Shareholder activists Just Share and environmental law organization ClientEarth have written to more than 50 funds in Africa’s most-industrialized nation about their duty to savers. The local industry oversees about 4.2 trillion rand ($300 billion) in retirement investments, according to the two groups.

Legal opinion commissioned by the campaigners shows that failing to meet the requirement on climate change “would likely amount to a breach of duty by the board of a pension fund,” they said in a joint statement Monday.

Oil companies and Norway’s sovereign wealth fund are responding to climate change through steps ranging from planting forests to divesting from fossil fuels. South Africa is dependent on coal for almost all of its power generation, and with unemployment at about 27 percent this complicates the debate about reducing this reliance, should it lead to mine closures and job losses.

The ultimate effects of climate change and the cost of transitioning to a low-carbon economy should form part of money managers’ investment strategies, Tracey Davies, executive director for Just Share, said by phone. “The primary reason is the fiduciary responsibility for the funds to invest in the long term.’’

South Africa’s 2030 energy plan sees coal-generated power dropping to less than 50 percent of the total, as investment increases in renewables such as wind and solar.

But, South African companies have been highlighting some of the potential costs. Anglo American Platinum Ltd., the world’s biggest producer of the metal, said April 9 that a planned carbon tax in the country will add cost pressures for marginal and loss-making operations.

Sasol Ltd., the biggest manufacturer of fuel from coal, wants to “be part of the solution” in terms of what South Africa agreed to in the Paris Accord, co-Chief Executive Officer Bongani Nqwababa said Friday in an interview. The company, which is held by a number of pension funds, plans to set its own emissions targets next year, he said.

Reaction from funds that responded to the campaigners’ questions ranged from interest in discussing the issue to asking whether they were being accused of doing something wrong, Davies said. The initial purpose of the letters was to raise awareness. “You’ve got to understand how exposed your portfolio is to climate policy.”