A few months back, a book arrived in the post – tiny, not much larger than a bank card. Though the cover was grey, its pages were a riot of pinks, from deepest persimmon to pale rose. Printed on them were dense, technical essays referencing everything from fish farming to Adam Smith’s The Wealth of Nations. The title was Salmon: A Red Herring.

Fish is an unexpected topic for an art book – but then the duo who created this little volume, Daniel Fernández Pascual and Alon Schwabe, aren’t really going for the coffee-table market. Operating under the name Cooking Sections, the pair have a thing for food. Their art is about what we eat and its impact on the Earth.

In previous projects, they have explored irrigation issues in Sicily, soil rights in Ukraine and migrations of Alpine cattle, in addition to creating installations in such places as the Peggy Guggenheim in Venice and Berlin’s Neue Nationalgalerie. At an architecture exhibition in the UAE in 2019, they planted a “desert garden” in the grounds of a school in Sharjah – an exploration of how farmers in the driest parts of the world could use drought-resistant plants to create more sustainable agriculture.

Cooking Sections’ enthusiasm for salmon came about after an invitation from Tate Britain in London to create an exhibition – one that was open for just a matter of days in late November before being shut by lockdown. (Pascual and Schwabe hope that when the museum eventually reopens, their show will too.)

A modest one-room installation, it resembled a sort of natural history diorama, plunging you into the realities of Scottish fish farming. Over 15 minutes, a bare white stage populated with static sculptures of various animals (seal, penguin, lobster, flamingo) was illuminated pink, then blood-red, while a voice solemnly explained how salmon are industrially farmed.

The facts were grim: crammed into pens for up to two years and fed processed food, many end up deformed, blind, riddled with sea lice, and are often driven to eat each other. Then there’s the pollution. According to the Scottish Environment Protection Agency, insecticides from the country’s 76 fish farms are leaching out in quantities that harm other marine life. Despite all this, Brits are guzzling farmed salmon at record rates: it’s now the most popular seafood in supermarkets, worth an estimated £1bn annually to the UK economy. “Not pleasant,” says Pascual mildly.

If all this weren’t enough to make you think again about what you’re cooking for dinner, Schwabe and Pascual discovered that industrial fish farmers use a special colour swatch called the SalmoFan to customise their product. Unable to feed on their natural diet of krill or baby lobster, farmed salmon flesh is naturally grey – but no one wants grey fish, so the animals are fed dye pellets, as if they were being ordered up from Dulux. Different global markets even prefer different pinks: redder, more tuna-y tones for Japan and east Asia, lighter ones for Europe.

But why put all this in an art gallery. Isn’t it education? Environmental activism? Pascual shrugs. “The gallery is an amplifier of ideas. We see a lot of potential in cultural spaces trailblazing, paving the way for others.”

The pair started working together in 2012, when both were students at Goldsmiths in London. Pascual trained as an architect in Spain and Berlin, while Schwabe, who grew up in Tel Aviv, has a theatre and performance background. Three years later, they began work on a project they call Climavore, which illuminates issues around agriculture and climate change. Salmon: A Red Herring is just one part of something they hope will go on for years.

“Food is a tool,” explains Schwabe. “It enables you to understand environments and landscapes and geopolitics.” Pascual adds: “It touches on many different levels. Food is one of the biggest contributors to the dispersal of emissions into the atmosphere. It’s also one of the driving forces behind deforestation. It’s everywhere.”

The installation that made their name was the “oyster table” they built in 2017 in an inlet near Portree on the Isle of Skye. A humble-looking, metal cage-like structure perched on the shoreline, when the tide is high it acts as a habitat for bivalves and seaweed; when the seawater recedes, it can be used as a table for communal meals. It aims to highlight how, as traditional fishing has faded, Skye’s economy has become dependent on the industrial fish farms that now blanket the island’s waters.

