The California State Teachers' Retirement System plans to start measuring how many greenhouse gases it produces from its Sacramento headquarters and two-car fleet.

If the pension fund is going to urge companies to reduce climate-changing emissions, it figured it better take the same medicine itself, even if all the system is measuring is its 214,000-square-foot headquarters and two cars.

The new tactic follows the fund's decision to join the California Climate Action Registry, which the Legislature created five years ago to help companies and organizations track, publicly report and reduce their emissions of gases that can lead to global warming.

CalSTRS, the largest teachers' retirement fund in the United States, has about 755,000 members and assets of $132 billion. The fund has become more interested in climate issues this year. In May, it lent its name to support the United Nations-backed "Climate Risk Disclosure Initiative," a project to disclose corporate emissions and encourage plans to address climate risks.