So that's it. The world's worst polluters – the people who are drastically altering the climate – gathered here in Copenhagen to announce they were going to carry on cooking, in defiance of all the scientific warnings.

They didn't seal the deal; they sealed the coffin for the world's low-lying islands, its glaciers, its North Pole, and millions of lives.

Those of us who watched this conference with open eyes aren't surprised. Every day, practical, intelligent solutions that would cut our emissions of warming gases have been offered by scientists, developing countries and protesters – and they have been systematically vetoed by the governments of North America and Europe.

It's worth recounting a few of the ideas that were summarily dismissed – because when the world finally resolves to find a real solution, we will have to revive them.

Discarded Idea One: The International Environmental Court. Any cuts that leaders claim they would like as a result of Copenhagen will be purely voluntary. If a government decides not to follow them, nothing will happen, except a mild blush, and disastrous warming. Canada signed up to cut its emissions at Kyoto, and then increased them by 26 per cent – and there were no consequences. Copenhagen could unleash a hundred Canadas.

The brave, articulate Bolivian delegates – who have seen their glaciers melt at a terrifying pace – objected. They said if countries are serious about reducing emissions, their cuts need to be policed by an International Environmental Court that has the power to punish people. This is hardly impractical. When our leaders and their corporate lobbies really care about an issue – say, on trade – they pool their sovereignty this way in a second. The World Trade Organisation fines and sanctions nations severely if (say) they don't follow strict copyright laws. Is a safe climate less important than a trademark?

Discarded Idea Two: Leave the fossil fuels in the ground. At meetings here, an extraordinary piece of hypocrisy has been pointed out by the new international chair of Friends of the Earth, Nnimmo Bassey, and the environmental writer George Monbiot. The governments of the world say they want drastically to cut their use of fossil fuels, yet at the same time they are enthusiastically digging up any fossil fuels they can find, and hunting for more. They are holding a fire extinguisher in one hand and a flame-thrower in the other.

Only one of these instincts can prevail. A study published earlier this year in the journal Nature showed that we can use only – at an absolute maximum – 60 per cent of all the oil, coal and gas we have already discovered if we are going to stay the right side of catastrophic runaway warming. So the first step in any rational climate deal would be an immediate moratorium on searching for more fossil fuels, and fair plans for how to decide which of the existing stock we will leave unused. As Bassey put it: "Keep the coal in the hole. Keep the oil in the soil. Keep the tar sand in the land." This option wasn't even discussed by our leaders.

Discarded Idea Three: Climate debt. The rich world has been responsible for 70 per cent of the warming gases in the atmosphere – yet 70 per cent of the effects are being felt in the developing world. Holland can build vast dykes to prevent its land flooding; Bangladesh can only drown. There is a cruel inverse relationship between cause and effect: the polluter doesn't pay.

So we have racked up a climate debt. We broke it; they paid. At this summit, for the first time, the poor countries rose in disgust. Their chief negotiator pointed out that the compensation offered "won't even pay for the coffins". The cliché that environmentalism is a rich person's ideology just gasped its final CO2-rich breath. As Naomi Klein put it: "At this summit, the pole of environmentalism has moved south."

When we are dividing up who has the right to emit the few remaining warming gases that the atmosphere can absorb, we need to realise that we are badly overdrawn. We have used up our share of warming gases, and then some. Yet the US and EU have dismissed the idea of climate debt out of hand. How can we get a lasting deal that every country agrees to if we ignore this basic principle of justice? Why should the poorest restrain themselves when the rich refuse to?

A deal based on these real ideas would actually cool the atmosphere. The alternatives championed at Copenhagen by the rich world – carbon offsetting, carbon trading, carbon capture – won't. They are a global placebo. The critics who say the real solutions are "unrealistic" don't seem to realise that their alternative is more implausible still: civilisation continuing merrily on a planet whose natural processes are rapidly breaking down.

Throughout the negotiations here, the world's low-lying island states have clung to the real ideas as a life raft, because they are the only way to save their countries from a swelling sea. It has been extraordinary to watch their representatives – quiet, sombre people with sad eyes – as they were forced to plead for their own existence. They tried persuasion and hard science and lyrical hymns of love for their lands, and all were ignored.

These discarded ideas – and dozens more like them – show once again that man-made global warming can be stopped. The intellectual blueprints exist just as surely as the technological blueprints. There would be sacrifices, yes – but they are considerably less than the sacrifices made by our grandparents in their greatest fight.

We will have to pay higher taxes and fly less to make the leap to a renewably powered world – but we will still be able to live an abundant life where we are warm and free and well fed. The only real losers will be the fossil fuel corporations and the petro-dictatorships.

But our politicians have not chosen this sane path. No: they have chosen inertia and low taxes and oil money today over survival tomorrow. The true face of our current system – and of Copenhagen – can be seen in the life-saving ideas it has so casually tossed into the bin.

'You can watch Johann explaining some of the appalling loopholes being smuggled into the Copenhagen treaty here

j.hari@independent.co.uk