Reporting on its unveiling, Frieze magazine observed that, unusually for an art opening, the dress code featured wellies and fisherman’s bibs. Despite the seriousness of their work – in person, Pascual and Schwabe are as earnest as you might expect – a vein of playfulness and celebration runs through it too. They’re currently fundraising to extend the project, and have grand ambitions for how it could help change the economy and ecology of the island.

They’ve used food to lay bare other uncomfortable truths, too. One of my favourite Cooking Sections projects – arguably even more timely, given debates about the UK’s colonial history, than when it was originally created in 2016 – is one they called the Empire Remains Shop. It was inspired by their discovery of a 1920s advertising campaign by Britain’s Empire Marketing Board (slogan: “Buy Empire”). This urged British consumers to spend their hard-earned shillings on goods sourced from overseas territories under British colonial control.

One of the original wheezes was a recipe for a so-called “Empire Christmas pudding” using 17 ingredients that included cloves from Zanzibar, Palestinian oranges and rum from British Guiana – revealing how this most traditionally British of desserts relied, in fact, on colonisation.

Pascual and Schwabe created a pop-up shop in central London, which hosted discussions, dinners and screenings, and in 2018 published a book exploring the issues it raised through food.

As Schwabe explains, they also work with agronomists, food producers, restaurants, politicians and more, trying to find more ecologically sound solutions to the problems they pose. “Without all of these working together,” he says, “from our perspective it’s impossible to envisage change.”

The fact that Tate was founded by a sugar baron – profits from a foodstuff built on slavery literally funding art – adds a certain pointedness to their installation at Tate Britain. Whereas artists have struggled for decades with how to represent the climate crisis, anxious about seeming preachy or unsure what their role should be, Cooking Sections make no bones that want to make a real difference, even if much of the work is unglamorous and largely behind-the-scenes.

They’re not alone: fellow Goldsmiths alumni Forensic Architecture have melded design and activism, undertaking investigations into state violence or human-rights violations.“Socially engaged” collectives such as the Edinburgh-based Arika group run projects linking art with social change.

And the broader art world seems finally to have woken up to its own role in the climate emergency. Art is, after all, a globalised industry, both directly and indirectly responsible for pumping out vast quantities of CO2. Lucia Pietrouisti, curator of the General Ecology project at London’s Serpentine (and who helped create the powerful, climate-themed Lithuanian pavilion at the 2019 Venice biennale), has been vocal about the need to “infect other art institutions with the ecological bug”.

“More and more people are realising that we need to take concrete action,” says Pascual. “We need new public forums.”

Do they feel they’re part of a new movement? Schwabe shrugs. “It works both ways. There’s an urgent question we need to respond to as humanity. Many artists are asking these questions in brilliant ways.”

Which reminds me: what about salmon? Tate was one of the first major art institutions to acknowledge the climate emergency, in summer 2019. And it is currently working on a carbon-cutting plan. But I’m sure I’ve nibbled at least one smoked salmon sandwich in a Tate cafe. No longer, Schwabe says triumphantly: anyone visiting the four museums when they reopen will notice that farmed salmon has been banished entirely from its cafes and restaurants. They’ve been working with the catering team to come up with alternatives promoting “regenerative aquaculture”.

Though the show is currently closed, when we catch up over Zoom a few weeks later, it turns out that they’ve hardly been idle. As well as continuing to teach at the Royal College of Art, they are among 60 artists to participate in a new multi-year project with London’s Serpentine Gallery called Back to Earth, which launches in the spring – another indication of how seriously the art world is taking the climate emergency.

They’re still figuring out what form it’ll take, but it’ll build on the Tate show, spreading the word about sustainable agriculture, food waste, related issues. If other cultural institutions can make the leap, maybe whole cities can – who knows?

As I peer more closely at the screen, I notice both are wearing matching T-shirts, salmon-pink, if I’m not mistaken. Schwabe grins. “Well, what else?”

• Salmon: A Red Herring is published by Isolarii. Tate Britain, London, will reopen 17 May at the earliest.

• This article was amended on 4 May 2021. The dye pellets fed to salmon are not synthetic as an earlier version stated. And a reference to “pesticides” has been changed to “insecticides”.