[Easy. Start with €10 million.]
… Europe’s carbon market, a pioneering effort to use markets to regulate greenhouse gases, is having a hard time staying upright. This year has been stomach-churning for the people who make their living in the arcane world of trading emissions permits. The most recent volatility comes on top of years of uncertainty during which prices have fluctuated from $40 to nearly zero for the right to emit one ton of carbon dioxide.
More important, though, than lost jobs and diminished payouts for traders and bankers, the penny ante price of carbon credits means the market is not doing its job: pushing polluters to reduce carbon emissions, which most climate scientists believe contribute to global warming.
The market for these credits, officially called European Union Allowances, or E.U.A.’s, has been both unstable and under sharp downward pressure this year because of a huge oversupply and a stream of bad political and economic news. On April 16, for instance, after the European Parliament voted down the proposed reduction in the number of credits, prices dropped about 50 percent, to 2.63 euros from nearly 5, in 10 minutes.
Maley's Energy Blog 
Anthony Watts has a decent [not to mention FUNNY] analogy when it comes to the cost of EUA’s: they are worth less than a bag of Kingsford Charcoal (one 10lb bag runs between $7 and $9 at my local Lowe’s).
Happy Grilling, EU carbon traders.