Western Climate Initiative (WCI)  is a non-profit corporation formed to provide administrative and technical services to support the implementation of state and provincial greenhouse gas emissions trading programs.

In February 2007 the governors of five western US states came together to work on collective and cooperative ways to reduce greenhouse gases in the region.

A few months later Utah, British Columbia and Manitoba joined the Initiative.

Since then, the organization grew to include the states and provinces shown in the map on this page. As of summer 2008, WCI represented approximately 73% of Canada’s economy and 20% of the US economy.

Their defined goal was to reduce greenhouse gas emissions to 15% below 2005 levels by 2020.

In November of 2011 Arizona, Montana, New Mexico, Oregon, Utah and Washington left WCI formally.

As of December 2011, the remaining WCI members were California, British Columbia, Manitoba, Ontario, and Quebec.

In 2018, Nova Scotia chose the WCI to run its cap-and-trade system.