From Rio to Tokyo, Hamburg to Johannesburg, it was seven continents united in a 29-hour global call for action on climate change as musicians and audiences stood together as one.

The worldwide television audience is estimated to have hit 2 billion.

The marathon of music featured acts like Madonna, Bon Jovi, Dave Matthews Band, Beastie Boys, Metallica, Red Hot Chili Peppers, Kelly Clarkson, the Smashing Pumpkins and the Police.

Like benefit concerts of the past, this show was all about raising awareness, and in this case, it was the environment aglow in the spotlight.

One man was responsible for pulling together the entire event: former U.S. Vice-President Al Gore.

On stage at the New York Live Earth concert following a performance by the Police, joined by Kanye West and John Mayer, Gore had a simple message, "With all this energy in this heart, help us solve the climate crisis."

As part of the effort to influence change, Gore has unveiled a seven-point pledge that organizers want viewers and concert attendees to sign. It asks signatories to plant new trees, increase energy efficiency in their homes and offices, buy from eco-friendly businesses and reduce their own CO2 pollution.

To control energy consumption, Live Earth organizers implemented "green event guidelines," which include only using electricity from renewable resources to power the shows, using LED lights as part of production lighting, offsetting staff and artist air travel with carbon credits, minimizing waste through recycling and reuse, and by using hybrid or high-efficiency cars for ground travel when possible.

CTV launched the event Friday night at 9 p.m. from the MuchMusic building on Queen Street in Toronto. The network decided to forego the edited world feed in favour of a made-in-Canada, customized marathon broadcast, allowing Canadians to see live highlights from each concert around the world, all in High Definition. On-air guests included Sam Roberts and Canadian Idol judge Zack Werner.

Ten different CTV crews, involving more than 300 employees, worked to receive feeds from the nine concerts as well as the live hits from New York and London for the 29-hour marathon television show.

The concert was also available on the Internet. More than 10 million people tuned in to the video broadcast on LiveEarth.MSN.com, making it the most watched online event ever.

The first concert to come online was Australia at around 10 p.m. EST on Friday, with a concert in Sydney kicking off with a political reggae-infused jam from Blue King Brown.

Tokyo joined in later with a holographic form of Al Gore, who was soon to be upstaged by an amazing local band called Rize, who sweated their way through their set of pop-metal hybrid jams. Pop star Rihanna performed her hit "Umbrella" later.

Then with a crash of drum,s Live Earth London came to life in Wembley Stadium at 8:30 am ET -- a concert that went on to feature headline acts like Madonna, Foo Fighters and the Beastie Boys. Over 70,000 people filled the recently revamped stadium that hosted the July 1 Concert for Diana, an event to commemorate the life of the former princess who died in 1997. About a half-hour earlier, Hamburg's concert sprung to life.

Al Gore first appeared in the flesh at 10:30 am ET Saturday morning in jeans on the somewhat smaller stage in Washington, D.C. to introduce Garth Brooks, who in a rare live performance sang "We Shall Be Free." He took mass transit from Washington to his Giants Stadium appearance.

Later in the afternoon, Johannesburg and Rio de Janeiro also launched their concerts.

New York's show, which was actually held at Giants Stadium in New Jersey, was slowly brought to life with a performance by Kenna, and then kicked into high-gear when KT Tunstall brought her acoustic-soul hits and shiny gold tights to the stage.

Undeniably the coolest performance came from researchers in Antarctica. Their hobby band, "Nunatak," looked surprisingly at home in the company of superstars.

Madonna, clad in black, strummed and strutted in her finale performance in London, even inviting obscure folk-freaks Gogol Bordello onstage to take part in her show.

Featuring some of the biggest acts of the entire "Live Earth" event, New Jersey's hometown pride Bon Jovi was one of the final performers of the day, receiving the biggest and warmest reception from the audience.

Gender balance

Usually festival events like "Live Earth" are loaded with male dominated bands, but it's interesting to note that gender representation was balanced across the course of the event. For every all-guy bands like the Police or the Red Hot Chili Peppers, there were headlining female acts like Madonna, Rihanna, Macy Gray, Joss Stone, Shakira, Melissa Etheridge and Alicia Keys.