He took on Bush and Blair over the Iraq war. Now the controversial editor of one of the world's top medical journals will challenge them on climate change.

Dr Richard Horton, editor of The Lancet, says his journal will continue to be a thorn in the side of the world's political elite by making global warming the subject of a major new campaign.

The Lancet will lobby for a reduction in carbon emissions by focusing on the damaging health impact of greenhouse gases.

Dr Horton will speak tonight in Edinburgh, where he will be awarded the Edinburgh Medal on the opening night of the city's International Science Festival.

The award honours "men and women of science and technology, whose achievements are judged to have made a significant contribution to the understanding and well-being of humanity".

Dr Horton will receive the award for The Lancet's ongoing campaign to highlight the appalling welfare of children under five, 10 million of whom die every year from preventable diseases.

But he is best known for publishing a study which estimated that 650,000 Iraqi civilians died during the current invasion - more than 15 times the official estimate of 40,000 given by the US government.

The study was immediately dismissed as unsound by the Bush administration and by Mr Blair, although it has now emerged that the government's own scientific advisers believed the Lancet study's methodology was robust.

Dr Horton drew personal criticism for speaking at an anti-war rally, but yesterday he said both he and The Lancet would continue in their highly-politicised stance by lobbying governments to take action to reduce carbon emissions.

He said: "The Iraq study took the journal into a political sphere that we had never been in before. To suddenly have George Bush appearing on the White House lawn rubbishing one of our studies is unprecedented.

"I will continue to use the Lancet as a campaigning instrument, not just in the UK, but on a global scale.

"We are not translating science into societal benefit and that's what I want to do."

His next step will be the launch of a campaign linking climate change to health. "At the moment, we're looking at climate change in a far too narrow context," he said.

"We need to think much more broadly about how we use energy in society and what the impact of energy use across transport, agriculture and in the urban environment means to human health."

In his speech, "Can Science Save Us?", Dr Horton will argue that we must take a more scientific approach to battling poverty, disease and humanitarian crises.

In particular, he cites new bio-mathematical studies which advocate pairing each wealthy person with a poorer person in the developing world.

"We now know the scientific rules by which we can promote co-operation between human beings. The basic rule is that we must develop a few very close, personal contacts with others who are less well-off, personal commitments, from one person to another.

"Imagine if every single one of the richest three billion people was linked up to one of the poorest three billion, in the way that the Action Aid child sponsorship scheme works.

"Not only would that make a great difference to another person or another family, it could also trigger a whole wave of human collaboration."

Dr Horton will be joined at the Edinburgh science festival by Professor Steve Jones, who will argue against TV psychiatrist Dr Raj Persaud, who will reveal ways to make yourself irresistible to the opposite sex.