History
CW-7 was a cooling agent that was used to cool down the temperatures of the planet in response to climate change. However, CW-7 was too effective and instead froze the planet, starting a new ice age. Before CW-7 was released, Mr. Wilford knew that CW-7 would freeze the planet, which led to the creation of the Snowpiercer. In the graphic novels, CW-7 was a weapon of mass destruction that was activated during a war. It is unknown who activated CW-7.