HSBC is setting aside $100m (£50m) for an initiative to tackle climate change.
More than 400 million people reliant on major rivers are under threat
The funding by the UK's largest bank will help charities and environmental groups to research some of the global causes and effects of climate change.
The partnership will look at ways to protect the world's most important rivers and identify how cities can respond to environmental threats.
HSBC also said it would create "a green taskforce", to ensure climate awareness was central to its own business.
HSBC is the latest UK company to pledge changes to the way it operates in the face of calls for big business to do more to prioritise environmental concerns.
HSBC is teaming up with climate campaigners the Climate Group, environmental groups the Earthwatch Institute and the Smithsonian Tropical Research Institute (STRI), and the conservation charity WWF in a five-year partnership
HSBC, which will spend $5m of the $100m on managing the project, said it would enable the four bodies to expand their climate-related research and undertake work in new countries such as China and India.
Priorities include conducting research into the impact of climate change on the world's largest forests and improving management of freshwater systems to increase water security.
Climate Group: $17m
Earthwatch Institute: $35m
"By working with four of the world's most respected environmental organisations, we believe we can tackle the causes and impacts of climate change," said Stephen Green, HSBC chairman.
The Climate Group said its funding would be used to speed up action against global warming in five of the world's most polluted cities - London, New York, Hong Kong, Mumbai and Shanghai.
"Many of the solutions lie in cities," said its chief executive Steve Howard.
"We have a short period of time left to take action."
The partnership is modelled on a previous five-year, HSBC-funded environmental campaign, which ended last year.
This $50m initiative helped save 12,000 plant species from extinction, according to the firm.
In conjunction with the donation, HSBC has launched an internal plan to educate its workers on the issues of climate change, at an estimated further cost of $8m.
An online module about global warming has been launched and is accessible to the firm's 312,000 employees.
"Over the next five years HSBC will make responding to climate change central to our business operations and at the heart of the way we work with our clients," said Mr Green.
However, the initiative does not mark a change in the bank's lending policies.
Mr Green said pulling out of "sensitive" sectors, including mining, chemicals, energy, forestry and energy, "would not be the right decision".
The firm declared itself carbon neutral in 2005, mainly by investing in offsetting schemes.
HSBC saw its own emissions rise by 23% in 2006, largely due to acquisitions, explained Jon Williams, head of group sustainable development.