started a grassroots campaign to encourage citizens worldwide to sound out a message of hope...in an effort to pressure each country's leaders and delegates to the U.N Climate Change Conference to enact change.

The challenge, of course, is convincing enough people to shout out. So advertising agencies, led by Ogilvy Earth in New York City, have created an aggressive but positive public-relation campaign called Hopenhagen. "You can't bore people into caring about climate change. And you can't threatem then into caring," says Freya Williams, a senior partner at Ogilvy & Mather. Just like convincing them to want a product, she says, "you have to inspire them."

The tag lines of the campaign are "When people lead, leaders follow," and "Let's turn Copenhagen into Hopenhagen." Ogilvy, its ad partners, and sponsors such as SAP and Coca-Cola have created a series of beautiful, inspirational ads, including the ones you see here.

The ads have begun running in major media worldwide and will continue in magazines and on billboards and television through the Cop 15 meeting, which ends Dec. 18. The Hopenhagen movement lives online at www.hopenhagen.org, where individuals can sign the U.N. Climate Petition calling for action. As of Nov. 13 more than 378,000 people had signed. But campaigns will also run on YouTube, Twitter and Facebook, where enthusiasts can obtain a Hopenhagen passport.

Williams says the city of Copenhagen may also agree to temporarily change certain high-profile signs at airports, train stations and other key locations, pasting a translucent green H over the C in Copenhagen. The stated goal of all the efforts is to let the Cop 15 delegates know "the world will be watching and holding them accountable for outcomes."