WASHINGTON -- The United States and China will sign the global climate agreement next month and intend to start putting it in place later this year, the White House said Thursday.

The international agreement was reached in December in Paris, but needs a critical mass of countries to sign on before the pact is in force. The White House says the U.S. and China hope that by joining soon, global action to reduce emissions can kick in well before the formal start date in 2020.

The United Nations has invited countries to sign the deal at a ceremony on April 22, the first day they can do so.

The U.S. has run into a major roadblock. In February, the Supreme Court put on hold President Barack Obama's emissions limits for power plants. Obama was counting on those cuts to meet the U.S. commitment under the deal.

Brian Deese, an Obama adviser, said the White House is confident the limits will be upheld in plenty of time. He said tax credits for wind and solar will help bridge the gap until the power plant emissions limit take effect.