The Greens have launched their election manifesto with an appeal to voters to help them into parliament as a challenge to what they termed the unambitious, “more of the same” policies of Labour. Setting out their plans in Brighton and Hove, the location of one of the party’s key target seats, the co-leaders, Carla Denyer and Adrian Ramsay, said their proposals for higher taxes – mainly on wealthier people – were the only realistic way to improve public services and undertake vital environmental policies. “This manifesto isn’t more of the same,” Ramsay told a crowd of activists at the Sussex county cricket club ground. “It’s a look at what things could be like – and soon, if we’re willing to invest at the rate necessary and to be bold and ambitious.” He added: “We reject the pessimism of the other parties who don’t believe we can safeguard our publicly funded health system, [who think] that we can’t provide warm and secure homes for everyone, that tackling the climate crisis is too challenging for us.” Setting out ideas including a four-day working week, the nationalisation of water and energy firms, and mass-scale plans to build new homes and insulate existing ones, Denyer said the UK should not accept “an economy when most people are working harder and yet getting poorer”. She accused the Conservatives and Labour of “a race to the bottom on tax”. She said: “They think that people don’t cotton on that this means even more devastating cuts to public services, like the NHS, that we rely on every day.” Other policies set out in the manifesto, titled Real Hope, Real Change, include a maximum 10:1 pay gap ratio for public and private companies; rent controls; a £49bn investment programme over the next five years to insulate homes and public buildings; and a plan to let councils requisition empty properties or ones without proper insulation. The plans would be financed by tax changes, including a wealth levy of 1% on individual taxpayers with assets worth £10m or more, rising to 2% for those with assets above £1bn. Capital gains tax would be aligned with income tax, and higher earners would pay more national insurance. In a post-speech Q&A, Ramsay was asked if the party was comfortable asking people to pay more national insurance on incomes above £50,000. He said someone on £55,000 would pay an extra £5 a week, calling this “a modest amount that’s affordable”. Denyer said the Greens were “the only party being honest that that’s the level of investment needed to get the kind of public services we need in this country”. The Greens in England and Wales – the Scottish and Northern Ireland parties are largely independent – are running a heavily focused election campaign based around four key seats. Poll projections suggest they are on course to win two, which would double their number of MPs. The two most likely bets are Brighton Pavilion, held by Caroline Lucas since 2010 and now being contested by Siân Berry, and Bristol Central, where Denyer could unseat Labour’s Thangam Debbonaire. Ramsay is contesting the new constituency of Waveney Valley, straddling Norfolk and Suffolk, where his main competitor is the Tories. The fourth target is North Herefordshire, where Ellie Chowns is aiming for the Tory-held seat. Much of the message at the manifesto launch was aimed at voters who realised Labour was likely to win the election and would want a Green presence to push Keir Starmer’s party on areas including poverty and the environment. Speaking after the launch, Denyer told the Guardian that while she supported some Labour plans – such as the idea for publicly run power generation firm Great British Energy – it “doesn’t touch the sides of what’s needed for decarbonising our energy system or in our society as a whole”. Labour was not even looking properly at more important areas for decarbonisation such as home heating and transport, Denyer said. “They aren’t offering very much on those areas, which I think shows voters that Labour are not taking the climate crisis seriously. They are treating it as a bolt on extra that they abandoned when the going gets tough.”