Here’s an interesting post on the carbon offeset market. The post begins with a criticism about the lack of transparency with Terrapass, and moves onto discussing this problem within the industry in general:
What would be wonderful would be if there could be a genuine market in carbon credits, rather than the inefficient mix of semi-competition and secretiveness which characterizes the status quo. Prices have to become much more transparent than they are now: merchants should sell their carbon offsets not directly to consumers but rather only through a market with real price transparency. At the very least, every trade should be reported to a central price recorder, even if it was sold bilaterally.