Brian Pope's enthusiasm for environmental taxation (NCE 24 May) is heartening. So is Mark Whitby's emphasis on sustainability. But it is the taxation of fossil fuels that has received most attention in comments and letters.
Burning petroleum fuels causes air pollution, CO 2emissions and congested roads.
The most serious long term effect may yet be the exhaustion of regional and then global hydrocarbon stocks.
However, the political difficulties of introducing environmental taxes are daunting.
Research has shown that price increases would have to be considerable to reduce demand but the public has to be persuaded. For example, the annual fuel tax escalator introduced by the Conservatives was suspended by the Labour government in the face of well publicised, if ill informed, protest.
There are also special problems for poor countries where people cannot afford fossil fuel even at current prices. These problems are probably as difficult to solve as those presented by commercial self-interest in rich countries.
The consequence is that fiscal incentives for sustainability may only be practicable if introduced and increased gradually. This is not to dispute the urgency as several decades may pass before market intervention is effective.
In the meantime, civil engineers and their colleagues in other sciences should pursue options to reduce future energy shortages and to anticipate different market conditions resulting from fiscal action.
Tom Carpenter tcarpent@lineone. net