As pressure grows from students who want to see their schools use financial clout to address environmental issues, Yale University’s investment office wrote to its money managers asking them to assess how investments could affect climate change and suggesting they avoid companies that do not take sensible “steps to reduce greenhouse gas emissions.”

The letter, from David F. Swensen, Yale’s chief investment officer, stopped short of asking managers to sell shares in companies with a “large greenhouse footprint.” Instead, Yale asked them to “discuss with company managements the financial risks of climate change and the financial implications of current and prospective government policies to reduce greenhouse gas emissions.”

Mr. Swensen, who has run the $20.8 billion endowment since 1985, said in an interview that “while divestment is a blunt tool, considering the economic costs of greenhouse gas footprints is more subtle, influencing in a positive or negative fashion the risk and return profile of every investment position, existing and potential.”

“I think it is a valuable experiment,” he added. “We will see how it plays out.”

The strategy is part of a program just announced at Yale that includes a $21 million capital investment for energy conservation.