To ask the Chancellor of the Exchequer what benchmark financial cost per tonne of carbon dioxide emissions saved he uses when appraising expenditure on greenhouse gas abatement measures. (267635)

Supplementary guidance to the Treasury Green Book explains how greenhouse gas emissions are valued in policy appraisal. The guidance is available at:

http://www.defra.gov.uk/Environment/climatechange/research/carboncost/index.htm