The sharp fall in organic food sales is not a bellwether indication of a lapse in green consumerism, as other sectors of the market have continued to show strong growth.

Last week figures collected by market research company TNS showed that spending on organic food fell from a peak of nearly £100m a month earlier this year to £81m in the most recent month.

The fall is the sharpest in the past decade, and has prompted media speculation that environmental consumerism will fall by the wayside in an economic crisis.

But statistics suggest that the credit crunch is actually boosting sales in most green consumer verticals.

July's figures from the Society of Motor Vehicle Manufacturers and Traders (SMMT) show that alternative-fuelled vehicles are bucking the sliding trend in UK car sales and are up almost 20 per cent on last month.

While total new car registrations were down 13 per cent in July and diesel registrations fell for the first time since February, the demand for alternative-fuelled vehicles increased by 19.4 per cent to 1,479 units.

Paul Everitt, SMMT chief executive, said subsidies would help this trend and lower emissions.

"Industry needs the support of government to encourage the uptake of lower-emitting vehicles and ultimately lower the cost of motoring for consumers, " he said.

Recent research from the RAC shows that more than 50 per cent of motorists say they will check emissions levels before purchasing their next vehicle.

And further research funded by the Low Carbon Vehicle Partnership indicates that the cost of refuelling a car is now at a level which provides motivation to consumers to take positive action to reduce fuel costs, such as buying more efficient cars and traveling less – congestion on UK roads fell by 12 per cent in the first six months of this year.

Sales of energy-efficient equipment are also booming.

Tesco has seen sales of its energy-saving lightbulbs quadrupled in the last quarter while Homebase says these sales are up 60 per cent year on year.

And charity shops are seeing a boom in sales as consumers look to buy second-hand clothes rather than new ones.

Sales at Oxfam stores across the country rose seven per cent year on year in the last quarter, while the British Heart Foundation has seen sales up six per cent in the same period.

Sales at the Body Shop, which " supports environmentally responsible materials and technologies by promoting the use of renewable resources and sustainable raw ingredients," were better than its parent company L'Oreal, which does not follow these guidelines.

The Body Shop saw second-quarter 2008 sales rise 7.4 per cent to €166m (£135m), almost two percentage points more than the 5.5 per cent increase L'Oreal group saw as a whole.

Meanwhile, many scientists and MPs say that organic farming is not actually environmentally friendly at all.

A study last year by the Department of the Environment, Food and Rural Affairs found that there is insufficient evidence available to state that organic agriculture overall would have less of an environmental impact than conventional agriculture.

"In particular, organic agriculture poses its own environmental problems in the production of some foods, either in terms of nutrient release to water or in terms of climate change burdens," says the report.