As Elizabeth Fraser’s gentle vocals on ‘Teardrop’ – “Love, love is a verb, Love is a doing word” – dropped on a soaked yet entranced crowd in Clifton Downs, it marked the pinnacle of Act 1.5, and Massive Attack’s first live performance in Bristol in half a decade. But this was more than a homecoming gig. Much more. Four years in the making, it was the realisation of the band’s dream of hosting a carbon-busting festival. Despite difficulties with permits, suppliers, logistics and politics, not to mention the fierce winds of storm Jocelyn which resulted in the festival structures being reassembled not once but twice; it all came together on the day to lead the music industry’s charge for climate change and human rights.

Act 1.5 called on a team of experts from Tyndall Centre for Climate Change Research, Ecotricity and Zenobe Energy among others to build a prototype festival that leaves no trace. For starters, the entire site and operations were powered by renewable energies and batteries, saving 5,340kg of carbon emissions. Other measures included electric shuttle busses, railway incentives addressed local and national transport, making all food outlets 100% plant-based, a zero waste / landfill policy and planting a new woodland outside of the city.

Steven Meersman of Zenobe said: “The UK’s music festivals are one of the most wasteful public events, using over 12 million litres of diesel annually. And diesel generators lose about 65% of the energy they produce. But this festival sets the precedent by demonstrating how a festival can be powered purely by renewable sources.” Mark Donne, lead producer of Act 1.5 added: “If you’re listening to the science and you’d like us all to avoid catastrophe, there’s no meaningful alternative to immediately reducing GHG emissions. The response has been incredible as we show that major live music shows can be done differently, collectively and dynamically.”

The key to ongoing success is getting the buy-in from punters and suppliers alike by showing that festival enjoyment isn’t dinted, and that money can still be made. Sure, gimmicky ideas like kinetic dancefloors and people-powered lights sound exciting but cost a fortune to implement and don’t produce sufficient electricity.

Instead, Act 1.5 gave us experiences that we could get hold of. We made our own festival merch by printing Robert Del Naja's artworks on T-shirts supplied by No Sweat, a local company fighting sweat shop fashion. We listened to talks at The Novara Media stage from experts on topics including Bristol's Black history and the eco-credentials of the new Labour government. And we walked through a pre-apocalyptic marketing suite for (S)hell by artist Darren Cullen spoofing the company’s greenwashed claims. ‘We’re recycling the water we use in fracking into a refreshing drink!’

And then came the music. First up was Sam Morton, accompanied by XL boss Richard Russell, whose recently released album ‘Daffodils & Dirt’ is a bittersweet journey through the famed actor’s painful childhood. Her heartfelt singing and spoken word evoked memories of how music became a transcendent lifeline while living in care homes. With sonic references to everything from early 90s rave (we hear you, ‘Mr Kirk’s Nightmare’) to synth pop via UB40, this was the sound of healing.

Lankum filled the field with their mesmerising doom folk, rich with brutal strings, hypnotic soundscapes and tales of woe. The Mercury Prize nominees centred a performance of their re-worked track ‘The Rocks of Palestine’, put a riot in our souls with ‘The Rocky Road to Dublin’ and finished us of with the funeral song ‘Go Dig My Grave.’ Exquisitely sung by Radie Peat, her a cappella was followed by chords that built and built until they engulfed us all.

Killer Mike of Run the Jewels roused our spirits with his big rap energy and soulful passion, ably assisted by sassy backing crew, the Mighty Midnight Revival. Speaking on the US elections, his solidarity for Palestine, women’s right and his deep-held respect for his grandmother – not to mention Bristol’s high-grade weed – his was an uplifting, gospel-tinged set that reminded us to embrace the ‘other’.

As darkness fell, Palestinian photojournalist Motaz Azaiza was given the stage to address this 30,000-capacity crowd about the 40,000 people killed in Gaza and the West Bank so far, including 160 of his colleagues. As he vowed to continue to document and share stories of this unfolding atrocity, he urged: “Together, we can change this.”

And then, as the heavens opened hard, Robert Del Naja and Grant Marshall took to the stage. Set against an onslaught of visual stimuli – Putin, warfare, housewives on acid and a myriad of conspiracy theorist messages of the type that feed our doom scroll culture – Massive Attack got to work. Nothing could deaden the warmth and beauty of this performance as each classic track felt as poignant as ever. The brooding ‘Risingson’, the hypnotic ‘Safe From Harm’ and the anthemic ‘Unfinished Sympathy’ (featuring Deborah Miller on vocals) kept fans dewy-eyed while the tingling ‘Girl I Love You’ marked Horace Andy’s first appearance of the evening – later coming back for ‘Angel’.

Massive Attack’s more recent bedfellows Young Fathers blasted into view to relive ‘Ceasefire’, their joint single released to raise money for MSF’s emergency operations Palestine, as well as the jittering masterpiece ‘Voodoo In My Blood’. But we were continually drawn back to the veteran vocals of Elizabeth Fraser, who lent her magic to ‘Black Milk’, ‘Song To The Siren’ and ‘Group 4’, to bring the evening into all of our hearts. Here, love is a doing word. And with Act 1.5, Massive Attack have followed through. Indeed, these trip hop pioneers and activists always do.