California released an ambitious plan to cut its output of heat-trapping greenhouse-gas emissions on Jan. 20, the same day that the newly minted Trump administration signaled it will undo federal carbon regulations.

California's plan details how it will achieve its goal of cutting emissions 40% below 1990 levels by 2030, which state air regulators called the most ambitious target in North America.

The plan includes an extension of the state's controversial carbon cap-and-trade program and calls for the state's oil refineries to cut their greenhouse-gas emissions by 20%.

"Climate change is impacting California now, and we need to continue to take bold and effective action to address it head-on to protect and improve the quality of life in California," said CARB chair Mary Nichols, who called the plan's target the most ambitious one of its kind in North America.

California's aggressive move to tackle the issue of global warming stands in stark contrast to President Donald Trump, who has cast doubt on the degree to which human activity causes climate change.

The Trump administration on Jan. 20 removed all mentions of climate change from the White House website and said it would eliminate the Climate Action Plan, which seeks to cut emissions in part by preserving forests and encouraging increased use of cleaner renewable fuels.

The battle over climate change policy between California, the nation's most populous state, and the Trump administration will likely include a fight over the state's decades-old authority to set limits on emissions.

During a congressional hearing on Jan. 17, Scott Pruitt, Trump's nominee for Secretary of the Environmental Protection Agency, would not commit to allowing the state to set more stringent emissions standards for vehicles through a federal waiver.

"Administrators in the past have not granted the waiver and have granted the waiver. That is a review process that will be conducted," he said.