This morning I woke up outside of prison for the first time since 26 September. I was jailed for 16 months after being convicted of causing a public nuisance for a four-day protest on top of a lorry at the UK’s first fracking site. On Wednesday the verdict was quashed by the court of appeal, on grounds that the sentence was, as the lord chief justice, Lord Burnett, put it, “manifestly excessive”.

Many people are saying justice has been served – but we know there is still a long way to go before we get there.

Injustice takes innumerable forms in the UK – and the systems that underpin that injustice and social oppression have only been bolstered by a Conservative government over the last few years.

The “justice” of releasing three white middle-class men from prison does represent a minor victory, but this is dwarfed by the injustices that motivated our protest to begin with. Around the world, the planet’s poorest, most vulnerable people, who have done the least to cause climate change, are those most affected by it. They – those communities who are already marginalised and oppressed on a daily basis – are the first to feel the real impacts. People of colour, queer people, trans people and other oppressed communities are also all more vulnerable to the impacts of climate change because they have least access to safe spaces and resources in times of emergency.

Here in the UK, the prison system is also hugely unjust. Our sentences were a drop in an ocean of people wrongfully imprisoned, in both the UK’s prison and detention systems. Most of the people I met in prison did not need to be in there. The system exacerbates existing inequalities in our society, disproportionately affecting people of colour, those on low incomes, working-class people and those struggling with mental health or addiction problems.

We need to reduce the prison population and expand public services. Yet the government is doing the opposite. Keeping someone in prison costs four times as much as sending them to university. At a time of austerity, prison expansion is driving forward inequality and harming communities.

We oppose the government’s plans to create 10,000 new prison places by 2020. We don’t need more people behind bars, we need stronger support structures for people in need.

The coverage and support we have received as a result of our trial has been hugely overwhelming and appreciated – but it also exacerbates the perception that white middle-class environmentalists are leading the resistance against injustice. We need to do more to ensure that grassroots groups, especially those led by marginalised voices and those experiencing real impacts, are the ones who are given platforms – and that they are part of decision-making processes for implementing change. The rest of us should follow their lead.

We took action against the fracking industry because the fossil fuel industry represents a further injustice. The UK is suffering the worst levels of fuel poverty in western Europe, with recent figures for winter showing that one older person dies of cold every seven minutes in England and Wales. Again, it is the most vulnerable people in our society who are the most affected.

Our energy system is monopolised by the big six energy companies – British Gas, EDF, E.ON, npower, Scottish Power and SSE – and their accomplices, such as Cuadrilla, are trying to lock us into further decades of fossil-fuel use to maximise their profits at the expense of people and the planet.

I organise with the activist network Reclaim the Power because we need to build an energy system that is clean, affordable and publicly owned – and that meets our need for warm, safe houses.

The solutions are already out there. Insulation, renewables and community energy projects have existed for years. The thing we now need to develop is a social movement that dismantles corporate power, puts the needs of the most vulnerable communities at the forefront of the fight and empowers the rest of us to act as genuine allies.

• Simon Roscoe Blevins is a soil scientist and anti-fracking protester