USCA meaning in Regional ?

The United States Climate Alliance is a bipartisan coalition of states and unincorporated self-governing territories in the United States that are committed to upholding the objectives of the 2015 Paris Agreement on climate change within their borders, by achieving the U.S. goal of reducing greenhouse gas (carbon dioxide equivalent) economy-wide emissions 26–28% from 2005 levels by 2025 and meeting or exceeding the targets of the federal Clean Power Plan.

The Alliance was formed on June 1, 2017, following the announcement earlier that day by U.S. President Donald Trump that he had decided to withdraw the United States from the Paris Agreement. The Alliance also forms a forum for its members to further develop and strengthen their existing Climate Action Plans, through sharing of information and best practices.

As of July 1, 2019, the 23 members of the Alliance at the time made up 50% of the U.S. population and over 50% of U.S. GDP as of 2016. After excluding Puerto Rico figures from the emission total, the members' combined share of U.S. carbon dioxide emissions was 25.51% in 2014.