200 nations, one mission: to repair the mess left by Copenhagen

The conference which begins in Cancun today must restart the battle to lower emissions, says Michael McCarthy

(EPA)

Officials and ministers from nearly 200 countries meet in Mexico today to attempt one of history's greatest repair jobs: the mending of the world's project to cope with climate change, which was comprehensively wrecked in Copenhagen a year ago. For the delegates gathering in the Caribbean "super-resort" of Cancun, it will not be possible to achieve the aim of the failed conference in the Danish capital, which was a new, legally binding treaty involving all countries, to slash the emissions of the greenhouse gases which are causing global warming.

But what they may be able to do is "put the wheels back on the wagon" and restore momentum to the climate change negotiating process – which after the Copenhagen meeting seemed to have been smashed to pieces – in the hope of achieving a legal treaty at a future United Nations climate conference, perhaps even the next one, which is scheduled for Durban, South Africa, in a year's time.

They badly need to, because although climate change may have fallen out of the headlines and slipped down the political agenda in recent months, not least because of international financial turmoil, the threat of rising world temperatures has continued to mount. Last week, the Met Office in London released a report which asserted that evidence of global warming was stronger than ever, and later this week the World Meteorological Organisation is expected to announce that 2010 has been either the hottest or the second-hottest year ever recorded. Today, another group of British scientists claims that if the warming is not checked, children born today may live to see a world on average 4C hotter, which is unprecedented in human history.

It remains no less a critical issue, then, on the table at Cancun. The two-week meeting it is about to host will be seen, and even defined, in terms of the failure at Copenhagen last December. That was the most traumatic event in the two decades of international talks which have gone on since the global warming issue burst on to the scene in the late 1980s, not least for the enormous weight of expectation which had built up behind it. "Hopenhagen", the young climate campaigners were calling it beforehand. Never have hopes been so dashed.

The disenchantment was the greater for the fact that the 194 countries involved in the talks all accepted that if radical cuts in greenhouse gas emissions were not made, average temperatures might rise by up to 6C by the end of the century. The threshold for dangerous climate change is generally thought to be a rise of about 2C. The UN's Intergovernmental Panel on Climate Change (IPCC) calculated that to be on a path to halt the warming, global emissions of carbon dioxide (CO2) had to be cut by between 25 and 40 per cent by 2020. A new, legally binding agreement to achieve this was Copenhagen's central aim.

But such a deal would have to go much further than the existing climate treaty, the Kyoto Protocol, which did not include the world's two biggest emitters of CO2 – the US and China. George Bush had withdrawn America from Kyoto shortly after taking office in 2001; and under the terms of the protocol, China, along with all other developing countries, was not obliged to make actual emissions cuts. (Only the rich developed nations were so bound). Yet the US and China were each annually emitting about seven billion tonnes of CO2, making up nearly a third of the global total.

The project to construct a new, all-embracing legal climate treaty that would incorporate them fell apart principally because of dissension about the form of the new agreement. The developing countries, led by China and India, were strongly attached to Kyoto, and wanted a renewal of its commitments (which run out at the end of 2012), because Kyoto made sure the rich countries were doing something, while they – the developing nations – did not have to do anything. Perhaps not unreasonably, they take the view that the rich world put most of the CO2 up there, and should take the lead in dealing with it.

The developed countries, on the other hand, strongly led by Britain and the other EU states and backed by the US – which under the leadership of President Barack Obama was prepared to re-engage with the process and had set itself an emissions target for the first time – wanted to tear up Kyoto and replace it with a new deal, to set legally binding targets on the developing world alongside those on the rich nations.

The gap between these two strongly divergent positions proved unbridgeable and the negotiations foundered. As more than 100 world leaders arrived for what was intended to be the triumphant final agreement, they faced the nightmarish prospect of there being nothing to agree on. The situation, and their faces, were saved by a last-minute, patched-up deal for which the main architect, it is entirely fair to say, was the former British prime minister, Gordon Brown, and for which the credit was taken by Mr Obama. This was the so-called "Copenhagen Accord" – a three-page, 12-clause statement of intent, legally binding on no one, saying in effect that climate change is a Jolly Bad Thing and promising that We're Jolly Well Going To Work Together To Stop It.

On one level – in terms of the legally binding agreement which is needed – it is meaningless. But over the past year, the Copenhagen Accord has proved to have virtues, not least because all countries were invited to submit plans (entirely voluntary ones) for how they might cut emissions, to be inserted into an Appendix of the Accord, and 80 of them have now done so, including the leading carbon emitters, China, the US and India.

Some of the targets (China's and India's for example) are for reducing the energy intensity of their economies rather than for actual emissions cuts, and the US target, to cut emissions by 17 per cent on 2005 levels, was dependent on the Senate passing legislation which is not, for now, going to happen.

Nevertheless, it was unthinkable even two years ago that the US, China and India, along with other major emerging economies such as Brazil, Indonesia, Mexico and South Africa, would have set out specific pledges to reduce their carbon emissions, yet all have done so, and this is a major step forward – as long as the pledges are carried out. An analysis published last week by the UN Environment Programme calculated that, if implemented in full, they might go 60 per cent of the way towards the emission cuts needed by 2020.

