What is fourth wave coffee?

Fourth wave coffee extends the third wave from roughly 2015 onward by layering science, data and technology on top of it: controlled fermentations (anaerobic, co-ferments), AI-assisted roasting, sensor-driven extraction, blockchain traceability and more individual profiles. Where the third wave revealed terroir, the fourth wave puts it on the lab bench.

The 'fourth wave' label is not a registered trademark or an official standard like SCA specialty coffee. It is an editorial shorthand that began circulating in the English-speaking coffee press from around 2015-2017 to mark a shift: where the third wave had centred on origin and roasting, the fourth wave reaches upstream into post-harvest processing and downstream into measured extraction. A symbolic turning point is Australian barista Sasa Sestic's victory at the 2015 World Barista Championship in Seattle, where he used a Sudan Rume from Finca Las Nubes in Colombia (producer Camilo Merizalde, Cauca) processed with carbonic maceration washed — a technique borrowed from Beaujolais wine. That moment popularised so-called 'innovative' fermentations: anaerobic washed and natural, co-ferments with fruits or selected yeasts, thermal shock, lactic process, kombucha process.

The fourth wave is also a technology wave. On the roasting side, platforms like Bellwether Coffee (an electric roaster with cloud-controlled profiles) and Decent Espresso (an open-source espresso machine with real-time pressure, flow and temperature sensors) embody the philosophy: extract, measure, adjust, share. On the traceability side, blockchain projects such as Farmer Connect — a consortium launched in 2020 with IBM and several industry players — let the drinker scan a QR code and trace the cup back to the cooperative, sometimes to the individual farmer. NFT experiments around microlots appeared between 2021 and 2023, without yet becoming mainstream.

Lastly, the fourth wave is the wave of espresso without a traditional machine: manual presses like Flair and Cafelat Robot, compact stove-heated units like 9Barista, and the AeroPress (invented in 2005), which has become a global experimentation platform through the World AeroPress Championship. In Europe, the Belgian scene — Brussels, Ghent, Antwerp, Liège — gradually integrates these tools, often in specialty-oriented wine bars that treat morning coffee as another vertical of their drink list, notably around La Hulpe and Genval.

Markers of fourth wave coffee

What the fourth wave adds to what the third wave built

If the third wave was about quality — proving that coffee deserved the same thoughtful attention as wine, cheese and artisanal food — the fourth wave is about systems: examining whether the entire infrastructure of specialty coffee (sourcing, logistics, roasting, retail, consumption) is operating in a way that is sustainable for the planet, equitable for the people who produce it, and honest in its communication with the people who consume it. The fourth wave's defining concerns — carbon footprint, producer income equity, land use, water consumption, packaging waste — are not new in sustainable food discourse, but their application to specialty coffee requires confronting some uncomfortable realities about a market that has successfully marketed itself as already ethical.

Fourth-wave coffee business models challenge third-wave conventional assumptions at several points. The specialty premium's distribution — where does the additional margin above commodity end up? — becomes a fourth-wave question: if a roastery charges €35/kg for specialty coffee that cost €8/kg at the green stage, are the intervening 27 euros distributed in proportion to the value created by each party in the chain, or concentrated in the roasting and retail stages? The Direct Trade pricing transparency movement — roasters publishing what they paid at origin — is a fourth-wave mechanism for making this distribution visible. Carbon accounting for coffee — measuring the emissions embodied in growing, transporting, roasting, packaging and disposing of coffee — is another fourth-wave analytical layer that specialty's third-wave framing didn't address.

Going deeper

For Belgian specialty coffee consumers, the fourth wave manifests in several observable ways. Roasters publishing detailed sustainability reports with verified supply chain data (Koppi's annual transparency report, Square Mile's Direct Trade pricing publications). Compostable or recyclable packaging as a standard rather than a premium option at quality roasters. In-store bean-to-cup waste education programmes that acknowledge coffee's full environmental footprint including water consumption at origin (approximately 140 litres per cup when agricultural water use is included). The fourth wave doesn't replace the third wave's quality commitment — it adds a systemic lens through which quality claims must survive additional scrutiny. The best specialty coffee of the fourth wave is both excellent to drink and honest about its full environmental and social context.