As the fraught negotiations in the Danish capital ended in chaos, acrimony and recriminations yesterday, experts agreed there was now little hope of keeping the average rise in global temperatures below 2°C.

They predicted instead that temperatures would increase by 3°C or more, bringing widespread flooding, major droughts and mass migrations, along with serious food and water shortages.

“It really couldn’t be any more serious,” said James Curran, the director of science at the Scottish Environment Protection Agency and one of the Scottish government’s top advisors on climate change.

“It’s staggeringly frightening and deeply disappointing that Copenhagen has failed. This is extremely dangerous for Scotland and the world.”

A temperature rise of 3°C could trigger runaway climate change that will be impossible to reverse, he argued.

“That deeply worries me, because the effects could be catastrophic and unpredictable,” he told the Sunday Herald.

“This puts half the species on the planet at risk of extinction, and takes us into the zone where whole ecosystems begin to break down.

“It will cause coastal and river flooding, endanger hundreds of millions of people, cause serious water supply problems, and the complete breakdown of food supply.”

His predictions were backed up by expert climate consultants, Michiel Schaeffer and Niklas Hoehne, in Copenhagen. He was also supported by a leaked United Nations report and an analysis from the environmental group, WWF.

After the third all-night session in a row, 193 countries agreed yesterday to simply “note” a Copenhagen Accord drawn up on Friday by the US, China, India, Brazil, South Africa and Ethiopia in private talks brokered by US president, Barack Obama.

Many developing countries felt betrayed by the accord, because it lacked any legally-binding targets or timetables for cutting pollution.

But they were forced to endorse it because it offered them $30 billion (£18 billion) from 2010 to 2012 and $100bn (£61bn) a year from 2020 onwards to help combat the effects of climate change.

The summit exposed “a failure of leadership”, according to the Scottish first minister, Alex Salmond.

“Copenhagen was a tiptoe forward when what the world required was a giant leap,” he said.

The Green MSP, Patrick Harvie, who was in Copenhagen as convenor of the Scottish Parliament’s climate change committee, blamed Obama and the UK prime minister, Gordon Brown.

“They should be ashamed of this disgraceful betrayal of the world’s hopes,” he said.

But Obama, Brown and other leaders did their best to sound positive about the accord, though they all accepted that it would not be enough to prevent dangerous climate change.

“We have much further to go,” stated Obama, though he claimed the accord was a “meaningful breakthrough”.

The Stop Climate Chaos Scotland coalition, which involves 60 organisations and represents 40% of Scotland’s population, dismissed claims that Copenhagen Accord was a success as “empty rhetoric”.

The coalition’s chair, Mike Robinson, pointed out that its promises were vague, its targets inadequate and it had no legal framework or timetable for future talks.

“It’s hardly the leadership we had all been hoping for and we have a right to be disappointed,” he said.

 

US-led Copenhagen deal:

 

No reference to legally binding agreement.

 Recognises the need to limit global temperatures rising no more than 2C above pre-industrial levels.

 Developed countries to “set a goal of mobilising jointly $100 billion a year by 2020 to address the needs of developing countries”.

 On transparency: Emerging nations monitor own efforts and report to UN every   two years. Some international checks.

 No detailed framework on carbon markets -- “various approaches” will be pursued.