General Motors, the largest US automaker, on Wednesday joined a call for the United States to take greater action on climate change as it said that environmental concerns were critical for business.

General Motors became the first automaker among 40 US companies in a joint appeal for policymakers in Washington to lead a "coordinated effort" against climate change, after the failure of earlier legislative proposals.

"We want to be a change agent in the auto industry," Mike Robinson, GM vice president of sustainability and global regulatory affairs, said in a statement.

GM is the maker of the Chevrolet Volt, the first electric plug-in car on the US market, and has set company-wide goals that includes reducing energy intensity by 20 percent over the decade to 2020.

The stance marks a turnaround. Detroit's Big Three long protested fuel economy standards and produced gas-guzzling trucks and sports utility vehicles as their Japanese competitors made inroads with eco-friendly cars.

The so-called Climate Declaration, launched in April, also includes major companies such as online retailer eBay, tech giant Intel, coffee leader Starbucks and numerous makers of sportswear.

The declaration warns that climate change is a real threat and urges action so that the United States can "remain a true superpower in a competitive world," although it does not endorse specific proposals.

President Barack Obama has vowed new efforts by the world's largest economy to reduce emissions of greenhouse gases blamed for the planet's rising temperatures and increasingly frequent disasters.

Efforts for nationwide restrictions on emissions have failed in Congress, with lawmakers of the rival Republican Party questioning the science behind climate change and saying that action would be too costly.