Regarding the recent letters in The Herald about the problems of parking cars, dare I raise a policy or a process that, to paraphrase Oscar Wilde, dare not, in our present climate, speak its name?

The motor car is now a social problem, indeed a menace. What was once a great democratic liberation in travel for masses of people has now become a threat to the proper functioning of society.

We all have to face up, however reluctantly, to the urgent need to get cars off the road by reducing our dependency on them now. Obviously this will be tremendously difficult, but ultimately will have to be done to ensure a worthwhile and sustainable future for our children and grandchildren. And, of course, it would have a great positive effect on our environment, lowering pollution for the consequent better health of all.

Apropos this point, there is a proposal to build in the Highlands the biggest quarry in Europe - for aggregates for road-building. Vision is all in the news just now. Is this what we want for Scotland?

John Kay, 183 Brackenbrae Avenue, Bishopbriggs, Glasgow.

I am concerned that the public is not being given the whole story about biofuels (Sugar-for-fuel plant will cut carbon emissions, November 23).

Your report states: "The aim is to reduce carbon emissions from transport." But, according to the US National Review (November 5): "Petroleum is a major input in the manufacture of ethanol - it is required not just to make ethanol, but to transport it to points of sale (since ethanol is corrosive to pipes, and must be moved by truck)."

The article goes on: "In fact, there's good evidence that making ethanol requires more petroleum than making gasoline does This inconvenient truth also means that ethanol won't do much to reduce CO2 emissions." It also points out that its production will disrupt water supplies - to irrigate the additional acreage needed - and cause more erosion and run-off into rivers.

In the US, fertiliser content in this run-off has already led to rampant algae growth in some river deltas, decreasing oxygen content to the point of major fish deaths. Is this going to be a classic case of good intentions gone awry? And with the "government support framework" being called for "in order to allow investment", the UK runs the risk of what has already happened in the US: government policies overheating the industry, wherein "it has become a welfare system for mega-farms that expand and overproduce year after year, purely to receive more subsidies". We need, in short, to keep a close eye on this new industry, in order that the UK doesn't make the same mistakes.

Stan Stanfield, Cluny Hill College, Forres.

You published a letter from Paul Shaw on Friday saying that "we have overwhelming evidence that carbon is the cause of global warming". I hope you will allow me to point out that not only do we have no actual evidence (a theory is not evidence), but that we know for a fact that no unprecedented warming is taking place.

It has been known for a long time that the Middle Ages were warmer than now, the late Roman period even warmer, and 10,000-5000AD warmer yet. The closest thing to catastrophe was that in the latter the Sahara was covered in vegetation and animals such as hippopotamuses. It has also been recently proven that the "evidence" that 1998 was the warmest year in a thousand is rubbish - it was actually only the warmest year since 1934.

Neil Craig, 200 Woodlands Road, Glasgow.