Some of the world’s largest financial institutions have stopped putting their money behind oil production in the Canadian province of Alberta, home to one of the world’s most extensive, and also dirtiest, oil reserves.

In December, insurance giant The Hartford said it would stop insuring or investing in oil production in the province, just weeks after Sweden’s central bank said it would stop holding Alberta’s bonds. And Wednesday, BlackRock, the world’s largest asset manager, said that one of its fast-growing green-oriented funds would stop investing in companies that get revenue from the Alberta oil sands.

They are the latest in a flood of banks, pension funds, and global investment houses starting to pull away from fossil-fuel investments amid growing pressure to show they are doing something to fight climate change.

“If you look at how destructive oil sands can be, there’s a very strong rationale,’’ Armando Senra, head of BlackRock’s iShares Americas funds, said in an interview, saying that Alberta’s oil fields, along with coal, are “the worst offenders, if you want, from a climate perspective.’’

In a sign of the potential power of the financial industry to influence climate policy, Alberta is fighting back hard.

In April, voters elected a provincial leader who promised to punish companies that stopped financing the oil sands. Then, in December, Alberta opened what it called a war room to attack anyone perceived as criticizing the industry.

“We have been targeted by a foreign-funded campaign of special interests,’’ Alberta’s premier, Jason Kenney, said after winning office last year. “When multinational companies like HSBC boycott Alberta, we’ll boycott them.’’ HSBC, the largest bank in Europe, has said it will stop financing new oil sands developments.

Alberta officials didn’t immediately respond to questions about BlackRock’s announcement Wednesday.

The brawl over billions of dollars in lending and investment, while centered on Alberta’s oil sands, shows the potential power of the financial industry to speed the shift to cleaner energy sources, even as the world’s governments fail in their pledges to cut greenhouse gas emissions. It also shows how quickly financial-industry pressure can instill a degree of political panic.

But financial institutions worldwide are coming under growing pressure from shareholders to pull money from high-emitting industries. At the same time they are waking up to the fact that they have underestimated the climate-change risk in their portfolios.

Oil has made Alberta one of the wealthiest regions in North America, but the process of extracting petroleum from oil sands releases an unusually large volume of greenhouse gases. Because Alberta’s oil is locked in geological formations that make it particularly energy-intensive (and therefore environmentally damaging) to extract, it has provided an easy early target for investors eager to make a statement.

The oil sands have long been a target of environmentalists’ ire. But in 2017, the campaign against them shifted to the world of finance. That summer, the largest pension fund in Sweden, AP7, said it had divested from TransCanada, the company building Keystone XL, a pipeline to carry crude from the oil sands to the United States.

Other international lenders followed, announcing they would divest not only from pipelines but from oil-sands extraction projects as well.

It wasn’t just financing that suddenly seemed at risk. Some of the world’s largest insurance companies, including AXA, Swiss RE, and Zurich Insurance, announced they would stop providing coverage to projects in the oil sands.

In response to that pressure, Alberta has only increased its support of the oil sands.

Kenney, Alberta’s premier, has publicly vilified investors that left, complaining that some of those same investors also finance oil production in countries such as Iran and Saudi Arabia, which have lower greenhouse gas emissions per barrel but far worse human-rights records.