PITTSBURGH (AP) — Some of the largest pension funds in the U.S. and the world are worried that major fossil fuel companies may not be as profitable in the future because of efforts to limit climate change, and they want details on how the firms will manage a long-term shift to cleaner energy sources.

In a statement released Thursday, leaders of 70 funds said they're asking 45 of the world's top oil, gas, coal and electric power companies to do detailed assessments of how efforts to control climate change could impact their businesses.

"Institutional investors must think over the long term, which means that we must take environmental risks into consideration when we make investments," New York State Comptroller Thomas DiNapoli told The Associated Press in a statement. The state's Common Retirement Fund manages almost $161 billion of investments.