The EU capped 11,000 plants' carbon, crashed the price once, then rebuilt the market

After Kyoto set binding targets, the EU faced allocating cuts across 25 countries and thousands of plants. Command-and-control quotas per plant would have frozen inefficiency in place. In 2005 the EU launched the world's first international emissions trading system, covering CO2 from power generators and energy-intensive industry.

Phase 1 (2005–2007) was explicitly 'learning by doing': caps were set nationally on estimated emissions, nearly all allowances were given away free, and the penalty was just €40 per tonne. Member states over-allocated — allowances exceeded actual emissions, and in 2007 the price collapsed to zero. By any market test the pilot failed.

But the pilot built the monitoring, reporting and verification infrastructure and, crucially, real emissions data. Phase 2 cut the cap ~6.5% below 2005 using verified numbers, and phase 3 (2013) replaced national caps with a single EU-wide cap and made auctioning the default. Trading grew from 321 million allowances in 2005 to 7.9 billion (worth €56 billion) in 2012 — 84% of the global carbon market.

Cap the total, auction the permits, and let the market find the cuts

A cap guarantees the environmental outcome; trading minimizes the cost of meeting it

Free allocation in phase 1 bought industry acceptance of a brand-new market

The pilot's failure produced the verified data a serious cap requires

Switching to auctioning ended windfall profits from free permits

A market mechanism can be launched before the data is perfect if you treat phase one as instrumentation: the pilot's real output was the verified emissions data that made a serious cap possible.

Now in its fourth phase (2021–2030), the EU ETS covers around 40% of EU emissions including aviation, with a Market Stability Reserve managing surplus allowances. Carbon prices rose from near zero in 2007 to record levels in the 2020s, and the system became the model for carbon markets from China to California.