The legislative package, akin to that on energy and climate change agreed in 2008, would include initiatives to rein in growing emissions from transport, Hedegaard said.
She spoke of the "huge challenge" facing the sector as continued growth in carbon emissions from transport is currently offseting efforts made in other areas.
One of the new climate commissioner's first initiatives will be to introduce legislation on cutting CO2 emissions from lorries. She said she would also seek to revise EU legislation on CO2 emissions from cars, which she said is outdated considering the speed at which technology is moving.
In general, the future climate commissioner supported pricing CO2 emissions in the transport sector. In her opinion, "internalising externalities," which has been a guiding principle of the EU's emissions trading scheme, would also work for transport.
Mainstreaming climate change
The exact scope of Hedegaard's new Climate Action portfolio remains unclear as it was carved out of the Commission's previous environment department.
Hedegaard said she sees herself as a horizontal coordinator, with the daunting task of mainstreaming climate action into all EU policies, she told MEPs during her three-hour grilling by the Parliament's environment committee.
"It is not going to be easy to reconstruct [the climate directorate-general]," Hedegaard admitted. "Climate can be almost anything," she said, giving examples of overlaps between areas as diverse as industry, development and research on top of the obvious links between environment and energy.
But the Dane said it would not be possible to put everything under one hat. "Therefore you must do it the other way around by mainstreaming," she said.
Hedegaard pledged to work closely with other commissioners, saying legislative initiatives would often be triggered in conjunction with them. But she admitted that it would be "a bit of a fight" to push other commissioners with their own priorities to make room for a climate dimension in their portfolios.
"Climate, energy security and job creation must be the EU's vision," she stressed.
Green growth, without protectionism
The former Danish energy and climate minister made strong statements in favour of green growth. But she argued strongly against measures to safeguard European industry from international competition, warning about "protecting our businesses out of business".
"We should be careful not to be so cautious, so balanced, that in the end we do not benefit our businesses," Hedegaard said. She warned that China will go on investing in green technologies and do it fast, so Europe's industry cannot afford to miss the boat.
Moreover, MEPs demanded answers on how she planned to secure financing for her initiatives with the modest resources behind the new climate action department.
Hedegaard promised to work to redirect funds towards developing clean energy and phasing out fossil fuels. She also seemed to snub the new innovation commissioner, who in her hearing promised to boost nuclear research.
"I don't think we should pump vast amounts of money to nuclear research at the expense of sustainable energy," she said. "In my universe, nuclear is not a renewable source," she added, to applause.
However, Hedegaard's statement that she would not support a binding target on energy efficiency raised concern among environmentalists. "We don't need that thing to be binding," she said.
'Do not drop the UN process'
Hedegaard was adamant that securing a global deal on climate protection under the auspices of the United Nations should remain the top priority for the EU.
"We should not give up the UN, not at this stage," she said, setting her sights on securing a binding agreement at Mexico City by the end of the year.
The former Danish energy and climate minister had to defend progress made at the Copenhagen climate conference she hosted amid accusations that the talks had been a failure and a dent on her credibility as the EU's climate chief.
"We should not forget that we have finance delivered," she said, adding that all developing countries had accepted co-responsibility for climate protection.
"I don't think it's fair to criticise those who spent years mobilising the world," she said, saying that the EU and the Danish Presidency of the UN process had done their best to achieve results.
The EU is set to report its 2020 emission reduction target to the UN at the end of the month. While some member states had hoped to make a unilateral move to 30%, Hedegaard signalled that the EU was more likely to stick to 20% and only take on a higher target if other countries follow suit.
"I have been a strong advocate for Europe going to 30%," she said. But in hindsight, it would be better to stick with a conditional offer "to squeeze out some more percentages" from other countries, she said, referring to the disappointing results of Copenhagen climate conference.
"There is a big risk that we cannot any more agree on the 30%," she said. She referred to deep divisions between member states, some of which have been airing numbers like 20% or 25% in recent talks.
Short on concrete proposals
Hedegaard was hailed for her commitment to climate protection and excellent communicating skills. But she was criticised for not committing to many concrete legislative initiatives, speaking on very general terms instead.
"Everybody keeps repeating that the environment must be combined with the economy," said one MEP. "The same words can mean anything."
A lack of individual vision has plagued the hearings of the new Commission. MEPs have not been impressed with the guidelines that the EU executive's president, José Manuel Barroso, issued to the commissioners-designate, which the socialists equated to a vow of silence.