At the international climate talks in Durban, South Africa, there's deadlock on extending the legally-binding pollution reductions in the Kyoto Protocol. That could spell trouble for one of the Protocol's other provisions: a pollution credit trading system called the Clean Development Mechanism, or CDM. Ironically, some of the few items moving forward at the talks would expand that system – one would issue carbon credits for burying greenhouse gases underground; another would issue credits for conserving forests. Those measures would expand the supply of carbon credits, even as demand is slacking off. Brian Edwards-Tiekert has more from Durban.