Today, if they could, they would be weeping.

After two years of fraught international negotiations, a week of organisational chaos and three long sleepless nights, the Copenhagen climate summit has failed to deliver an agreement.

As a result, hundreds of millions of people across the globe are now condemned to floods, droughts, exile and famine as sea levels rise, the climate destabilises and food production breaks down.

“This is a tragedy that will harm the many millions of people in developing countries who are already suffering the effects of climate change,” said Nelson Muffah from the charity Christian Aid.

“Powerful nations didn’t come to negotiate, they came to play hardball. Lives will be lost as a result. Already more than 300,000 people a year die as a result of climate change. That number will go up.”

Although most world leaders put a brave face on the “Copenhagen Accord”, they all accepted that it does not do enough to cut the pollution that is disrupting the climate. The targets set “will not be by themselves sufficient to get to where we need to get by 2050”, admitted US President Barack Obama. The final agreement recognises “the scientific view that the increase in global temperature should be below two degrees Celsius”. But the reductions of greenhouse gas emissions agreed will lead to a temperature rise of 3C or more. That was widely agreed by expert scientists in Scotland, Copenhagen and elsewhere yesterday.

According to the UK government’s authoritative report by economist Lord Stern, a 3C rise would put 550 million people at risk of hunger, and make 170 million people vulnerable to coastal flooding, including London, New York, the Netherlands and Bangladesh. Half of the world’s plant and animal species would face extinction.

Climate consultants Michiel Schaeffer and Niklas Hoehne said in Copenhagen that there were sufficient loopholes in the accord to put the world on track to warm by 3.5C by 2100. Scotland’s leading climate expert, Professor James Curran from the Scottish Environment Protection Agency, made a similar analysis, as did the environmental group WWF.

A leaked United Nations report last week concluded that there was a 4.2 gigatonne gap between the emissions cuts needed to keep the rise below 2C and those on offer. Unless the gap was closed, it warned, the world would remain on “an unsustainable path”.

But after the emotional, fractured and frantic talks in Copenhagen, that is exactly the direction in which the world is heading. There are no legally binding targets, no timetable for further discussions and no date set for when global emissions should peak.

“This hollow and meaningless political outcome will leave millions of people in developing countries fighting to keep their heads above water,” said Rowan Popplewell, the Scottish Catholic International Aid Fund’s leading expert in Copenhagen.

“Vulnerable countries within the 193-nation summit have been virtually forced into recognising this fig leaf of an agreement to help prevent the summit from collapsing altogether. Poor nations have had their worst fears confirmed.”

The only tangible commitment in the accord is money, but even this comes with strings and may not be enough. Rich countries have promised to pay poor countries “approaching $30 billion” between 2010 and 2012 to help them cope with the effects of climate change.

They’ve also committed to “a goal of mobilising jointly $100bn a year by 2020”. But developing countries wanted at least twice as much, plus they were told they wouldn’t get anything unless they signed up to the accord.

The accord was agreed at a series of private meetings convened by Mr Obama through Friday, involving only China, India, Brazil, South Africa and Ethiopia. The other 186 countries involved in the Copenhagen talks were effectively excluded, including the European Union.

Before he left on Air Force One, Mr Obama accepted that the agreement was inadequate but insisted it was still a “meaningful breakthrough”. He left ministers and officials from other countries to sit up through the night trying to decide how to treat his accord.

After bitter and angry discussions, all they agreed to do yesterday morning was to “note” it, leaving a host of issues about its status in the UN process unanswered. Some developing countries reluctantly accepted the accord so that they could gain access to the money on offer.

A handful, however, held out against what they saw as betrayal and blackmail, including Bolivia, Venezuela, Nicaragua and others. The head negotiator from Sudan, Lumumba Di-Aping, caused offence when he compared the accord to the Holocaust.

“This asks Africa to sign a suicide pact, an incineration pact in order to maintain the economic dominance of a few countries,” he said. “It is a solution based on values, the very same values in our opinion that funnelled six million people in Europe into furnaces.”

Most rich countries talked up the new accord. Prime Minister Gordon Brown described it as a “vital first step”, while the UN secretary-general, Ban Ki-moon, called it an “essential beginning”.

French President Nicolas Sarkozy said the accord was vital but imperfect. And the president of the EU, Jose Manual Barrosso, expressed disappointment that the agreement “falls far short of our expectations”.

Campaigning groups and opposition politicians, however, were unanimous in their fierce condemnation. “It is shameful that after two years of blood, sweat and tears, we didn’t finish the marathon on time,” said Robert Bailey, senior spokesperson for Oxfam International.

“World leaders had a genuine chance here in Copenhagen to deliver the fair, ambitious and binding deal the world needed. But as the deal got cooked up, fairness was taken off the table and ambition watered down.”

According to Friends of the Earth Scotland it was “the weakest possible conclusion that could have come out of Copenhagen”. WWF Scotland described the accord as “half-hearted” and “half-baked”.

The more radical Climate Justice Action coalition insisted the summit had always been doomed to fail. “We need system change to stop climate change,” said Glasgow-based activist Dan Glass.

It will take a while for the full implications of what some have termed the “Copenhagen cop-out” to become clear. But it is likely to strengthen the arguments of those who don’t believe that the existing world order can deliver a solution.

It could severely damage the credibility of the UN, and make future negotiations more difficult. It could also increase cynicism, defeatism and denial, though this is something that almost all those involved are anxious to avoid.

Perhaps most worried are the low-lying countries that will be submerged by the sea, like the tiny Pacific island state of Tuvalu.

“We are being offered 30 pieces of silver to betray our people and our future,” said the country’s chief negotiator, Ian Fry.

Disturbingly, Tuvalu and a number of other small island nations were notable by their absence on a huge globe displayed at the Bella centre in Copenhagen, as if they had been wiped off the face of the Earth. As exhausted delegates left the centre yesterday, they could be forgiven for thinking that this was not a mistake, but an omen.