The European Commission last month closed the electronic warehouses where permits are kept, called national registries, after the theft of EU allowances (EUAs) worth at least 45 million euros.
Five registries reopened on Friday, in France, Germany, the Netherlands, Slovakia and Britain, while the Paris-based BlueNext spot exchange resumed trade.
Some 125 EUA lots had traded by 1400 GMT on the exchange, compared with 740 lots for the whole day on the corresponding date last year.
Some traders feared that unidentified stolen permits were still in circulation. Unclear rules on liability meant that buying these risked a loss of their full face value.
"You'd have to be a brave man to trade that stuff," said Trevor Sikorski, carbon analyst at Barclays Capital, which earlier this week demanded urgent new rules limiting market access to polluters and regulated financial intermediaries.
"There's a very high probability there are [more] stolen EUAs," Sikorski said. "You don't know how many there are in circulation. If you were to lose full face value on, say, 100,000 tonnes, it would take a long, long time to get that back in trading revenue."
"I don't know who's going to take that risk."
The value of lost spot trading revenue since the market was shut on 19 January was about 110 million euros, estimated Point Carbon Thomson Reuters analyst Kjersti Ulset.
The International Emissions Trading Association (IETA) lobby welcomed the re-opening of the market, but demanded an official EU statement on the serial numbers of all the stolen EUAs, as well as clear rules on ownership liability and sweeping scrutiny of registry account holders.
The Green Exchange said that its spot market was also closed until further notice. "Despite the resumption of operations at the emission registries a complete list of serial numbers of the EUAs that are alleged to have been unlawfully transferred is currently not available," it said in a statement.
Some market experts said that the BlueNext move was premature. "I'm surprised somewhat that BlueNext has opened. I am not sure that's the best approach," Sikorski said.
The spot market accounts for about one tenth of total EU carbon trade, which is dominated by a futures market for December delivery so far unscathed by the thefts.
Bulgaria resumes trade
Meanwhile, carbon traders will find little comfort in learning that Bulgaria, known for its problems with corruption and organised crime, is now ready to resume carbon trading.
The Bonn-based UN Climate Change Secretariat restored Bulgaria's carbon trading rights on Saturday (5 February) after it had suspended the Balkan country last June for violating reporting rules under under the Kyoto Protocol.
The restored rights will allow the Balkan country and its industrial companies and utilities back to greenhouse gas trading schemes under Kyoto and lift restrictions on their participation in the EU ETS.
"By restoring the accreditation of the country for participation in the emission trade, the connection to the international registry for transactions is open," the Environment Ministry said in a statement.
A UN mission to Bulgaria in October said Sofia had improved its emissions record and addressed other shortcomings, allowing it to receive back its accreditation under the protocol.
Industrial producers will now be allowed to transfer allowances to and from the national register and participate in EU spot trading.
A weak economic recovery after a prolonged recession means Bulgaria's industrial sector is likely to become a net seller of EU carbon permits.
Some 130 Bulgarian utilities and industrial companies received 34.7 million tonnes of C02 allowances in 2010 and will get the same amount this year.
The decision also will allow Bulgaria to sell the surplus sovereign emissions rights it has accumulated under the Kyoto Protocol.
The centre-right government had hoped to sell at least part of its surplus of 200 million emission rights last year, but the suspended accreditation blocked its efforts.
(EurActiv with Reuters.)