The specific patterns of change are not known precisely, but the risks of continuing on our current global course are widely appreciated. However, we must remember that global opinion is not unanimous, e.g. the United States has refused to sign the Kyoto Protocol, which does little to change the long-term course of events on the planet, since it calls for only small steps up to the year 2012.

Under the terms of the UN treaty on climate change, the signatories-virtually the whole world – are to gather each year to discuss the treaty's implementation. The conference in Montreal – the 11th such meeting - should look beyond 2012, so that the world gets onto a safe and sustainable long-term climate path.

The actions that are needed are difficult to introduce, because they go to the heart of the world's use of energy, particularly its use of fossil fuels (coal, oil, and gas), which, when burned, release carbon dioxide-the key source of rising greenhouse gases – into the atmosphere. Yet the world economy depends on fossil fuels, and developing countries will need to use more, not less, of them as their economies grow. Even if the world runs out of oil and gas in the coming years, coal will prove to be plentiful, and solid coal can be converted at relatively low cost to liquid fuels for automobiles and other uses.

Unfortunately, clean, renewable energy sources that do not emit carbon dioxide, such as wind power and geothermal power, are not yet sufficient. Solar power can be produced on the required scale but is too expensive under current technologies. Nuclear power is relatively cheap, and could be plentiful, but poses huge dangers for increased proliferation of nuclear-weapons materials.

So: fossil fuels are plentiful, but harmful; renewable sources like wind are good for the climate but not plentiful.Solar power is plentiful but not cheap. Nuclear power is plentiful but not safe.

Improved technologies can offer a way out of this bind, but only if we think and act ahead.There are two main kinds of technologies that look most promising. The first is energy conservation through more fuel-efficient vehicles. A massive change over to more fuel efficient vehicles would make a big difference especially as the numbers of vehicles on the road soars in China, India and other developing countries.

The second big technology that could make a major difference is called "Carbon Capture and Storage". The idea is to "capture" the Carbon Dioxide that is emitted in power Plants and other Big Factories when fossils fuels are burnt.

The problem is timing. The change over of the world's vehicle's to hybrid and other efficient technologies will take decades. So will the change over the power plant to carbon capture and storage.

All major regions of the world will need to be involved. Therefore, all countries, both developed and developing, need to do their part, with rich countries helping poor countries cover the financial cost of adjustment.

 Plenty of carbon dioxide will be emitted into the atmosphere even as the world's climate negotiators fly to and from cities and criss-cross the globe while they seek a solution. Let us hope that they will make real progress when they meet; otherwise they will merely be adding to the problem.