New Live Aid concerts under the Live 8 banner are happening ahead of the G8 summit in July - 20 years after the original Live Aid and weeks after organiser Bob Geldof said another one would happen "over my dead body".
By Ian Youngs
BBC News entertainment reporter
Until now, Geldof has refused to repeat the events of 1985, when the first Live Aid was part of the campaign to combat famine in Ethiopia.
Bob Geldof (right), Midge Ure (centre) and Elton John are involved
That event was "almost perfect in what it achieved", Geldof said.
"I couldn't see how anything could possibly be better than that glorious day 20 years ago."
But the situation in Africa has not improved and there is now a "unique opportunity" to permanently solve the problem, he says.
Top of Geldof's reasons for returning are figures that estimate 50,000 people in Africa die unnecessarily every day as a result of extreme poverty.
It would take the G8 world leaders - from the world's leading industrialised nations plus Russia - "moments" to solve the problem, he argues.
He is also frustrated at seeing his Commission For Africa report, which was published in March and recommends debt cancellation, increased aid and fairer trade laws, "gather dust on the shelf".
The G8 gathering gives him the perfect opportunity to step up the pressure to get those plans put into action.
The 20th anniversary of the original Live Aid is a fortuitous coincidence.
U2 singer Bono and campaigner Richard Curtis - who wrote films such as Notting Hill and Four Weddings and a Funeral - persuaded him to take up the project, Geldof said.
"It seemed to be that we could gather together again - this time not for charity but for political justice," he said.
The concerts in London, Philadelphia, Rome, Paris and Berlin will be free, raising pressure on the leaders instead of money.
Expanding on the reasons behind the concerts, Geldof said more people die of hunger every year in Africa than die of Aids, TB, malaria, polio and conflict combined.
European governments give poor person in Africa 0.65 euros (£0.44) a year each compared with 848 euros (£572) for every surplus cow, he told reporters.
"Still 20 years on, it strikes me as morally repulsive and intellectually absurd that people die of want in a world of surplus," he said.
He urged the public to send a message to leaders that they cared about the issue - and told the leaders they must be prepared to do something.
"We know what it costs. In the global economic scale, it is absolutely nothing," he said.
"We can't live like this. We cannot live like this. We just can't, not at the beginning of this century.
"We've never been wealthier, we've never been healthier, we know what it costs, we know what to do - do it. Do it."
Curtis has been at the forefront of the Make Poverty History campaign and added his voice to the arguments.
Some 70 million people have died of Aids in Africa, he said. "We've got our own private holocaust going on now."
If 50,000 people a day died in Europe, leaders would "find the money to solve that particular problem as they walked from the front door at Gleneagles to the reception", he said.
"It absolutely can be done. In terms of the global scale of finances, it is a tiny amount of money."
Geldof wants a million people to travel to Edinburgh for the summit to make their voices heard, Geldof said.
"What Live Aid did, joyously and enthusiastically, was open up the avenues of possibility," he said. "Finally Live 8 invites you to walk down them."
Former Ultravox singer Midge Ure, who helped organise Live Aid and Band Aid, is among those co-ordinating the gathering in Edinburgh.
It would be "something special", he said, urging everybody to "be part of it" and telling Edinburgh residents to play their part.
"It may never happen again, we may never have the opportunity of having these people on our shores and we can tell them what we want," he said.
"We want people to stand up and be counted. We want every church, chapel, synagogue, mosque to open their doors and let these people in.
"We are big-hearted, we mean well. Let these people into your garage, your spare room, your garden - whatever it happens to be.
"They are going to come, whether we ask them or not, they are going to be there. It's going to be amazing."