Even if President-elect Joe Biden can reassemble the pieces of climate policy shattered by President Donald Trump, it is not likely to be adequate to tackle the challenge of global warming, which has grown substantially after four years of inaction.

Biden faces science that paints a more alarming picture than it did four years ago and federal courts that, with Trump appointees, will be more skeptical of presidential power to act than when President Barack Obama put in place the first U.S. regulations to cut greenhouse gas emissions. 

For Biden to bring the United States back into the Paris climate accord and achieve his ambitious goal of setting the United States on path to net-zero carbon emissions by mid-century, his team will have to attain deeper cuts in pollution than Obama sought, while having to work harder to bulletproof their actions against legal challenge.

The Trump administration has rolled back more than 100 environmental regulations in the last four years—including rules on offshore drilling, management of water pollution at coal power plants, monitoring air pollution at oil refineries, and permits for pipeline construction.

“President Biden will have his work cut out for him to reverse the damage done,” said Dan Lashof, U.S. director of the World Resources Institute. “To be successful, he’s going to need to focus on a smaller number of very high-impact actions.”

Climate policy experts say they expect Biden’s team to focus on five Trump rollbacks in particular that have set back the nation’s progress in cutting emissions: rollbacks on clean cars, clean power, climate super-pollutants, methane leaks from oil and gas operations and gas from landfills. Taken together, those will result in the release of at least an additional 1.8 billion to 2.1 billion metric tons of greenhouse gases into the atmosphere by 2035 if they are not reversed, according to a recent analysis by the consulting firm, The Rhodium Group. That’s equivalent to more than one year’s emissions from Russia.

The Trump administration currently is in court facing multiple legal challenges over all five deregulatory actions—cases that the Biden administration now will inherit, and almost certainly will ask the courts to hold in abeyance while it reviews and revises the regulations. (The Trump administration did exactly that with litigation over the Obama rules when it took over in January 2017.)

Although the Biden administration will want to move quickly, there are few viable shortcuts in the process of writing new regulations, a process that can take two to three years. In fact, the Trump administration faced numerous setbacks in the courts, mainly because it did not adequately justify its actions or skipped the needed notice and comment procedures. The Institute for Policy Integrity at New York University Law School tallied some 80 adverse rulings for the Trump administration in lawsuits over its weakening of environmental rules. 

“Whether you’re building the building up, or you’re tearing the building down, or rebuilding it up again, you have to go through the same steps,” said David Doniger, director of the climate and clean energy program at the Natural Resources Defense Council, an environmental group that has led many of the legal challenges of Trump’s regulatory rollbacks.

Some had hoped that Biden would be able to rely on Congress to help repeal some of the Trump deregulatory actions. Using a Newt Gingrich-era law called the Congressional Review Act, Congress repealed 17 Obama administration rules after Trump took office.

But unless the Democrats gain control of the Senate by winning Georgia’s two runoff races in January, the party will not be able to bring such measures to the floor without the approval of Republican Senate Majority Leader Mitch McConnell. 

Still, Doniger believes that Biden has an advantage that Obama lacked when he embarked on climate policy—a groundswell of public support and attention. Climate change was a focus throughout the 2020 campaign, with Biden repeatedly framing it as one of the four great crises he faces, along with the coronavirus, the economy and racial justice.

“We have enormous challenges ahead of us, but we have a new opportunity for forward motion, and for action and for hope,” Doniger said.

Even those who believe that Biden’s authority to use the regulatory process on climate is limited think the atmosphere is favorable for progress. Jeff Holmstead, a partner in the law and lobbying firm Bracewell, who represents industry clients on clean air matters, argues that, even with a Republican-led Senate, the Biden White House should make its case to Congress instead of relying too heavily on new regulations. “There are many people in the business community who would like to see climate legislation,” Holmstead said. “They would like the business certainty.”

Here are the big climate regulations that environmental law experts believe will be high on the Biden team’s agenda, as well as the challenges they will face.

Clean Cars

Biden talked about his vision for an electric vehicle future in a campaign ad that featured his vintage 1967 Corvette Stingray, a wedding gift from his father, a car salesman. The message: He is seeking a transformational move away from the internal combustion engine that doesn’t leave behind the American love of the automobile.

Biden will have a chance early on to show if he can bring the auto industry aboard. One of the highest priority items for his climate agenda will be to undo the largest of the Trump administration’s regulatory rollbacks—eliminating the Obama program to boost the fuel economy of cars and SUVs to 54.5 miles per gallon by Model Year 2025. 

The Trump plan, which ratcheted down the goal to 40 mpg by 2026—a mark automakers were expected to hit with or without a rule—has the potential to release 1 gigaton of additional greenhouse gas pollution into the atmosphere by 2035, according to the consulting firm, the Rhodium Group. That’s close to one year’s emissions from Japan, and equal to the impact of the four other big climate rollbacks put together.

