Exclusive: AI writing hasn't overwhelmed the web yet

The big picture: A 2022 report from Europol estimated that 90% of online content would be generated by AI by 2026.

• According to Graphite's analysis of 65,000 URLs that were posted online between 2020 and 2025, the percentage of AI-generated articles rose sharply after ChatGPT's launch in 2023.
• The percentage of AI-generated articles in this data set briefly surpassed human-written articles in November 2024, but the two have stayed roughly equal since.

What they did: Graphite used an AI detector called Surfer to analyze a random sample of URLs from Common Crawl, an open source database of over 300 billion web pages. The database spans 18 years and adds 3–5 billion new pages monthly.

• The pages had publish dates between January 2020 and May 2025 and were classified as either articles or listicles using Graphite's article page type classifier.
• Articles were deemed AI-generated if 50% or less of the content was found by Surfer to have been written by a human.

Zoom in: Distinguishing between machine and human-written content is tricky.

• To evaluate Surfer's accuracy, Graphite tested it with its own sample of AI-generated articles and with a set published before ChatGPT's launch, which were likely written by humans.
• Surfer had a 4.2% false positive rate (labeling human-written articles as AI-generated) and a 0.6% false negative rate (labeling AI-written articles as human) for articles it generated with GPT-4o.

By the numbers: Content farms may also be learning that AI-generated content isn't prioritized by search engines and chatbot responses, according to a second report from Graphite.

• Graphite found that 86% of articles ranking in Google Search were written by humans, and 14% were generated by AI.
• The pattern held across chatbots, too. 82% of articles cited by ChatGPT and Perplexity were written by humans, and only 18% were AI-generated, according to Graphite's research.
• When AI-generated articles do appear in Google Search, they tend to rank lower than human-written articles.

Yes, but: Researchers told Axios that a definitive count of AI-made content isn't possible with today's tools and definitions.

• It's hard to determine what content is AI-generated and what is human-generated because humans are increasingly working together with AI.

• There are so many different degrees by which someone might utilize AI in their work that it's challenging to definitively say something is AI-generated or not, a Google spokesperson told Axios.
• "At this point, it's a symbiosis more than a dichotomy," Stefano Soatto, professor of computer science at UCLA and VP at Amazon Web Services, told Axios.
• Not all content created with AI is considered spam, the Google spokesperson said.

The intrigue: Common Crawl isn't the entire web, but it is one of the largest sources of training data for large language models.

• As a result, some paywalled websites — where content is presumably human-written — are blocking Common Crawl from indexing their pages.
• This could mean that the volume of human-written articles is even larger than what Graphite's data shows.

What we're watching: Clearly labeled AI summaries of closed, proprietary content do well in search, Graphite CEO Ethan Smith told Axios.

• But it's a different story for AI summaries that are auto-generated by search engines.
• A Pew survey from last week found that enthusiasm for most AI summaries in search is modest: Just 20% of users say those AI summaries are extremely or very useful, and only 6% say they trust them a lot.

The bottom line: For now, humans still want to read content that is written mostly by humans.