replacing HFCs with natural refrigerants worldwide today

CO₂ UN ammonia HFC Mexico EU global warming greenhouse gas Montreal Protocol climate 1234yf hydrocarbons refrigerant Kyoto Protocol chemical take action

At least 65 world leaders have agreed to attend the Copenhagen summit on climate change in December, raising the stakes on a deal being reached and lending “critical mass” to the meeting, according to senior officials

The Danish government announced this weekend that leaders of most of the world’s biggest economies were planning to attend, including the UK, Germany, France, Spain, Japan, Australia, Brazil and Indonesia. In total, 180 nations are expected at Copenhagen.

The talks aimed originally to bring together environment ministers, but as the deadline has begun to loom without agreement on important issues, the Danish government has stepped up efforts to bring in heads of state and government for the final day of the conference, on December 18.

Barack Obama, US president, has not guaranteed his presence, nor has Hu Jintao, Chinese president . The two countries are the world’s biggest emitters and their absence from the talks could jeopardise a deal.

But a senior UK government official said on Sunday that the number of leaders agreeing to attend had reached “critical mass”, making it likely that others would also want to attend.

The intervention of world leaders is necessary, officials believe, to break some of the entrenched positions countries have occupied for months and sometimes years. The senior UK official said: “The presence of leaders does not guarantee success but it makes it harder to fail.”

Although a binding international treaty is no longer expected at Copenhagen, leading figures are still hoping to forge a deal covering the main points.

Such a deal would require developed countries to specify by how much they would cut their greenhouse gases by 2020 and the finance they would offer to poor nations to help them do the same. Developing countries would have to set out measures to curb the growth of their emissions.

The US has been unable to agree an emissions target. A bill detailing such a target is before the Senate but is unlikely to pass ahead of the summit. But White House officials are confident they will be able to suggest some form of target at Copenhagen.