This week marks a first for China - the first time that the world's largest emitter of greenhouse gases, and therefore (you can argue) the country whose decisions will most affect the global climate over the next few decades, has hosted a meeting of the UN climate convention.

Whether the location will play a part in the progress of the talks is an unknown at this point.

Will China use the stage to announce a measure that could rebuild trust in the fractured UN process, such as tighter regulations on energy efficiency or concessions on international verification of its emissions?

Will it tighten the verbal screws on industrialised nations, especially the US, which it says have not lived up to their pledges on the issue?

Answers may materialise by the end of the week, along with signs of whether trust and progress are on an upward or downward path as December's summit in Cancun, Mexico, looms.

What is certain, though, is that almost a year after the Copenhagen summit, there is tangible fear among some long-time observers that the UN process is close to becoming moribund.

As one such observer recently said privately:

"We are now on the edge of seeing the entire international climate regime system disintegrate and fail more or less irreversibly."

And with it, many would argue, would go any hope of restraining the global average temperature rise within the 2C limit that has become such a commonly-cited touchstone of "maximum safe" warming.

Indications are that the US - which effectively holds power of veto over the talks - is angling to downgrade the role of the UN process.

Officials have constantly and openly praised the Copenhagen Accord, the document agreed behind closed doors by a handful of countries in the last throes of that summit, as a template for action - conscious as they are that it does not have the status of an official UN agreement, and that it's predicated on the concept of unilateral, voluntary actions, rather than the negotiated approach implicit in the UN climate convention.

China has the highest per-country - but not per-capita - emissions

Assuming that developed countries do come up with significant finance to help their poorer brethren, the Obama administration's preference is to channel this through the World Bank rather than through a UNFCCC body.

And short-term "fast-start" finance, meanwhile, is proceeding through a set of bilateral and multilateral channels without the necessity for any central clearing-house.

All of these acts, and others, work to downplay the central importance of the UN process, and to open up the entire field of climate change agreements to the forces of "politics as usual".

As we have seen over the last year, some developed countries are lobbying for regulations on counting emissions from deforestation in a way that allows them to claim high credits and continue, therefore, to increase industrial emissions.

Fast-start finance can be allocated on the basis of historical ties and in the context of western countries' desire to cement important trade relationships.

There is little notion here of the world finding itself in a mess that affects everyone, and plotting a coherent path out of that mess in a way that helps those at the greatest risk most - which is what the UN convention is ostensibly about.

Now, the talk from officials and politicians is "no binding deal in Cancun - but aiming for a binding deal in South Africa (at the end of 2011)".

If anyone can show me (a) that the US will be able to demonstrate by then that it can meet its Copenhagen Accord target of a 17% cut in emissions between 2005 and 2020, or (b) that there will be genuine desire across all important parties for a binding deal by the end of next year, then please post a comment.

Away from the negotiating halls, environment groups continue to seek new ways of "getting the message across".

Climate change has always been a difficult push for campaigners - and as the years go by, a number of different tacks are inevitably tried, some with more success than others.

Into the "others" category come June's incident with the Saudi Arabian flag and the German toilet bowl - and, last week, the video message from the 10:10 campaign that saw children in a classroom being erased from the register of life if they didn't sign up to urgent climate action.

Written by Richard Curtis of Four Weddings and a Funeral fame, the video went a fair way to redressing the numerical imbalance between celebrations and wakes inherent in that earlier effort.

By way of an apology, 10:10 themselves say:

"With climate change becoming increasingly threatening, and decreasingly talked about in the media, we wanted to find a way to bring this critical issue back into the headlines whilst making people laugh."

... a statement that testifies to the increasing desperation many campaigners are feeling at the way things have been going since the beginning of the end of Copenhagen.

Whether or not it made anyone laugh, it's certainly backfired. Dissent among campaigners extended to some groups, including Bill McKibben's 350.org, publicly dissociating themselves from the video.

Gillian Anderson starred in the "No Pressure" video

And as with the Saudi toilet incident, people are talking about a campaign bloop rather than the campaign itseif.

The environmental lawyers' group FIELD, meanwhile, is disinterring one of the oldest ideas in the campaigner's handbook - that countries affected by climate impacts could take their higher-emitting counterparts to court for damages.

I first heard of this notion - and I doubt it was new then - back in 1997, at the Earth Summit Plus Five meeting in New York.

There, President Maumoon Abdul Gayoom of the Maldives told me that he and the Alliance of Small Island States was exploring the possibility of suing high-emitting governments if and when their countries disappeared under the waves.

FIELD's new analysis harks back to the 1972 Stockholm Declaration - agreed at the first UN environmental summit - Section 21 of which states that governments have the responsibility...

“...to ensure that activities within their jurisdiction or control do not cause damage to the environment of other States or of areas beyond the limits of national jurisdiction”.

A number of actions have been brought under this rule in various courts, one recent example being the suit lodged by Ecuador against Colombia in 2008 over herbicide spraying along the border, which the plaintiff said was damaging people and wildlife along the Ecuadorian side.

The complexities of building a quantified case for "emissions damage" would be immense.

The fact that such a possibility is being explored again is yet another example of how disillusioned many are feeling about the prospects of governments coming up with anything meaningful through the channel they are all publicly committed to using - the UN convention.