DOHA, Qatar — When representatives of nearly 200 countries meet in Qatar for annual talks on slowing global warming starting Monday, one of the main challenges will be raising climate aid for poor countries at a time when budgets are strained by financial turmoil.

Rich countries have delivered nearly $30 billion in grants and loans promised in 2009, but those commitments expire this year. And a Green Climate Fund designed to channel up to $100 billion annually to poor countries has yet to begin operating.