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‘One ad slot auctioned 28,000 times’: the carbon cost of ineffectual bidding


By Ellen Ormesher | Senior Reporter

April 19, 2023 | 6 min read

The latest data from Scope3 highlights the scale of programmatic advertising’s billions environmental short-comings in never-before-seen detail.

Scope3 Programmatic

Ad selection counts for 60% of programmatic's carbon footprint / Unsplash

The ad industry has understood for some time now that every aspect of marketing and advertising’s supply chain creates carbon emissions that contribute to global heating. However, ineffective measurement has left many marketers scratching their heads over where the biggest contributions come from – and how to minimize them.

Enter Scope3, the organization measuring the end-to-end emissions created across advertising and media, which has today (April 19) released its inaugural State of Digital Advertising Report. A landmark study into advertising emissions across five major economies: the UK, France, Germany, the US and Australia, The Drum sat down with co-founder and COO Anne Coghlan to find out more about what it unearthed.

Programmatic advertising generates 215,000 metric tons of carbon emissions every month across those five major economies. That’s equivalent to about 24m gallons of gasoline, “or around 36 Olympic-sized swimming pools,” says Coghlan. And with every 1,000 digital impressions requiring the same amount of energy as a load of washing, it’s not hard to see how the numbers stack up.

While the average emissions per thousand impressions vary just slightly by region, going just one level deeper tells a different story. Charting the impressions at the publisher level highlights the difference between efficient and inefficient domains becomes clear, Coglan explains.

“When you’re a publisher, you’re likely working with 20 or 30 SSPs and sending out requests to each of them to get the best ad in the slot. But what often happens is those slots are resold, so you have the same slot being auctioned multiple times. In one very extreme case, we saw one impression auctioned 28,000 times. We thought it was broken.”

Average publisher emissions can range anywhere from as low as 187 gCO2pm (metric tonnes of carbon per 1,000 impressions,) all the way up to 1772 gCO2pm, (in layman’s terms, that’s enough to power 41 passenger vehicles for a year, versus 394.) This means on one end of the spectrum, there are incredibly carbon-efficient publishers, but the other side is a major problem area for digital advertising. These domains have unnecessarily high carbon emissions and should be considered a climate risk, according to Coghlan.

For instance, the worst 10% of domains contributed 33,500 metric tons of CO2 monthly across the five countries studied. That’s equivalent to driving a car 86m miles, so 3,449 trips around planet Earth or 360 times to the moon or nearly all the way to the sun.

Coghlan was not at liberty to disclose the publishers concerned, but she added: “The ad selection process really highlights the redundancy and waste, and there is no correlation between revenue and these wasteful emissions.”

She says we are starting to see a correlation between better user experiences and better ads served on the site with a decrease in emissions. “Where revenue strategy aligns with emissions strategy,” is the sweet spot, she says citing how Insider had already displayed promising results after implementing Scope3’s recommendations, reducing its carbon emissions significantly from the start of the year.

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Moreover, Coghlan warns that if carbon emissions reduction is not a business strategy imperative right now, soon brands will have no choice but to comply. “In the EU, corporate sustainability reporting is coming into play and so reducing emissions across all departments, including marketing, will reach a new level of pressure.”

Want to learn more about the most important issue of our time? Senior reporter Ellen Ormesher will explore the role of advertising and marketing in the climate crisis. Case studies, tips, interviews and more. Register your interest here.

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