Hot and cold oil in Cancun climate
Campaigners have accused governments of having their heads in the sand regarding the urgent need for action
Reading the runes of Cancun's first week at a distance (the BBC, unlike Britain's best-selling daily paper The Sun, is deploying its correspondent on site for only the second half of the meeting this year), it seems that the familiar top-line story of villains and double-dealing is underpinned by something a little more subtle.
You can interpret some of the developments as indicating that governments are looking at the latest data on temperatures and weather, then looking back to Copenhagen and asking "what have we done?"
The fingers of blame so far have been pointed principally at a fairly unfamiliar target: Japan.
A leader on energy efficiency, and a champion of the Kyoto agreement around the time it was signed 13 years ago, it now finds itself in the firing line from developing countries and from campaigners over its decision to say a categorical "no" to any chance of setting further targets for emission reductions under the Kyoto Protocol (KP).
This is a story that began in the middle of the year at one of the preparatory meetings in Bonn, when Japanese and Russian negotiators lined up side-by-side against more KP.
On the surface, the reasoning is simple. Not all big emitters are inside the protocol; so why seek a further agreement that doesn't set targets for, for example, the US and China, the biggest two emitters?
The reason why China isn't covered in this way is simple, yet something that some western governments apparently have trouble remembering from day to day; it's a developing country, and thus under the terms of the UN climate convention itself, it does not have to take the lead in cutting emissions.
Its per-capita emissions remain much lower than those of the US or Japan.
Japan's Prime Minister found himself lampooned over objections to the Kyoto Protocol
What's exercising Japan, principally, appears to be the fact that China is set to emerge as the dominant East Asian economy.
At a time when Japan-China relations are also strained by a spat over ship collisions in the waters of a disputed island and by China's restrictions on exporting rare earth elements to Japan, giving way to Beijing on climate change is, it appears, not feasible.
On the face of it, Japan's stance makes agreement on an eventual package near impossible; it won't take more cuts under the KP, but developing countries won't budge without extending the protocol.
Add in the fact that no-one can yet be sure how the US can meet its target for emission cuts, and potentially you have a recipe for stalemate.
But this is where the more subtle undercurrents come in.
Exhibit One is India. In Copenhagen, its government was bullish, sticking out for nothing that could be taken as international restraints on its emissions, and co-leading with China the BASIC group of big developing nations that wielded the most power during the conference's final days.
Now, we have Environment Minister Jairam Ramesh talking of "being a bridge between the developed and the developing world".
As part of that bridge-building, Mr Ramesh has been working on a proposal for monitoring, reporting and verification (MRV) - in other words, making sure countries are constraining emissions as they say they are - that could answer concerns China has about preserving its sovereignty, while allowing the US administration to tell the Senate it has its eyes on what China is up to.
India, so I hear, now has reservations about the BASIC bloc - as do Brazil and South Africa - although a rending asunder isn't imminent.
Exhibit Two - much more profoundly - is the progress being made by countries involved in the Cartagena Dialogue.
Australia, Bangladesh, Costa Rica, Ethiopia, Peru, Samoa, Thailand, the UK... just some of the loose grouping of countries from very different circumstances that all want to see progress within the UN climate framework.
Its genesis is curious.
China's protection of rare earth elements has angered Japan - and others
On the final morning of the Copenhagen meeting, a group of about 20 leaders assembled in a chilly room expecting to meet Danish Prime Minister Lars Lokke Rasmussen and talk about a political agreement.
Mr Rasmussen didn't turn up - the previous evening, he'd launched his new-look, stripped-down Copenhagen Accord on unsuspecting leaders at the state dinner, and was busy pursuing that elsewhere.
Not quite knowing what to do, the leaders decided they might as well use their time constructively; and so the Cartagena Dialogue was born.
Meetings have taken place during the intervening year - and so it comes to be that there is at play in the meeting a group of nations determined to be constructive and build more than bridges.
They've managed to set up an informal group to discuss the Japanese/Kyoto issue and its wider context, for example - something that various blocs have vetoed in the past.
Finally come the comments from President Nasheed of The Maldives, who I interviewed in London at the launch of a new report on climate vulnerability.
He went further than developing country chiefs generally do in public about the case for breaking down the traditional silos that countries usually inhabit.
The G77/China bloc encompasses nearly 130 nations including oil-rich Saudi Arabia, small island developing states, really poor countries such as Togo and Haiti and ones that are rapidly developing towards western levels of affluence.
By any analysis, their interests in the climate issue are not the same. Yet historically, the shape of the UN process has assumed they are, by having them all inside the G77/China umbrella.
I'm told that privately, The Maldives isn't the only country wondering whether it's worth it, or whether countries should instead work in alliances that truly reflect their interests.
The bridge-building isn't without its domestic perils.
Mr Ramesh's efforts are being condemned in India - while in the US, four senators are now demanding that the administration withdraws the $1.7bn it's earmarked for climate assistance in poor countries this year, citing the national debt (measured in trillions of dollars).
It's far too early to speculate on whether Cancun will be a failure or a success - partly because no-one really knows how to define those terms - and at the time of writing, rumour has just emerged that a separate political agreement, a Cancun Accord maybe, is being drafted.
That, if it's true, will bring very uncomfortable echoes of Copenhagen. Usually reliable sources think it isn't true - in which case, there's a question to be asked about who said it was, and why.
Lots of smoke, and obscured mirrors - that's the UN climate process.
But some see in the shape of Cartagena a reason to hope that some of the smoke can be dispelled over the remaining week.