Britain needs to do more to reduce its carbon emissions, Tony Blair has told the liaison committee of senior MPs.
Tony Blair will face the committee again before quitting No 10
"We have done better than most... but we haven't done well enough," he said.
The prime minister said international agreement was vital, rather than just penalising Britons who were only a small part of the overall problem.
People would have to be greener, but he did not expect them to give up cars or flying, adding that he thought science could make the "biggest difference".
Mr Blair was being quizzed by the liaison committee, which is made up of the 30 chairmen of Commons select committees.
Mr Blair began his tenth appearance before the committee by outlining his policy reviews and defending his record on climate change and carbon emissions.
Environmental Audit Committee chairman Tim Yeo asked him if he was happy that carbon emissions were higher in his last months in office, than they were when he became prime minister in 1997.
Mr Blair said if it hadn't been for measures like the Climate Change Levy, things would have been worse.
He said the government's Climate Change Bill would outline a more rigorous approach to reducing CO2 emissions.
Policies could include allowing people to measure their own "carbon footprint" to help them take steps to reduce it.
Mr Blair said there was now a "fairer wind" behind climate change policies than there had been when he first came to power.
Britain had "been a leader in the climate change debate" and had reduced its greenhouse gas emissions "significantly".
Asked about green taxes on things like air flights and fuel, Mr Blair said "you've got to balance these things and get them right" adding that "however radical proposals are they have also got to be sensible".
He said that he knew that much of what he had to say might not be popular with green groups, but the fact was government could not impose massive additional fuel duties without risking a backlash like the fuel protests of 2000.
He said: "There will be requirements for individuals to change their behaviour, although I personally think you will not get people to give up the motor car or give up cheap air travel.
"But there are lots of things that we will ask individuals to do or help individuals to do.
"However, the thing that will make the biggest difference is if you get the investment in the science and the technology that will allow us to develop, for example, you know fuel cell for the motor vehicle, carbon capture and storage which would mean that you deal with a lot of the problems that otherwise burning a lot of coal and oil give you.
"I think nuclear energy - again you know this is controversial - but I am sure that is going to be part of the mix in the future."