Letter: Food from the global greenhouse

Sir: The articles in part three of "Our scorched earth" (2 April) take a very one-sided view of the role of carbon dioxide in the atmosphere. There is no mention that carbon dioxide is, with water, the main food of green plants, and that increasing the concentration of carbon dioxide in the air increases the rate of growth of plants.

There is no mention also of the fact that raising temperature in general increases rate of growth. So, although a rise of sea level, if it takes place, would take land out of cultivation, the productivity of the remainder should be increased.

Instead of regarding carbon dioxide as a poison it would be more sensible to try to ascertain what is its optimum concentration in the air. Have we any reason to think that the present level is ideal? Is it not possible that an equilibrium could be struck at a higher level with more production of carbon dioxide being balanced by higher extraction by the quicker-growing plants, producing more food?

Dr Roger James

Southsea, Hampshire