U.N. Secretary-General Ban Ki-moon announced Stoltenberg will replace former British Prime Minister Gordon Brown on the advisory group on climate change financing immediately.
"Prime Minister Stoltenberg will now work with the other co-chair, Prime Minister Meles Zenawi of Federal Democratic Republic of Ethiopia, to complete the work of the Advisory Group," said Ban in a weekend statement.
Ban activated the advisory group in February. The panel is tasked with drafting long- and short-term financing options to help developing countries adopt green-energy technology.
The advisory group is expected to issue its final recommendation before delegates meet for the U.N. Framework Convention on Climate Change conference scheduled to begin in November in Mexico.
Brown was co-chairman of the advisory group until May when he was defeated by Conservative leader David Cameron.