Biden can’t tackle climate without action on passenger vehicles, which have driven transportation to surpass electric power as the No. 1 source of greenhouse gas emissions.

A key will be California, which has for 50 years had the leeway to set its own tough standards under the Clean Air Act, because it acted on pollution before the rest of the nation. As part of its rollback, Trump revoked California’s authority to act on greenhouse gas emissions. The result has been exactly what the carmakers said they didn’t want: the uncertainty of litigation, with 14 states supporting California’s battle against the Trump administration. 

There’s already one compromise solution that might provide a template for Biden. Five automakers (Ford, Honda, BMW, Volkswagen and Volvo), accounting for 30 percent of the U.S. market, have cut a deal with California, agreeing to improve fuel economy from 38 mpg today to 51 mpg by 2026, a slightly less ambitious timetable than the Obama plan.

“That may well become the foundation for a new federal regulation,” said Michael Gerrard, founder and faculty director of the Sabin Center for Climate Change Law at Columbia University. The result would be the kind of nationwide uniform standard that carmakers had under the Obama plan, and that all agree they prefer. The trick will be mapping out a U.S. auto future beyond 2026; California Gov. Gavin Newsom in September pledged to ban all sales of gasoline-powered vehicles in the state by 2035.

General Motors, the largest carmaker and manufacturer of Biden’s beloved Corvette, has not signed on to the California deal. Like the other American carmakers, General Motors is dependent on sales of highly profitable, gas guzzling pick-up trucks and large SUVs. But it recently has sent signals in sync with the Biden plan, announcing a $2.2 billion investment in EV production in the United States, with factories in Michigan and Tennessee. GM also rolled out an all-electric Hummer that will be available next year. 

“As soon as soon as it became apparent that Biden was going to win the election, that was a signal to all the automobile manufacturers that these new, stricter standards are coming,” said Gerrard. “And I don’t think that they’re waiting for the conclusion of the rulemaking process. That work is probably already underway.”

In addition to regulation, Biden plans other moves to hasten an EV transition, including consumer incentives or rebates, the deployment of 500,000 charging stations across the United States and federal fleet purchases of electric vehicles.

Clean Power And Beyond?

One of the toughest legal strategy challenges the Biden administration will face in addressing climate change is what to do about electric power plants and other industrial sources of greenhouse gases. Obama’s signature climate policy, the Clean Power Plan, was never implemented because of a stay issued by Supreme Court Justice Antonin Scalia days before his death in 2016. 

And last year, the Trump administration put in place a weak replacement, the Affordable Clean Energy rule, which would reduce carbon emissions less than 1 percent when fully implemented in 2030. Even though half the states are on track to meet their goals under the Obama plan anyway, the rollback could mean 241 million metric additional tons of  greenhouse gas in the atmosphere by 2035, according to Rhodium.

The Trump administration, supported by some industry groups and coal-dependent states led by  West Virginia, has maintained that the Environmental Protection Agency had no authority to put in place a sweeping program like the Clean Power Plan. 

Under the Obama administration, the EPA treated electric power plants as part of an interconnected system, and gave states the flexibility to allow utilities to meet pollution reduction goals by switching the power plants they relied on, moving from coal to natural gas and renewable energy. But the Trump administration argued that the Clean Air Act only gave EPA authority to require efficiency improvements within each individual power plant.

Even with the Trump administration gone, any attempt by the Biden team to simply reinstate the Obama approach will meet with a legal challenge from industry and from some states, which are  confident that the Supreme Court, as now remade by Trump, will see things their way. 

“The Clean Air Act contains very circumscribed regulatory programs that the EPA can use when it comes to industrial sources, including power plants,” said Holmstead, who served as a top official in President George W. Bush’s EPA. “All they can do is require existing facilities to improve their operations or to install emission controls. And neither of those things is going to accomplish very much in terms of reducing CO2 emissions.”

Although Biden’s environmental law advisers disagree with that legal interpretation, the team is looking for ways to make progress without getting mired for years in a legal battle. Some legal scholars have proposed that the administration consider shifting to the use of another provision of the Clean Air Act: one that gives the EPA power to require states to address emissions that contribute to air pollution that endangers public health or welfare in other countries, as long as those countries provide reciprocal protections. Another approach would be to focus on tightening the U.S. air quality standards for other pollutants from burning fossil fuels—like smog-causing pollutants and particulate matter—which would have the effect of reducing carbon emissions.

Doniger said that approach might especially make sense for the Biden administration, which will be trying to meet environmental justice goals at the same time as it tackles climate change.

“This is hard, but worth doing,” said Doniger. “You would envision that the Biden EPA would not only focus on power plant carbon but power plant emissions of other pollutants that especially burden people living in those communities which are over-polluted.”

