Human life "as we know it" could be threatened by climate change, economists at JP Morgan have warned.
In a hard-hitting report to clients, the economists said that without action being taken there could be "catastrophic outcomes".
The bank said the research came from a team that was "wholly independent from the company as a whole".
Climate campaigners have previously criticised JP Morgan for its investments in fossil fuels.
The firm's stark report was sent to clients and seen by BBC News.
While JP Morgan economists have warned about unpredictability in climate change before, the language used in the new report was very forceful.
"We cannot rule out catastrophic outcomes where human life as we know it is threatened," JP Morgan economists David Mackie and Jessica Murray said.
Carbon emissions in the coming decades "will continue to affect the climate for centuries to come in a way that is likely to be irreversible," they said, adding that climate change action should be motivated "by the likelihood of extreme events".
Climate change could affect economic growth, shares, health, and how long people live, they said.
It could put stresses on water, cause famine, and cause people to be displaced or migrate. Climate change could also cause political stress, conflict, and it could hit biodiversity and species survival, the report warned.
To mitigate climate change net carbon emissions need to be cut to zero by 2050. To do this, there needed to be a global tax on carbon, the report authors said.
But they said that "this is not going to happen anytime soon".
Developed countries were worried that cutting emissions would affect competitiveness and jobs, while less developed countries "see carbon intensive activity as a way of raising living standards."
"It is a global problem but no global solution is in sight," the report added.
The bank has warned about climate change before, although not in such strong and sweeping terms as its economists.
In March 2019 Bloomberg reported that an executive had warned that the US needed to significantly cut its carbon footprint, and in May of that year iJP Morgan called climate change a "global challenge" that presents risks for business.
Large organisations such as JP Morgan face a challenge in that inaction on climate change could have a huge hit on revenues - but so could taking action.
JP Morgan itself has been strongly criticised in the past for heavy investment in fossil fuels.
The Rainforest Action Network released a 2019 report claiming that the US banking giant provided the most fossil fuel firm financing of any bank in from 2016 to 2018.
Rupert Read, an associate professor of philosophy at the University of East Anglia, and a spokesperson for campaign group Extinction Rebellion, said that the bank is "taken by some to be the largest fossil fuel funder in the world."
He said if the bank's own researchers were "saying the very future of the human race is at stake" then the bank itself should change its direction.
"It's good they [the researchers] are telling the truth more - it's not good they [the bank] remain a strong funder of fossil fuels," he said.
"Everyone has to have responsibility for change, whether they are asset managers, or institutional investors, or chief executives, or shareholders," he added.
A JP Morgan spokesperson said the research team's view was "wholly independent from the company as a whole, and not a commentary on it" and declined to comment further.
Mark Cutifani, chief executive of mining giant Anglo American, told the BBC how the firm wants to reduce its carbon footprint, and ''can see a pathway to creating carbon neutral mines''.
Talking about a timeframe he added: "We are a bit concerned about putting a date on it as yet because some of the technologies are still evolving. We will get there, the only question is how quickly we can get there.''