New York City officials announced this week that two pension funds for city workers will divest an estimated $4 billion in securities related to fossil fuel companies in order to promote clean energy use.

“The divestment from fossil fuels is possible and necessary,” said City Comptroller Scott Stringer, who joined Mayor Bill de Blasio at a video briefing on Tuesday. “Smart investment policy and smart climate solutions go hand in hand. And we are putting our money where our mouth is.”

De Blasio and Stringer announced Monday that the boards of the New York City Employees’ Retirement System, worth $91.4 billion, and the New York City Teachers’ Retirement System, worth $77.4 billion, had voted to approve fossil fuel divestment. A third pension fund, the New York City Board of Education Retirement System, is expected to vote for divestment soon.

“Fossil fuels are not only bad for our planet and our frontline communities, they are a bad investment,” de Blasio said in announcing the pension funds’ actions.

De Blasio and Stringer, both Democrats, set a goal to divest city pension funds from the fossil fuel industry in 2018. Environmentalist and author Bill McKibben said he knew then that New York City’s push to divest would have an impact.

“What I said at the time was, I thought this was particularly significant because of the signal it sent if the financial center of the world had gotten this message,” said McKibben, who joined Tuesday’s video call. “And I said New York’s actions would be heard loud and clear.”

New York state Comptroller Thomas DiNapoli announced last month that the state’s $226 billion pension fund would drop many of its fossil fuel stocks in the next five years and sell its shares in other companies that contribute to global warming by 2040.