(CNN) The Supreme Court on Thursday dealt a major blow to climate action by handcuffing the Environmental Protection Agency's ability to regulate planet-warming emissions from the country's power plants, just as scientists warn the world is running out of time to get the climate crisis under control.
It is a major loss for not only the Biden administration's climate goals, but it also calls into question the future of federal-level climate action and puts even more pressure on Congress to act to reduce emissions.
Experts tell CNN it could set the US back years on its path to rein in the climate crisis and its deadly, costly impacts.
The opinion makes it "more difficult to achieve larger-scale emissions reductions," Andres Restrepo, senior attorney for the Sierra Club's Environmental Law Program, told CNN. "To avoid the worst impacts of climate change we need to do a lot more and move a lot faster. That's why today's ruling is such a setback."
At the heart of Thursday's opinion was a question over the EPA's authority to regulate planet-warming emissions from power plants, which are a huge contributor to the climate crisis.
Around 25% of planet-warming greenhouse gas emissions around the globe and in the US come from generating electricity, according to the EPA. And coal, the dirtiest fossil fuel, powers about 20% of US electricity. Emissions from power production rose last year for the first time since 2014, an increase that was mainly driven by coal use.
The surge in fossil fuel use is worrying not only for Biden's climate goals -- the President, in his first months in office, pledged to slash US emissions in half by 2030 -- but also the planet.
"Failing to regulate heat-trapping emissions will harm people and ecosystems worldwide," said Kristina Dahl, a senior climate scientist with the Union of Concerned Scientists. "We're already dangerously behind what the science shows is necessary, and the court's majority has made solving the problem much more difficult."
Scientists have become increasingly urgent in their warnings that to make headway on the climate crisis, emissions need to not only be reduced going forward, but the world needs to develop ways to also remove the greenhouse gas that's been pumped into the atmosphere in decades past.
In a landmark report last year, scientists reported that the planet is warming faster than they had previously imagined it would. As it does, they said, extreme weather will become more deadly; water crises will develop and worsen; food insecurity will grow and disease will spread.
To avoid the worst consequences, the world must limit global warming to 1.5 degrees Celsius (it's already passed 1.1 degrees), and the only way to do that is to keep the vast majority of the Earth's remaining fossil fuel stores in the ground.
The Supreme Court said the Clean Air Act does not give EPA broad authority to regulate planet-warming emissions from power plants. The agency still has options to regulate emissions, but the court said that the law does not empower the agency to put a limit on emissions and force power plants to move away from fossil fuels and toward renewable energy.
"The one thing EPA won't be able to do is what the Clean Power Plan did," Richard Revesz, an environmental law expert at NYU School of Law told CNN.
The Clean Power Plan was an Obama-era rule that set a goal for each state to limit carbon emissions, while letting those states determine how to meet those goals. In many cases, ditching coal and natural gas in favor of solar and wind was the most economically viable solution.
Shifting from fossil fuels to renewables "is the most effective, efficient and lowest cost way of reducing greenhouse emissions from fossil fuel-fired power plants," Restrepo said. "By taking that tool off the table, the court has removed EPA's most effective tool for controlling greenhouse gas pollution from existing power plants."
Environmental attorneys are digesting the Supreme Court's opinion and determining how the agency could act on climate change going forward.
"This may be about as bad as it could be in terms of limiting EPA's regulatory authorities," Revesz said. "This case by its nature provides significant constraints EPA's authority to regulate the power sector — but not other sectors of the economy" like transportation or industrial emissions.
Revesz said the EPA will now have to consider what action it can take within the confines of the ruling.
"For example, it might consider carbon capture and sequestration and see whether the costs are ones that are reasonable," Revesz told CNN.
Carbon capture and sequestration is where the carbon is scrubbed out of power plant emissions before it enters the atmosphere. It's an expensive technology and scientists have warned that it's not on its own a significant enough solution to power plant emissions.
Kirti Datla, an attorney for Earthjustice, a nonprofit focused on litigating climate issues, said this case paves the way for Republican-led states and fossil fuel companies to challenge current and future EPA rules on planet-warming emissions.
"I think the biggest takeaway is that the court produced an opinion that did exactly what the challengers [GOP-led states and coal companies] wanted," Datla said.
In its opinion, the court cut back agency authority by invoking the Major Questions Doctrine -- a ruling that will impact the federal government's authority to regulate in other areas of climate policy, as well as regulation of the internet and worker safety. It says that the biggest issues should be decided by Congress itself, not agencies like the EPA.
"Prior to today, the court would look at [an agency] and say 'this decision is within your lane and expertise and we're going to defer to your technical decision here,'" said Jay Duffy, an attorney and expert on power plant emissions at the Clean Air Task Force. "Today, unless the actual rule you have chosen has been clearly authorized by the Congress, you don't have the authority to do it."
Duffy said that as agencies craft new rules, they will have to go back to Congress to get explicit authorization, assuming the court deems it important.
"It's surprisingly unprincipled," Duffy said. "It's a can of worms that has been opened and without much guidance as to how important is important. How major is major? I think it could create a lot of problems."
Carrie Jenks, the executive director of Harvard Law School's Environmental & Energy Law Program, shared Duffy's concern about the uncertain definition of a "major question."
"The court is saying you can't do big things without Congress speaking, so what is a big thing?" Jenks told CNN. "This doctrine is just starting to emerge from the court. This doctrine is starting to be more defined. I think they will continue to use Major Questions Doctrine to oppose EPA rulemakings."
The court in its opinion did not touch EPA's ability to regulate other sources of greenhouse gas emissions -- for example from vehicles, or methane emissions from oil and gas. But cases on those issues are already circulating in the lower courts and could eventually be elevated to the Supreme Court.
"This [Major Questions] Doctrine is just starting to emerge from the court; this doctrine is starting to be more defined," Jenks told CNN. "I think they will continue to use Major Questions Doctrine to oppose [future] EPA rulemakings."
The Biden administration must now craft a regulation for power plant emissions that will fit within the confines of the Supreme Court's opinion.
Spokespeople for the White House and EPA said in statements they were reviewing the court's opinion and would work to move forward with a rule dealing with power plant emissions. The EPA has publicly committed that rule by March 2024, though it could move faster.
"While I am deeply disappointed by the Supreme Court's decision, we are committed to using the full scope of EPA's authorities to protect communities and reduce the pollution that is driving climate change," EPA administrator Michael S. Regan said in a statement. "We will move forward to provide certainty and transparency for the energy sector, which will support the industry's ongoing efforts to grow our clean energy economy."
Regan has previously said that the EPA will work on a strategy to combat other environmental pollutants coming from power plants, including cutting sulfur dioxide, nitrogen oxides, and coal ash waste from coal-fired power plants.
Even though those regulations deal with environmental pollution from power plants, they also have the effect of cutting greenhouse gas emissions.
"Our lawyers will study the ruling carefully and we will find ways to move forward under federal law," a White House spokesperson said. An EPA spokesperson added the agency is still "committed to using the full scope of its existing authorities."
Practically, the court's ruling says the EPA can't write rules similar to the Obama-era Clean Power Plan. But it didn't explicitly say how EPA should regulate going forward, environmental law experts noted.
"The court is clear that the Clean Power Plan went too far, the court is much less clear on what EPA can do going forward," Datla said. "Everything in the opinion is going to be used as ammunition by groups that want to challenge what the Biden administration does next, but that doesn't mean the opinion doesn't leave room for EPA to act and hopefully it acts with some speed."
Datla added that EPA still has the ability to carefully look at the statute and "issue a regulation that tries to address this really huge source of emissions for this incredibly pressing problem."