How much does talking about climate change pollute? If the question seems absurd, the numbers say otherwise. COP conference websites emit up to ten times more CO2 than an average website. This is confirmed by a study by the University of Edinburgh published NOW (I'm not kidding, I was there waiting) on PLOS ClimateSince 1995, the year of the first Conference of the Parties, COP digital emissions have grown by 13.000%. The COP29 homepage generated 116 kilograms of carbon dioxide: it would take ten mature trees working for a year to offset it. The COP30 website, which opens today in Belém, emits 0.52 grams per visit and does not run on renewable infrastructure. A detail? Perhaps. But it reveals a contradiction.
COP30: Thirty Years of Digital Growth
The team led by Professor Melissa Terras ofInstitute for Design Informatics of Edinburgh dug into web archives from 1995 to 2024. The analysis published in PLOS Climate It shows that until 2008, emissions remained low: 0.02 grams of CO2 per page view. Then came the leap. Videos, animations, and multimedia content caused energy consumption to skyrocket. Today, a COP site emits an average of 2.4 grams per visit. A typical website emits 0.36 grams.
The paradox lies in the numbers. In 1997, during COP3 in Kyoto, visits to the site generated 0.14 kg of total CO2: the amount a mature tree absorbs in two daysIn 2024, the COP29 homepage alone in Baku produced 116.85 kg of emissions. It takes ten trees a year to absorb them. An increase of 83.000%.
The increase corresponds to the exponential growth of the Internet itself, which today accounts for 3% of global emissions. Ma Scottish researchers They emphasize that COP sites still pollute much more than average. The problem isn't just traffic. It's how they're built.
Multimedia and computing power
What makes a website more polluting? The computing power required to load it. Autoplaying videos, complex animations, high-resolution photo galleries. Each element puts a strain on the servers. And servers consume energy. From 2008 onwards, COPs began to use increasingly sophisticated portals, with content designed to attract media attention. The result is a growth in emissions that outstrips that of the web as a whole.
David Mahoney, a doctoral student involved in the study, explains that websites remain the most widespread form of human-computer interaction. Even more so than artificial intelligence, which is currently capturing so much attention. "Websites are one of the biggest contributors to the internet's environmental impact. Our work shows how reusing web archives can expose this blind spot, even among organizations like COP30, at the heart of climate discussions."
COP30 gets off to a bad start
The study does not yet include, of course, definitive data on the website of the last Belém conference, COP30, scheduled until November 21, 2025. But researchers have found preliminary data that speak for themselves. The site emits 0.52 grams of CO2 per visit. This is less than the COP average, but still above the web standard. And it isn't hosted on servers powered by renewable energy. This means that every megabyte transferred weighs on the atmosphere more than it should.
It's estimated that around 50.000 people will visit the official website among conference attendees alone. Public traffic will be higher. Using the study's methodology, Delegate visits to the homepage alone would generate approximately 313 kg of CO2. That's equivalent to what fifteen mature trees absorb in a year. Once again, please, details. Right?
How to reduce digital emissions
Researchers propose practical solutions. Limit page sizes. Optimize layouts by reducing heavy graphic elements. Host servers on renewable energy-powered infrastructure. These are trivial measures, in theory. Difficult to apply when the logic is that of visibility at all costs.
The study is the first example of using web archives to track environmental impact over time. The code developed by the team will be freely available and can be used to assess the historical footprint of any site. A method that could be applied to companies, institutions, public bodies. Maybe in the end it's not a detail at all.
Symbols matter
Of course, 116 kg of CO2 for a website is a fraction of the overall emissions of an international conference. - delegates' planes, hotels, logistics weigh much moreBut symbols matter. When an event that should represent the global commitment to combating climate change pollutes (even) digitally more than necessary, the message weakens.
Melissa Terras he says it clearly:
"The digital footprint of websites deserves greater attention. The environmental cost of an online presence is often ignored, even by those concerned with environmental protection. We hope our recommendations, and our tool, can help institutions identify and address this problem."
The internet isn't neutral. Every click counts. And if those who advocate ecological transition fail to make even one website sustainable, the message risks ringing hollow.
Small contradictions, sure. Sure.
