What has changed is that the notion of a fossil-fuel-free energy system is no longer just the rantings of wild-eyed environmentalists (I was one of them and it was pretty lonely), but is now the stated policy of a growing number of countries. There are open discussions about "the end of fossil fuels", which are still dismissed by most of the large economic powers and oil-producers, but now they look nervously over their shoulders while saying so.
What hasn't changed is the old debate over whether it is better to have the US inside a weak treaty or outside a strong treaty. US negotiators are struggling to justify what they call the "counterintuitive reality" of a weak treaty that has no legally binding targets. Sounds like Orwellian Newspeak to me ...
This was the same debate we had in 1991/1992 when the first Climate Convention was being negotiated. The decision at the time was to go for a weak treaty with the US included in it. Three years later in Berlin at COP 1 it was clear this was not working, so it was agreed to go for a strong treaty - the Kyoto Protocol. Ironically, the US played a key role in designing Kyoto; then walked away before the ink was dry.
Now we're back to where we were in 1992, with most agreeing that a weak treaty including the US is the way to proceed, and the emergent design of the treaty to be agreed in Paris in December 2015 is looking like an early Japanese proposal from the 1990s, known as "pledge and review". But with little being pledged now and the review process weakening all the time, it could be more like "pledge and chat", as one seasoned negotiator put it.
Given where we are now politically, a broad treaty framework with lots of flexibility may be sub-optimal, but it's probably the best we can do; and we will need some framework in place when things come to a head not so many years from now.
However, there are still some very fundamental obstacles to overcome before COP 21. My top four are:
Loss and damage
In the wake of Typhoon Haiyan that devastated the Philippines in 2013, the previous COP in Warsaw agreed a loss and damage mechanism, which could theoretically establish financial liability, or at least a financial obligation, for the (mostly rich) polluting countries to the (almost exclusively poor) countries upon whom the major burden of climate impacts will fall first. The former category of countries is now pushing back on this, and all but passing reference to it was deleted from the final text in Lima. This is a "red-line" issue for many developing countries, who insist it must be included; and for the US, who insist it must not.
Both the original Convention and the Kyoto Protocol were based on separating the world into two categories: Annex 1 (rich) countries with obligations to reduce emissions, provide finance, etc; and non-Annex 1 (developing) countries without obligations to reduce emissions at the same pace, who would be recipient of the finance from the Annex 1 countries.
The first cracks in that firewall came in Durban, and the joint Chinese-US announcement in November ripped a big hole in it. Some Annex 1 countries want to tear it away, while some non-Annex 1 countries consider the divide sacrosanct and believe the world should be classified just as it was in 1992. Neither position is reasonable, but coming up with a reasonable middle ground has eluded negotiators for the last 15 years.
The famous promise of $100 billion a year by 2020 first mooted by then-UK prime minister Gordon Brown in June 2009 and brought to Copenhagen by then-US secretary of state Hillary Clinton later that year, has now reached a total of $10 billion, to be disbursed over four years. The issue of how much of this $100 billion (a completely arbitrary number) will be "new" government money, how much will be existing development aid and how much will be finance leveraged from the private sector, remains to be worked out; and if and how the private sector is going to be incentivised to play its part.
Ah yes, this was the main point, was it not? It seems countries will put forward their intended nationally determined contributions by 1 October, and we will then add them up and see how much of a gap there is between what is offered and what is required. It will be large. What happens then is not clear.
Finally, I was somewhat bemused by the generally positive atmosphere at Lima, with comments such as "something is moving", and "wasn't the US-China announcement great?". But everyone knows we are going to have to confront the gap between the real world and the COP bubble at some stage. Sooner, please.
Steve Sawyer is CEO of the Global Wind Energy Council