From an Antarctic research base and the Great Pyramids of Egypt to the Empire State Building in New York and the Sears Tower in Chicago, illuminated patches of the globe went dark Saturday for Earth Hour, a campaign to highlight the threat of climate change. Time zone by time zone, nearly 4,000 cities and towns in 88 countries joined the event sponsored by the World Wildlife Fund to dim nonessential lights from 8:30 p.m. to 9:30 p.m. The campaign began in Australia in 2007 and last year grew to 400 cities worldwide. Organizers initially worried enthusiasm this year would wane with the world focused on the global economic crisis, said Earth Hour executive director Andy Ridley. But he said it apparently had the opposite effect. "Earth Hour has always been a positive campaign; it's always around street parties, not street protests, it's the idea of hope, not despair. And I think that's something that's been incredibly important this year because there is so much despair around," he said. Crowds in Times Square watched as many of the massive billboards, including the giant Coca-Cola display, darkened. Steps away, the Majestic Theater marquee at the home of "The Phantom of the Opera" went dark, along with the marquees at other Broadway shows. Mikel Rouse, 52, a composer who lives and works nearby came to watch what he called "the center of the universe" dim its lights. "C'mon, is it really necessary? ... All this ridiculous advertising ... all this corporate advertising taking up all that energy seems to be a waste," Rouse said. In Chicago, one of 10 US Earth Hour flagship cities, a small crowd braved a cold rain to count down as Gov. Pat Quinn flipped a 4-foot (1.2 meter)-tall mock light switch that organizers had to brace against high winds. A second later, the buildings behind him went dark. "I don't see why people shouldn't always turn off the lights," pondered 15-year-old Chicagoan Tyler Oria, who was among those gathered. More than 200 buildings pledged to go dark in the city, including shops along the Magnificent Mile. "No matter what your individual beliefs are about climate change, energy efficiency is something everyone can understand in this economic environment," said WWF managing director Darron Collins, who helped Chicago officials organize for the night. The Smithsonian Castle, World Bank, National Cathedral and Howard University were among several buildings that went dark for an hour in the nation's capital. "This was the first year that Washington, DC, became an official Earth Hour city," said Leslie Aun, WWF spokeswoman. In the Chilean capital of Santiago, lights were turned off at banks, the city's communications tower and several government buildings, including the Presidential Palace where President Michelle Bachelet hosted a dinner for US Vice President Joe Biden. The two leaders and dozens of guests dinned at candlelight. In Mexico City, the city government and business owners turned off all "nonessential" lights at more than 100 buildings, including 31 city buildings and monuments and 17 hotels. In San Francisco, some of the city's best-known landmarks went dark, including Coit Tower, the TransAmerica building and the Golden Gate Bridge. Los Angeles dimmed the lights at the Griffith Observatory, the Santa Monica Ferris wheel, City Hall and other area landmarks. A DJ led a crowd at a dimmed-down dance party outside downtown's LA Live entertainment complex. Organizers said nearly 1,000 people were at the event. UN Secretary Ban Ki-moon called Earth Hour "a way for the citizens of the world to send a clear message: They want action on climate change." An agreement to replace the Kyoto Protocol, which expires in 2012, is supposed to be reached in Copenhagen, Denmark, this December, and environmentalists' sense of urgency has spurred interest in this year's Earth Hour. In Bonn, WWF activists held a candlelit cocktail party on the eve of a UN climate change meeting, the first in a series of talks leading up to Copenhagen. The goal is to get an ambitions deal to curb emissions of heat-trapping gases that scientists say are dangerously warming the planet. "People want politicians to take action and solve the problem," said Kim Carstensen, director of the global climate initiative for WWF, speaking in a piano bar bathed by candlelight and lounge music. China participated for the first time, cutting the lights at Beijing's Bird's Nest Stadium and Water Cube, the most prominent 2008 Olympic venues. In Bangkok, the prime minister switched off the lights on Khao San Road, a haven for budget travelers packed with bars and outdoor cafes. In Rio de Janeiro, the iconic Christ the Redeemer statue that watches over the city of 6 million was darkened, along with the beachfront of the famed Copacabana and a few other local sites. Earth Hour organizers say there's no uniform way to measure how much energy is saved worldwide. Earth Hour 2009 has garnered support from global corporations, nonprofit groups, schools, scientists and celebrities - including Oscar-winning actress Cate Blanchett and retired Cape Town Archbishop Desmond Tutu. McDonald's Corp. planned to dim its arches at 500 locations around the US Midwest. The Marriott, Ritz-Carlton and Fairmont hotel chains and Coca-Cola Co. also planned to participate. In the Chicago suburb of Blue Island, Eli Rodriguez, 41, owner of a Mexican restaurant called Tenochtitlan switched off not only the lights but also the television, which was playing a NCAA tournament basketball game. "Everybody was happy I did it," Rodriguez said. "They support this. They understood." But after a few seconds, he turned the game back on and kept the lights dim.