What must be done?

The world's governments signed up to the Climate Convention in 1992. By doing so, they agreed to try to limit the build-up of greenhouse gases in the atmosphere from the burning of fossil fuels, at a level that 'would prevent dangerous human-made interference with the climate system.'

The Climate Convention states: 'Such a level should be achieved within a timeframe sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.'

Scientists on the Advisory Group on Greenhouse Gases (AGGG) working for the United Nations Environment Programme (UNEP), found that temperature increases beyond 1°C, or a rate of increase exceeding 0.1°C per decade, may lead to 'extensive ecosystem damage.'

Greenpeace therefore believes a long-term increase in temperature of 1°C above pre-industrial levels is the absolute maximum that policy-makers should accept and that the rate of change should be kept to less than 0.1°C per decade.

It is possible to estimate a 'budget'for fossil fuels: how much we can extract from the ground and burn, while limiting the temperature increase to 1°C. The small amount of oil, gas and coal which we can afford to burn could then be used wisely, in an ordered phaseout.

Based on the scientific work of the IPCC, calculations of the world's climate show that, to stay within the 1°C temperature rise over the next 100 years, the total amount of carbon dioxide from the burning of fossil fuels that can be released is around 225 billion tonnes - or gigatonnes - of carbon (GtC). There are many uncertainties in these predictions, but they are a useful guideline.

To protect the world's climate, then, to the best of our current knowledge, it will be necessary to stick to a fossil fuels budget of 225GtC. If no action is taken on deforestation (which also releases carbon dioxide into the atmosphere), the amount will be lower.

On this basis, at the current rates of fossil fuel use, a 225GtC budget is exhausted in 40 years. In fact primary energy demand is increasing at over 2% a year globally: at such a rate, the budget would be exhausted in under 30 years.

It will mean that 75% of the known, economically recoverable reserves of conventional fossil fuels (as carbon) can never be burned. They must remain in the ground.

So climate protection dictates an end to fossil fuels. They will not 'run out'(in fact 'reserves'are growing) - they will have to be closed down.

By making much better use of the oil, coal and gas we do burn by improving energy efficiency and introducing clean, renewable energy technologies, we can phase out fossil fuel use in a rational way.

As a first step in the phaseout plan, we should halt the exploration of new frontier areas for oil. As UK Chancellor Dennis Healey said: 'When in a hole, first stop digging.'