U.S. Secretary of State Hillary Rodham Clinton announced today that, if agreement is reached here this week, the United States will participate in a $100 billion fund to help developing countries most affected by climate change.

Jennifer Morgan, director, Climate and Energy Program, World Resources Institute:

"A serious climate deal will only be possible with the resources to provide humanitarian assistance to the most vulnerable, protect the world's forests and build a clean energy economy."

"The United States has joined other rich economies to signal a greater seriousness about helping developing countries and building a more solid international deal."

"Countries are going to be asking for more details, including how much public finance is involved; how much is really new; and how decisions around spending the money will be made."

"The world will need further clarification on the specifics of the announcements, particularly whether this money will be additional to current funding, but this is a solid first step."

"Financing was one of the missing pieces in Copenhagen. This announcement offers a more hopeful story about what can be achieved here."

Further details of the funding are still being discussed here as the conference wraps up by Saturday. On Wednesday, representatives from African countries, France and the U.K. negotiated with U.S. President Barack Obama on climate funding options. Today's announcement by Clinton builds on those talks.