--- title: "Who is using AI to code? Global diffusion and impact of generative AI · AI Fault Line" url: https://aifaultline.com/research/p/doi-10-1126-science-adz9311/ description: "AI Fault Line is a neutral, evidence-cited field guide to why experts looking at the same developments disagree about AI's effect on productivity, jobs, inequality, regulation and the pace of change." --- [Research](https://aifaultline.com/research/) # Who is using AI to code? Global diffusion and impact of generative AI [Simone Daniotti](https://aifaultline.com/authors/network/#map=simone-daniotti), [Johannes Wachs](https://aifaultline.com/authors/network/#map=johannes-wachs), Xiangnan Feng, Frank M. H. Neffke · Science · 22 Jan 2026 [Read original source](https://doi.org/10.1126/science.adz9311) Open access Where this sits in the debate - [Will AI actually boost productivity and growth?](https://aifaultline.com/debate/productivity/) · its finding: it depends ([why studies differ](https://aifaultline.com/debate/productivity/#why)) - [Will AI widen inequality?](https://aifaultline.com/debate/inequality/) · its finding supports the claim ([why studies differ](https://aifaultline.com/debate/inequality/#why)) - [How fast will the impact arrive?](https://aifaultline.com/debate/pace/) · its finding supports the claim ([why studies differ](https://aifaultline.com/debate/pace/#why)) Direction of the finding as read from the abstract by an AI model ([AI-written](https://aifaultline.com/about/)). ## Abstract Generative coding tools promise big productivity gains, but uneven uptake could widen skill and income gaps. We train a neural classifier to spot artificial intelligence (AI)-generated Python functions in more than 30 million GitHub commits by 160,097 software developers, tracking how fast, and where, these tools take hold. Currently, AI writes an estimated 29% of Python functions in the US-a shrinking lead over other countries. We estimate that quarterly output, measured in online code contributions, consequently increased by 3.6%. AI seems to benefit experienced, senior-level developers: They increased productivity and more readily expanded into new domains of software development. By contrast, early-career developers showed no significant benefits from AI adoption. This may widen skill gaps and reshape future career ladders in software development. ## About this publication **Top journal.** One of the journals economics departments rank highest: the “top five” economics journals, and the general-science journals Science and Nature. Placed by: General-science journal. [How sources are ranked](https://aifaultline.com/about/#source-ranking). Published 2026 (9 months ago) Citations 20 (OpenAlex) ## Citations in context [Chart: 20 citations, cohort median 0] 20 citations — 99th percentile among the 188 indexed papers from 2026 in this collection. Citation counts favor older papers; this compares only same-year papers here, not the whole literature. [Chart: published 2026] Frank Neffke, Simone Daniotti signed the wemustactnow.ai letter — part of why this paper is in the collection. ## Cited elsewhere in this guide - [Evidence for Frank Neffke's position on “Will AI actually boost productivity and growth?”](https://aifaultline.com/debate/productivity/) ## More on this topic Related by theme, not necessarily by method or conclusion. - [Navigating the Jagged Technological Frontier: Field Experimental Evidence of the Effects of Artificial Intelligence on Knowledge Worker Productivity and Quality](https://aifaultline.com/research/p/doi-10-1287-orsc-2025-21838/) Organization Science · 2026 - [Navigating the Jagged Technological Frontier: Field Experimental Evidence of the Effects of AI on Knowledge Worker Productivity and Quality](https://aifaultline.com/research/p/doi-10-2139-ssrn-4573321/) SSRN · 2023 - [Generative AI at Work](https://aifaultline.com/research/p/doi-10-1093-qje-qjae044/) The Quarterly Journal of Economics · 2025 - [The Impact of AI on Developer Productivity: Evidence from GitHub Copilot](https://aifaultline.com/research/p/doi-10-48550-arxiv-2302-06590/) arXiv · 2023 Overview assembled automatically from collected metadata. [How this site is built](https://aifaultline.com/about/).