http://www.rtcc.org/us-sets-out-terms-to-sign-the-2015-global-climate-deal/

The US has laid down the conditions under which it would sign the 2015 global deal to cut emissions.

Special envoy for climate change Todd Stern, said there were two main principles on which its participation in the new universal deal on binding emissions reductions depended, with the responsibilities placed on big emerging economies top of that very short list.

"We can't draw a line down one side of the world and if you're on one side you have no obligations and if you're on the other side you have all of them," said Stern. "It's got to be built on national capabilities, not ideologies."

The UN negotiations have three main strands. The Long term Cooperative Action (LCA) track looks at support, financial and otherwise, for developing countries to deal with climate change. The Kyoto Protocol, which binds rich nations only to greenhouse gas cuts. A second round of cuts is on the table in Doha.

The third set is the Durban Platform (ADP), created at the last major summit in 2011, which is aiming to establish a deal similar to Kyoto for all nations, with varied burden sharing for rich and poor states.

The US backed out of Kyoto because it put no constraints on emerging economies classing oil rich nations like Saudi Arabia as developing.

He told a press conference that the US had two key conditions for the new climate deal, firstly that it be applicable to all, and secondly that its spread of differentiated responsibilities for rich and poor, did a better job than the Kyoto deal of representing the real world.

"The fact that is for the world of the 2020s means it will be more in the direction of what we have been pushing since the start of the Obama administration. That is to say that while there certainly needs to be differentiation [between different nation's responsibilities], we would argue that differentiation needs to be made on the basis of practical, pragmatic, real world material considerations," said Stern.

The US has also said it has faith in the ADP negotiations and expected a "process outcome", a timetable from the Doha talks on how to get the 2015 deal up and running on schedule.

"We have two co-chairs of the ADP who enjoy quite a high level of trust and credibility from parties on allsides...and that's saying something in this context. They'll be leading the process and as long a we keep a high level of engagement and even step up that engagement, then we'll be fine."

European commissioner for climate action Connie Hedegaard echoed Stern's emphasis on the Durban Platform reminding assembled journalists that the deal will bring those repsonsible for 85% of the world's emissions under the umbrella of a legaly binding emissions reduction regime.

"It's important to see strong US involvement. There was an agreement in Durban to pursue the new regime and that's where the big effort from the United States and indeed the rest of us has to be," added Hedegaard.

Many developing nations, particluarly climate vulnerable small island states are calling for a greater urgency on sort term emission reductions.

Some of these groups are increasingly frustrated at the perceeved failure of developed nations to cut emissions fast enough.

For many of these islands, where coastal erosion is taking its toll, and freshwater resources are being spoiled by encroaching sea water, it is literally an issue of life or death.

Several bodies of research say significant cuts to our carbon output are required by 2017 to prevent us exceeding the predicted safe level of warming of 2C.