While the climate clock ticks louder and data centers gobble up more of the world’s resources, Microsoft has dug deeper under the hood of its own infrastructure. In a Nature paper, the firm’s researchers compared the environmental costs of four leading cooling technologies through their entire life cycles—yielding a nuanced picture of gains, trade-offs, and contradictions in the pursuit of sustainable computing.

The two-year life cycle assessment examined air cooling, cold plate cooling, and both one-phase and two-phase immersion cooling. While all three alternatives outperformed traditional air cooling in emissions, energy use, and water consumption, two-phase immersion cooling emerged as the most promising—cutting greenhouse gas emissions by up to 21%, energy usage by 20%, and water consumption by more than half.

But there’s a catch. That same technology relies on polyfluoroalkyl substances (PFAS), chemicals currently under regulatory scrutiny for their environmental persistence. So even as it shows promise, it might be fighting a losing battle against tightening global environmental standards.

Interestingly, cold plates—long considered a less radical option—nearly matched immersion’s performance without the PFAS baggage. For Teresa Nick, Microsoft’s director of natural systems and a co-author of the study, the takeaway wasn’t a clear winner, but rather a better framework for decision-making. “You’re trying to understand the context of what you’re doing and what the impacts are,” she said.

The study also underscored that no cooling system alone can shoulder the weight of data center emissions. A switch to 100% renewable energy slashed emissions by up to 90%, regardless of cooling method.

Microsoft isn’t deploying immersion cooling at scale yet, but this research may shape how it—and others—build future facilities. Because in the end, making a sustainable cloud may be less about one perfect solution, and more about understanding every imperfect piece.