Britain’s Chancellor of the Exchequer Rishi Sunak holds up a green briefcase as he arrives for a speech at the COP26 U.N. Climate Summit in Glasgow, Scotland, on Wednesday. The British government plans to make the U.K. “the world’s first net-zero aligned financial center” as companies and investors seek to profit from the drive to build a low-carbon economy. Alberto Pezzali/Associated Press

GLASGOW, Scotland — Governments and big investors announced fresh plans Wednesday to pour trillions of dollars into curbing global warming, reflecting the financial world’s growing embrace of efforts to fight climate change as both a business necessity and opportunity.

But some social justice activists called for scrutiny of investors’ motives, warning that the same financial institutions that profited from funding fossil fuel firms were now being presented as green champions.

There is a growing consensus that the private sector must be involved if the world is to avoid catastrophic global warming. Speaking at the U.N. climate summit in the Scottish city of Glasgow, Britain’s treasury chief Rishi Sunak said that while countries such as his are stumping up more cash to fund the shift to low carbon economies around the world, “public investment alone isn’t enough.”

He praised a pledge Wednesday by a group of over 450 major financial institutions to align their investments with the 2015 Paris climate accord – which calls for reducing carbon dioxide emissions and other efforts to limit global warming to 1.5 degrees Celsius (2.7 Fahrenheit) above pre-industrial levels.

“This is a historic wall of capital for the net-zero transition around the world,” Sunak said at the conference known as COP26.

The Glasgow Financial Alliance for Net Zero – launched this year by former Bank of England chief Mark Carney – promised to follow scientific guidelines for cutting carbon emissions to “net zero” by 2050.

That goal – which means limiting greenhouse gas emissions to the amount that can be absorbed again through natural or artificial ways – is increasingly being embraced by companies and governments around the world.

Experts say fossil fuel use has to drop drastically over the coming decade to cap warming at 1.5C, meaning investors would likely have to dramatically cut back money going to oil, gas and coal producers.

“It is huge that financial institutions managing $130 trillion in assets are now leading the charge to a net-zero future,” said Helen Mountford, a senior climate expert at the World Resources Institute think tank.

She said that mobilizing massive public and private finance will be key to tackling global warming.

To that end, Sunak said U.K. financial institutions and publicly traded companies will be required to publish plans detailing how green their investments and their own businesses are – in order to ensure they’re actually contributing to reductions in global warming.

As home to the City of London, one of the world’s major financial centers, the U.K. “has a responsibility to lead the way” in financing efforts to fight global warming, said Sunak, potentially becoming “the world’s first net-zero aligned financial center.”

But James Thornton, founder of the environmental law charity ClientEarth, questioned how effective the U.K. effort would be.

“The U.K. market is still hooked on fossil fuels,” he said, calling for a task force to ensure companies don’t “greenwash” their activities – that is, using high-profile announcements of so-called green initiatives to mask other “dirty” activities. Experts also caution there are various ways to calculate net zero – and deciding on one standard definition is one of the big challenges going forward.

Some campaigners were distrustful of the motives of big investors in general.

“Many of the financial institutions meeting today have made a killing from the climate and ecological crisis, and we should be deeply suspicious of any attempt to spin them as the heroes,” said Dorothy Guerrero, head of policy at the nongovernmental group Global Justice Now. “Governments must regulate the process and lead the transition, instead of just handing it over the corporations.”

But Alok Sharma, the British official chairing the talks in Glasgow, insisted the shift was genuine.

“What we have seen over the last few years is a big move in the private sector and the financial services sector to go green,” he said, adding that this was not the case when he became a financial adviser in the 1990s. “I do believe it is now mainstream.”

U.S. Treasury Secretary Janet Yellen noted one of the reasons that may be the case: She described combatting climate change as both a huge financial challenge, with a price tag of $100 trillion, but also “the greatest economic opportunity of our time.”

“Many renewables are now cheaper than carbon-based fuel alternatives and have lower long-term operating costs,” she said. “In many cases, it’s simply cost effective to go green.”

President Biden issued an executive order earlier this year aimed at requiring companies to disclose climate-related financial risks.

Investing with an eye on the environment has been one of the biggest trends reshaping the financial industry for years, graduating from niche to a major force.

Around the world, $35.3 trillion was invested in sustainable funds at the start of 2020, according to the most recent data from the Global Sustainable Investment Alliance. That accounted for nearly $36 of every $100 invested under professional management, and it includes everything from funds that directly finance environmentally friendly projects to funds that simply refuse to buy shares of the most-polluting companies.

While that’s still the minority of all investments, it’s been growing faster than other areas of the market. Four years earlier, sustainable investments accounted for less than $28 of every $100.

But an analysis of the holdings of 130 climate-themed funds this summer by London-based think tank InfluenceMap found more than half weren’t as green as they purported to be. Some that were classified as “fossil fuel restricted” owned shares of oil refiners and distributors, for example.

Alina Averchenkova, an expert on climate change policy at the London School of Economics, said the announcements by investors and governments were an important step in the right direction – but independent audits would be required going forward.

She also noted the growing urgent need for rich nations to fund climate-related projects in parts of the world that can’t afford the measures themselves.

“We need finance to help developing countries to adapt to the impacts of climate change, for example, to adapt to increased flooding to extreme weather events such as hurricanes,” she said.

Poorer countries were angered last month by news that wealthy nations had failed to meet a previous commitment to provide them with $100 billion in climate finance each year by 2020.

That target is now expected to be met in 2023.