An environmental group says Hawaii is a leader when it comes to global-warming policies.

The report by the Environment America Research & Policy Center found policies adopted by the state to promote energy efficiency, promote renewable electricity and cap emissions will reduce global warming pollution by 3.8 million metric tons by 2020.

The report cites Hawaii's adoption of polices to cap emissions.

The report's authors reviewed more than 100 policies adopted by states, most over the past decade, and estimated the emission reductions. The report says six states — California, Connecticut, Hawaii, Maryland, Massachusetts and New Jersey — have adopted global-warming pollution limits.