The green taxes announced by Gordon Brown do not go far enough in fighting climate change, the Lib Dems say.
Vince Cable said personal debt was a serious problem
Treasury spokesman Vince Cable said about 1% of GDP was needed to take preventive action, but the taxes only "amount to about one tenth of 1%".
He added that Gordon Brown's efforts at boosting his green credentials were undermined by recent transport and planning reports.
Mr Brown announced fuel and air duty increases in his pre-Budget report.
This comes after the Stern report said global action, amounting to 1% of GDP, was needed to combat climate change.
In his response to Mr Brown in the Commons, Mr Cable said: "I wonder where the other 9/10th are going to come from."
"The chancellor's environmental credentials are not really helped by publishing in parallel the Barker report, which is really a property developers' charter, and the Eddington report which has an unashamed plea for the expansion of airports."
Mr Cable said the chancellor was right to emphasise the long-term challenges of international competitiveness and making a knowledge-based economy, but he questioned why "after all the billions" put into maths and science, the number of students at A-level in those subjects was falling.
Addressing personal debt, Mr Cable said there were 2 million people in "extreme debt", and one in six with "severe debt" problems.
"Who is responsible for this? Is it adequate just for the chancellor to be a passive spectator or does he have a role in all of this?"
Mr Brown responded by saying individuals' debt repayments were on average about 8% of their income, compared with 15% during the 1990s.
Mr Cable also questioned why MPs should believe Mr Brown's figures.
"As long as he resists a fully independent audit of the government's assumptions and outcomes he will have as much credibility as a schoolboy who marks his own exams," Mr Cable said.
With expensive continuing commitments, including the Iraq war, defence procurements, the Trident nuclear weapons system, the 2012 Olympics, and ID cards, Mr Cable sought assurances that key public spending such as for police, health and pensions "are going to be sustained in this environment".
He said that while he was sure the chancellor would like to be remembered for progressive policies for social justice, as well as economic prudence, he said income inequality was as bad as when the Conservatives left power.
Mr Brown highlighted the government's success in removing two million children from absolute poverty and one million children out of relative poverty as a "major achievement given that child poverty trebled in the years of the Conservative government".