# Earth Hour’s first global replication

> Sydney’s one-hour switch-off became a shared ritual across cities and countries.

- Owner: WWF / Earth Hour
- Kind: Activity
- Sector: Politics & civic
- Seed date: 2007-03-31
- Milestone date: 2008-03-29
- Date basis: Documented milestone; not a measured attention peak.
- Spread Score: 40 (Notable, provisional), v1.2
- Mechanics: Low-effort copy, Real-world spectacle, Press loop

## Summary

Earth Hour began in Sydney in March 2007. City governments, news partners and recognizable landmarks helped reproduce the one-hour switch-off abroad. WWF counted 371 participating cities in 35 countries in 2008, followed by 88 countries in 2009.

## Timeline

- 2007-03-31 — WWF Australia (Open web) — Sydney held the first Earth Hour, inviting residents to turn off lights for one hour.
- 2007-09-19 — Nate Tyler / Lights Out San Francisco (Press) — Nate Tyler planned a separate San Francisco switch-off after experiencing Sydney’s event.
- 2008-01-18 — WWF Canada / Toronto Star / City of Toronto / Virgin Mobile (Open web) — Toronto’s partners offered newspaper/web promotion, customer texts, a mayoral video and reusable footage.

The full timeline, metrics and sources are on the case page, or via the Pro API (https://howitspread.com/developers).

Canonical URL: https://howitspread.com/cases/earth-hour-sydney-to-global-replication

Cite as: How It Spread (2026). “Earth Hour’s first global replication.” Case HIS-01076. Spread Score v1.2: 40/100. Updated 2026-10-17. https://howitspread.com/id/HIS-01076