After Attacks Derailed First Effort, Climate Sign Shines on the Eiffel Tower

Read the rest of our COP21 coverage in our special report, Climate of Hope.

PARIS -- A new sign adorned the Eiffel Tower at dusk Sunday night: a hand forming the letter "C" in American Sign Language, for climate change.

Founders of the Climate Sign campaign said they were forced to move away from their original symbol quickly after the Islamic extremist attacks here, and hope with the "C" they've just unveiled can become a global signal for climate advocacy and justice.

The "Climate Sign" appears on the Eiffel Tower on the night of December 6, 2015. (Camilla Andersen/GroundTruth)

The concept was developed over the last year by a group of students and alumni from two universities in California and chosen by Paris Mayor Anne Hidalgo. It will be splashed upon Paris' iconic monument all week as the city hosts the Conference of Parties (COP21) under the United Nations Framework Convention on Climate Change (UNFCCC). Representatives from around the world are working to reach an agreement to limit global warming.

More than 45,000 government officials, NGO representatives, students and activist groups have travelled to Paris for the conference. Around the city, activist groups and artists are creating displays that bring attention to the challenges climate change will create for the world. The Climate Sign campaign hopes to galvanize their efforts around a single gesture.

"There was really a need for a uniting symbol or icon, or something, to really amplify those voices," said Hadley Greswold, an alum of the University of Southern California and one of the founders of the Climate Sign campaign. "People are involved in climate action for a variety of different reasons or different sectors."

Greswold, 22, and her classmate Sonia Guggenheim, 21, began developing the idea when they attended the People's Climate March in New York City in September 2014. When they returned to California, Guggenheim and Greswold created a team which included Greswold's mother Kate, a veteran conservationist.

They found coming up with a symbol for the campaign to be difficult, Greswold said. The group started by narrowing down ideas that had been submitted online, then sent their final choice to contacts from 50 countries to ensure it was cross-culturally appropriate.

They settled on the letter "D" in American Sign Language, four fingers shaped into a circle and the index finger pointed up. It would stand for "decarbonize," but could also be adopted by divestment campaigns. Mark Ruffalo, Bill McKibben and Moby agreed to take selfies with the climate sign. Greswold said she and her team began to promote their campaign on Facebook and Twitter using the hashtag #climatesign . Ahead of the climate conference they ordered 500 T-shirts and 20,000 stickers and filmed two ads for their campaign, all featuring the "D."

But two weeks before the climate conference, the deadly attacks in Paris changed Climate Sign's direction. More than 130 people were killed in shootings and explosions that were organized by the Islamic State of Iraq and Syria (ISIS).

It turned out that Hadley and her team had chosen a hand sign that resembled one used by Islamic State fighters to signify "One God." Pictures of militants with their index fingers pointing to the sky have circulated throughout social media.

So the Climate Signs team regrouped and decided on the "C" that this week will shine on the Eiffel Tower.

"Once the attacks happened, we decided we've got to change," said Kate Griswold. "It was a hard thing to do, and then we wanted to ask the mayor because it's her city, she's hosting this and she's been through this horrible thing."

Mayor Hidalgo approved it on Monday, and the group is now promoting the revised campaign around Paris.

"The climate sign is really the peace sign of our time," Guggenheim added. "Climate change is such a huge issue, it's overwhelming. Right now we feel powerless, but we still have our voice. We have the power to show that we care."

This post is part of a series produced by The Huffington Post and The GroundTruth Project , in conjunction with the U.N.'s 21st Conference of the Parties (COP21) in Paris (Nov. 30-Dec. 11), aka the 2015 climate-change conference. GroundTruth will have six reporting fellows in Paris, each of whom will be filing solutions-oriented climate-change stories for The Huffington Post, which will be a part of HuffPost's What's Working editorial initiative. To view the entire series, visit here .