Digital Carbon Footprint References
| Source | Estimate / Claim | Notes & Context |
|---|---|---|
| Pawprint Eco pawprint.ecoLink opens in a new window |
~ 0.3 g CO₂e for a short text email | Based on Mike Berners-Lee's "How Bad Are Bananas?" — higher for attachments or longer messages |
| Carbon Literacy The Carbon Literacy ProjectLink opens in a new window |
Spam email ~ 0.03 g; short email ~ 0.3 g; long email (10 min write + 3 min read) ~ 17 g | Gives a breakdown by email type and length |
| Greenly greenly.earthLink opens in a new window |
Storing 1 GB of data ~ 0.1 kWh/year (→ ~ 0.04 kg CO₂e/year in U.S. grid) | They estimate ~ 0.1 kWh/year per GB of storage; scale depends heavily on electricity mix |
| Stanford Magazine stanfordmag.orgLink opens in a new window |
3 to 7 kWh per GB (transfer + storage) | "Saving & storing 100 GB per year → ~0.2 ton CO₂" under U.S. electricity mix assumptions |
| Shift / AgainstData Shift BrowserLink opens in a new window |
Spam ~ 0.03 g; text email ~ 0.3 g; email with large attachment up to ~ 50 g | They cite typical ranges and caveats about attachments & recipients |
| +1Biosphere Sustainable Biosphere SustainableLink opens in a new window |
Sending: 4–50 g; Storing: ~ 10 g/year | Says storing an email (i.e. keeping it alive on servers) causes about 10 g CO₂ annually |
| Scientific study on data storage ScienceDirectLink opens in a new window |
~ 1.73 g CO₂ per GB (minimum scenario) | From "Exploring the sustainability challenges …" — this is for data storage more broadly, not just emails |
| "Green Algorithms" arXivLink opens in a new window |
Framework for estimating carbon cost of computation | Useful methodology, though not specific to email storage per se |
| "Chasing Carbon" arXivLink opens in a new window |
Emphasises uncertainty in estimating carbon of computing | Highlights that estimating is "elusive" and depends on many factors |