This is where Cancun begins. There is no possibility of the 16th conference of the parties of the UN Climate Convention – COP-16, in the jargon – agreeing a new, legally binding climate treaty. The subject is not even on the agenda. So what can it do? The first thing is that it can regularise the Copenhagen Accord and the pledges it contains. The accord is not a decision of the COP, which is what is needed to give it legal status; it is at present merely a document which the conference of the parties has "noted". More than that, the pledges, which were put forward from the end of January onwards, have not been formally acknowledged by the UN Climate Convention in any way at all, other than by being listed on its website. They need to be brought into the convention legally so they can be regularised and possibly improved. British officials are working towards this.

Second, Cancun can make real progress on a number of climate side-issues, of which the most prominent are finance and forestry. The meeting can agree on the structure of a new fund to control the huge sums of money which were promised at Copenhagen, in its main positive outcome, to help developing countries cope with a warming world – $30bn (£19.2bn) by 2012 and $100bn annually by 2020. Third and finally, it can – it must – start out once more on the road to that treaty, and the object of cutting world emissions by 25 to 40 per cent by 2020.

For its part, the British Government (along with the rest of the EU) now accepts that the attachment of developing countries to the Kyoto Protocol is very strong. It will contemplate a double deal, with a renewed Kyoto running alongside a new agreement which sets climate targets for developing as well as developed countries.

But there is a price. Any new agreement, as far as the UK is concerned, has to be legally binding on the signatories. Countries might set their own targets, but once set, to avoid cheating they must have a legal obligation to meet them.

This, potentially, is the crucial stumbling block on the road ahead. The Chinese made it crystal clear at Copenhagen that they were absolutely unwilling to be legally bound with regard to their future emissions.

As for the US, Mr Obama's pledge to cut emissions by 17 per cent last year was predicated on the US Congress agreeing it. Since the triumph of the Republicans in the midterm elections, that agreement and that legislation are dead in the water.

The climate project ran into the ground in snowy Copenhagen. Now there is a chance to resurrect it in sunny Cancun. But nobody is saying it will be easy; the road ahead will be long and hard.

Climate change: the paperwork

* The United Nations Framework Convention on Climate Change

The basic international mechanism under which the fight against climate change is carried on. Signed in June 1992, the convention now covers virtually every country, including the US (which has withdrawn from Kyoto).

* The Kyoto Protocol

Signed in Japan in December 1997, this treaty commits countries to making legally binding cuts in their emissions. So far, only the rich nations have targets. The US was part of this group until George Bush withdrew in 2001. Kyoto's targets do not go far enough to slow down warming, and it does not set targets for developing countries.

* The Intergovernmental Panel on Climate Change

A UN body which reviews the science of global warming. There have been four assessment reports so far. The last, published in January 2007, warned that if emissions were not drastically cut, world average temperatures could rise by up to a devastating 6.4C by 2100.

* The Copenhagen Accord

The outcome of the 2009 UN meeting (COP-15), at which it was hoped that a new treaty would be signed to make much more drastic cuts in emissions. It fell apart because the industrialised nations wanted a new treaty binding all states; the developing countries wanted to renew Kyoto. The patched-up accord instead consisted of pledges with no official status whatsoever.

* Cancun – COP-16

The Cancun meeting will try to pick up the pieces of the wreckage of last year; one of its tasks will be to try to make the pledges of the Copenhagen Accord an official part of the convention.

WHAT AN AVERAGE TEMPERATURE RISE O F 4 °C WOULD REALLY MEAN FOR THE PLANET

OVERVIEW

The average rise will not be spread uniformly, and temperatures over land will be significantly higher (5.5C on average) than over the ocean, as the land heats up more quickly than the sea.

THE ARCTIC

Temperatures at higher latitudes, particularly in the Arctic, will rise much more steeply in a four-degree world as they experience climate feedbacks due to the loss of sea ice and snow cover.Already, scientists have detected signs of unusual permafrost melting in Siberia and the release of vast quantities of underground methane, a powerful greenhouse gas.

SOUTHERN EUROPE

The summer of 2003, when night-time temperatures were far beyond normal, caused many thousands of deaths through heat stroke and other related conditions. A four-degree world will make such summerscommonplace, causing environmental as well as medical problems.

INDIAN SUB-CONTINENT

A growing population puts pressure on water supplies, which will be exacerbated in regions of the world that will experience the greatest increase in numbers of people, such as India. In a four-degree world, however, the problems of water shortages will be primarily caused by climate change – a double whammy for the most populated countries.

AMAZON

At higher temperatures, the Amazon rainforest is vulnerable to drought and uncontrolled spread of fires. Some climate models predict increased rainfall, while other "more realistic" computer projections predict severe drying in the Amazon.

SOUTH-EAST ASIA

Sea level rise is inevitable in a warmer world, but the problem will be significantly worse in a four-degree world because of melting ice sheets, glaciers and thermal expansion. Low-lying, heavily populated river deltas and coastal regions are especially vulnerable to flooding. Small oceanic islands will experience increased storm surges and problems with increased soil salinity.

SUB-SAHARAN AFRICA

At 4°C, virtually all cereal-growing regions of the world experience crop failures or shortages. The areas affected most will be semi-arid regions where agriculture is already difficult, such as parts of sub-Saharan Africa. Some regions may become uninhabitable with widespread famine