MADRID – More than 600 institutional investors managing a whopping $37 trillion in client assets called Monday for governments to step up their efforts against climate change.

The investors, including banks, pension funds and insurance companies, directed their message to countries participating in a two-week U.N. climate conference in Madrid.

Firms such as Britain’s Aviva, the California Public Employees’ Retirement System and Zurich Insurance Group demanded an end to thermal coal power plants worldwide, the introduction of a “meaningful” price on carbon, an end to fossil fuel subsidies and for governments to increase planned emissions cuts beyond what has already been pledged.

Similar appeals have been issued by investment companies before, but Monday’s is the biggest so far. The 631 companies involved held assets worth more than the GDP of the United States and China together last year.

Separately, a financial research group said major companies themselves can significantly cut emissions of planet-warming greenhouses gases by making their suppliers switch to renewable energy.

The London-based nonprofit group CDP said it analyzed data from thousands of firms that supply big corporations such as Walmart, Samsung and L’Oreal, concluding that shifting a fifth of their energy purchases to renewable sources like wind or solar could reduce emissions by 1 gigaton of carbon dioxide – or about the combined amount released by Brazil and Mexico in 2017.