Water vapor is the most abundant greenhouse gas, but it is more often than not a result of climate changes rather than man-made emissions.

To stabilize concentrations of carbon dioxide at present levels, it said, "an immediate reduction in global man-made emissions by 60 to 80 percent would be necessary."

- If water vapour is the key greenhouse gas, why are man-made emissions important?

That agreement, signed by more than 100 nations, calls for reducing man-made emissions of carbon dioxide and other global warming gases by industrialized countries.

What is clear though is that by reducing man-made emissions the level of acidity will improve and this will reduce the impact on the environment.

"It therefore makes it even more important for there to be strong and urgent reductions in man-made emissions."

For a country like the UK, which produces only 2-3 per cent of global man-made emissions, this makes no sense.

About 48 tons of mercury are emitted each year from power plants, about 40 percent of total man-made emissions in the country.

However, let us accept for the moment that man-made emissions are a bad thing for various reasons.

That's true; but what threatens to shatter the global balance isn't nature but a century of man-made emissions from automobiles, electrical utilities and industry.