Climate negotiators meeting in South Africa this week face fresh worries over saving the planet from global warming now that a tonne of carbon trades at the price of a pizza.

A European steel plant producing a tonne of steel pays as little as $12 (Dh44) for the resulting carbon emissions, spelling trouble for Europe's carbon emissions trading scheme, the world's largest.

At those prices, there is little incentive for industry to lower its carbon output, meaning one of Europe's major tools in fighting climate change is broken.

Analysts say carbon prices would need to return to 2008 levels in order start making a difference. "Given current commodities prices, we would need €20 (Dh97) a tonne to achieve a significant emissions reduction," said Per Lekander, an analyst at UBS.

"I look at the price in the morning and don't want to get out of bed," said a London-based emissions trader.

London is the EU carbon market's hub, with traders, brokers, power generators and project originators responsible for the bulk of trade. But with carbon prices down more than 50 per cent since June, some have decided to cut their losses and have left the market.

The EU Commission declined to comment on current carbon prices when asked by Reuters but speaking in Brussels last Thursday, Denmark's climate, energy and building minister Martin Lidegaard acknowledged concern.

"Carbon prices are low because there is a crisis. This is a serious problem that threatens stability for investors," Lidegaard said.

How Europe tackles that problem will be a hot theme in Durban, South Africa, where negotiators from more than 190 nations are gathering for a two-week summit to map out a successor to the Kyoto Protocol which expires next year.