The Live Earth concerts spanning seven continents with an audience of more than 2bn people - 1 in 3 people on the planet - are underway. The first concert began in Sydney at 1.10am BST and they will run until 4am BST tomorrow in New York. In between the music will chase the sun from west to east, with concerts in Tokyo, Shanghai, Johannesburg, Hamburg, London and Rio de Janeiro. In Rio, as many as 1m may turn up for the free concert on the Copacabana Beach, while in London 60,000 people have paid ё55 each to be at the concert in the new Wembley Stadium. The eight concerts will feature 150 of the world`s top bands and artists and will be broadcast in 120 countries. All will carry the message that the Earth has to wake up now if it is to meet the challenges posed by global warming. The aim is to get millions of people committed to changing their lifestyles and demanding change from their own governments. London will have Madonna, the Red Hot Chili Peppers, Kasabian, Keane and Snow Patrol. New York gets the newly-reformed Police, Bon Jovi, KT Tunstall and the Smashing Pumpkins. Smaller symbolic concerts will take place in other cities, including Kyoto, where the Protocol aimed at reducing greenhouse gases was signed. Another show will be held at the British base in the Antarctic, where some of the first effects of global warming are the most visible. Live Earth founder Kevin Wall said: "This monster line-up will ensure Live Earth meets our goal of bringing together people from around the world to combat the climate crisis." "Live Earth will be a monumental event both in terms of entertainment and in turning the tide against global warming." Al Gore, the former US Vice-President, whose film "An Inconvenient Truth" about climate change has made him a leading light in the environmental movement, says one of the key aims is to urge a massive reduction of carbon dioxide (CO2) emissions by 2050. "If we are going to solve the crisis, we have to commit, and we have to do it now," he said. "Live Earth will ask people across the world to commit to changes in their lives and to move other people, communities, companies and governments to reduce our carbon output by 90 per cent by 2050 and ensure there is a new, global treaty on climate change by 2009." All the artists are appearing for free and the proceeds will go to the Alliance for Climate Protection, The Climate Group, Stop Climate Chaos and other international NGOs. But the concerts, which are meant to be the springboard for change, know that they have a credibility problem. If they want to save the Earth how do they explain their own considerable carbon footprint? John Rego, who was recruited from the private sector to act as environmental adviser to all the concerts, said: " It would be fair to say I have had some sleepless nights but we have done as much as we can to cut our emissions and make the concerts as near as possible carbon neutral. "We know we will be criticised but we think it will be carbon well spent." The measures organisers have taken include: taking electricity from a green supplier, using biodiesel in the generators, food served in containers made from starch, all waste, including the plastic water bottles, will be recycled. What cannot be recycled will be composted. At the end of the concerts the figures will be added up and money spent on carbon offsetting. "We will be emitting carbon but with the reductions we make it will be better than past concerts - maybe cutting emissions by 25 per cent - and we hope that we will set the standard for similar sustainable events in the future," said Mr Rego.