The author of the government's report on climate change today refused to endorse the limited green taxes outlined by Gordon Brown in last month's pre-budget report. When asked by a committee of MPs whether he was disappointed by the measures, Sir Nicholas Stern said: "I'm a civil servant - it's not for me to pronounce disappointment or enthusiasm with government policy." The limited green taxes on flights and motorists' fuel were widely criticised by environmental campaigners as being too weak a response to the Stern report.