Ghosts of Kyoto haunt climate discussions
As the first phase of the Kyoto Protocol draws to a close, the world will dissect its record for successes to emulate in the fight against global warming - and pitfalls to avoid.
If all goes well, Kyoto will eventually be replaced by a new global treaty, the design of which is being negotiated at UN talks in Qatar.
Its job will be to limit global warming to a manageable 2C from pre-industrial levels.
But what should the post-2020 pact look like?
Searching for an answer, many are scrutinising Kyoto - the most ambitious but also most contested climate pact ever seen.
"The protocol was the best we could produce in 1997. Now, things are different. The situation has changed radically," said Argentine diplomat Raul Estrada, a midwife at Kyoto's birth.
Adopted in 1997 after 30 months of tough negotiations, the protocol was then held up by further wrangling about its rule book before finally taking effect in 2005.
It bound 37 industrialised nations and the European Union to curbing Earth-warming greenhouse gas emissions by 5% from 1990 levels. In Doha, Qatar, negotiators are wrangling about a second set of pledges that will run from next year.
Developing nations and greens favour Kyoto because states that are historically to blame for today's global warming have legally binding commitments on their emissions.
Critics, however, say it is flawed.
Their sharpest barbs are reserved for a rich country/poor country divide that may have held true in 1997, but is out of date today.
Developing countries have no targeted commitments - the idea being that they should be able to use cheap fossil fuels to power their rise out of poverty.
That category includes Niger and Burkina Faso - and newly rich South Korea, Saudi Arabia, Kuwait, Singapore and Malaysia.
As a result, China, which has emerged since 1997 as the world's No1 carbon spewer, has no targets.
The US, too, does not have targets, despite it being the world's No2 emitter. Although the US is a signatory to Kyoto, it refuses to ratify it, citing unfairness.
"In practice, the 1997 treaty did little to curb emissions of greenhouse gases," science journal Nature commented this week.
"Most of the parties to the treaty met their commitments easily, but total emissions are rising faster because of growth in coal consumption by China."
Global energy-related carbon emissions rose 3.2% last year to reach a record high of 31.2 gigatons - pointing to potential warming of 3.6C, according to the International Energy Agency.
Even so, Kyoto has spawned innovations that are likely to remain part of the climate landscape, analysts say.
They include carbon markets that allow countries to trade emissions allowances and the clean development mechanism, which enables rich nations to earn credits for sponsoring cleaner fuel projects in poor countries.
"The success of the Kyoto Protocol depends on your measure," executive director of the Global Campaign for Climate Action Kelly Rigg said.
"Has it cut emissions down to levels that would stop climate change? No, but it was never expected to do that.
"Was it instrumental in triggering investments and legislation in pioneer countries that will eventually lead the world economy to a low-carbon transition? Yes. We need Kyoto now and its binding rules need to inspire a new treaty", Rigg said.
But punishing climate violators is easier said than done.
Countries that exceeded their targets by this year have to make good in the follow-up period.
But nothing prevents them from walking away from Kyoto without facing the concomitant consequences, as Canada did last year.
Estrada said: "You cannot go to the UN asking to make an expedition to a defaulting country."
In that light, observers contend there are simpler measures, such as taxes and incentives, which set a price on carbon and get countries to pollute less.