"The disappointment concerns the fact that Russia ... and China de facto did not appear in terms of any obligations to deal with climate change," RIA Novosti quoted Biden as saying at a press conference in Rome following the results G20.
He also expressed confidence that significant progress has been made, "but more needs to be done."
Earlier, Russian Foreign Minister Sergei Lavrov spoke about a conversation with Biden on the sidelines of the G20 in Rome.