In June 2010, nine climate change activists who had broken into Aberdeen airport in protest against the soaring CO 2 emissions caused by aviation were convicted of a breach of the peace. On 25 August, after taking our urgent message on climate change seriously, the judge and court imposed on us very modest fines, ranging from £300 to £700 each and adding up to a total of £4,000-£5,000. This was the first climate trial in Scotland's history. Here's why it's unlikely to be the last.

Like the Greenpeace protesters who occupied Kingsnorth power station three years ago, we argued that any crimes we committed paled in comparison to runaway climate change.

Like them, we aren't robbers, kidnappers or terrorists. We are secretaries, parents, cooks, community workers, architects and saxophonists. We are part of a growing movement of concerned citizens who are prepared to put our bodies in the way of dangerous high-carbon developments.

We do so because we believe this is justified, proportionate and necessary in the face of catastrophic climate change, and that the negative consequences of our actions are more purposeful than the consequences of continued inaction. Sometimes, we believe, we have to break the law to disrupt lawful activities that are harming the prospects of future generations.

As Michael Mansfield QC, one of Britain's best-known defence barristers, said two days in advance of the sentencing at Aberdeen crown court: "As I write, one fifth of Pakistan, already blighted by earthquakes, is covered with flood waters threatening the health and safety of over six million people. Without conscientious and principled protest which focuses on the undoubted factors which contribute to this decimation of the environment, the urgency of the problem will not be addressed. I trust these entirely legitimate and selfless objectives will be reflected in the way the Climate 9 are judged by the court."

But why, or rather how, do we justify lawbreaking? To understand our activities, we have to look at the context in which they took place. Despite recent pronouncements on Heathrow and Stansted, aviation remains the fastest growing source of CO 2 emissions in the UK. The courts recently ruled that the government's aviation white paper was incompatible with the UK's climate change targets. Meanwhile the committee on climate change's warning that we're on course to miss those CO 2 targets was met with colossal indifference by ministers keener on slashing public spending than on cleaning up after themselves and their chums in the City.

Geoff Meaden, an expert in biogeography and coastal hazards, outlined to the court the impact climate change will have on the global south. It's all right for us to talk about building coastal barriers and moving food production to more clement locations; people in Bangladesh and the Maldives don't have that luxury. Individuals with the lowest carbon impact will bear the brunt of the emissions from the UK's carbon-intensive infrastructure.

It's not just the inequity of greenhouse gas emissions; it's about who profits from our careless attitude towards the environment and biodiversity. But here, as across the world, people are coming together to fight back.

The Scottish legal system defines breach of the peace as activities "causing fear and alarm to the ordinary and reasonable person, and which threatens serious disturbance to the community".

I can't think of a better way to describe climate change. Interestingly, this has a caveat attached: the disturbance must be "serious and threatening enough for community to take the law into their own hands". By the time the state understands that climate change is increasingly urgent, manmade and that humanity cannot wait until 2050 to realise we have missed the targets, concerned people will be taking action, not out of retribution but out of a considered sense of duty and concern.

At this critical point in human history, civil disobedience is not just a good idea. It is vital. While Westminster and Holyrood dither, concerned citizens will keep coming together to forge their own solutions.