Exclusive:The world must follow Scotland�s lead in environmental policy if global catastrophe is to be averted, Barack Obama�s climate adviser has warned.

The world must follow Scotland's lead in environmental policy if global catastrophe is to be averted, Barack Obama's climate adviser has warned.

Professor Diana Liverman urges world leaders to take "ambitious and urgent climate action" to save the lives of millions of the planet's poorest people.

Though she stops short of mentioning Scottish policy directly, the Oxford scientist and presidential adviser has given her backing - printed below - to a new report from Oxfam that singles out Scotland as a paradigm for the rest of the world to follow.

Politicians from the rich G8 nations will meet in Italy this week to discuss the future of Eearth's climate, and the Oxfam report calls on them to emulate Scotland's pioneering stance on environmental damage.

Malcolm Fleming, the charity's Scottish campaigns manager, said: "Scotland is already leading the world with our Climate Change Bill, with targets guided by science rather than political expediency. This legislation can be held up as an example to the rest of the world. If Scotland can do this, why can't others?

"Oxfam urges world leaders meeting in Italy to follow Scotland's lead, listen to the science and act now, before it's too late."

Professor Liverman, who was appointed to the newly created committee on America's Climate Choices by request of the US Congress in January, told The Herald: "If we do not make deep cuts in emissions now the changing climate will bring heat stress, sea level rise and more extreme drought and floods.

"Scientific observations tell us the world is already warming and it appears many of the most vulnerable people are starting to experience the impacts of climate change."

The devastating impact of climate change could permanently undo 50 years of work to eradicate poverty, Oxfam warns, and it predicts climate-related hunger will be the defining social ill of the 21st century.

The Oxfam report states 375m people will likely be affected by climate-related disasters by 2015, and that 200m people may need to migrate each year by 2050 because of hunger, environmental degradation and loss of land.

Mr Fleming said: "Climate change is exacerbating poverty worldwide. It is happening today and the world's poorest people, who already face a daily struggle to survive, are being hit hardest.

"It is scandalous that world leaders continue to resist doing what's needed, and within their power, to tackle the climate crisis.

"G8 leaders, who represent the world's richest polluting countries, must take personal responsibility for delivering a global climate deal, which has the needs of the world's poorest people at the heart."

In its in-depth and comprehensive report, Suffering The Science - Climate Change, People And Poverty', Oxfam urges leaders to put science ahead of rhetoric and act immediately to minimise the threats posed by the earth's changing environment.

More than 100 countries base their climate targets on a global temperature increase of 2C by 2100, but even this figure "entails a devastating future for at least 660m people", the report warns.

It adds: "Politicians' performance so far in international negotiations has been appalling."

The G8 meeting is scheduled to run in L'Aquila from Wednesday to Friday and will include leaders from the UK, America, France, Italy, Germany, Japan, Russia and Canada, as well as from the G5 group of emerging economies, Brazil, China, India, Mexico and South Africa.