France’s largest insurer will scrap holdings in coal companies because of concerns about climate change, broadening support for the fossil-fuel divestment movement to a major mainstream investor.

AXA SA Chief Executive Officer Henri de Castries said he’s working to sell 500 million euros ($559 million) of coal assets and triple “green investments” to 3 billion euros by 2020. He joined investors in Paris saying companies must act to contain global warming.

“There is one thing which is absolutely clear: If the warming goes beyond 2 degrees, it’s going to become tougher and tougher and probably impossible” for insurers to cope with damage to the environment, De Castries said in an interview on Bloomberg Television in Paris on Friday. “Insurers are the mirror of what happens in the economy and in the society. We try to increase what we do on the prevention side.”

The decision could bring to the market shares of some of the largest mining concerns. For environmental campaigners, it also adds a major traditional investor to the growing list divesting from fossil fuels. AXA had 925 billion euros ($1 trillion) under management at the end of last year, including money it oversees for third parties.

To date, the biggest names supporting the movement have been churches, universities and socially conscious funds such as the Rockefeller Brothers Foundation. Earlier this week, Oxford University joined Stanford in saying it would halt investments in coal. The Church of England also is reduced coal investments.

Stranded Assets

Their concern is that rising temperatures caused by burning fossil fuels makes holding shares of companies that produce oil, natural gas and coal more risky. The International Energy Agency says half of all known fossil-fuel reserves need to stay in the ground to prevent the planet from overheating.

“There is a legal risk that is coming,” Philippe Desfosses, chief executive officer of ERAFP, a pension fund for French civil servants, said at the climate event in Paris where the Axa CEO also appeared. “If there is a carbon risk for a business, how can CEOs of pension funds justify that they don’t give a damn and won’t mitigate it?”

AXA didn’t name the companies whose shares it would sell. It said it will divest mining companies that get more than 50 percent of their revenue from coal and electric utilities with more than half their energy from thermal coal plants.

Last year, AXA paid out 1 billion euros in weather-related insurance claims, putting climate risks at the heart of its strategy. Insurers including AXA, Munich Re and Swiss Re AG invest over long periods to cope with liabilities that may crystallize far in the future and have expressed concerns that rising temperatures will increase claims in the coming decades.

About 200 institutions with assets of more than $50 billion have said they’d scale back on investing in polluting industries, according to the environmental group 350.org led by Bill McKibben that’s at the heart of the divestment movement.

The campaign has given momentum to the three-decade-old effort to rein in greenhouse gases as the United Nations works this year to bring together more than 190 nations in a historic deal to limit emissions everywhere for the first time.

Investor Pressure

“Pension funds are saying they are very concerned about this,” Colin Melvin, chief executive officer of the biggest pension fund adviser, Hermes Equity Ownership Services Ltd., said in an interview. “They’re under pressure about climate from their beneficiaries. They recognize the world is warming and this will damage their own livelihoods and governments aren’t able to deal with it.”

Melvin, whose company has 40 funds in 10 countries managing $230 billion, said investors have already begun to weigh in on the climate debate.

At least 14 energy companies are facing shareholder resolutions on environmental and social policies this year, a the strongest action on record. More than 190 resolutions have been proposed this year, up 88 percent since 2011 when Ceres, a Boston-based coalition of investors with more than $13 trillion in assets, began collecting the data.

Exxon Mobil Corp., Royal Dutch Shell Plc., Total SA, Chevron Corp. and Eni SpA are among the major oil companies targeted, according to data compiled by Bloomberg.

‘Shining Light’

“The data tells us that investors are looking at less carbon intensive investments,” Jose Lopez, executive vice president responsible for operations at Nestle SA, said in an interview. “They are shining the light on some companies.”

Engie, formerly known as GDF Suez SA, and Electricite de France SA, two French utilities, faced questions about its their coal investments this year at annual shareholders’ meetings in Paris. French Finance Minister Michel Sapin said Friday they would be encouraged by the government, which has a substantial holding in each, to “reorientate” their investments away from new or existing “dirty” coal plants.

Failing to examine the climate impacts of some investments could be seen as negligence of the fiduciary responsibility of fund managers, Desfosses said.

To be sure, some executives said shareholders’ top priorities still aren’t the environment.

“Investors will first ask about earnings per share, ebitda and all that and when they are finished with that they will ask about environmental policy,” said Rudolf Staudigl, CEO of Wacker Chemie AG, a German chemical maker that supplies makers of solar cells with their chief raw material.

–With assistance from Caroline Connan and Javier Blas in London and Stefan Nicola in Berlin.