CO2 debate must go on

We hear time and again that manmade is the cause of global warming. Yet it is an extremely small share of greenhouse gases and that the man-made content is minuscule, 0.117 per cent; that water vapour represents 95 per cent of such gases, with 99.9 per cent of it not man-made.

Take the Intergovernmental Panel on Climate Change's claim, based on model assumptions, that warming during the 20th century was entirely caused by man-made emissions. That may be true, but it may not be, because other climate scientists put forward the proposition that the cause could lie in land-use changes, particularly the explosion in urban development worldwide and deforestation.

Given the differences in opinion among scientists, the case for and against global warming by humans is not proven, and that more, not less, open debate is required.

JIM SILLARS

Grange Loan

Edinburgh

Canon Kenyon Wright should not be astonished at the reaction to his earlier letter stating his belief that global warming is a fact, when he bases his arguments on the one-sided, messianic campaign by Al Gore. I suggest he redresses this imbalance by reading Michael Crichton's equally authoritative State of Fear.

He also says there is close correlation between and global temperature over the past 650,000 years. This contradicts the United Nations' second assessment report (1996) showing global temperatures to be 3 degrees higher in the Middle Ages than they are at present.

Finally, the temperature increases and sea level increases predicted in the UN's third assessment report (2001) have not been realised. Why, therefore, should we expect future theoretical predictions to be any more valid? The debate is far from over; it's only just beginning.

(DR) GM LINDSAY

Whinfield Gardens

Kinross