Citigroup, Inc. (NYSE: C) unveiled a $50 billion initiative on Tuesday to address global climate change by supporting the commercialization and growth of alternative energy and clean technology.

Citigoup says it will use investment, financings and related activities for the goal, including $10 billion in activities the bank has already undertaken.

The comprehensive program we are announcing today is not a wish-list, but a realistic, achievable plan that serves a critical global need and responds to an emerging investment opportunity, said Citigroup Chairman and CEO Charles Prince in a statement.

The announcement comes as global firms are under increasing pressure to invest in environmentally friendly companies. Banking rival Bank of America announced a similar bid in March worth $20 billion over 10 years.

Citigroup cited its involvement in the development of best practices for social and environmental risks in project finance through the Equator Principles.

The company adds that it will boost its spending to $10 billion, from the current $1 billion, to reduce its own greenhouse gas emissions throughout its global facilities by 10 percent by 2011.

The company also said that its Markets & Banking group plans to invest or finance over $31 billion in new and existing business over the next ten years in clean energy and alternative technology.

From June 5-6, Citigroup plans to bring together investors and leaders from the corporate, political, regulatory and advisory fields to discuss the issue.