The U.S. climate bill signed into law this week restores the country's credibility as a leading player in U.N. climate negotiations, international officials said.

The $430 billion bill passed by President Joe Biden on Tuesday, after more than a year of tense negotiations, lays out policies and investments to curb greenhouse gas emissions in the world's largest historical emitter.

Research suggests the measures could result in reducing U.S. emissions to about 40% below 2005 levels by 2030 - not quite the 50% reduction Biden had pledged under last year's Glasgow Climate Pact.

Years of failed Congressional action had left climate-focused presidents reliant on executive actions, which can be easily undone by other presidents or by courts. This made other countries wary of U.S. emissions-reduction promises.

The new bill "puts America on track to achieve our climate goals and encourage others in the world to increase their efforts," said John Kerry, U.S. special envoy on climate change, on Twitter.

U.S. allies welcomed the milestone as a sign that the country is matching its often-ambitious climate rhetoric with action.

Bahamas Prime Minister Philip Davis said that both the United States and Australia, which passed its own climate change legislation earlier this month, had taken "historic" steps to address emissions even as global geopolitical and economic turmoil make some countries backslide on their climate goals.

"The world's wealthiest and most powerful countries generate 80% of global emissions. They can act - when they choose to," Davis said before the opening of a Caribbean climate summit on Tuesday.

Barbados Prime Minister Mia Mottley told reporters following the summit that she hopes the new U.S. law will help Americans understand the severity of climate impacts to come, including stronger hurricanes that threaten island nations like hers.

"The recognition of the issue is welcomed by us for sure," Mottley said.

From across the world on the Pacific island nation Fiji, which faces severe climate impacts including sea level rise, Prime Minister Frank Bainimarama said on Twitter that the law was a "win for the planet," even as he urged the United States to do more to account for its emissions over the last century.

"President Joe Biden's new climate law is the USA's most important show of solidarity to the Pacific since its re-entry to the Paris Agreement," Bainimarama said.

But China, currently the world's largest carbon emitter, cast doubt on whether the climate bill would help the United States achieve its greenhouse gas reduction goals.

China this month called off diplomatic discussions with the U.S. on climate change, halting what had been a rare instance of cooperation between the two economic powerhouses.

In an exchange on Twitter, the Chinese foreign ministry's official account questioned U.S. Ambassador to China Nicholas Burns for celebrating the bill's passage on Twitter and calling on China to follow with a law to reduce its emissions by 40% in less than 10 years.

"Good to hear. But what matters is: Can the U.S. deliver?" the ministry said.

China has resisted past calls to speed up its emissions reduction by arguing that the United States had no laws to carry out its climate promises.