To meet Biden’s goal of carbon-free electricity by 2035, whatever plan his team develops will have to go well beyond the Obama Clean Power Plan, which sought a 32 percent drop in carbon emissions by 2030. And the Biden administration can be expected to begin looking at regulating greenhouse gas emissions from industrial facilities beyond power plants, analysts say.

“Refineries, cement plants, other facilities—their greenhouse gas emissions are not being regulated,” said Richard Revesz, director of the Institute for Policy Integrity at New York University Law School. “In order to meet his ambitious goals, he’ll have to look at the potential for reductions economy-wide. And I assume that other significant categories of polluters will come under the EPA’s regulatory reach. Strengthening, extending and regulating new areas will have to be undertaken.” 

Methane From Oil and Gas

The Biden administration should have at least some industry support in its effort to restore the Obama administration regulation on methane emissions from oil and gas operations. 

Some leading oil and gas companies opposed the Trump administration’s rollback of the rules. Detecting and capturing methane, the main component of natural gas, is something the companies know how to do, and they would prefer a level playing field, where all companies are doing their part. The methane that they capture is natural gas that can be sold, although the payback for the investment in controls may be slow with natural gas prices low. The largest industry group, the American Petroleum Institute, supported Trump’s loosening of the regulations.

Because methane is 86 times more potent in warming the atmosphere over a 20-year period than carbon dioxide, the Biden administration will be able to make large progress in a short time by acting on the super-pollutant. And there is new outside pressure to do so: The European Union is working toward adopting a methane strategy that may result in tariffs or border adjustments on the United States if the nation leaves methane from oil and gas unregulated.

Expect the Biden administration to do more than reinstate the Obama rules, which only covered new oil and gas operations. In order to get a handle on methane from the oil and gas industry, the EPA will have to tackle the much larger problem of methane leaking from existing operations. “That’s where the big reduction potentials are,” said Revesz.

One of the first steps the Trump EPA took was to halt an effort begun under the Obama administration to gather information and measure just how large the methane problem from existing facilities was. Recent studies, using state-of-the-art monitoring techniques, have indicated that methane releases from the industry are twice as high as the federal government previously estimated.

Climate Super-Pollutants

Earlier this year, the Trump administration repealed rules designed to curb the leaking and venting of a powerful group of greenhouse gases known as hydrofluorocarbons (HFCs) from refrigeration and air conditioning systems. The greenhouse gas impact of the move was equivalent to adding at least 625,000 new cars to the nation’s highways.

The Trump EPA said its goal was to save businesses $24 million a year, and a group of industry players including BP, Boeing and Koch Industries pushed hard for the repeal. But the manufacturers of alternative refrigerants, including Honeywell and Chemours, a DuPont spinoff, support a global phase-out of HFCs, as nations had agreed to in 2016 in an international pact reached in Kigali, Rwanda.

Biden’s effort to reinstate HFC regulation may get a boost from Congress, where bipartisan legislation to phase out the super-pollutants, co-sponsored by Sens. Tom Carper (D-Del.), and John Kennedy (R-La.) has 31 co-sponsors, including 16 Republicans. One provision of the bill is designed to make clear that EPA has the authority to regulate HFCs.

Landfill Gas

The Trump administration hasn’t disputed that there is a need to address air pollution from landfills. It has simply delayed doing anything about it. 

Municipal waste landfills not only are the nation’s third-largest source of methane pollution (behind the energy and agriculture industries), the landfills also emit hazardous pollutants like benzene and volatile organic compounds that lead to the formation of smog.

In its final year, the Obama administration approved a rule that required states to submit their plans for controlling landfill gas within nine months. But the Trump administration put off enforcement of the requirement, and after lawsuits by states and environmental groups, the administration last year approved a new rule that gave states three years to act. Late last year, U.S. District Judge Haywood Gilliam, an Obama-appointed federal judge in Northern California, accused the Trump administration of attempting to sidestep its previous orders and the law.

“This scenario presents a serious concern that in cases where a judgment is premised on an agency’s failure to meet deadlines, that agency can perpetually evade judicial review through amendment, even after a violation has been found,” Gilliam wrote.

But in October, the Trump administration got a reprieve, when a three-judge panel of the Ninth U.S. Circuit Court of Appeals, including two of Trump’s own appointees, reversed that ruling and said that the EPA could take more time to act on landfill gas. 

By reinstating the Obama rules, the Biden administration could cut greenhouse gas emissions by the equivalent of 46 million metric tons of carbon dioxide through 2035—the equivalent of closing down a dozen coal-fired power plants. But among the obstacles the Biden administration may face are courts like the Ninth Circuit and the U.S. Supreme Court, which may be inclined to extend the deregulatory legacy of Trump long after he leaves office.