It's really easy to see the hand of "speculation" where there is none. Gas prices last fall may have gone up due to speculation or they may have gone up because demand outpaced declining supply. Seeing as oil imports fell a lot and oil inventories did not rise, I'm inclined to believe the latter. Likewise, the decline of the price of European carbon credits has a much simpler explanation then speculation. GDP tanked last year while energy prices went up. This decreased demand for electricity. Also, eastern europe suddenly felt all the investment from abroad dry up, further reducing electricity demand in the regions most dependent on carbon intensive electricity production. Given that a cap and trade system is only meant to bring carbon emissions below a certain ceiling, it's not surprising that this decline in electricity demand would result in a steep fall in the value of carbon credits. Speculation is something we need to worry about in carbon credit markets as elsewhere, but it is poor economic policy to go chasing bogeymen where none exist.