More than half of the largest US companies are doing a bad job reporting climate change to investors, according to a new report from Ceres and Calvert.

The environmental investor organisation and the socially-responsible investment firm analysed climate reporting by companies in the Standard & Poor's 500 index of the largest US companies and concluded that most "still aren't taking climate change seriously enough".

In a 31 January report, Boston-based Ceres and Maryland-based Calvert said big emitters, such as electric utilities and industrial firms, are moving to cut GHGs. But the same urgency has not taken hold at lower-emitting firms, including retailers, banks and insurers.

That is clear from their failure to respond to the Carbon Disclosure Project's surveys on climate strategies, Ceres and Calvert noted. Only 47% of the S&P 500 responded to the CDP in 2006, compared 72% in the FT500. And many that responded set no targets or schedules for reductions. Others kept responses confidential, which does not serve investors, they said.

Low-emitting firms that ignore the issue are already suffering, the report said. Insurers lost $45 billion from Hurricane Katrina alone, while JP Morgan Chase recorded $400 million in credit losses from the storm. BellSouth lost $102 million from damaged facilities, plus $187 million from reduced revenue, uncollectable bills and other expenses. Retailers and food outlets also lost business.

Regulatory change also threatens these companies because "momentum for mandatory federal climate legislation is growing", while state and regional GHG caps are already underway, Ceres and Calvert stressed. They also cited "reputational and competitive risks".

The report "underscores the need for the [Securities and Exchange Commission] to include climate risk as part of their 'materiality' standard for corporate reporting", said Howard Rifkin, deputy treasurer for the state of Connecticut and a member of Ceres' board of directors.