Spending £100bn a year on the climate crisis, raising corporation tax and radically overhauling the tax system – all while stopping Brexit – will form the centrepiece of the Green party’s appeal to voters in what they hope to frame as “the climate election”.

The key campaign pledge allocates £100bn to be spent on measures from retrofitting homes to new rail networks and green buses in the “biggest investment in infrastructure ever seen in this country,” according to the party co-leader Jonathan Bartley. “This is transformative, and that’s what’s needed, as we only have 10 years [to solve the climate crisis],” he said.

Under plans to be unveiled at the party’s general election campaign launch in Bristol on Wednesday morning, airport expansion would be stopped and HS2 scrapped and replaced with investment in rail electrification and local bus services. The target for reaching net-zero carbon emissions would be moved forward from 2050 to 2030.

Bristol West will be a key battleground for the party, where councillor Carla Denyer will be seeking to unseat Labour’s Thangam Debonnaire. Other target seats are likely to include the Isle of Wight and Newport West, where the party’s deputy leader Amelia Womack is standing.

Details of a potential pact among the Greens, Liberal Democrats and Plaid Cymru – similar to the one seen in August’s Brecon and Radnorshire byelection when the Lib Dems achieved a 1,400 majority over the Tories after the Greens and Plaid Cymru did not field candidates – are still to be worked out. One complicating factor is the number of ex-Tory independents likely to stand in some seats.

Bartley said between 20 and 100 seats could be subject to such an electoral pact, but experts predict the final number is likely to be closer to 50. Outside any pact, the Greens would field “as many candidates as possible”, he said. The party has only one MP, Caroline Lucas in Brighton, despite receiving more than one million votes nationally.

Bartley said voting Green was not a wasted vote even under the current parliamentary system. “Every single vote for the Green party will shift British politics,” he said. “Other parties have to respond. Where the Green party has led, others have followed. We have shifted the whole argument and changed the agenda, making other politicians and parties change, too.”

Labour has come forward with policies for a “green industrial revolution”, including a national programme of home insulation that Bartley dismissed as inadequate compared with Green party plans, and the Conservatives announced a moratorium on fracking at the weekend. The Lib Dems, Labour and Scottish National Party have called for a televised election debate on the climate.

Bartley, who became co-leader with the London mayoral candidate Siân Berry last year, denied that voting Green would split the leftwing and pro-remain votes and allow the Tories into government, pointing to Conservative-held seats such as the Isle of Wight. “People are more and more willing to vote with what they believe in,” he said. “People don’t want to hold their nose and vote for the least worst [party] any more.”

“When you have people being arrested on the street in their thousands, young people leaving school to strike for the climate, you have gone beyond the constraints of this electoral system,” he said.

Bartley accused the Conservatives and Labour of putting forward broadly similar policies that would fail to move the economy to a low-carbon footing. “They are not offering change; this is business as usual,” he said. “Unless you have seismic change, we will not deal with the climate emergency.”

The party is hoping that its record showing in this year’s local and European elections – which returned 362 Green councillors and seven MEPs – will translate into general election votes across the country and that its 50,000 members and the strength of climate protest movements such as Extinction Rebellion will galvanise voters. However, it faces an uphill climb; at the 2017 general election, the Green vote share fell from its 2015 level.

Of the £100bn the Greens would spend yearly on infrastructure over the next decade, the vast majority – £91bn – would come from increased borrowing. Bartley said this was sustainable because borrowing is currently cheap and the beneficial effects of the infrastructure spending would be reaped over decades to come.

The Greens would to seek redistribute wealth to people on low incomes, offer a universal basic income to protect the poorest and replace complex benefits. It is also pushing for a four-day week – a policy that Labour is also considering.

Bartley does not believe the current electoral system of first-past-the-post constituencies based on a presumption of two-party politics can survive, as it does not reflect people’s priorities and the way they want to vote. “The old [two-party] system is dying under populist nationalism. The vote to leave was its death rattle, and the electoral system is on its knees.”