The approach of a general election is usually the time when party leaders make a speech on the environment, and Mr Kennedy is first out of the stalls this time.
His speech on 1 March was sponsored by WWF, Green Alliance and the Royal Society for the Protection of Birds, which want to get a competition going between the parties.
Mr Kennedy denied that his was a party leader's box-ticking speech giving "a new coat of green paint to freshen up the party for another year." Rather, it was "part of a concerted and determined effort by the Liberal Democrats to push the environment up the political agenda and keep it there."
The LibDem leader attacked Labour for failing on its 1997 manifesto pledge to put the environment at the heart of policy-making. Instead, it had put it far out on a limb.
Many environmental indicators were going the wrong way. Municipal waste volumes were up by 17% since 1997, while Britain languished at the bottom of the European recycling league. Domestic energy consumption was up by 7%. The UK was generating a "truly pathetic" 2.5% of its electricity from renewables. And road traffic was up by 8%.
"This is not sustainable development," he said. "This is old fashioned, uncontrolled, unsustainable development."
Part of the problem lay in the "grave mistake" of delinking the environment and transport after the last election. The creation of DEFRA, said Mr Kennedy, "has served only to marginalise environmental decision-making."
The LibDems would create a Department of Environment, Energy and Transport, "taking DEFRA's environmental responsibilities and the DTI's water and energy roles and integrating them with transport. This would create what you could call a department for sustainable development and truly put environment at the heart of government."
The other hallmark of Mr Kennedy's speech was a strong emphasis on economic instruments, with revenues being recycled into offsetting tax cuts so that people understood that green taxes were not stealth taxes.
Mr Kennedy saw a need for a twin-pronged attack on aviation, which pays nothing like its true environmental cost. He supported "in principle" the taxation of aviation fuel at European level, and wants air passenger duty replaced with a tax on all aircraft leaving the UK, whether carrying passengers or freight. The present duty, he said, "gives no incentive for the operators to fill up their flights," and leaves freight planes untouched.
Incentives were also important, said Mr Kennedy. Motorists should be rewarded for driving less polluting vehicles, and VAT should be cut from 17.5% to 5% on all domestic energy-saving products.
Those are two old favourites, but Mr Kennedy also saw potential in "green reward cards", such as a successful scheme in Rotterdam. "The scheme works like a store loyalty card but gives 'points' for buying sustainable products, for recycling and even using public transport.
"I think people will take to schemes like this. I think they will change their behaviour if given the incentive to do so."
Shadow Environment Secretary Theresa May also made a speech on the environment at the Tories' spring forum, but focused on attacking Labour.
"Tony Blair 'proved' his green credentials by signing up to endless European environmental Directives that he has no idea how to implement," she said. That was why there are fridge mountains, fly-tipping, abandoned cars, and a countryside "blighted by the construction of ten thousand wind turbines."
There were no signs of new policy thinking from Ms May, merely examples of issues needing to be tackled: "What we do about GM crops. How we deal with mounting problems of waste. The creation of a roadmap to a sustainable balance of environmental priorities."
Ms May claimed that her party has now embarked on the "most radical and wide-ranging" consultation on the environment it has ever undertaken. The only consultation she launched at the forum itself concerned fly-tipping - though this, too, was "wide-ranging" and the "first ever countrywide consultation" on the subject.