Speaking at an event hosted by CB Richard Ellis, Lord Adair Turner insisted that the government will have to respond to the committee's suggestions and justify any significant amendments.
He said: "It will be quite difficult for the government to substantially diverge from the target. It would be pressed hard in both the Lords and the Commons.
"It is quite easy for us to commit to an 80 per cent cut by 2050. But we will need to look at serious changes to consumer behaviour and low-carbon energy."
Turner added that the UK may have to raise its carbon reduction targets if an international agreement is struck at a global summit in Copenhagen next year.
On 1 December, the committee will offer its recommendations on how much carbon the UK should emit in the next 15 years, outlining carbon budgets for 2008-12 and 2013-17. By 2022, emissions must be 26 per cent below 1990 levels.
The Climate Change Bill, which is set to become law in the coming weeks, will commit the UK to cutting carbon emissions by 80 per cent by 2050 compared with 1990.
Last week, Turner maintained that no further coal-fired power stations should be built in the UK unless their carbon dioxide emissions can be captured for safe storage.