Who would have thought it would come down to trees? Yet it is on the highly-charged issue of forests and their use as "sinks" for carbon-dioxide emissions that the sixth UN climate change conference in The Hague is floundering, even deadlocked.
Yesterday, with four days to get a credible deal on how to halt global warming, the European Union and the United States were still at loggerheads on capping the use of such carbon sinks. The EU wants a cap, but the Americans don't.
Watching the hard bargaining like hawks are the various environmental NGOs (non-governmental organisations), all with their own experts on every crunch issue facing the conference, including the "sequestration" of carbon.
According to a detailed position paper prepared by Greenpeace, if the deal cut here on Friday includes assisted afforestation projects in Third World countries, it will have the effect of letting the rich industrialised nations "off the hook".
"Developing countries will set aside vast tracts of their land to soak up the carbon emissions of industrialised countries, instead of those countries reducing their emissions at source. The relationship will be nothing short of colonial," it said.
Greenpeace has calculated that the cost to industrialised countries of offsetting carbon-dioxide emissions could be as high as $100 per tonne. By contrast, investing in "sink" projects in the Third World could work out at just $1 per tonne.
"The result will be that instead of promoting sustainable technologies like renewable energy in the developing world, the Clean Development Mechanism (CDM) will simply become a mechanism to avoid reduction commitments at a rockbottom price," it says.
The position paper points out that there are other serious problems with sinks. For example, it is impossible to guarantee that newly planted forests will store carbon permanently over hundreds of years, to offset emissions to the atmosphere.
"Forest fires, illegal logging and severe weather events can all destroy forestry projects. The recent extensive fires in the US and south-east Asia underline this problem, as vast tracts of forest have been burned", in Indonesia quite deliberately.
There is also pressure from the US and its allies for the inclusion of "avoided deforestation", allowing credits to be claimed for helping to protect forests that might otherwise be destroyed. But here, too, how is this to be calculated?
The UN's Intergovernmental Panel on Climate Change, of more than 2,000 scientists, has estimated that afforestatation projects in developing countries could mop up between 170 and 415 million tonnes of carbon per year by 2010.
Given that the 29 OECD countries have committed themselves to reducing their carbon-dioxide emissions by 504 million tonnes by then, the potential value to them of having sink projects included in the CDM package is quite enormous.
Furthermore, if the highly-contentious US proposal that credits against emissions could be claimed for simply managing domestic forests was to be accepted - which seems unlikely at this stage - there would be no need to cut such emissions.
That's why the EU has been so scathing about the US seeking "free credits" for looking after its existing forests, and pressing for worthy (but bargain-basement) afforestation projects in developing countries included under the CDM umbrella.
Friends of the Earth is also opposed to the CDM being used for forestry projects, saying these would not even "buy time", as the US maintains. "Every tonne claimed through such projects will lead to another tonne of greenhouse gases being released elsewhere."
There is also an argument about defining sinks. The Australians, for example, want any vegetation more than 15cm high to be included, which is why someone has tagged little plants on the restaurant tables as "Australian sinks".
Sinks are not the only loophole either. There's also what is known as "hot air", not to mention "super-heated air", clever dodges that could arise under an international emissions trading system if the US and its allies on the issue get their way.
Because of industrial meltdown in the former Soviet Union, Russia and Ukraine will easily meet their Kyoto targets and could sell 150 million tonnes of carbon credits per year - equivalent to the UK's annual total - to the US and others.
"Allowing such `hot air' into the system would thus seriously undermine any incentive to take real action," according to Friends of the Earth. For that reason the EU is insisting on a "concrete ceiling" on the use of such loopholes.
Tony Juniper, campaigns director of Friends of the Earth UK, said yesterday that whatever deal finally emerges here this week "needs to send out a signal to stimulate the development of new technologies so that we can begin phasing out fossil fuels".
However, this would not happen if the industrialised countries were allowed to fulfil their commitments under the 1997 Kyoto Protocol by availing of loopholes such as sinks to meet 50 per cent of the target cuts, with real cuts making up the remainder.
The US has apparently set a ceiling of $15 per tonne on the price it is prepared to pay for Kyoto. "Quite simply, it is putting money before people and the future of the planet," Mr Juniper said. "It may even get away with doing nothing at all."