In a bid to help meet its ambitious climate change and clean energy targets, China is methodically building the world’s largest trading system. China has been testing out city-level carbon-trading projects, and is using the data gathered from these projects to build its carbon trading system slowly and deliberately. The system will initially only cover the electricity sector, but that already is enough to qualify it as the world’s largest trading system, covering roughly 3.5 billion tons of CO2. Many essential details about this ambitious project are due to be announced in the coming year.