COPENHAGEN — In a last-minute attempt to achieve a breakthrough at the U.N. climate summit in Copenhagen, Japan and the United States announced Wednesday and Thursday short- and long-term financial pledges for developing countries to mitigate the effects of climate change over the next three years and to adapt to the future effects of global warming by 2020.

The announcement of new aid packages came on the ninth and final day of formal negotiations on a deal for new emissions reduction targets for the post-2012 period, following the expiration of the first period of commitments under the Kyoto Protocol.

On Wednesday evening, Japan pledged ¥1.75 trillion ($15 billion) in public and private funding to help developing countries adjust to climate change between 2010-2012. The U.S. announced Thursday morning it would work to help provide developing countries with up to $100 billion annually through yet-to-be-determined financial mechanisms and incentives by 2020 for adaptation to future climate change.