The U.S. Supreme Court dealt a blow to President Joe Biden’s plans to tackle climate change on Thursday with a ruling that limits the powers of the nation’s top environmental regulator to accelerate the shift to cleaner energy sources.

The conservative court's 6-3 ruling restricted the Environmental Protection Agency's authority to regulate greenhouse gas emissions from existing coal- and gas-fired power plants under the Clean Air Act anti-pollution law.

The ruling was based on what is called the "major questions" legal doctrine, which requires explicit congressional authorization for action on issues of broad importance and societal impact.

“The EPA has entered a newly inhospitable era for regulatory action,” said Leif Fredrickson of the Environmental Data and Governance Initiative, an organization that tracks environmental agencies.

'PRESIDENT BIDEN WILL NOT RELENT'

“While the Court’s decision risks damaging our ability to keep our air clean and combat climate change, President Biden will not relent in using the authorities that he has under law to protect public health and tackle the climate change crisis,” said White House spokesman Abdullah Hasan.

Biden, a Democrat, came into office with the aim of slashing power sector emissions to net zero by 2035. Biden's EPA is currently working on a new proposal to tackle power plant emissions, which is expected to come out next spring.

There are currently no regulations in force to reduce carbon emissions from power plants, source of about a quarter of the nation’s greenhouse gases. The Obama-era Clean Power Plan was blocked by the Supreme Court in 2016 and a narrower replacement crafted by Republican former President Donald Trump's administration was struck down by a federal appeals court in 2021.

Carbon emissions from the sector have dropped in recent years as coal-fired power plants have been retired and replaced by cleaner-burning natural gas plants, and renewable sources like wind and solar. But without regulation, the outlook for further coal retirements remains uncertain.

"This is a lifeline to extending the use of coal," wrote Harvard environmental and administrative law professor Jody Freeman. "The shift to clean energy may happen more slowly as a result of the Court protecting the industry via this ruling."

In the absence of direct regulation, the Biden administration’s options to tackle power industry emissions include pursuing legislation in Congress - a tough proposition given its partisan divisions - or regulating greenhouse gases indirectly as a co-benefit of other air pollutant or water rules - a step that could face stiff legal challenges.

"The overall importance of the case is clear. EPA and other agencies need explicit authorization to proceed in addressing major questions that have profound effects on the economy," said Jeff Holmstead, a former assistant EPA administrator for air and radiation and partner at law firm Bracewell.

Eric Schaeffer, executive director of the Environmental Integrity Project and former EPA enforcement chief, said the Supreme Court decision will force “EPA back to drawing board.”

He said the agency could end up seeking to target power plants with tough standards for other pollutants, requiring expensive retrofits that could hasten the closure of old coal plants.

The decision does leave the EPA authority to mandate specific levels of "emissions limitation."

INTERNATIONAL CREDIBILITY

The United States, behind only China in greenhouse gas emissions, is a pivotal player in global efforts to combat climate change.

But without a clear plan to tackle emissions from the power sector, the Biden administration could face a credibility crisis on the global stage as it seeks to rally international ambition to fight global warming.

Biden's climate credentials have already been hit in recent months as his administration seeks to expand exports of liquefied natural gas to help Europe cut its dependence on Russian supply, and calls on the oil industry to pump up production to ease soaring consumer energy costs.

"U.S failure to deliver on its emissions reductions target will only worsen the pressures caused by the softening stance on fossil fuels,” said Yamide Dagnet, director of climate justice at Open Society Foundations, and former climate negotiator for the UK and EU.

Karen Sokol, a law professor at Loyola University New Orleans, agreed: “The agency is going to have to work around and dance around hitting carbon head-on, which is really the only meaningful way to respond to the climate crisis."

The EPA said in a statement that it was reviewing the Supreme Court decision.