Publish a schedule of future target-level reductions ... i.e.: 5% per year, or something? And, set a exercise date for the credits (i.e.: how long they last) - that would give them a calculable future value, something like stock options.

http://www.sustainabilityzone.com

The Guardian published a very interesting op-ed from Michael Grubb, a well-known expert on climate issues.

http://commentisfree.guardian.co.uk/michael_grubb/2006/05/emissions_impossible.html

Euractiv has also collected some very useful news articles and official documents that are helpful in understanding what happened and what it means.

http://www.euractiv.com/en/sustainability/question-marks-eu-co2-trading-scheme/article-155349