I am a retired doctor, a husband, a father and grandfather – I am also one of more than 1,000 Extinction Rebellion protesters who have been arrested by police. During the April demonstrations in London, I sat on Waterloo Bridge with many others and refused to move in full acceptance that this nonviolent action would lead to my arrest.

For many years I have been aware of the growing threat to life on Earth due to our overconsumption of the planet’s finite resources, our pollution of land, air and sea, our disregard for other forms of life and, in particular, our reckless burning of fossil fuels. It’s now clear that global heating and biodiversity loss are proceeding even faster than predicted just a few years ago and we are reaching a tipping point beyond which it will soon be too late to avoid the extinction of life as we know it. Like most of my generation living in the wealthy parts of the world, I must accept the guilt and responsibility of my own contribution to this situation.

I share the frustration of those people who have been warning about this for decades – who have observed the totally inadequate response of governments and the deliberate lies and distortion of the facts by the fossil fuel industry, among others. I welcome the formation of Extinction Rebellion: I share its aims, I want to take part in its actions and I am gratified by the results it has achieved so far.

Play Video 3:37 Extinction Rebellion: 10 days of protests draw to an end – video

And yet, I also recognise that there is still a very long way to go before we have any chance of mitigating the ecological and social disaster that faces us. More and more people are waking up to the scale of the emergency: members of the public voice their concern, councils declare a climate emergency, and some politicians utter fine words. But we are yet to see this translated into effective action and there is no general acceptance or understanding of what that will entail. Because it will mean changing the way we live. The system that has brought us to this cliff edge is based on greed and inequality – we will only sustain life on this planet if we accept the need for less consumption and more social justice.

On Tuesday Extinction Rebellion was accused of being an anarchist organisation. To my mind, anarchists are anti-government, are destructive in their aims, and are not afraid to use violence. We are none of those things: we are resolutely nonviolent, recognise the need for a government, act in the interests of the people and are trying not to destroy, but to save life on Earth.

Occupying Waterloo Bridge in April gave me a glimpse of the sort of community we could all enjoy living in. Full of energy, imagination and creativity. A community organised to look after its members and its surroundings. A simple society but one rich in love and respect for each other.

Sitting on the bridge, waiting to be arrested, I was mainly thinking of my grandchildren. I was also thinking, desperately, that the world must change course before it is too late.

• Bob Rivett is a retired general practitioner and Extinction Rebellion member