Each model generates a certain number of “thinking tokens” per query, and those tokens correlate with CO₂ emissions. At OpenAI, for example, GPT-4o and GPT-4o-mini are considered “generalized” models, while versions like o1 and o3-mini are classified as reasoning models. The end goal is for reasoning models to generate more human-like responses. The most obvious by-product of that, for anyone who has used these, is that reasoning models take longer to generate answers. Similarly, Project Stargate—a joint initiative by OpenAI, SoftBank, and Oracle—has also pledged to spend $500 billion on AI-focused data centers.