What uses more: the footprint of a prompt

Recommended for: Any course, as a ten- to fifteen-minute activity; particularly apt in sustainability, earth sciences and computer science

Background for the instructor

Public argument about AI and the environment is polarised and mostly innumerate: either every prompt is boiling a lake, or the whole question is a distraction. Students are entitled to a better basis than either. A calculator that lets them vary the assumptions gives them one, and it teaches something more durable than the numbers — that the footprint depends on what you asked for, where the data centre is, and how its electricity is made.

The shape of this activity is worth copying for other topics: something active, one short critical text, and a moment of reflection, inside a quarter of an hour.

Preparation

Pick one short critical reading on the environmental cost of AI. Have students note, over the preceding week, roughly what they asked AI to do for a specific piece of coursework.

Procedure

1. Students inventory their own AI use on one assignment: how many prompts, of what kind, generating what.
2. They run those through the calculator and compare the result with reference points they recognise — charging a phone, an hour of video calling, a load of laundry.
3. They vary one assumption: the power source of the data centre, or its climate, and see what it does to the figure.
4. Read the critical text against their own numbers.
5. Brief reflection: does this change when you would and would not reach for AI?

Discussion questions

• Which comparisons here are fair, and which are rhetorical?
• Generating a three-second video can cost many times what charging a phone does. Does the kind of thing you ask for change your judgement more than the number of times you ask?
• Whose responsibility is this figure — yours, the university's, or the provider's?

Assessment opportunity

Students attach the inventory and a two-sentence justification to a piece of work that involved AI.

Reference

• Jon Ippolito, professor of new media, University of Maine. What Uses More, a public calculator for the energy and water cost of AI and non-AI tasks, released August 2025. umaine.edu
• Used in exactly this way, with a spreadsheet inventory, by Mark C. Marino at the University of Southern California.
• Discussed in The Norton Guide to AI-Aware Teaching (Vee, Watkins & Bruff, W. W. Norton, 2026).