Carbon futures hit 13-month highs as traders reacted to the European Commission’s plan to postpone sales of some allowances. The move is fueling speculation that factories and utilities will buy more of the pollution credits.

Permits for December jumped as much as 3.6 percent to the highest since Dec. 28, 2012, on the ICE Futures Europe exchange in London. Carbon surged 39 percent this year, the most among 80 commodities tracked by Bloomberg.

The EC could reduce permit sales as soon as next month in an attempt to raise carbon prices that would cut fossil fuel use and encourage spur investment in cleaner energy. The EU’s executive arm plans to withhold the equivalent of about half of a year’s supply of emission allowances through 2016 and return them to the market at the end of the decade. The benchmark contract for December climbed as high as 6.92 euros ($9.48) a metric ton on ICE and traded at 6.87 euros.

Permits allow holders to emit one ton of carbon dioxide are allocated for free or auctioned to about 12,000 factories and utilities that must have enough to account for their discharges or pay fines. Prices plunged from almost 30 euros a ton in 2008 as the global financial crisis curbed manufacturing, cutting demand for pollution permits.