to invest in improving their energy efficiency. The slight initial extra costs incurred by standards are beneficial, and should be perceived as an investment that pays a return in terms of consumption and as a source of innovation. But this system cannot be readily applied to all product categories, and, sometimes, it is impossible to foresee all of the additional costs that it causes.

Quotas are another tried and tested mechanism, particularly well-suited to energy-intensive indus- tries. But they are exposed to pressure from lobbies and they also assume that public authorities are capable of correctly sizing quotas and gradually reducing them in line with the economic situation.

Taxes have also demonstrated their usefulness. The example of petrol shows how taxes are an effective means of changing our individual habits and what s on offer from manufacturers. But high taxes are politically damaging, because they

Climate scepticism s time is up

Today, it is broadly recognised that greenhouse gas emissions produced by humans are changing the climate, and that they must therefore be limited. The most efficient way is to give them a value, so that anyone who reduces their emissions stands to benefit economically. Emissions of each one of these gases can be measured in carbon equiva- lents. This is the reason why substantial carbon tariffs are the only way of producing long-term changes of habits and significantly reducing green- house gas emissions. Today, most companies are prepared to pay a price for carbon, but only if it is understandable and does not upset balanced competition. More and more companies are even turning this imperative into an innovative strength.

Ideally, carbon tariffs should be based on a combination of several mechanisms

Regulation has shown that it can be effective, in particular for the automotive industry and the real estate sector. Regulation has forced manufacturers

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