Yesterday I was given an enormous honour and great responsibility in being elected as the leader of the Green party of England and Wales.

This is a time of tremendous opportunity for the Green party. Voters across Britain are seeking new answers – they want to know why in the world's sixth-richest economy, millions feel insecure, frightened about the future, worried about their children's future.

They know that after decades of growth based on the financial and retail industries, with a long-hours working culture and growing job insecurity, Britain has the unhappiest children in the developed world, that levels of mental illness and stress are extremely high, that huge numbers of people are not sure they can keep a roof over their heads.

And they know that our entire economy is based on treating the Earth as though it were a mine and a dumping ground, and the poor as though they were rubbish.

They understand that the 20th-century approach of neoliberalism and globalisation, of outsourcing and financial speculation, cannot continue. The model is broken.

Yet the Labour party, which was so relaxed about people getting "filthy rich," which was so keen to outsource NHS services and encourage academy schools, hasn't changed its tune – it just wants to cut a little more slowly than the coalition.

Only the Green party has the vision of radical change. It understands that we need to invest in the future, to invest in housing, in jobs, in energy conservation and renewable energy.

Cuts are only throwing more people on to unemployment benefits – what we need to do is create jobs and provide essential services – health, social care, education and social housing. And to fund that investment we need to collect a proper level of taxes from multinational companies and rich individuals, not cut tax rates and allow them to hide billions in tax havens.

That investment can restructure our economy to prepare for a low-carbon world, relocalise our manufacturing industries and food supplies, make Britain a leader in renewable energy and create jobs, opportunities and security. We can build all of this around a financial industry that's fit for that purpose, based on credit unions, mutuals and small local banks.

Rather than giant multinationals, we need to encourage co-operatives and small businesses rooted in their communities and meeting their needs. And we need to ensure that the law allows unions a significant role in the workplace – an important corrective to our current low-pay, casualised workplaces.

The Green party also accepts that we need to acknowledge that some people in society will need a helping hand, some of the time or all of their lives. Benefits are an essential support in a decent society, and they should be at levels that allow a proper standard of living. The demonisation of benefit recipients, the grossly unfair Atos disability tests, the slashing of disability living allowance all stand as testament to the wrong directions we have been taking.

The Green party thus offers a new answer to voters seeking it – and so this is a time of tremendous political opportunity.

We finished as clearly the third party in the recent London elections. In the West Midlands, to take just one example, we've been growing fast in numbers of councillors, and after the election of Caroline Lucas as MP in Brighton Pavilion in 2010, we've shown we can win first-past-the-post elections at all levels.

In my two-year term as leader, I will be aiming to help get many more Greens elected on to councils around England and Wales, and to see us trebling our number of MEPs in 2014, meaning many more voters have at least one elected Green representative. That will be a foundation stone for the 2015 Westminster elections and beyond.

We are seeing many Lib Dem voters come to us, but we also know that the Labour vote is very soft – many who might vote for the party of Blair/Brown/Miliband when they think they are the only alternative are delighted to shift their vote to the Greens when they realise they have the option.

It's clear we are in troubled times, but the Green message is that we can emerge stronger, with a more equal, fair and balanced society – and a better quality of life for everyone.