SO A FEW more metres of runway at Southampton airport are to bring an end to planet A, as we have no planet B, say the Green Party.

You cannot have life on earth without CO2, because CO2 is the basic ingredient of the metabolic pathway that is the basis of life on earth - photosynthesis.

It is the source of the carbon based lifeform we all are.

CO2 along with water, plus sunlight, are the basic ingredients of life on earth.

Every carbon element that makes up our carbon-based bodies comes from CO2.

Carbon forms the backbone of every protein, fat, and DNA molecule that makes up life.

All of which comes from CO2.

Photosynthesis is quite literally the source of energy that powers life on earth.

It does it by metabolically transforming CO2 and water into sugar, life's first stage energy storage molecule.

This metabolic chemical pathway can only run by adding energy to the input side of photosynthesis using chlorophyll (the ' green ' catalyst in the environment). This added energy comes from sunlight.

Photosynthesis is also life's metabolic pathway that build and replenish the 20% free oxygen necessary for animal life on earth to exist.

Animals, including us, only live by either eating plants, eating animals that eat plants or eating animals that eat animals.

This is ecology, the science of the web of life on earth.

Ecology is part of biology, the basic science of life.

Dave Christian