WASHINGTON • US Democrats have agreed to include a tax on carbon-intensive imports from nations that lack aggressive climate change policies as part of a sweeping US$3.5 trillion (S$4.75 trillion) budget plan stocked with other provisions aimed at ratcheting down fossil fuel pollution in the country.

The move to tax imports was made public on Wednesday, the same day that the European Union outlined its own proposal for a similar carbon border tax, a novel tool that is designed to protect domestic manufacturing while simultaneously pressuring other countries to reduce the emissions that are warming the planet.

The two actions in concert suggest that government leaders are turning towards trade policy as a way to attack climate change.

Top Democrats called the timing coincidental but said both the US and Europe must work together to put pressure on China and other heavy-polluting countries to reduce emissions.

"The United States and the EU have to think in terms of the leadership we can provide and the message we have to send to China and other countries that would take advantage of the high standards that we are going to enact," Senator Edward Markey said.

Unlike the Europeans, who outlined their plan in a 291-page document, Democrats released no details about their proposal, calling it simply a "polluter import fee".

The framework does not explain what would be taxed, at what rate or how much revenue it would expect to generate. But in theory, a carbon border tax would require companies that want to sell steel, iron and other goods to the US to pay a price for every tonne of carbon dioxide that is emitted during their manufacturing processes. If countries cannot or will not do that, the US could impose its own price. But verifying the amount of carbon pollution produced by foreign manufacturing is tricky, experts say.

NYTIMES