Environmental policies promoted by the three main parties are "soggy, muddled, and compromised", says the Green Party.
Caroline Lucas said the Greens had 'courage'
European Parliament member Caroline Lucas said there was "a gulf between rhetoric and reality" especially when it came to aviation policy.
As the main parties increasingly focus on green issues, she said her party needed to promote a "more up-beat message... with practical solutions".
Labour, Conservatives and the Lib Dems have all developed green policies.
But Ms Lucas, speaking on BBC Radio 4's Today programme, said: "Their policies are soggy, quite frankly."
She questioned how the Labour government could acknowledge that climate change is a fundamental issue facing the world while at the same time approve airport expansion in the UK.
She also raised the same point about Tory and Lib Dem policies.
Her party had nothing to learn policy-wise from them, but could communicate their message better, she said in an edition of the Today programme edited by Zac Goldsmith, editor of the Ecologist and a Conservative candidate hopeful at the next general election.
"We should be having a much more up-beat message, saying that the Green Party isn't about brown bread...and it certainly isn't about wacky ideas - it's about practical solutions," Ms Lucas said.
She accused the other parties of lacking "political guts and courage" to suggest cutting aviation. Instead, the Labour government has proposed emissions trading schemes that, over 20 years, would only slightly cut expansion from 145% to 138%, she said.
"This is a massive challenge and it is the Greens who have the courage to say this is what needs to be done."
The chancellor announced several green taxes in his pre-Budget report, and the government plans to introduce a climate change bill which will make it's long-term goal of a 60% reduction in carbon dioxide emissions by 2050 a legally binding target.
The Conservatives have said a climate change bill must include annual binding targets.
Both the Lib Dems and the Tories have also said they back the use of green taxes in some form, possibly including aviation tax and congestion charging.