Canada can't do anything about global warming....

Our political leaders act like global warming is local - if Canada cuts back, we will solve global warming for us. It's ridiculous. Because of India and China, CO2 emissions will continue to rise - no matter what Canada does.

It is a well-rehearsed point that the Kyoto Protocol was a terribly inefficient, hugely costly way to do virtually no good. Even if every industrialised country, including the United States, had accepted the protocol, and everyone had lived up to its requirements for the entire century, it would have had virtually no impact, even a hundred years from now. It would reduce the global temperature increase by an immeasurable 0.15C by the year 2100. The cost of implementing Kyoto, taking the average figure from the various top macroeconomic models, would have been almost £100 billion annually for the rest of the century.

The US declined to sign up to Kyoto and many countries, including Spain, Japan, Canada, and Greece, have had a hard time living up to their pledges. It is likely that the total reduction in carbon emissions will be less than 5 per cent of what Kyoto promised.

Yet the EU and others advocate that Kyoto-style policies are still right, only that much more than Kyoto is needed. The EU has promised to cut its emissions by 20 per cent by 2020, through a 20 per cent increase in renewables. There seems to be no better reason for this decision than that 20 and 20 in 2020 sounds good. Gordon Brown has wholeheartedly backed the plan, which includes making a dramatic increase in renewables - mainly 3,500 wind turbines in the North Sea.

The British Government estimates the cumulative carbon saving from all its plans at somewhere between 950 and 1,100 million tonnes of CO2 by 2030. The Department for Business will not give a figure beyond that timeframe but, given that wind turbines have a lifetime of about two decades, this seems the relevant cumulative reduction given the investment. The department confirms that the total investment from public and private sources into renewables will be about £100 billion.

Computer modelling - using DICE (dynamic integrated model of climate and the economy) - shows that the net effect of the UK renewables effort is impossibly tiny. The temperature increase by 2100 without Mr Brown's plan would have been 2.4536181C. With the best-case scenario the huge UK effort means that the temperature at the end of the century would be 2.4532342C. The effect is a difference of about 0.00038C - or about one three-thousandth of a degree in a hundred years. This is the equivalent of delaying the temperature increase by the end of the century by a little less than a week.